Nebosh unit ic questions matrix - ans

1
NEBOSH UNIT-IC Questions Matrix
S# - UNIT -
S. #
Questions
Dates
Element IC1 General workplace issues
1-IC1 - 09 A sewage drain has collapsed and it is necessary to inspect the damage prior to its repair. The inspection requires entry into a
confined space 10 metres deep. OUTLINE the possible risks to those entering the sewer. Marks-10
- Restricted space for entry causing RISK of head injury, slip and trip, - Risk associated with the presence of gases and vapours
either toxic and / or flammable - Risk of oxygen deficiency which could lead asphyxiation and /or suffocation - Working on
slippery surface and the presence pipe, cables or tools which could result in falls - The possibility of the sudden ingress of
water with the danger of drowning - The presence of chemical or biological contaminants either on the surface water or in the
sludge deposited in the sewer with the risk of contracting illness such as weil’s disease. - Working in a restricted space with
low headroom which might lead to musculoskeletal injuries. - Thermal issues such as heat exhaustion that might occur when
working in high temperatures. - Contact with sharps with the resultant needle stick injuries - The ever present risk of
entrapment which could be caused by the collapse of the sewer
Jul 2012
Jan 2011
2-IC1-05 (a) OUTLINE the possible health and safety effects of inadequate workplace lighting. Marks-4
(b) OUTLINE the factors that should be considered to ensure that lighting in a workplace is adequate. Marks-16
a). Health effects includes: headache, visual fatigue , eye strain, blurred vision; -inadequate posture creating neck and backache to
get adequate VIEW for the tasks to be performed.
- Safety implications : likely to increase the incidents such as slip, trip and fall, striking with objects because of insufficient
lighting arrangements causing unidentified objects – wrong type of lightings which are creating stroboscopic effects - Human
error which may put others at risk
- Factors that should be considered: - The type of work to be taken - The amount of precision required and whether tasks
require general, local and/or localised lighting - The level of natural light available - The workplace layout giving attention to
the effects of screens, furniture or racking - the considerations of those objects casting shadows - The different types and level
of lightings required for stairs, corridors and outside security lights. - The level of lighting in adjacent areas in order to avoid the
effects of moving from a strongly lit area to one which is dimly lit and vice versa; - The individual needs of the employee
whether on account of age or disability - The possibility of glare on display screen - The colour and type of lighting fitted o
prevent stroboscopic effects - The need for emergency lighting particularly for fire escape routes - The need for portable
lighting when work has to be carried out in confined space - The ease of maintenance whether replacing spent bulbs or
cleaning the light fittings for probable - All glazed windows and skylights used for the lighting of workrooms shall, so far as is
practicable, be kept clean on both the inner and outer surfaces and free from obstruction,
OUTLINE the health and safety issues which should be identified during a lighting audit of a factory which includes production,
maintenance workshops and offices
Jan, 2012
Jan, 2009

2
3-IC1 - 01 A contractor is to repair the felt roofs of an office. OUTLINE the measures that should be taken to reduce the risks to workers and
members of the public. -10
1-Selection of contractor 2– Risk Assessments, SSW, method statements 3– Access and egress 4– Correct use of ladders 5– Edge
Protection / Fall protections 6 – Means for transporting tools, materials 7– Garbage chute – 8 Competent employees 9 –
Precautions while handling gas cylinders 10– Precautions for possible contacts with hazardous substances such as tar, asbestos
11– PPE (knee pad etc) 12 – Additional measures / protection of public: Barriers, Signs at ground, Arrangement for vehicle
movement – Restricted access / security, Traffic control / flagman.
Jan -09
4-IC1 -02 A rectangular warehouse building (40m x 100m ground area and 18m high) was constructed on a structural steel framework, with
a flat roof and coated steel walls. During a storm, the warehouse suffered a catastrophic failure of one of its long walls which in
turn caused the collapse of the roof and buckling of the other walls.
(a) OUTLINE the possible causes of this structural failure. -10
(b) OUTLINE the health and safety issues to be considered when planning the subsequent Demolition of the damaged
warehouse. -10
- Cause of failure – 1.Exceeded the designed wind loading due to adverse weather, - 2.Overloading of structure by excess
weight on roof due to accumulation of snow or rain water. – 3.Alteration to the structural members which had invalidated
the original design calculations. – 4.Collapsing or nearby excavations and tunneling operations creating instability – 5.
Vibrations caused by the volume of passing traffic 6. Wind variations which would result in fatigue. – 7. Poor workmanship -
Even superior quality materials, if used imperfectly, may not successfully serve the planned function, or be as durable as
designed. -8. Faulty Construction- occurs when inappropriate material is used for construction. Faults that result in structural
failures include bad welds, improper torque used on nuts and bolts, sand that is too salty for concrete, bad riveting and
inferior steel. -9.Bad Foundation - cause displacement which alters the stress distribution of the building so the construction
and design are changed and no longer meet the necessary specifications.
- Safety issues for demolition: 1-Selection of Demolition contractor (competency) 2– Risk Assessments, SSW, method
statements 3– Access and egress 4– Correct use of ladders 5– Edge protection / fall protections 6.Identifications / insulations
of buried services (EWG), 7. Inspection, examination and maintenance of plants / equipment 8 – Means for transporting
tools, materials 9– Garbage chute – 10 Competent employees 9 – Precautions while handling gas cylinders 10– Identification,
Precautions for possible contacts with hazardous substances such as lead paint, asbestos, 11. Protections of adjoining
property 12– PPE 13 – Additional measures / protection of public: Barriers, Signs at ground, Arrangement for vehicle
movement – Restricted access / security, Traffic control / flagman.
Jan,
2009, Jan
2007
SSW –
safe
system of
work
EWG –
electricit
y, water,
gas
5-IC1 -03 A company has been contracted to undertake maintenance work on the roof of a building, which is partly constructed of fragile
material.
a. IDENTIFY the characteristics of the fragile materials that may contribute the risk of falls through the roof. 5
b. OUTLINE the measures to be taken to reduce the risks to those involved in the roof work and those who may be affected
by it. 15
a / Characteristics: The age and condition of material; The type of material such as fiber board, asbestos or polycarbonate and
thickness; The sheet profile; The span between roof supports; The design of supporting structure such as the purlins; The
July 2008

3
condition of the fixings; The slippery nature of the surface and The fact that the fragile materials might well be hidden by deposit
of dirt, grass etc.
b/ 1-Selection of Demolition contractor (competency) 2– Risk Assessments,3. Consequent production of a method statement
detailing the SSW,
- 4. The SSW should be followed, which will include - Access and egress, access scaffolds, crawling board 5– Edge protection /
fall protections - harness with suitable anchorage 6. Identification and demarcation of areas of the roof containing fragile 7.
Demarcation can be done using barriers and signages 8- Suitable Cover can also be used to prevent fall through the fragile
areas 9- Provision of Safety nets or and air bags under the areas of the roof which contain fragile materials can provide
additional safeguards 10- Means / hoists for transporting tools, materials, equipment 11– Garbage chute – 10 Competent
employees 11– PPE 12 – Additional measures / protection of public: Barriers, Signs at ground, Arrangement for vehicle
movement – Restricted access / security, Traffic control / flagman
06-IC1 - 06 It is proposed to inspect, clean and repair the inside of a tank that is 6 metres in diameter and 10 metres high and which has
previously been used for storing leaded petrol.
OUTLINE the arrangements that should be considered in order to comply with the Confined Spaces legislation.
Or, OUTLINE the steps that should be considered in order to enter this confined space and to carry out the work safety.
The relevant specified risks in this case relate to fire and explosion, and loss of consciousness due to asphyxiation or high
temperatures, works at height.
A SSW is required for entering confined space, to comply with confined space legislation and to carry out work safely –
To develop a safe system of work a full RISK ASSESSMENT needs to be carried out considering the likelihood of
- Toxic effects of lead, - Flammable atmospheres from the previous contents of the tank - Air contamination from the
cleaning or repair methods used - The build-up of heat within the tank – hazard associated with Working at height -
Completion of the risk assessment would point to appropriate arrangements / preventive measures / precautions such as
- Initial Arrangements - The need to purge the tank with an inert gas, - The use of forced ventilation, - Atmospheric testing
before and during entry, and - The provision of PPE including air-fed breathing apparatus - The requirements for
electrical equipment (e.g. intrinsically safe, flameproof) and earthing arrangements – If heat were to be a foreseeable
problem, then consideration should be given to issues such as job rotation and fluid intake.
- The physical arrangements for working at height would need to be considered in terms of both prevention of falls from
height and, means of access and egress in the event of escape or rescue.
- Procedural arrangements would centre on the - Implementation of an entry permit - Limiting the number of people
working in the tank, - Communication with standby personnel and - Drawing up the emergency arrangements
- The emergency arrangements to be considered would include issues such as The provision and maintenance of cutting
equipment, - Tripod / Hoists, - Fire-fighting equipment, - PPE (e.g. breathing apparatus) - First-aid facilities including CPR
apparatus and Liaison with emergency services
Additionally, Arrangements should also be in place to ensure that all personnel involved in the operation have received
sufficient training in the work methods, the precautions needed and emergency procedures.
JUL 2008,
JUL 2005
SSW –
safe
system of
work
07-IC1 - 08 (a) GIVE the meaning of the term ‘confined space. Marks-2
(b) OUTLINE the factors that should be considered to ensure that emergency rescue arrangements for confined space work
Jul 2007,
Jul 2009

4
are suitable and sufficient. Marks-8
Confined spaces are defined as ‘any place . . . in which, by virtue of its enclosed nature, there arises a reasonably
foreseeable specified risk’ (i.e. of serious injury, drowning or asphyxiation).
Or any enclosed o partially enclosed place such as a chamber, tank etc or other similar space in which, by virtue of its
enclosed nature, there arises a reasonably foreseeable specified risk such as lack of oxygen or the possibility of drowning
in free flowing solids.
- Confined spaces include: Chambers, Tanks (sealed and open-top), Vessels, Furnaces, Ducts, Sewers, Manholes, Pits,
Flues, Excavations, Boilers, Reactors and Ovens.
- The risks identified and how an emergency rescue might take place and could include -
o The means provided for emergency access / egress,
o The equipment required e.g. Life lines, lifting equipment (Tripod / Hoist), air fed breathing apparatus,
o Methods for raising the alarm with others outside the confined space e.g. Radio, personal alarms etc, to initiate
rescue procedures
o The availability of first aid assistance until the arrival of professional medical help.
o Ensuring that there are persons present who are competent to undertake (CPR) resuscitation procedures,
o The number and competence of those who would be involved in the rescue operation.
o Precautions taken to protect rescuers from the risks to health and safety identified in the risk assessment
o Precautions taken in the event of fire such as the provision of fire extinguishers;
o Identification of plant which may need to be shut down during an emergency rescue and
o Means provided for contacting public emergency services and supplying them with relevant information.
o Training or refresher trainings for emergency personnel.
08-IC1 - 05 A vegetable packing plant employing 200 men and 60 women is about to open.
OUTLINE the specific welfare arrangements that need to be provided before the plant opens. Marks-10 / 20
Sanitary Conveniences: Sufficient numbers of well-lit and ventilated sanitary conveniences
- Maintained in a clean and tidy condition. - Provision of Toilet paper, a coat hook - Separate rooms or blocks for men
and women (or capable of being locked from inside if the sanitary conveniences in the same room).
Washing Facilities: Sufficient numbers of well-lit and ventilated washing facilities - Changing rooms and Showers to be provided
and maintained in a clean, tidy condition - Supply of hot and cold or warm running water, - Soap and a means of
drying
Drinking Water: An adequate supply of drinking water with cups - Readily accessible, located away from sources of contamination
- Marked conspicuously
Accommodation for Clothing / Facilities for Changing Clothing: Clothing accommodation with a hook/peg located in a clean,
warm, dry, ventilated place should be provided for each worker to hang their own clothes if not worn during the
working day.
- Changing facilities separate for men and women and contain means of drying wet clothing and separate storage of
contaminated clothing - Decontamination facilities with shower and a clear division between clean and dirty areas
JUL 2010
JUL 2008

5
Facilities for Rest and to Eat Meals: Rest and eating facilities - Readily accessible, contain adequate seating and tables
- Be maintained in a clean condition - Arrangement for preparing and heating food and for boiling water
- Means or procedure for preventing contamination of the area where food and drinks are taken
- Rest rooms and areas should be arranged to ensure that non-smokers do not have to be exposed to smokers -
separate rooms/areas, prohibition. - Adequate Facilities for nursing mothers and pregnant women to rest.
First aid facilities including trained personnel taking into account the number of persons employed and the
proximity of emergency services
09-IC1-12 OUTLINE the main design features of a workplace designed to reduce the risk of injury associated with INTERNAL
TRANSPORT.
OR. OUTLINE the main design features of a ware housing operation design to reduce the risk of injuries associated
with INTERNAL TRANSPORT.
Features that could have been included are: -
1. SEGREGATION of vehicles and pedestrians. - Separate pedestrian access and egress; Inclusion of passing places and
refuges; barriers, guard rails, raised walkways and curbs to protect pedestrians, and clearly marked crossing places.
2. TRAFFIC ROUTE should be sufficient width, on stable leveled ground, Suitable road surfaces; Design of layout to avoid
sharp bends and blind corners and to avoid the need to reverse, through use of one ways systems. Provision Convex
mirrors on blind corners to improve visibility; Route should have speed limit, speed retarder and suitable road marking.
Provisions of hazard signs – to warn blind corners, crossings, low-head rooms or width restrictions.
All the routes should be well lit – including color balance, avoidance of glare in the transitions area between inside and
outside the buildings, -
3. VEHICLE Movements should be carried out in safe area with sufficient space and operatives provided with high visibility
clothings. Vehicle should be fitted with reverse alarm and flashing beacon lights. Designated parking spaces to avoid
congestion.
4. PROCEDURAL ARRANGEMENTS – control of visitors in the premises, training and certification for the drivers, prevention
of unauthorized use of vehicles; training and information to pedestrians on the risks, selection for suitability and
maintenance of vehicles , monitoring and reporting the defects, maintenance of traffic routes, enforcement of speed
limits and the use of banksman will further reduce the risks.
Protection of racking or other vulnerable items, to reduce the likelihood of items falling and to avoid from collision with moving
vehicles. Provision of suitable and sufficient
Jan 2008,
Jan 2010
Q of
Me.IC07.
01
END OF UNIT 1

6
Element IC2 Principles of fire and explosion
10-IC2-04
Compartmentation in buildings consists of fire resisting doors, walls, floors, ceilings and windows. Window frames are
potentially a weak point in this fire resistance.
(a) OUTLINE how window frames made with the following materials might behave in a fire:
(i) wood; Marks-3 ; (ii)metal; Marks-3; (iii)plastic. Marks-3
(b) IDENTIFY which of these window frame materials gives the best overall fire resistance. Mark-1
Jan 2012
July 2009
11-IC2-07 You have been asked to investigate a boiler explosion at one of your company’s sites. The maintenance manager has
drawn you a sketch showing the position of the water column isolating valves at the time of the explosion (see below
diagram will be given).
(a) Describe the chain of events that could have led to an explosion due to the water column valve being closed. 6
(b) Other than the safety feature on the water column, identify FOUR other safety features that you would
expect to find on the boiler. Marks-4
Jan 2012
July 2010
12-IC2-02 In relation to dust explosions:
(a) Outline the conditions that must be present for a primary dust explosion to occur; Marks-4
(b) Outline the additional conditions necessary for secondary explosions to occur; Marks-4
(c) IDENTIFY FOUR factors that may affect the reliability of a nitrogen inerting system used in a powdered aluminium process;
Marks-4
(d) IDENTIFY the design features that would minimise the likelihood and effect of a dust explosion. Marks-8
a. Conditions that must be present for a primary dust explosion: - The dust must be combustible – the concentration of
dust must fall within the explosive limits – The ignition source must come in the contact with the dust – Sufficient
Oxygen should be present in the atmosphere to sustain the combustion. (the dust must be capable of becoming air
born and mixing with air, the particle size must be capable of propagating flame)
b. Conditions necessary for Secondary Explosions: Dislodgement / Force removal of accumulated dust from horizontal
surface within the affected building by the pressure wave and consequent air turbulence.
Ignition: When lying dust is distributed by the primary explosion and form a second dust cloud , the dust cloud then can
be ignited – By the combustion of products from primary explosion - By the heat released through the primary
explosion - Any other source of ignition within the area with sufficient heat energy
c. Factors that may affect the reliability of a nitrogen inerting system: The number and location of sampling points - The
type and calibration of the sensors - The presence of containments in the system which could interfere with readings
Inadequate provision of a safe means of shut down if oxygen levels are too high - The adequacy of supply of inerting gas -
The number of locations where air can enter the plant or process and the reliability of the electronic control system
d. The design features that would minimise the likelihood and effect of a dust explosion
Jul 2012
Jul 2011
Jan 2009

7
- The initial design of ducting and equipment to withstand the effects of an explosion, - Ensuring that the ducting was
dust tight, - Providing local exhaust ventilation at point of transfer, - Installing explosion relief or suppression systems
together with systems for suppressing fire, - Using screw conveyors instead of pneumatic systems for moving materials
Providing a magnetic extraction system for removing metal from product fed to the plant, - Interlocking equipment to
prevent overfilling of vessels and over pressurization, - Using instrument systems with integral emergency shutdown -
Using intrinsically safe electrical equipment and bonding all metal work to earth, - Preventing dust build up in the plant
by the use of sloping surfaces and introducing a mechanised system for humidification of the air.
13-IC2-01 A diesel engine is being used to power a machine in a potentially flammable atmosphere.
(a) IDENTIFY the sources of ignition from the diesel engine. Marks-4
(b) OUTLINE the protection that should be applied to the engine to minimize the risk of an explosion. Marks-6
OR, (a) Identify the sources of ignition from a typical diesel-engined fork-lift truck.
(b) Outline the protection that should be provided on such a truck in order to minimise the risk of explosion when it is required to
work in a potentially flammable atmosphere.
a. Source of ignition: Flame and sparks from the exhaust and inlet system – sparks arising of Trucks electrical system – sparks
arises to static electricity – through over speeding / over loading – from frictions / surface temperature – Fuel get hotter than
Flash point
b. Precautionary measures: 1. Fitting of spark. Flame arrestors to prevent flash back to the atmosphere, - 2. Inspect, test and
maintenance of electrical joints on diesel engine systems – 3. Electrical equipment on the truck should be suitable for zones 1 and
2 4. Electrical starters wired to plug and socket in a safe area. 6. Inspect, test and maintain cooling systems on diesel engine
systems – 7. The use of a water jacket on the exhaust system together with thermal sensors and air cooling for ‘hot spots’ would
provide additional protection. 8. Mechanical alternatives (e.g. fuel gauge) should be fitted where possible. 9. The use of
electrically conducting materials for parts such as tyres and drive belts would reduce static build up
10 The engine and exhaust system should be designed in such manner that their surface temperature are always below the flash
point of flammable substances – diesel etc.
Jan 2011
Jan
2007N
A process plant stores and use large quantities of a substance that has the potential for giving rise to an explosive atmosphere.
OUTLINE a range of control measure which will minimize the possibilities of explosion. 10 marks
- Avoid / minimize release by using enclosed systems and maintenance of plant to prevent loss of containment.
- Control release at source by using early detection and auto shut off systems
- Prevent formation of an explosive environment by using ventilation or inert atmosphere
- In case of release – ensure that it is suitably contained, safely collected and removed to a safe place, or otherwise
contained safe by use of bunding.
- Emergency arrangement – for tackling major spillage.
- Avoid ignition source by ensuring that areas are zoned, and flame proof electrical equipment are selected and used.
a. Build of static charge is obvious – therefore all the storage tanks, pump needs to be properly grounded,
suitable clothing, Safety shoes (anti-static) to be worn by the operatives.
b. No Smoking policy must be adhered and PERMIT to Work system to be followed.

8
- Avoid adverse conditions by protection of storage vessels against weather and vehicle
- Finally ensure segregation of incompatible dangerous substances.
14-IC2-03 OUTLINE the principles of a vapour cloud explosion AND give an example of a major incident associated with a vapour cloud
explosion. -8
OUTLINE the effects of a vapour cloud explosion. Marks-2
Or With examples of actual incidents, describe the principles and effects of a vapour cloud explosion.
Principle: A vapour cloud explosion may be confined (in a tank, vessels or building etc) or un confined when released in large
quantity in the air.
- For Explosion to occur – The presence of flammable vapour concentration above the lover explosive limits, the
source of ignition such as a spark, is required with energy greater than the minimum ignition energy.
- The (unconfined) vapour cloud can travel large distances before igniting / explosion and Cloud dispersal may bring
the mixture below the lower exposure limit depending on the condition
- The vapour cloud may be produced by a rapid release of liquefied gas following vessel rupture due to overpressure
and subsequent vaporisation. It may also be produced by an uncontrolled build-up of vapour above the lower
explosion limit inside a vessel.
The effects of Vapor cloud explosion: Overpressure, Fire, explosion, and thermal effects and debris over a wide area from
confined vapour cloud explosion.
In confined Explosion – vessel or containment rapture may occur resulting in a rapid release of liquefied gas. Example - The
explosion in process vessels at the Hickson and Welch chemical plant
In unconfined explosion – damage to people and property may be caused by pressure wave and thermal radiation –
Example - the explosion in flixborough
July 2010
Jan, 2008
With examples of actual incidents, describe the principles and effects of a BLEVE – boiling liquid expanding vapour
explosions.
Principle of BLEVE: A BELEVE (boiling liquid expanding vapor explosion) is initiated by an external heat source applied to a
container of liquid. A drum of petrol on a bonefire is a simple example. The vessels loses containment, by rapture or pressure
release valve opening, which vents the vapour with subsequent ignition. There is rapid spread of boiling liquid and vapour and a
fire ball ensues.
Effects: The explosion generates debris and missiles from the vessels and also a thermal radiation shockwave. The explosion of
tanker carrying a flammable substance at the san carlos de la rapita Spanish campsite is a notable example. LPG cylinders in fire
situation are a typical example.
July 2012

9
15-IC2-R The investigation of an accident at a food processor handling corn starch products concluded that the explosion had taken place in
two stages, a preliminary explosion followed by a more severe secondary explosion.
a) IDENTIFY the principles underlying the control measures that may be needed to prevent or minimize the effects of such
an accident.
b) For each of principles identified, suggest control measures which are based upon the principle.
a. Principles needed to prevent or minimize the effects of such an accident.
- Elimination of sources of ignition; Limitation of dust cloud generation and Minimizing harm by controlling explosion.
b. Control measures to eliminate ignition sources are:
- To ensure electrically conducting safety footwear is worn; - The use of non sparking tools and correctly rated ex electrical
equipment; - No smoking; - Prevention of equipment hot spots; - Magnetic extraction of rogue ferrous metals;
- Electrical bonding and earthing; - Carrying out an assessment to meet the requirements of relevant legislation (e.g. DSEAR
The Dangerous Substances and Explosive Atmospheres Regulations 2002 of the UK) and; - Correct zoning of areas.
Dust cloud suppression could be achieved by:
- Damping down combined with the use of a pressure monitoring device; - Having LEV at point of transfer;
- Use of an interlock to prevent overfilling of silo; - Good housekeeping to prevent dust build up and
- Ensuring all ducting is dust tight.
Controlling explosion could be by use of: Equipment that is able to withstand explosion; - Explosion relief venting and explosion
panels; - Ensuring building integrity.
ETA, RRC
16-IC2-05 In 1974 a plant in Flixborough, United Kingdom, producing highly flammable pressurized gas developed a leak on the fifth of six
reactors. In order to continue production the fifth reactor was removed from service and a bypass assembly then installed
between the fourth and sixth reactor. The bypass assembly subsequently ruptured and an UNCONFINED VAPOUR CLOUD
EXPLOSION followed.
(a) DESCRIBE the mechanism for an unconfined vapour cloud explosion. Marks-3
(b) OUTLINE the technical failings that contributed to this major accident. Marks-7
a. There were 6 numbers of reactors (R1 to R6), R5 got some repair works. Therefore to get the production continues it was
decided to make some bypass pipe between R4 and R6. This decision initiated the trouble- and given chance to
uncontrolled release of gas, cyclohexane, from that temporary pipeline which was used to bypass a reactor R5 taken out
for service for repair.
- On release the gas formed a flammable mixture in air within the explosive limits.
- The large vapour cloud either immediately came across a source of energy or
- Travel some distance to find an ignition source where it was quickly detonated causing rapid flame propagation.
b. Probable technical failure:
-The absence of professionally qualified mechanical engineer / work manager who could oversee the modification
between R4 and R5.
- A plant modification had been done without assessment of the potential consequences of its installation.
- The constructed assembly was of unknown strength: Pneumatic test were carried out for leak testing and not in order
to assess the strength of the assembly
- Only limited calculation were undertaken on the integrity of the bypass line: The flow and pressure calculation were
taken on straight pipe line not the fitted by pass dog leg pipe, No calculation had been taken for the dog leg shaped
Jul 2009

10
assembly to withstand the likely strains
- No reference were made to any recognized standards
- No drawing was proposed for the assembly
- No reference were taken from the designers’ guidelines so that the bellows were used out of line without adequate
support. - and insufficient support were provided for the newly installed pipework
17-IC2-05 In November 1984 the San Juanico gas storage facility near Mexico City exploded with catastrophic consequences.
(a) OUTLINE the circumstances of the disaster. Marks-8
(b) OUTLINE how a Boiling Liquid Expanding Vapour Cloud Explosion (BLEVE) occurs with a gas storage vessel constructed of
metal. Marks-8
(c) OUTLINE the immediate rescue and restoration measures that took place. Marks-4
a. Circumstances of the Disaster: At approximately 5:35 hours, 19 NOV 1984 a major fire and a series of catastrophic explosions
occurred at PEMEX LPG terminal at San Juanico Near Maxico city. As a result some 5000 people died and 6000-7000 people
suffered from severe burn and the LPG terminal was completely destroyed.
- The terminal was supplied with LPG from 3 refineries on daily basis, The terminal was being filled from a refinery 400 km
away. As on the previous day it had become almost empty. Two large sphere and 48 cylindrical vessels were filled upto 90%
and 4 smaller sphere to 50% capacity.
- A drop in pressure was observed in control room but the operator was unable to know the cause of such pressure drop,
actually an 8 inch pipe between a sphere and a series of cylinders had raptured causing the release of LPG. This uncontrolled
release was continued for 5-10 minutes. And the gas was accumulated around the surrounding tanks measuring 150m to
200m and 2m high, which was drifted to flare stack and exploded.
- This resulted in numbers of ground fire. Also a series of BLEVE occurred four of SIX spheres and numbers of cylindrical
vessels. Injuries were caused by radiated heat and burning droplets of LPG.
b. BLEVE with a gas storage vessel made of metal: The gas such as butane and propane are stored under pressure in the liquid
form in the metal storage vessels. When the valve to the vessels is open, the resulting drop in pressure restores the LPG in
gaseous state.
- BOILING LIQUID: If the vessels involve the fire, the liquid gas boils and the content of vessels will revert to gaseous state with
a resulting increase in pressure inside the vessels.
- EXPANDING: The pressure relief valve opens and vaporized liquid escapes causing liquid level in vessel dropped. The less
liquid cannot absorb the heat and then the metal start to deform and weaken, ultimately rapture as result of ductile failure.
- Vapour Cloud Explosion: The remaining contents burn out and vaporize under atmospheric pressure sending debris from
the vessels to the surroundings area. The vapor cloud which includes the LPG droplets find the ignition source and EXPLODES.
C. Following the explosion, some 4000 emergency workers were drafted into the terminal. The primary measures were concerned
with the temporary evacuation and transport of the injured. Further measures were aimed at the prevention of an epidemic, the
removal of debris and identification of those who had been killed. Fires were extinguished, temporary shelters provided and
arrangements made for the mass internment of those who died.
Jan 2010
July 2009
18-IC2-08 In 2004 at ICL Plastics Glasgow nine people were killed and 45 seriously injured by an explosion in the unventilated basement of a
building. Liquid Petroleum Gas (LPG) had leaked from a crack in a corroded unprotected underground pipeline that had been laid
35 years earlier. The LPG leak had migrated into the building Describe how corrosion occurs in buried LPG metal pipework.
Marks-6 Outline how buried LPG metal pipework can be protected against corrosion. Marks-4
Jul 2010

11
(a) Excluding corrosion protection, outline additional factors to consider in preventing a recurrence of an explosion in similar
LPG pipework installations. Marks-10
a. The corrosion in the buried LPG pipework is an electro-chemical process which is caused due to
- Presence of moisture together with the possibility of containments in the soil, - The presence of corrosion cells such as
pitting of the metal pipework, - The roles played by anode, cathode and electrolytes, - The liberation and transfer of
electrons
b. Protection against corrosion by - Wrapping with protective tape, Coating it with bitumen, Galvanizing, Sleeving with a dry
envelop, Providing cathodic protection or a sacrificial anode
c. Identification and prioritizing at risk installations such as
o Those where hazardous features arise from the design and layout of the building;
o where there are inherent hazards in the layout or the condition of installation and pipework such as the presence of
unventilated voids
o those which are least well maintained or located in the most corrosive soils
o The older installations and the extent of their existing protection.
o For inspection and maintenance of the systems, plan and drawings will be required, though it must be acknowledged
that disturbing the pipe work may increase the risk of leaks.
o There will also be a need for the introduction of a systematic programme of replacement of metallic pipes with
polypropylene pipe and the condition of at risk systems will need to be monitored pending the replacement
19-IC2.10
new
Many household aerosol canisters contain propellants that are a mixture of highly flammable materials such as iso-propane and
iso-butane. These canisters are used for multiple purposes including cleaning products, furniture polishes, cosmetics, deodorants,
(a) DESCRIBE how a fire and explosion may occur when large quantities of these canisters are stored in a commercial
warehouse. Marks-5
(b) OUTLINE the fire precautions that could be taken to limit the spread of any resulting fire and explosion in such a
warehouse. Marks-5
a.
The canisters may have suffered damage for example to the valve or body of the canister, leading to loss of containment and the
formation of flammable vapours which if between the upper and lower flammable limits can be ignited by a heat source, perhaps
a nearby fire or hot work and even by direct sunlight.
The canisters may then be propelled from their original position as projectiles as the radiant heat from the initial fire causes
boiling of the contents of adjacent canisters. This causes the release and ignition of additional vapour sources resulting in multiple
BLEVEs.
a) b. Fire precautions that can be taken to limit the spread of any resulting fire and explosion in a similar type of warehouse include
 The segregation of the canisters from other flammable products;
 The separation of high flammability canisters by physical barriers;
 Using compartmentalization within the warehouse with fire resistant partitions;
 The provision of containment cages to prevent projectiles;
 The installation of automatic fire detection and alarm systems;
 The use of automatic extinguishing systems and venting and explosion reliefs.
 The canisters should be fitted with pressure relief valves.
July 2011

12
END OF UNIT 2
Element IC3 Workplace fire risk assessment
20-IC3-02 OUTLINE the issues that should be included in a fire safety training session for workers. Marks-10 Presentation on training
- The consequences of fire such as the effects of smoke inhalation on those involved : - The potential costs to the business
- The principles of the fire triangle; Fire Types / Classification
- The basic elements of fire prevention such as the storage of flammable materials, good housekeeping and the need to
prevent the accumulation of rubbish;
- The action to be taken on discovering fire such as RACE – raising alarm, alerting concerned/ procedure for calling fire
services, and the action to be taken by personnel on hearing fire alarm (confined fire, evacuate)
- The procedure for calling the fire service; - The action to be taken by personnel on hearing the alarm;
- The location and use of firefighting equipment with practical training for selected employees
- The escape routes and exits from the premises together with the assembly points
- The head counts / roll call that would have to be carried out
- The arrangements for the evacuation of people with disabilities, assisting visitors and members of the public;
- The identity and role of fire wardens and marshals; - The importance of fire evacuation practices and drills and
- Issues directly concerned with personal behavior such as refraining from re-entering the building after evacuation until
instructed to do so
July 2012
Jan, 2010
Jan, 2008
21-IC3-05 A factory manufactures upholstery using fabrics and plastic pellets. These raw materials are delivered to a warehouse.
The fabrics and plastic pellets are machined to form furniture coverings and cushions. The finished product is then stored
in a dispatch warehouse prior to distribution. The movement of goods around the premises is carried out by Liquid Petroleum
Gas (LPG) fuelled forklift trucks. The company is located on the outskirts of a small town and employs 230 people.
OUTLINE the range of factors that must be addressed to ensure an on-site Fire Risk Assessment is made for the premises. 20
Fuel (LPG, flammable cover, untreated fillings, material of construction )– Ignition source(electricity, smoking, hot work, arson) – People issues
(no of person to be evacuated, visitors, disabled employees) – Preventive actions (Compartmentalization, separate store for LPG-with fixed
sprinkler, use of fire resistance cover materials, minimizing amount of combustibles ) – Mitigation actions (Detection – Suppression – Alarm
system,)– Means of access (clear, fire doors, travel distance, sign and emergency light) – Assembly points.
Jan 2012
July 2009
22-IC3-01
A four-storey general Hospital is to be refurbished and upgraded on a floor by floor basis, with three floors of the hospital
remaining operational at all times.
OUTLINE the factors to be considered when writing fire evacuation procedures for the parts of the hospital that remain
operational during the project. Marks-10
- The various sections and activities of hospital – such as ward, operation theater, ICU, offices, outpatient, visitors etc.
- The number of patient and staff to be evacuated
- The mobility of patient including their health condition and age
- Identifying the temporary procedure and means of route to evacuate the be ridden patient
- Review ing the current evacuation procedure and considering the escape routes, assembly points and fire brigade access
- Ensuring that the escape routes and assembly points are clear from construction materials
- The provision of emergency lighting and appropriate sign ages
- Considering of two stage evacuation procedure
Jan, 2009

13
- Considering the possibility of emergency zoning and classification for example – full or partial evacuation, area wise
nearest assembly point as per zone (burz khalifa)
- Assessing the effect of construction work on the existing fire detection system, Alarm and firefighting equipment and the
possibilities that might increase the risk of fire.
- Assessing the need for first aid provision and firefighting and fire protection provisions.
- Adequate training for the existing hospital employees as well as the construction employees.
23-IC3-08 OUTLINE the issues that need to be addressed when planning a fire evacuation procedure for an office building occupied by a
number of different companies. Your answer should include examples where appropriate. ERP for Al thurath
1. Identification of emergency scenario – such as Fire, Earthquake, Riot etc.
2. Selection for employees to form an emergency control team – Described responsibilities, - Adequate training to Fire
warden , Security and other members
3. Means of Raising Alarm and Alerting Building occupants
4. Liaison with emergency services – such as their access requirements and appropriate locations of assembly areas.
5. Considering the health situation of occupants and member of visitors in the building , their sensory disabilities and
physical disabilities etc. to be considered
6. Physical Measures – Such as travel distance, number of access, Emergency lights, Exit signs, Evacuation routes etc.
7. Firefighting Equipment – Alarm, Smoke detector, heat detector, Suitable Fire extinguishing media (DCP, CO2, sprinkler
system, Hose reel etc.)
8. First Aid measures – First aid providers, first aid medicines, first aid equipment, CPR arrangements etc.
9. Emergency Rescue Equipment – Stretcher, Wheel chair etc.
10. Providing door marshals to prevent entry or re-entry to the store.
11. Security considerations such as minimizing the opportunity for theft would also be an issue.
12. Assembly points - Well defined, Displayed and communicated
13. The procedure, once drawn up, would need to be summarized on prominently displayed fire notices and tested with
regular fire drills.
ETA 27
24-IC3-02 A large shopping complex is arranged on four levels, with retail outlets on basement, ground floor and first floor levels and with
restaurant facilities on the top level. Movement between floors is achieved by the use of escalators, lift and stair. LULU center
i. Review, with valid reasoning, the systems that might be installed in the building to detect, suppress and warn of fire
ii. Describe the design features of the building to assist in the safe evacuation of persons in the event of fire.
i. Fire Detection System: might include Heat sensors in the restaurant areas, Smoke Detectors in general areas, Flame
Sensors in furnishing areas and CCTV – closed circuit television to monitor throughout.
Fire Suppression System: Sprinkler system, Provision fire hose reel, Portable Fire Extinguishers, Fire blankets in kitchen
Fire Alarm System: could be automatically triggered on detection of FIRE, but controlled manual activation might be
preferable to avoid panic situation. The alarm itself could be bells, sirens or verbal instructions over public addressing
system. Consideration might be taken for zoning and a staged alarm system.
ii. Design features of the building to assist in the safe evacuation of persons in the event of fire
RRC – IC
3 –LA-Q
1

14
- Escape routes – distance / requirements: The building design should primarily take the consideration of escape route
distances and travel distances
- Fire resistance of materials / Fire doors: Design features for evacuation should include escape route requirements
such as fire resistance of materials used, and protection against fire and smoke using fire doors in staircases and
corridors
- Maximum numbers / location of persons on the premises: Account must be taken to the expected maximum number
of the persons and their locations , such as higher concentration of persons in the dining areas – food court
- Number and width of stair case: other design feature should include the numbers and width of staircases
- Protected areas / Control of use of lifts : The need of protected areas and control of use of lifts, particularly for
mobility impaired persons and fire fighters
- Compartmentalization: would need to be considered, although difficult in common areas in an open plan store, and
- Protection of dust and voids: Also protection of ducts and voids to minimize and content the spread of smoke
- Smoke extraction: through automatic roof vents and sprinklers and auto shut off of the ventilation system in the
event of fire
- Signage / Emergency lighting: Finally signages would need to be provided and emergency lighting where appropriate.
25-IC3-03 (a) In relation to automatic fire detection and alarm systems, outline the basic principle AND operation of:
(i) Heat detectors; Marks-4
(ii) Smoke detectors. Marks-4
(b) IDENTIFY the circumstances in which EACH type of detector would be inappropriate. Marks-2
i) Heat Detector: detects a rise in temperature two types of heat detectors –
a. Self Resetting – (Fixed rate heat detector and rate of rise type)
b. Fusible
- Fixed rate heat detectors operate when a fixed, set, temperature is reached, /
Has a sensing element fixed at particular temp. By means of a thermocouple or similar arrangement, it detects when
the predetermined temperatures is reached
- A rate of rise heat detectors operate when either the temperature rises at more than a certain rate, or when its fixed
temperature is reached / detects abnormally fast temperature rises by means of electronic resistors or thermistors
ii) Smoke detector:
- Smoke detectors are of two main types: ionisation and optical (or photoelectric).
- The ionisation type uses a small radioactive source, smoke passing into the detector is ionised, which is then detected
by an electronic sensor.
The detector reacts and sound alarm when the pre-set flow of electric current is reduced as smoke enters the detector.
- The optical type of detectors are designed to operate by either
- The absorption (obscuration) of light ray by smoke particles passing through them
- The scattering (Refraction) of light from an optical ray.
July 2011
July 2008

15
26-IC3-04 A conference center is planning to extend its existing building to incorporate childcare facilities on the ground floor and additional
conference rooms to hire out to local businesses on the upper floors.
OUTLINE the range of factors that would need to be reviewed following completion of the planned work to enable the company’s
fire risk assessment to be updated. Marks-20 DOHA Mall Fire case
…relate to The Planning and Construction phase: The design of the extension need to be addressed, - The material used for the
constructions, - Competent advise need to be obtained from the Fire Authority / civil defence, - And the means of access should
be remain clear from any obstructions and maintained at all the time.
On completion of the planned extension the additional risk factors would arises from the additional users such as:
- The small children, - Worried parents in case of fire, - The extra persons on premises attending the events in
conference areas, - The possibility that the delegates can be under influence of alcohol, - The allowance of smoking by
the delegate in such areas.
The above added risk factors would call for additional precautions such as
- Escape routes
- Procedures and conducting fire drills for children and delegates
- Extension to the existing alarm system
- Additional firefighting equipment, Emergency lightings, notices and signage
- Requirements of additional fire marshal experience in handling children in event of fire for evacuation
- Train employees in revised procedures
July 2007
27-IC3-06 During a Fire Drill Exercise at a large multi-storey office premises, the majority of the occupants evacuated the building in less
than three minutes. However, all of the people based in one area of the building failed to leave the building until a further four
minutes had elapsed. Fortune tower Fire incident
(a) OUTLINE factors that may have contributed to the delay in evacuation. Marks-15
(b) OUTLINE reasons for conducting regular fire drills in workplaces. Marks-5
a.
Fire Alarm: Fire Alarm too quit due to low volume; - number of fire alarm are insufficient; - Alarm may sound similar to other
alarming system creating confusion among people; - Alarm may be inactive due to maintenance work; - signal of alarm may be
weaken due to wall and doors or other obstruction.
Design of buildings: inadequate escape routes which are greater than recommended travel distance; - too complex to traverse ; -
too narrow slowing down the evacuation; less numbers of access comparing to strength of occupants; even blocked and locked;
inadequate lighting or no emergency lighting in the escape routes; incorrect signs showing emergency exits;
Deficiency in existing Evacuation procedure: FEP too difficult and complex to understand; - - the procedure may not be
communicated adequately; -no or insufficient instructions for staff mentioned in the procedure; - actions / responsibilities are
not well communicated; - fire marshal duties may not be well defined; - inadequate number of fire marshal deputed; -
insufficient training / drills conducted for the occupants of the building.
Execution / Compliance of Procedure: possible noncompliance of procedure during actual exercise ; - Delay in response to the
alarm by finishing work, finishing telephone call, by shutting of PC, gathering their belonging or may be investigating why alarm
sounded; No response at all Assuming the Alarm as FALSE alarm or a Drill.
Human factors: hearing disabilities; physical disabilities; general apathy; lack of will to participate; lack of familiarity with the
July 2010

16
layout of the building.
b. REASONS FOR REGULAR FIRE DRILLS: Quick evacuation; - Familiarity with procedure; - familiarity with evacuation routes,
Alarm, assembly points and DO’s and Don’ts in case of such situations; - legal compliances; - Insurance requirements; -
identification of troubles / defects to find out the scope for improvements; - Amendments in procedure to suit the
requirements maintaining its efficiency and suitability.
28-IC3-07
21a-IC3-02
19-IC3-01
For a large supermarket with restaurant facilities:
a) OUTLINE the automatic fire protection systems that should be in place; Marks-6
b) OUTLINE the factors to be considered when developing a safe means of escape for the supermarket. Marks-14
a) Fire Detection System: might include Heat sensors in the restaurant areas, Smoke Detectors in general areas, Flame Sensors
in furnishing areas and CCTV – closed circuit television to monitor throughout.
Fire Suppression System: Sprinkler system, Provision fire hose reel, Portable Fire Extinguishers, Fire blankets in kitchen
Fire Alarm System: could be automatically triggered on detection of FIRE, but controlled manual activation might be preferable
to avoid panic situation. The alarm itself could be bells, sirens or verbal instructions over public addressing system.
Consideration might be taken for zoning and a staged alarm system. Automatic Fire service calls out through auto dialer or
similar techniques.
b) Factors to be considered when developing a safe means of escape for the supermarket.
 The possible number of employees and visitors to be evacuated
 The type of person such as their sensory disabilities and physical disabilities and age (old age, child) etc. to be considered
 Means of Alerting and evacuating people through Public address system
 The distance of fire evacuation routes; and the numbers of such routes
 Ensuring that the escape routes and assembly points are clear from any obstructions.
 The provision of emergency lighting and appropriate sign ages for demarking the exit routes from super market and
restaurants, being sufficiently separated to avoid confusion
 Assembly points - Well defined, Displayed and communicated and always free from any obstructions
 Liaison with emergency services – such as their access requirements; without obstructing assembly areas and access to
the buildings
 The Appointment of trained Fire Marshals who can ensure clear escape routes and trained in evacuating people in safe
manner.
 Providing door marshals to prevent entry or re-entry to the store.
 Security considerations such as minimizing the opportunity for theft / vandalism/sabotage.
 The procedure, once drawn up, would need to be summarized on prominently displayed fire notices and tested with
regular fire drills.
Jan, 2011
29-IC3-09 OUTLINE the design features of a building intended to control the spread of fire and smoke.
 Fire resistance of materials: Design features to control the spread of fire should include escape route requirements such as
o fire resistance of materials used in the construction of walls, floors and
o Provision for Fire protection (insulation) for structural steel works – ERCO edible oil factory
o The treatment of timbers such as fire rated / retardant
ETA 24

17
 Protection against fire and smoke using fire doors in staircases and corridors
o Fire resistance closures at stairways and lift shafts
o Compartmentalization: would need to be considered, although difficult in common areas in an open plan store, and
o Fitting doors with intumescent stripes
 Protection of dust and voids: Also protection of ducts and voids (in roofs and ceilings) to minimize and content the spread of
smoke; Fire dampers and breaks in ducting
 Smoke extraction: through automatic roof vents and sprinklers and auto shut off of the ventilation system in the event of fire.
30-IC3-10 The owners of a large distribution warehouse business have secured a contract from a stationery manufacturer. Their insurers
have recommended that the proposed storage facility is sprinkler protected.
OUTLINE the design factors to be considered in providing an adequate sprinkler system for the facility.
 Arrangement for testing the system
 The means of activating the system (frangible bulbs or detector activated);
 Linking of the sprinkler to the fire alarms
 The need for a voting system to reduce the likelihood of false activation
 Protection of electrical system in the warehouse
 The capacity of water required, ; - The existence of an adequate and assured water supply and
 The provision of fire water runoff
 The availability of an alternative if this was to fail for any reason.
 The design of the pumping system would also be important with a diesel back up if the decision was taken to install
electrically operated pumps.
 The area to be covered and the presence of other combustibles apart from the stationery;
 The fire loading of the area to be protected
 Fire stopping for sprinklers and pipeworks passing through compartmentalization
 The spray pattern required; Will the system be dry or wet
 The height of the storage racks and their distance from the sprinkler heads;
ETA 26,
Jan
2007N
31-IC3-11 As Health, Safety and Environment Manager at a hazardous installation you are responsible for emergency planning. The site is
regulated under the International Labour Organisation (ILO) Code of Practice ‘Prevention of Major Industrial Accidents’ 1991.
(a) In the event of an uncontrolled release OUTLINE the need for emergency response measures. Marks-4
(b) OUTLINE the general emergency planning measures that should be taken by the ‘competent authorities’ in association
with the works management of the installation. Marks-6
The event of an uncontrolled release, there would be
- a need for emergency planning to localise the release and if possible, contain it; and to minimise the harmful effects of
the release on people, property and the environment both inside and outside the installation by the use of safety
systems, alarm systems and the emergency services.
- Clear and well defined plans should be made available for quick and effective use and
- Where emergency equipment and manpower are limited, provision should be made for mutual assistance between
neighboring industrial activities.
July 2011
July,
2009

18
General emergency planning measures that should be taken by the competent authorities include
- The need: to establish arrangements for an on-site emergency plan which should be drawn up by the management of
the installation;
- To establish arrangements for an off-site emergency plan to be drawn up by the competent authority in conjunction
with the installation’s management, which should be prepared following consultation with various bodies such as the
fire and police authorities and the hospital and ambulance services and which should be consistent with the on-site
emergency plan;
- to ensure that regular rehearsals were carried out in order to keep the off-site plan in a state of readiness and also
- to ensure that information on safety was provided to members of the general public.
END OF UNIT 3

19
Element IC4 Storage, handling and processing of dangerous substances
32-IC4-03
BBB
As part of a water treatment system, a manufacturer is to install a plant suitable for the reception and storage of sulphuric acid
and caustic soda, both of which will be delivered in road tankers. These substances are highly corrosive and can react violently
together. SULB Water treatment plant
OUTLINE the safety provisions required for:
 The design; Marks-10 (b) The operation; Marks-6 (c) The maintenance of the proposed storage facility. Marks-4
During Design ( Technical Req)of proposed plant:
 The need for the storage tanks and pipe work to be constructed of suitable chemical resistant material;
 The design, positioning and marking of the delivery inlets to prevent connection being made to the wrong tank;
 Bunding must be provided around the storage tanks – the bunds must be capable of holding the entire contents of the tanks
plus 10%;
 The erection of hazard warning signs clearly identifying the contents of the tanks and the colour coding of pipe work;
 The fitting of level indicators and high level alarms to prevent overfilling;
 The provision of good vehicle access including a hard standing for tankers with facilities for spill containment
 Provision of earthing and bonding for the tanker, connection and hoses
 Measures to avoid the tanker being driven away whilst still connected and
During Operation( procedural req)of proposed plant:
 The introduction of a safe system of work including emergency procedures to deal with spillages
 The provision of drench showers and eyewash stations and a good standard of lighting.
 The provision and maintenance of a contingency supply of neutralizing and absorbent materials and water;
 Providing training for the personnel involved including tanker drivers in the risks associated with the operation and the
control measures to be followed and
 The provision of PPE such as chemical suits, chemical resistant gloves and full face protection.
During Maintenance of proposed plant:
 The arrangements for the examination and testing of safety critical plant; The use of permit to work systems;
 The completion of the flushing out of tanks and pipe work and their isolation before the start of maintenance work;
 Regular cleaning of the bunds and The provision of training to maintenance staff in emergency procedures
July 2012
July 2009
Jan 2008
Jan
2008N
Jan
2006N
33-IC4-R-
SAQ3
32-IC4-11
BBB
Same Q
repeated
IC8-03
A road tanker is to be filled with petroleum (gasoline) at an installation.
(a) IDENTIFY FOUR hazards associated with this operation. Marks-4
(b) DESCRIBE how a vapor cloud explosion could be generated in this situation. Marks-4
(c) OUTLINE practical ways of minimizing the risk of an electrostatic charge. Marks-4
(d) OUTLINE control measures that could reduce risks with road tanker filling. Marks-8
Or,
An extremely flammable liquid is being transferred from a road tanker to a bulk storage tank.
a. OUTLINE the control measures which would reduce the risk of ignition of the associated vapour due to static electricity.
Marks-10
Jan 2012
July 2008
July 2010

20
Tanker drivers are routinely required to work on top of road tankers during transfer operations.
b. OUTLINE the factors that should be considered when assessing the risk for work on top of the road tanker. Marks-10
Or, Identify the safety features needed to protect against ignition by static electricity of the vapour of an extremely
flammable liquid while it is being transferred from a bulk storage tank to a road tanker. 10, JUL 2008, Jul 2010
a. Practical ways of minimising the risk of an electrostatic charge
- The use of tankers and pipework with high conductivity; Earthing the pipework and tanker and bonding to the same
electrical potential. ; Reducing the velocity of the filling or draining operation by controlling the pump rate
- Reducing constrictions by the smoother pipe unrestricted by strainers
- Avoid splash filling or water contamination in pipe; Increasing the relaxation time by using longer pipework
- Add anti-static additives ; Nitrogen blanketing of the road tanker to minimise the risk of explosion
- The uses of a vapour return system to improve containment.; The provision of instrumentation to detect earth leakage
- Using antistatic clothing and footwear
b. Control measures that could reduce risks with road tanker filling
- Preparation of written procedure and instructions; The identification of specified entry and exit routes
- High level of communication and cooperation between tanker’s driver and the site operator
- The use of pumps, hoses and other equipment which are suitable for the purpose, properly installed and regularly
maintained
- Fitting devices such as a high level alarm to prevent overfilling
- The erection of barriers or the use of bollards and warning cones to prevent a collision
- Installing a system to prevent tanker driving away to prevent the tanker driving away if hoses are still connected
- Ensuring the tankers are positioned correctly with wheel chokes and hand brake applied
- Ensuring hoses are coupled without submitting them to abnormal stress and valves operated in accordance with lay down
procedure
- Switching off electrical equipment which was not required for filling such as mobile phone and bonding and equalizing
the potential between the tanker and fixed installation
- Using bottom loading tankers in preference to those which are top loaded but if this is not possible ensuring that the top
loaded tankers have a fill pipe which touch the bottom of the tanker and handrails or fall arrest equipment is provided to
prevent falls
- Finally preparing procedure to be followed in the event of the emergency and ensuring that all workers are fully aware
about

21
34-IC4-R-
SAQ1
BBB
A chemical company is involved in the bulk storage and transport of concentrated solutions of sodium hydroxide.
OUTLINE the technical and procedural requirements needed to ensure the safety of these activities. 10 marks
Technical issues relate to Design of Tanks, The Filling Operation with the tanker whereas
- The presence of corrosive alkali and therefore, the tank and tanker should be made of suitable chemical resistant
material that will not be corroded, such as stainless steel.
- Avoid incompatible substance such as ACID, the location of Alkali storage should not be adjacent to any incompatible
substance (ACID).
- Bunding must be provided around the storage tanks – the bunds must be capable of holding the entire contents of the
tanks plus 10%;
- Usage of double skinned tanks; The erection of hard standings for vehicles and anti-collision barriers around the tank.
- The fitting of level indicators and high level alarms and possibly a trip system to prevent overfilling;
- Installing a system to prevent tanker driving away to prevent the tanker driven away if hoses are still connected
- The erection of hazard warning signs clearly identifying the contents of the tank and tankers and the colour coding of pipe
work;
Procedural Issues will include Emergency Procedure, Training, PPE and Maintenance.
- Chemical analysis prior to re-stocking, to avoid filling with incompatible materials
- There must emergency procedures to deal with spillages or other emergencies
- The provision absorbent materials and water;
- The provision of drench showers and eyewash stations and a good standard of lighting.
- Providing training for the personnel involved including tanker drivers in the risks associated with the operation and the
control measures to be followed
- The provision of PPE such as chemical suits, chemical resistant gloves and full face protection.
- Provision for maintenance of plant- PTW and isolation of stored energy, vehicles and flexible pipe works
- Since materials are being transported by tanker, there would be a need for safety advisor for dangerous goods.
35-IC4-R-
SAQ2
With the aid of fully labeled diagram, IDENTIFY the key safety features of a building to be used as a facility for the storage of highly
flammable solvents in 200 litre drums.
The storage facility
- The building of the storage facility should be
constructed of non-combustible and fire
resistant materials
- An impermeable / solid base to be constructed;
- Bunding must be provided to contain spills;
Facility for collection / disposal of spillage
- Light weight roofs and blast panels / fire
explosion vents to be ensured
- High or low level ventilation ;
- Adequate separation distance from other
buildings

22
- Adequate provision for access and egress, including emergency escape and ramps to facilitate handling
- Door locks and security – to avoid arson ; suitable warning / hazard signs and instruction displayed
- Indication of zone classification; Facility for external electrical isolation.
Fire safety / precaution
- Segregation of incompatible materials; Sprinkler system or provision of fire extinguishers
- Flammable vapour monitoring system and alarm
36-IC4-05 OUTLINE the factors to consider with respect to the design, construction and use of store room that is to be used for the storage
of bulk stocks of palletized containers of highly flammable paints and thinners. 20
As far as design and construction of storeroom were concerned the following factors such as –
- The construction of storeroom on an impermeable / resistant base with fire resistant materials with a light weight roof or
blast panels
- The provision of buildings to retain any spilled liquid; The provision of high / low ventilation
- The provision of adequate separation from occupied building ; Segregation from traffic / evacuation routes with the use of
fire walls if separation was not possible
- The stores should have at least two access points to allow a means of escape
- Ensuring that electrical installations were suitable for a zoned area
- The provision of fire / smoke detection system, sprinklers, fire extinguishers
- Adequate spacing between racking to allow the movement of FLT and The provision for separate access for pedestrians
and the trucks.
Use of the store room:
- The control of source of ignition such as the FLT and portable electrical equipment
- The storing of paint and thinner in a fire resistant containers away from source of heat and sun light
- Procedure for decanting which should be carried out outdoors or in a separate area
- Procedure for spillages where immediate clean up required using spill kit
- Ensuring a high standard of housekeeping for the FLT routes and pedestrian walk ways
- Regular inspection and maintenance of the racking and pallets
- Arranging the safe disposal of wastages; Providing information and trainings to workers on necessary precautionary
measures to be taken
- Controlling access to the stores by limiting it to authorized person only
Jan 2011

23
37-IC4-08 The physical and chemical properties of liquefied petroleum gas (LPG) dictate a number of precautions which should be taken in
the storage of LPG in cylinders.
a) Select four of these properties and explain how one of the precautions is related to each property.
b) Give, with reasons, additional precautions for the safe storage of LPG in cylinders.
a. The properties can be selected include:
- LPG is a flammable gas at standard temp and pressure;
- It is denser than air; Escape clouds cool and therefore are not buoyant on thermal diffusion;
- Liquid releases float on water; The lower explosive limit (LEL) is reached with small concentrations of LPG;
- It is slightly anesthetic and suffocating in high concentrations
b. Precautions for the safe storage of LPG in cylinders include:
- Preferably stored in the open air; Floors should be concreted;
- Noncombustible or fire resistant and Ventilated with an explosimeter installed.
- Minimise quantity;
- Elimination of ignition sources: no smoking, Provision of signage with 'extremely flammable' warnings;
- Intrinsically safe / flame proof electrical equipment;
- Only electrical apparatus for use in Zone 2 area should be allowed in storage area or within separation distance;
- Dry powder extinguishers at storage location;
- Control of combustibles; Removal of vegetation around storage area (not sodium chlorate weed killers / other
oxidizing agents);
- Segregated from oxygen cylinders (3m); Empty cylinders stored separately from full with valves shut / cap;
- Cylinders stored upright; Protective caps kept in place on valves;
- Storage compound should be protected from vehicle impact;
- Storage situation greater than 3m from
- cellars, drains or excavations and protected from the elements;
- If more than 400 Kg store must have 2m high mesh fence, 2 exits, with Cylinders at least 1.5m from fence;
38-IC4 -02 Workers in a vehicle maintenance workshop spray-paint vehicles using a highly flammable solvent-based paint.
OUTLINE the measures needed to assess and control the risks associated with the spray-painting activity. Marks-20
- Risk assessment to be carried out for
- The activities involved by using paints & solvents with hazardous properties (normally by reference to safety
datasheet).
- The circumstances in which the work was carried out.
- Possible ignition sources and likelihood that a fire or explosion could occur
- The control measures
- The workshop should be constructed of fire resistant materials; An impermeable / solid base to be constructed;
- Possibilities to replace the paint with less flammable
- An external fire resistant storeroom to be provided for the paints and solvents
- A reduced quantities of paint and solvent to be maintained at the workshop
Jan 2010
July 2008

24
- The paint and solvent should be kept in non-spill containers with lids.
- Procedures to made and followed for the containment and clean-up of spillages and for the cleaning of the spray
guns
- Provision for Local exhaust ventilation
- Safe electrical equipment with provisions of flameproof switchboards.
- Fire fighting equipment, means of escape route, emergency procedure to be drawn and communicated to the
workforce
- Instruction, training on the risks involved in the operation and the precautions to be observed
39-IC4-R-
LAQ2
A road haulage company which is an established carrier of nonhazardous bulk liquid, has been invited to tender for a contract to
transport significant quantities of bulk flammable materials in tank containers. Advise the hauler company on
i. The requirements for driver training and for the appointment of safety advisor 6
ii. The main duties of safety advisors in relation to the transport of dangerous goods. 14
i. The drivers of the tank and tank container carrying dangerous goods should –
- Attend a vocational course of instructions communicated for transportation of dangerous goods
- Sit in an assessment examination organized externally in order to obtain a competency certificate which needs to be
updated at specific intervals.
The Safety Officer appointed – must hold a vocational qualification where he had been instruction about the type of the
means of transportation such as water, road and train and the type of dangerous goods to be transported.
ii. The safety officer should act as catalyst and advise on Health, Safety and Environment matters in term of handling and
transporting dangerous goods to the management, other responsibilities includes –
- Developing a procedure for compliance with local rules governing the identification of dangerous goods – such as
HAZCHEM signs
- Developing procedure for purchasing vehicles – Complying the requirements for transporting significant quantities of
bulk flammable material in tank container.
- Procedure for checking equipment
- Procedure for conducting training and maintaining records of attendance
- Emergency procedure; accountabilities of employees during emergency
- Monitoring of compliance of all procedure through suitable techniques such as HSE audit
- Investigating incidents, accidents and Nearmiss
- Complying the control measures / preventive measures identified during investigation to avoid recurrence
- Prequalification and competency evaluation for sub contractors
- Ensuring the distribution of operational procedures among the employees
- Ensuring that the vehicles are maintaining required documents and equipment
- The implementation of verification / inspection procedure to ensure the compliance with legislation governing
loading and unloading of dangerous goods
- Preparing annual performance report to the employer

25
40-IC4-R-
LAQ3. IC04-
7
As the Health, Safety and Environment Manager to a group of manufacturing companies, you have recently discovered drums of a
highly flammable solvent being stored on open land at the rear of one of the group's factories.
a) Draft a memorandum to the Production Manager of the company concerned explaining why storage in this manner is
inappropriate.
b) Describe, with the aid of sketches, the main features of a storage facility that would be appropriate for the storage of such
drums.
OR,
With the aid of fully labeled diagram, identify the key features of a building to be used as a facility for the storage of highly
flammable solvents in 200 l drums.
a. Memo to the production manager: I have recently discovered that the drums of highly flammable solvents are stored in an
open area at the rear of one of our factory, which is potential to cause any eventuality at the factory leading harm and loss. I
therefore, would like to bring the issue to your kind notice / attention and set out the below reasons , why storing highly
flammable solvents are inappropriate in such manner –
- The risk of ignition leading fire as the drums are stored under direct sun - over heating from sun, on site ignition source
and malicious damage can be causes of such ignition.
- There is also significant risk of leaks or spillage which could lead to soil contamination as well as water contamination.
- The cost of cleanup could occur if the drums got damaged resulting in leakage and spillage
- The solvents also presents health risks to anyone in the vicinity
- Open area storage are inviting arsons, theft and vandalism
- Risk of drum handling using FLT and associated reduced stability in such location
- It is a non-compliance of local regulation concerning the storage of flammable materials, hazardous to health or
environment.
- Finally it is one of the major breaches of insurance condition and environmental accreditation.
b. The storage facility
- The building of the storage facility should be constructed of non-combustible and fire resistant materials
- An impermeable / solid base to be constructed; Adequate separation distance from other buildings
- The storage facility to contain the drums of highly flammable liquid should be provided with Bund to contain spills;
- Facility for collection / disposal of spillage or accumulated rain water
- Door locks, perimeter fencing and security – to avoid arson ; suitable warning / hazard signs and instruction displayed
- High or low level ventilation ; Indication of zone classification; Facility for external electrical isolation.
Fire safety / precaution
- Segregation of incompatible materials from the solvents such as acids, oxidizing agents to kept separately ;
- Sprinkler system or provision of fire extinguishers
- Flammable vapour monitoring system and alarm
- Adequate provision for access and egress, including emergency escape and truck ramps to facilitate and handling drums
ETA 31,
Jan 2007
N

26
41-IC4-10 A petrol storage tank in a bund containing three other similar tanks is overfilled during a transfer operation resulting in a large
spillage of petrol into the bund.
The petrol vapor is ignited from a remote source causing a catastrophic explosion and fire involving the whole of the installation
a. IDENTIFY the design and construction measures that could have prevented such an event 4
b. OUTLINE the range of measures that would be necessary to mitigate the effects of such an event 6
a. Design and construction measures that could have prevented the incident include:
- Adequate segregation between adjacent tanks and the use of separate bunding
- an interlocked pumping system with high level alarms with at least double redundancy of the alarm
- level detection and vapour detector monitoring systems fitted in the bund
- the provision of remote shut down systems
- good standards or earthing and bonding
b. The measures that would be necessary to mitigate the effects of such an event
- Provision of adequate fixed foam installations to spray the surface of pools in the bunded areas
- The installation of foam monitors capable of reaching the tops of tanks
July 2007

27
- The erection of radiation walls between adjacent bunds to prevent other tanks being heated
- An adequate supply of firefighting water
- The installation of remotely operated pumps and valves to empty affected tanks
- Easy routes of access for fire fighters
- The provision of drainage interceptors to minimize the environmental effects of fire water run off
- Regular draining and cleaning to remove rain water from bunds
42-IC4-04 In 1988 a disaster occurred on the piper alpha platform in the united kingdom
a. IDENTIFY mechanical failures that contributed to the initial explosion - 4
b. OUTLINE the systems failures associated with the permit to work system that contributed initial explosion - 6
a. The mechanical failures that contributed to the initial explosion-
- The removal of PSV (pressure safety valve) for service and its replacement with a blank flange (Blind flange)
- The blank flange was made of ordinary metal sheet (without any Lock or tag with switch of pump)
- The blank flange was fitted incorrectly and was not leak tight
- On the night A running (condensate) pump was tripped and a stand by pump associated with blanked flange was
operated by night shift without knowing about incorrectly fitted blank flange.
- The condensate and gas escaped from the blanked flange that resulted in gas explosion
b.
- There were two permits taken – one for two weeks maintenance in the pump and other for the work on pressure
valve of the same pump.
- The failure with the PTW which was in operation for the removal of the pressure valve.
 No mention of the need to cross reference permits / or
 No cross reference of the two permits to indicate the removal of pressure valve in the pump in each of the
permit.
 Failure in communication at the end of the working day with the suspended permit returned to the control
room but not displayed and not communicated to night shift team
 No place on the permit for the issuer to declare that the work had been left in a safe condition
- Inadequate written procedures for the permit to work in that there was reference of locking off or tagging valves to
prevent inadvertent operation
- A failure to check that the blank valve was leak tight at the time before pressurizing it
- A failure in communication at shift handover with the absence of any written procedure for this event
- The absence of formal training for those with the responsibilities of issuing permits
- No attention drawn to the potential dangers associated with the suspended of permits
- Finally inadequate monitoring and auditing by management of the permit to work procedure.
January
2010
43-IC4-01 Unless appropriate precautions are taken, chemical reactions in a batch manufacturing process can give rise to conditions which
can lead to a 'runaway reaction'.
a) EXPLAIN what is meant by 'runaway reaction' also called thermal runaway and
July 2011
Jan 2009
July 2007

28
b) IDENTIFY the conditions that may give rise to such an event.
c) DESCRIBE the design and operational features of chemical processes necessary to prevent such an event.
2+4+4=10,
a) An uncontrolled exothermic reaction where the heat produced by the reaction exceeds the heat removed. The surplus heat
raises the temperature of the reaction mass, which causes the rate of reaction to increase resulting in RUNAWAY REACTION.
Thermal runaway occurs because, as the temperature increases, the rate at which heat is removed increases linearly but the
rate at which heat is produced increases exponentially.
b) the conditions that may give rise to such an event includes –
- Presence of Strongly exothermic reaction;
- Inadequate provision, or failure in cooling of the reaction, and
- Presence of contaminant catalysis.
- Excessive quantities of reactants present in the reactor
- The lack of sensitive temperature detection and control
- the insulation of the reaction vessel where solid residues have build up on the internal walls of the vessel and mixer failure
with loss of agitation
- Increase in pressure and temperature from reaction serve to accelerate the reaction in accord with Le Chatelier’s principle.
c) Carrying out a hazard and operability study (HAZOP) on the reaction process would be appropriate in this scenario; this may
then have led to the inclusion of design features such as:
- High integrity temperature detection being linked to the cooling / reactant addition system;
- Pressure rise detection linked to cooling / venting / auto shut-down;
- Vessel protected by correctly sized bursting disc.
- Fitting of an agitation failure alarm system
Operational Features such as
- Only high caliber of operator required for such processes was employed;
- The decision making requirements by operators in response to adverse operating condition were minimized
- Ensure that maintenance activities / raw material handling do not introduce potential catalysts into the reaction;
- The rate of addition of reactants was limited and that inappropriate scale-up or fouling was avoided
44-IC4-01 A hot liquid was accidently and violently discharged from the feed port of reactor vessel following the addition of a chemical
regent during a chemical manufacturing process; The investigation suggested that the cause was a runaway exothermic reaction.
i. OUTLINE the factors that may have contributed to the event and explain the principle involved. 10
ii. DESCRIBE the measures that could be taken to prevent a recurrence 10
a) The factors that may have contributed to the event scenario
- It is likely that the incident was a violent exothermic reaction, which caused a thermal runaway, with subsequent rapid
increase in temperature and pressure causing the ejection of vessel contents.
ETA 29

29
- The system was based on wrong procedures or incorrect assumptions about the heat generation and dissipation from
quantities of chemicals used for the procedure.
- Equipment failure, for example automatic feed breakdown or a failure of critical component such as stirrer and mixers;
- Incorrect operating procedures such as the speed of addition or the method of mixing was wrong
- The vessel contents could have been incorrect or the wrong materials have been added.
- Contamination or contact with other chemicals reagent acting as catalyst.
- Design failure, commissioning failure if the plant was not build as per the recognized specification
- Human error – unauthorized modification.
b) Measures to prevent a recurrence include
- The feed of material should be controlled adequately, either manually or automatically to ensure correct speed of
delivery.
- Any engineering controls provided for temperature, pressure, level, quantities should be properly designed and
maintained and tested.
- Pressure changes and other warnings and alarms and
- Automatic process shutdown if the feed of the reagents or the reaction exceeds the pre-set parameters.
- Designed emergency neutralization or discharge of the process reactants if feed or the reaction exceeds the preset
parameter
- To prevent contamination, Procedural control measures such as quality control of feedstock purity and specification of
supplied materials should be closely monitored.
Allied to this would be the requirement for
- Adequate training, instruction and information for operators to reduce human error,
- Close supervision for normal operation and emergency conditions.
- The use of laboratory or pilot plant trials and
- The use of hazard analysis techniques (hazop).
END OF UNIT 4

30
IC 5 : Work Equipment
With the aid of labelled sketches, outline the characteristic features of, and factors that promote, the following types of materials
failure:
(a) Brittle Failure; Marks-5
(b) Ductile Failure. Marks-5
July 2012
Jan 2008
45-IC 05 - 11 Coal is delivered by train to a power station and is transported by belt conveyors to a furnace. Conveyor workers check
that the coal moves along the conveyors efficiently. These workers have received suitable information, instruction and training
and are supervised.
OUTLINE additional control measures that could reduce risks to conveyor workers. Marks-10
Jan 2012
Jan 2010
46-IC 05 –
08
Materials can fail through various modes.
(a) OUTLINE the meaning of ‘Metal Fatigue’. Marks-6
(b) IDENTIFY TWO factors which can contribute to such a failure AND, for EACH factor, outline ONE circumstance in which
it may occur. Marks-4
(c) OUTLINE:
(i) The characteristics of electrolytic corrosion. Marks-5
(ii)Factors which cause electrolytic corrosion. Marks-5
Jan 2012
Jul 2008

31
47-IC 05 – R-
LAQ 1
“A”
a) IDENTIFY the possible modes of structural failure of pressure vessels and, with reference to different types of pressure vessel,
describe the factors and conditions that may influence the mode and likelihood. 14
b) Review the measures that may be needed to prevent the structural failure of pressure vessels. 6
a. The possible modes of failures are as below
- Creep ; Corrosion ; Brittle failure; Ductile failure; Metal fatigue
The factors and conditions that may influence the mode and likelihood of such failure include:
- Temperature (Low)– is an important factor with brittle failure, more likely to occur at low temperature, for example in
LPG vessels
- Temperature (high) – Creep and ductile failure are more likely to happened at high temperature for example in steam
boiler
- Cyclical pressure variations are likely to promote metal fatigue
- Residual manufacturing stress, choice of materials, poor repair, welding and heat treatment can influence the likely
stress in the vessels.
- The contents of the vessels will affect the probability, extent and the type of any corrosion
- Weak components such as seems, welds and loose access plates may promote failure.
- Contamination – oil / grease in air receiver; Environment is also an important factors – Corrosive / hot
- Operating within design specifications:
o Overheating – low water level / scale formation; Over pressure – Safety gauge / valve failure
b. Measures that may be needed to prevent structural failure
- Designed safety feature – relief valves, sight gauge, level sensor and choice of material used
- Specified design standards – Quality control, proof testing
- Regular checks and test – servicing, maintenance and inspections
- Thorough examination by competent persons
- NDT (Non Destructive test) to identify the potential failure modes
- Operating procedures to keep within specified performance
- Water treatment for boiler and filters to remove contaminations.
48-IC 05 -04
“A”
With the aid of labeled sketches, OUTLINE the characteristics of, and factors that promote, the following type of material failure
a) Brittle Failure; b)Ductile Failure
a) Brittle Failure: A brittle fracture generally occurs without warning or prior evidence of distress.
It is a crystalline structure failure with minimal plastic or elastic deformation.
There are generally characteristics ‘chevron’ marks from the point of initiation and the failure is sudden from rapid stress loading.
The factors promoting a brittle fracture are
- High tensile stresses,; Residual or locked in stresses; Sudden loading which does not give the material time to deform
plastically,
- Case hardening; Low temperatures and The degree of brittleness of the material
b) Ductile Failure
A ductile fracture generally has a smooth fracture surface with plastic deformation of the material before final fracture.
There is evidence of necking and the final fracture is often brittle because there is insufficient material left to sustain a load.
July 2012
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32
This type of failure generally occurs as the result of a single stress overload though other promoting factors including
- High temperatures,; Cold work hardening and
- The plasticity of the material
49-IC 05 – R
SAQ 2
“A”
Describe, with practical examples and sketches the characteristics features of and that factors that promote the following types of
failures in metal.
i) Fatigue 10 ii) Creep 10
(NEBOSH diploma syllabus: Seven modes of failures- Ductile, brittle, metal fatigue, buckling, corrosion, Wear and creep)
i) Fatigue: Characteristics:
o Cracks spreading – repeatedly stressed, newly failed smooth surface
o Beachmark – 90 degree to crackdown
o Final failure ductile / brittle – insufficient material to withstand the load
Fatigue: Factors:
o Area of high stress concentration – corners, threads, holes
o Cyclical loading ; Temperature, pressure and forced vibration
Fatigue: Example: Rotating; Reciprocating ; Vibrating parts
ii) Creep: Characteristics: Yielding and extension; Continuously loaded materials; plastic deformation
Creep: Factors: unequal relaxation of stresses; Excess temperature; Choice of materials (Low creep)
Fatigue: Example: Pressurised pipework; high speed rotating blades
50-IC 05 – R
– LAQ 2
“A”
A report into the collapse of a passenger walkways at a ferry port concluded that the immediate physical cause of collapse was a
fatigue failure of a weld securing a stub axle to the walk ways. The walkways , which was designed and installed by contractor,
was attached to a floating pontoon at one end and was intended to accommodate the movement cause by the rise and fall of the
tide
i) Explain the mechanism of “Fatigue Failure” 5
ii) OUTLINE the design and maintenance procedure that could have helped in preventing incident 10
iii) OUTLINE the steps that the ferry port could have taken to ensure that the contractor was competent to design and
install the walkways 5
i. The mechanism of fatigue failure such as
- Microscopic progressive cracks (point of high stress, variable loadings, little deformation)
 Initiated at stress concentration. These Extend under Fluctuating stress until the material fails
- The final failure may be ductile or brittle (when there is insufficient material to sustain the load)
 There is Little or no deformation but the failure surface shows characteristics conchoidal marks

33
ii. Design and Maintenance procedure includes
- Deputing the competent and experienced designer
- A peer review of the design considering the service condition and loading
- Tidal and the possibility of the corrosion should be considered
- Stress concentration should be minimized; Material with suitable fatigue strength to be selected
- Risk assessment should be carried out at the design stage
- Provision for maintenance and inspections; Maintenance and inspection requirement should be specified
- Implementation of documented inspection and maintenance routine
- Training of personnel on maintenance requirements; Periodic thorough examination by the competent person
iii. Steps for prequalifying / ensuring competency the contractors
- Enquiries for experience in similar projects
- Verifications from recent clients – they could have provided the information about the performance of the
contractor
- Details of design personnel (qualifications, Experience etc.)
- Quality control techniques
- The use of Risk assessments for design stages should be queried
- The use of third party checks / inspection on design to be queried
- Finally the contractors should prepare a detailed plan Outlining the construction safety and installation
arrangements
51-IC 05-14
– R – LAQ 3
“A”
A serious accident occurred when a threaded steel rod in the braking mechanism of a hoist broke. An investigation revealed that
the cause of the breakage was fatigue failure.
a) DESCRIBE the mechanism and characteristics of fatigue failure 6
b) List THREE factors which can contribute to such a failure and for each factor describe one circumstance in which it may occur 6
c) DESCRIBE the measures that could have been taken to minimize the likelihood of such a failure 8
a) The mechanism and characteristics of fatigue failure such as
- Microscopic progressive cracks (point of high stress, variable loadings, little deformation)
 Crack propagation from points of stress concentration,
 Fluctuating stress environments and
 The characteristic fracture pattern.
- The final failure may be ductile or brittle when there is insufficient material to sustain the load
 Failed surface shows conchoidal beachmarks , which Progress as narrow rings at low and extended at full load
b) Factors which could give rise to fatigue failure in practice such as: (only 3 factor with 1 circumstance)
- High Fluctuating stress – Use outside the design criteria, Relative to fatigue strength of material,
- Stress concentration – sharp corners, threads, holes, defects / flaws / cracks / impurities
- Temperature – heat induces stress, change of material properties
- Residual stress – imposed during manufacture and assembly and induced bending stress, and
ETA 38,
Jan 2007
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34
- Corrosion – stress concentrations in corrosion pits
c) Measures to minimize the likelihood of fatigue failures such as
- Design, manufacture and installation
o Minimize stress concentration; specifying materials / components to match the service condition
o Quality assurance; Correct assembly
- The maintenance, inspection and examination (with NDT)
o Failure record ; Reliability data; Non Destructive test
o Examination of critical components
o Replacements at planned intervals
o Maintenance
o Statutory examination requirements
- Provision of training and instruction for those involved in the use and
- The keeping of service history records.
52-IC 05 -12
“A”
Prevention of pipework failures is critical in preventing major leaks and incidents. The construction of a new chemical plant is
nearly complete and some parts are being prepared for start-up.
a) OUTLINE an inspection strategy that could prevent pipework failures within this plant 10
b) OUTLINE the items that could be included on a checklist when inspecting pipework after construction. 10
a.
The inspection strategies that could prevent pipework failures:
- A thorough inspection must be done on current basis, more detailed manner than previous one.
- The use of NDT techniques such as dye penetrate for the detection of surface faults and
- And NDT techniques such as ultrasonic or radiography to detect those that were more serious
- The engagement of qualified personnel to interpret the results and management should resist the temptation to use
unqualified personnel for any type of pipe work inspection.
- Inspection should take place during and after the construction has been completed and should be ongoing throughout the
life of the plant.
- Those carrying out inspections should preferably include a member from design team who will be able to detect departures
from the design intentions and also a member of the startup team who suffer most from the results of construction defects.
b. Checklist
- Suitable material such as specified grade of steel to be chosen for the construction of the pipe work.
- The required tests have been carried out
- The pipes are not secured too tightly and are free to expand
- The flanges on liquid lines are not located above cables
- Temporary supports have been removed and permanent supports correctly installed
- Springs and hangers are not fully compressed or extended; No sub standards joint exists
- No screwed joints have been used and ; All joints have been leak tested
JAN 2010
Jan 2008

35
- Temporary branches, nipples and plugs have been removed and replaced with welded plugs
- Pipes do not touch the ground, are not laid underground and do not pass through pits or depressions containing water
- Relief valve drain lines are not too close to the ground so that blocking and freezing is avoidable
- Reinforcement pads are vented; dead ends, dead legs and water traps have been avoided
- Bellows are not distorted and support rings are not loose
- Vibrating pipes have been avoided and all pipe work has received hydrostatic testing
53-IC 05 –
15, R-SAQ 3
“B”
a. EXPLAIN the purpose of non-destructive testing (NDT) on items of plant. 2
b. Other than visual inspection, OUTLINE the principles, advantages and disadvantages of TWO NDT techniques 8
IC 05 - 16
“B”
(a) OUTLINE the purpose of non-destructive testing (NDT) on items of plant. Marks-2
(b) OUTLINE the principles, benefits and limitations of the following NDT techniques:
(i) Dye penetrant; Marks-4
(ii) Radiography. Marks-4
July 2011
July 2009
“B”
OUTLINE the principles, advantages and disadvantages of:
(a) Dye penetrant;
(b) Magnetic particle inspection;
(c) Radiography;
(d) Ultrasonics
as methods of non-destructive testing on the welded joints of a safety critical vessel. Marks-20
July 2011
July 2007
ANS of all
above 3
Questions
The purpose of non-destructive testing (NDT) is to check for faults (cracks etc) in components before they develop into total failure
without affecting the integrity of the component.
The main NDT techniques required are:
Principle of NDT Techniques Advantages Disadvantages
The use of a dye penetrant method
makes cracks visible as dye penetrates
into it.
It uses the principle of brightly coloured
or fluorescent liquid applied to the
surface of the component, which
penetrates into any surface cracks or
cavities.
Developer is then applied which draws
out the penetrant, so indicating cracks
etc, that are not normally detected
It is relatively cheap and is a
simple operation
It detects surface faults,
It is quick and easy to use on
large surfaces,
It is cost effective, allows
complex geometries to be
inspected and is a portable
technique (e.g. spray aerosol
cans of penetrant can be
used)
it does not detect sub-surface faults
It is only suitable for non-porous materials,
There must be direct access to the surface of the
component,
Surface finish and roughness can affect inspection
sensitivity,
It indicates the length of the defect but not the depth
and
There are health and safety considerations such as
possible confined space and flammability.
Additionally, the penetrant used may have toxic

36
visually. properties.
Impact or 'tap' testing involves
detection of the change of pitch of
reverberant sound after striking.
It is cheap as no specialist
equipment is required
But it gives no indication of where the fault is and
relies on individual sensitivity / skill.
Magnetic particle method involves
coating the surface of the item involved
to be tested with magnetic particles that
may be in powder form or within a
liquid.
It is a simple and quick
operation that is very sensitive
to surface cracks and, in
certain circumstances, can
detect sub-surface defects,
its drawback is that the interpretation of results may
be difficult, particularly on the inside surface of a
pressure vessel.
With radiography, x-rays or gamma rays
are used to penetrate the item to leave
an image on film.
Any defects are shown up by the
differences in the intensity of the
radiation striking the film.
The benefits of this technique
are that it detects internal
defects and
produces a permanent record
of the test
That it can be used on most
material (ferrous and non-
ferrous),
The space required for the equipment;
It is a time consuming process;
It is expensive;
It requires skilled operators to use the equipment and
interpret the results;
There is a health and safety consideration due to the
possibility of radiation exposure;
The results show length but not the depth of defect;
and There is a limitation of the thickness of the
material
Using an ultrasonic technique, short
pulses of high frequency ultrasound are
used, with the reflected waves being
detected and shown on an oscilloscope
or digital display.
This technique detects both
surface and sub-surface
defects, requires access to one
side of the joint only and takes
little time with portable
equipment that can be used in
most environments.
The limitations of the technique are that it requires a
high level of expertise and coupling the equipment
probe onto rough surfaces can be difficult.
54-IC 05 -10
“B”
A weld repair to a high pressure steam pipeline requires gamma radiography to be performed to assess the quality of the repair
a) OUTLINE the principle of gamma radiography
b) OUTLINE the advantage an disadvantages o this form of NDT
a.
Gamma radiography uses the transmission of gamma rays from a sealed ionizing radiation source through attest object on to film
placed on the opposite side. The film records the intensity of the radiation received and since cracks and flaws are hollow, a
greater intensity of rays pass onto the film and the defects are shown up as darker regions.
b.
Advantage:
- It can be used on most materials, ferrous and non ferrous, internal (sub-surface) defects are indicated
- A permanent visual image of the components under test is provide an coupling with surface of the piece under
July
2007N

37
test is not required
Disadvantage:
- Health and safety consideration due to possibility of exposure to radiation
- The space required for the equipments
- The amount of time taken in setting up the equipments and the delay in obtaining the results
- The requirements of skilled operators
- The limitation on the thickness of the materials that can be tested
- The process is expensive
55-IC 05 - 02
“C”
A pressurised steam boiler requires an examination; at the same time a repair on an electrically driven pump, associated with the
boiler, is needed.
(a) DEFINE the term ‘relevant fluid’ in relation to pressure systems safety. Marks-4
(b) OUTLINE the typical contents of a written scheme of examination form for the boiler. Marks-8
(c) IDENTIFY the practical measures that should be taken to carry out the pump repair safely. Marks-8
a) A relevant fluid means
- Steam (greater than atmospheric pressure)
- Any fluid or mixture of fluids which is at a pressure greater than 0.5 bar above atmospheric pressure, and which fluid or
mixture of fluids, is:-
o A gas
o A liquid which would have a vapour pressure greater than 0.5 bar above atmospheric pressure when in
equilibrium with its vapour at either the actual temperature of the liquid or 17.5 degrees Celsius; Or
o A gas dissolved under pressure in a solvent contained in a porous substance at ambient temperature and which
could be released from the solvent without the application of heat.
b) The typical content of written scheme of examination form for the inspection of boiler:-
- Identification of the items of plant or equipment within the system
- The parts of the system which are to be examined
- The nature of examination required including the inspection and testing to be carried out on protective devices
- The preparatory work needed for the items to be examined safely
- The maximum intervals between examinations
- Whether an imminent danger report is required to be given to the enforcing authority and / or the employer
- The critical parts of the system – if modified or repaired – which must be examined by a competent person before the
system is used again
- The name of the competent person certifying the written scheme
- The date of certification
c) The practical measures that should be taken to carry out the pump repair safety.
- The need to issue a permit to work which would specify the control measures to be taken such as:
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38
o The isolation and the locking off the electrical power to the pump
o The isolation of pipelines by locking valves or inserting blanks
o Releasing stored energy
o De-pressurising, draining and decontaminating the pump
- Allowing hot machinery to cool at least 50 degree Celsius
- Segregating the work by use of barriers and signs and providing safe means of access for the employees who were to
carry out repair work
- Engagement of skilled and competent employees for the work
- Adequate PPE usage by the engaged employees – head protection, eye protection, hand gloves, safety boots
- The provision of good standards of lighting and ventilation
- Coordination with the person conducting the examination of the boiler
56-IC 05 -
“C”
Failure of pressure systems can result in accidents.
(a) IDENTIFY FIVE examples of pressure systems AND give a workplace example in EACH case. Marks-5
(b) OUTLINE a typical written scheme of examination for pressure systems. Marks-5
(c) OUTLINE other control measures that could reduce the risk of pressure system failures. Marks-10
a) Examples of pressure systems such as
o Pressurized process plant and pipe work connected with chemical processes;
o Fixed or portable compressed air systems as used for painting or tyre inflation;
o Pressure cookers normally present in industrial kitchens; heat exchangers providing heating or cooling in industry;
refrigeration plant found in a food storage building;
o Boiler or steam heating systems providing general heating in workplaces; and
o Autoclaves or equipment sterilizers used in cleaning laboratory glass ware.
b) Typical written scheme of examination for pressure systems cover all protective devices and would include all pressure
vessels and pipe work that could give rise to danger if they failed. The type of examination would be specified such as, for
example,
o As a result of a statutory requirement, as would also the frequency with which the examination should be carried
out.
o The scheme would stipulate the special measures needed in preparing the plant for examination and in the case
of a fired or
o Heated pressure systems, the need for them to be examined when cold and also when in operation with a final
requirement
o The examination should be carried out by a competent person.
c) Control measures that could reduce the risk of pressure system failures: Equipment, Operating conditions, Protective
devices, The provision of maintenance and the provision of operator training.
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Jan 2006
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- Equipment, it would be imperative to ensure that installations are suitable for their intended purpose, and are installed
correctly with due regard to design conditions, installation standards and accepted codes of practice.
- Operating conditions require a knowledge of the nature, and pressures and temperatures of the gas or liquid being
pressurized or contained, the safe operating limits of the system and equipment linked with the system and the methods
of operating within these limits; the availability of operating instructions for the system and equipment linked with the
system and the accessibility by workers to instructions on what action to take in the event of an emergency.
- Protective devices, these should be suitable, adjusted to the correct settings and should function properly at all times.
- Maintenance is an important control measure and a programme should be drawn up for the whole system, monitoring it
for defects and for signs of corrosion and wear and ensuring that both the examination and any necessary remedial work
is carried out using safe systems of work and under competent supervision.
- Training would have to be provided for all operators, maintenance personnel, and those responsible for carrying out
inspections of the system to ensure they were in possession of the necessary knowledge and skills to perform their duties.
57-IC 05 - 19
“C”
Explain what is meant by a 'pressure system'.
a. DESCRIBE common causes of structural failure in pressure systems.
b. OUTLINE the technical and procedural measures to minimize the likelihood of failures in pressure systems.
A "pressure system" is:
- A system comprising one or more pressure vessels of rigid construction,
- Any associated pipework and protective devices;
- The pipework with its protective devices to which a transportable pressure receptacle is, or is intended to be, connected;
or
- A pipeline and its protective devices which contain or are liable to contain a relevant fluid, but do not include a
transportable pressure receptacle.
Examples of a 'relevant fluid', such as:
- Steam;
- A fluid or mixture of fluids which is at a pressure greater than 0.5 bar above atmospheric pressure,
- The fluid being either a gas, or a liquid which would have a vapour pressure greater than 0.5 bar above atmospheric
pressure when in equilibrium with its vapour at either the actual temperature of the liquid or at 17.5 degrees Celsius; or
- A gas dissolved under pressure in solvent contained in a porous substance at ambient temp and which could be released
from the solvent without the application of heat.
a. The possible modes of failure such as
- Excessive stress,
- Abnormal external loading,
- Overpressure,
- Mechanical damage or ductile failure;
- Overheating;
- Mechanical fatigue; thermal fatigue; Brittle fracture;
- Creep;
- Hydrogen embrittlement at welding repairs;
Jan 2006
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40
- Corrosion;
- Water / steam hammer and caustic embrittlement.
b. The design, operation, inspection, test and maintenance requirements that would be needed to minimize the risk of
structural failure.
- The design specification being correct (fit for purpose, CE marking etc);
- Specific safety features (pressure relief valves, level sensors, etc),
- quality control during the manufacture,
- inspection and maintenance arrangements (including statutory examination and the scheme of examination being
prepared by a competent person);
- The role of non destructive testing;
- Ensuring that the vessel operates within its performance envelope,
- In the case of boilers, the filtering and treatment of water; and the
- Training of personnel.
58-IC 05 – 5
“C”
a) Organizations may use a range of reactive and proactive strategies for plant maintenance.
IDENTIFY FOUR possible plant maintenance strategies AND outline the principles of EACH strategy. 10
b) OUTLINE the factors that you would advise the Engineering Department of an organization to take into account in
deciding on a maintenance strategy following the installation of an item of process plant. 10
a) Plant maintenance Strategies such as
I. Planned preventive maintenance (PPM),
II. Breakdown maintenance,
III. Condition monitoring and
IV. Emergency maintenance.
The principles of PPM include the need for planned maintenance and parts replacement set against a schedule of time or running
hours and driven by a record keeping system.
Breakdown maintenance, being reactive, means that maintenance is undertaken in response to reports of malfunction of
equipment and the maintenance activity is not required whilst the plant continues to operate effectively.
Condition monitoring requires monitoring of specified parameters, (for example, vibration levels or metal content of cutting
fluids, etc); specifying the level of each parameter when maintenance work needs to be undertaken and measuring continuously
or to a schedule.
Emergency maintenance includes maintenance undertaken to prevent more serious consequences such as reinforcement to
prevent failure or the use of temporary supports to prevent collapse.
b) Factors such as
- Statutory requirements including examples of the types of work equipment involved such as cranes and air receivers,
- The cost benefits analysis of PPM versus breakdown including the availability of spares, competent staff, and the
Jan,
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41
expected life-time of equipment.
- The outcome of risk assessments in terms of failure probability and consequences;
- The history of failure with example sources such as incident reports and maintenance data;
- Any relevant manufacturer's data or recommendations for the plant;
- The extent of and / or conditions of use;
- The opportunity for downtime and the integration with existing systems such as condition monitoring.
59-IC 05 – 6
“C”
A motor vehicle repair workshop has installed a new electrically powered, compressed air system.
OUTLINE the factors to be considered in developing a suitable Planned Preventative Maintenance programme. Marks-10
The first stage in the development of a maintenance programme would be to consider
o The design life and expected reliability of the system
o The manufacturer’s specifications
o The pattern of usage whether constant, periodic or only as a standby
o The anticipated fault pattern based on experience gained in using similar equipment.
Further factors such as
o The need for routine operations such as belt tightening, lubrication and filter changes
o The need for regular replacement of critical parts to prevent breakdown and
o The availability of the component parts,
o The operation that would be required at specific times to counter corrosion, wear and fatigue and
o Any statutory requirements or those required by insurance companies
Additionally thought should also be given to
o The need for safe system of work such as permits or electrical isolation
o The available occasions when shut-down maintenance might be performed
o The particular safety aspects of maintenance while equipment was running
o The availability of staff with the necessary skills and competencies to carry out the work
A written scheme of maintenance might then be prepared which include the safety precautions that should be taken and the
arrangements for recording details of the work carried out such as the result of inspections, the defects found, and the remedial
action taken such as the replacement of parts
Jan 2011
60-IC 05 – 9
/20
“C”
A compressed air system is to be installed in a motor vehicle repair workshop.
OUTLINE the safety requirements that should be met before the system is commissioned. 10,
The sitting of the equipment –
- Protection from vehicles; Protection of the public; Separation from flammable atmosphere; Control of emission of Noise
System design issues –
- Conformity of standards; Capacity, materials of construction and layout of features
Installation issues –
- The fitting of pressure gauge, relief valves and drain lines.
- Marking of safety related information – safe working pressures etc, suitable guarding.
Other safety measures such as
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42
- Maintenance procedures should be established
- Written scheme of examination of equipment
- Pre- commissioning check by the competent person.
- Providing information to operators on safety features, limits and the correct operation of the system
61-IC 05 - 13
“D”
Members of the public have been injured when collecting baggage from a baggage conveyor at an airport.
(a) IDENTIFY typical mechanical hazards when the conveyor is in use. Marks-4
(b) OUTLINE the control measures that should be in place to reduce the risk of injury from the mechanical hazards. Marks-6
a) Mechanical hazards such as: ENTICE
 Possibility of Entanglement when items of clothing or jewelry become caught in the moving conveyor
 Trapping between the interlaced parts of the conveyor bed,
 Trapping between moving items of baggage or between the lip and trapped baggage.
 Impact hazards from coming into contact with moving baggage which might have been inadequately stacked or in
attempting to replace items that had fallen from the belt
 Abrasion hazards from coming into contact with the moving belt
b) Control measures that should in place to reduce the risk of injury from the mechanical hazards includes:
 The control of the speed of the conveyor
 A reduction in gaps in the belt at critical points such as turns
 The replacement of worn conveyor parts
 The use of E-stops (Emergency Stop) in the event of blockage or other emergency
 Using a klaxon (A kind of loud horn formerly used on motor vehicles)or strobe warning lights in the case of an
inadvertent start up
 The use photo sensitive detectors
 Using workers to assess the conveyors for blockages and to assist passengers when this is seen to be necessary and
 Providing singage advising caution when
 Removing baggage from the conveyor
 On the action to be taken in the event of a blockage and
 Warning against placing hands or feet on the conveyor
Jan 2011
END OF UNIT 5

43
IC 6 : Machinery Safety
62-IC 06 -13
A
IC 06 – 04
R SAQ 3
(a) OUTLINE the features of industrial robots that may have particular implications for safety. (6)
(b) OUTLINE how the risk of injury to personnel working with, or in the vicinity of, industrial robots might be minimised. (14)
OR
a) OUTLINE the features of computer controlled equipment (e.g. robots, Computer Numerical
Controlled (CNC) machines, and wireless operated lifting equipment) that may have
particular implications on safety.
b) DESCRIBE how the risk of injury to personnel working with such equipment may be
reduced.
Or, IDENTIFY the particular safety problems posed by industrial robots in a work place
a. Features Robot / CNC such as:
- Sudden, rapid or and forceful movements
- Unpredictable , and Wide sweep of robot arm
- Aberrant behavior such as the robot moving outside its normal range,; Dropping a load or ejecting a material
- Software problem which are difficult to detect
- Danger from the type of work being carried out such as spot welding, painting,
- Particular dangers arising during maintenance and teaching when close access may be needed and unpredictable behavior
may be caused by the release of stored energy,
- The possibility of receiving foreign signals – can interfere with planned operations
b. Precautionary measures to reduce the risks: The risks of injury to personnel working with or in the vicinity of industrial robot
might be minimized by introduction of appropriate control measures:
- An initial risk assessment will identify hazard from the task performed (such as ejection, trapping, hot work)
- Identification of persons at risks (operators, maintenance staff, cleaners)
- And the evaluation of risks in term of likelihood, frequency and severity
- RA would identify the appropriate control measures to eliminate or reduce the risks. This might include:
 Restricting access by enclosing the robotic area with a high fence along with interlock access
 The provision of interlocked access using pressure mats or light curtains
 Safe system of work such as Lock off or interlock systems for maintenance or any non-routine work
 Pressure release systems to relive stored energy by hydraulic oil to reservoir and pneumatic air to atmosphere
 The provision of mechanical restraints to prevent physical movement
 Temporary fencing between any robot being maintained and taught and the other working robots
 Procedures for re-starting after interruption; Using an audible or visual pre-start up warning signals
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July 2007
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44
 Software checks : taking the robot to the cycle repeatedly to identify the faults
 Remote diagnostic facilities; Remote teaching with the use of pendants to avoid the need for close access
 Emergency stop system ;
 Elimination of stray radio frequency interference
 Training for relevant personnel
 Introduction of monitoring system including audit and the keeping of records of maintenance and defects
63-IC-06
A
Metal components are being manufactured by workers using metal turning lathes.
(a) IDENTIFY FIVE types of mechanical hazard associated with metal turning lathes AND give a practical example of EACH.
Marks-10
(b) OUTLINE control measures that minimize risks associated with metal turning
lathes. Marks-10
Jan, 2012
64-IC 06 –
01
A
OUTLINE the practical control measures that can be taken to minimise risk when operating a bench-mounted circular saw. -10
- The need for the correct operation and / or adjustment of the top guard,
- The effective guarding of the blade beneath the bench,
- The use of a push-stick to feed through the material being sawn,
- The riving knife correctly positioned,
- The correct selection, maintenance and adjustment of the blade
- A suitable risk assessment,
- Training and competence of operators,
- Provision of Sufficient space around the machine which should be kept free of
obstruction,
- Adequate lighting and ventilation
- The provision of a local exhaust ventilation system,
- The provision of emergency stops device and means of isolation,
- The provision and Use of personal protective equipment (e.g. Goggles and hearing protection),
- Stability of the machine and The need for regular maintenance of the machine and guards
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45
65-IC 06 -05
A
A plastics injection moulding machine is supplied to your workplace.
OUTLINE the moulding machine’s features that you would have expected to have been addressed in order to demonstrate that
the machine is safe. Marks-20
Features that should have been addressed to demonstrate the safety of the plastic injection moulding machine could have been
outlined under the following heading
- General features
- Feature dealing with controls
- Protection against mechanical hazards
- Protection against other hazards
- Maintenance and indicators
General Features: The general features of the machine include
- The safety integration principles such as the control hierarchy applied
- Mechanism to tackle Foreseeable abnormal use of machines
- Ergonomically suitable for the users.
- The prevention of danger to the user from the materials used in the construction of the machine or products such as
coolants,
- The lighting provided which gives adequate visibility without causing dazzle or producing stroboscopic effect; and
- The handling and installation of the machine so that sharp edges are avoided and the machine is fitted with
eyebolts.
Controls system: with regards to controls and control systems, their safety and reliability should be addressed to ensure they can
withstand the rigorous of normal use and take account of errors in logic, that
- The Control devices are visible, identifiable, well positioned, logical and sufficiently robust.
- Adequate means for starting the machine
- A stopping device is fitted which disengages power to the actuators and also
- An emergency stop which brings the machine to a halt quickly without creating additional risk that are failure of the
power supply and / or control circuit does not allow the machine to start unexpectedly and the protection devices
remain effective.
- User friendly interactive softwares (if fitted with machine)
Mechanical hazards:
- The stability of machine; The risk of break up during operation
- The risks caused by falling or ejected objects; The variations in speed
- Risks from moving parts which should be designed to avoid hazards or provided with protective devices
- The choice and characteristics of guards and protective devices whether fixed, adjustable,
- Issues arising from working at height
Protection against other hazards would need consideration of electrical risks, those arising from fire and explosion, extremes of
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46
temperature, noise and vibration, emission of dust and/or gasses,
As for maintenance, matters such as
- Remote adjustment and lubrication; Automatic cleaning; Isolation ; Means of access
While finally for indicators, issues which should have been considered include the
- Provision unambiguous and easily understood information and warning device
- Use and maintenance of the machine and its marking in particular the CE mark, its serial number and details of the
manufacturer.
66-IC 06 -10
A
DESCRIBE the risks associated with the task of cutting sheet metal with guillotine machines and the measures that should be
taken to ensure the health and safety of operators.
The risks associated with the task of cutting sheet metal with guillotine machines: ENTICE
- Cutting,; Crushing and trapping,
- Entanglement
- Manual handling risks from movement of the sheet metal,
- The potential for hearing damage from the noise generated by the cutting process,
and
- The risk of injury resulting from ejection of metal during cutting and disposal of off-
cuts.
A description of the main protective measures to be taken includes:
- The provision of fixed guards or other safeguarding systems such as photo-electric
devices ('light curtains') or pressure mats;
- Shrouding the foot pedal to ensure the guillotine was not accidentally operated;
- The maintenance of guarding systems;
- The possibility of introducing automated or mechanical systems for the handling of
the sheet metal;
- Methods for noise reduction such as hoods or absorbent bin lining;
- The provision of personal protective equipment for the operators' hands and eyes; and
- Operator training on safe guillotine operation.
ETA 54
67-IC 06 – R
SAQ 2
A
A new, self-contained air compressor is to be installed in an existing work shop
i) OUTLINE the built in protective devices that may be necessary in order to ensure its safe operation 4
ii) IDENTIFY the information that should be displayed on the air receiver in order to comply with the best practices 6
i)
- A safety valve – to relive excess pressure at receiver maximum
pressure
- A pressure gauge – to identify receiver pressure
- A pressure cut out or unloading device – to cut off the compressor
when working pressure is reached (Petrol station , Car Wheel air fill
station)
- A drain valve – to drain off condensed water vapour

47
- A fusible plug of metal – to protect against overheating
- Electrical device such as fused plug and earthing
ii) The information should be affixed in an easily legible and permanent form, either to vessel itself or on a data plate that
cannot be removed
- The maximum or safe working pressure
- The maximum, minimum safe working temperature
- The capacity of vessels in litre
- The name and mark of manufacturer
- The type and serial or batch identification
- The date of manufacture
68-IC 06 –
15- R SAQ 1
A
A manually operated lathe/ milling machine is to be fitted with a computer numeric control (CNC) system.
OUTLINE the additional risks that this may introduce and the measures required to
minimize such risk. 10
The fitting of a computer numeric control to a manually operated lathe would introduce
additional risks such as:
- An increase of speed in the machine and the Potential rise in noise levels that
could accompany this increase
- The possibility of unexpected movements
- Error in programming and software
- Operators may be unfamiliar with the new system
Measures that would be required to minimize the risks include:
- The completion of a risk assessment for the new system
- The provision of a fixed or interlocked guards to prevent access during the automatic cycle
- The provision of manual operation for setting and cleaning such as a hold to run system
- The relocation of the controls outside the danger zone
- The provision of additional training for operators and maintenance staff
- Updating the instruction manual for using, setting, cleaning and maintaining the machine and
- Carrying out regular testing of software
Jan
2008N
69-IC 06 -02
B
(a) OUTLINE the principles of an interlocked machine guard. Marks-4
(b) OUTLINE the principles of operation of trapped key control systems. Marks-6
a) An interlocked guard is linked to the machine controls by mechanical, electrical, hydraulic or pneumatic means.
The principles of operation are that the machine cannot become dangerous when the guard is open and, when the machine is in
an otherwise dangerous condition, either the guard cannot be opened or that by opening the guard it causes the machine to
Jan 2008

48
become safe.
Mechanical Interlock Electrical Interlock Hydraulic interlock
Outline the principle of operation of trapped key control system OR,
b) DESCRIBE the principles of operation of the following interlocking methods used to safeguard machinery
i. Captive key control system
ii. Trapped key control system
iii. A cam activated position (limit) switch operating in the positive (normally open) mode
i) As the name suggests, the ‘key’ is at all times held captive in the guard locking mechanism that incorporates an electrical
switch connected to the power supply of the machine. It is therefore necessary to turn the key to open the guard and this
has the effect of switching off the machine (often in a two stage process) – Real life example is car engine.
ii) Trapped key system recognizes the single transferable key that is either trapped in guard lock or the switch lock. The key
can only be released from the guard lock (and hence be used to switch on power) when the guard is closed and locked in
position. Once the key has been used to switch on the power it is locked in place and can only be removed when power is
switch off.
The most practical method of power interlocking is a trapped key system. The power isolation switch is operated by a key that
is trapped in position while the switch is in the ON position. When the key is turned, the isolation switch contacts are
locked open (isolating the power supply) and the key can be withdrawn.

49
iii) The principles of a positive-operated, cam-activated position switch relate to the making and breaking of an electrical
contact within the switch. When the guard is closed, a spring inside the switch forces contact; on opening the guard, the
action of a cam-follower on the cam of the switch breaks that contact against the force of the spring.
70-IC 06 -03
B
(a) IDENTIFY when a fixed guard would be an appropriate means of providing protection against mechanical hazards.
(b) OUTLINE the features of a ‘fixed guard’ in relation to machinery safety. Marks-5
(c) OUTLINE the factors to be considered in the design and use of fixed guards that minimise risks to workers. Marks-5
a) Fixed guards may be an appropriate method of providing protection against mechanical hazards when infrequent or no
access is required to dangerous parts of a machine during its normal operation. Such as pedestal fan covers, guards fixed
on moving parts of equipment etc
b) A fixed guard is a guard with no moving parts affixed in such a manner (eg by screw, nuts, welding) that it can only be
open or removed by the use of tools or destruction of the affixing means. It provides appropriate protection against
mechanical hazards when infrequent or no access is required to dangerous parts of a machine during its normal
operation.
c)
With respect to the design features, the factors such as:
- The material of construction, which should be sufficiently robust to withstand the rigours of the workplace and be
able to contain any ejected material, but still allow sight of the process when required;
- The method of fixing, usually requiring the use of a special tool for the guard's removal;
- The need to ensure that any necessary openings in guards are such that they do not allow access to the dangerous
parts (a function of the size of any opening in relation to the distance to the hazard); and
- The need to address the possibility of the guard reverberating and exacerbating a noise problem
Factors to be considered in the use of fixed guards include
- Monitoring and supervision to ensure that the guard is not compromised,
- Safe systems of work for the carrying out of maintenance operations with the guard removed, and
- The provision of information and training for both operators and maintenance staff
Jan 2010
July 2007
71-IC 06 - 07
B
An external lift on a construction site has an interlocked guard to prevent the lift operating when the gate is open. With reference
to the diagram:
(a) IDENTIFY the two types of switch shown (Switch A AND Switch B); Marks-2
(b) IDENTIFY the functional components associated with BOTH switches; Marks-4
(c) OUTLINE the normal sequence of operation for the electrically- operated, cam-activated switch assembly when the gate
opens and closes; Marks-6
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50
(d) OUTLINE ways in which electrically-operated, cam-activated switches may fail to operate as intended. Marks-8
a. Limit switch A is wired normally closed and is a positively operated switch
while switch B is wired normally open and is negatively operated.
b. The functional components of the switches are
- The cam follower or plunger, and
- Internal spring compressed from the bottom
- Internal electrical contacts attached to the cam follower with
the gate acting as the cam
c. When the gate is closed – the normal sequence of operations would be
- The depression of the plunger on switch B and
- The compression of the internal spring
- The release of cam follower on switch A
This allows electrical contact to the both switches, so making the circuit and allowing the operation of the lift.
When the gate is open –
- The cam follower on switch A is depressed
- The internal spring compresses while the cam follower in switch B is released causing decompression of the
spring.
This electrical contact is broken in both switches thus breaking the circuit and preventing the operation of the lift.
d. There are number of ways in which the type of switch described in the scenario might fail to operate as intended, these
include
- Failure of or damage to the internal spring which prevent the appropriate contact being made
- Damage to the other internal parts of the switch
- The presence of the debris or dirt within the body of the switch
- A contact weld through electrical arcing
- A misalignment between cam and cam follower or a wiring fault
- Wear of or damage to parts such as bent plunger
- Damage due to corrosive atmosphere and sabotage such as deliberate disconnection of wiring or the taping
up parts to simulate activation by the gate.
72-IC – 06 –
09- R LAQ 1
It is proposed to use an electro-sensitive safety system ('light curtain') to safeguard the otherwise unguarded entrance to a
fenced enclosure in which dangerous machinery operates at high speed.
OUTLINE the safety considerations and specific design criteria that would need to be addressed when assessing the
acceptability of the proposal.
ETA 52

51
Safety Considerations that are relevant include:
- Run-down time or braking performance of the machinery in relation to the distance from the light curtain;
- Dangers of whole-body access to the enclosure while the machine is running and if protection is not effective
- Light curtain will not protect from the danger of ejection of debris or parts;
- Neither it will provide any noise reduction
- Reliability issues; and
Alternative safeguarding systems and methods such as a trapped key system or close guarding of the machinery within the
enclosure by fixed or interlocking guards to avoid enclosure risk
There will be also a need for thorough inspections, test and maintenance for the safety system.
Specific design criteria that would have to be addressed include:
- The type of interlocking required, preferably dual circuit and self – monitoring.
- The geometry of the light curtain should extend to floor level to fully prevent access.
- Clear visibility into enclosure from point of reset, with the reset control not reachable from inside enclosure
- The need for presence-sensing devices to prevent operation of the system with an operator inside the enclosure;
- The positioning of the system reset control to allow visibility into, and to prevent access from inside, the enclosure;
- The possible need to monitor braking performance electronically as part of the safety system; and
- The lock-off and isolation arrangements for maintenance.
73-IC – 06 –
08- R LAQ 2
The horizontally sliding gate at the bottom of a construction site hoist used for raising and lowering both persons and materials
is electrically interlocked.
a) ILLUSTRATE, by means of a schematic diagram, a suitable interlocking arrangement and give reasons for the level of
protection shown.
b) OUTLINE the factors that could prevent effective operation of the interlocking mechanism and the measures that would be
needed to ensure continued effectiveness.
The aim of this question is to test candidates' understanding of possible interlocking arrangements on the sliding gate of a hoist
on a construction site and how such arrangements and their maintenance might be linked to the level of risk and the conditions
of service.
a) The level of protection given is needed because reliability is poor if one switch and single circuit used. Negative
operated switches can be defeated by tapping up and fail to danger by spring failure, contact weld or damage and / or
debris inside the switch. Positive operated switches can fail to danger by misalignment of the cam and cam follower, wear
and damage bending the plunger , gate over travel or physical removal of the gate.
b) The factors that could prevent effective operation of the interlocking mechanism
- The environment of cement dust and sand is likely to promote switch failure
- The physical Arduous environment of heavy material being handled,
- The multiple use of the hoist, their possible lack of training , care and likely abuse of the equipment makes it more
prone to physical damage
ETA 50,
Jan
2007N

52
- Exposure to adverse outdoor weather conditions may allow water ingress into the switch
- The desire to improve efficiency may lead operators to interfere with the interlocking mechanism
- Mechanical switch failure caused by Spring failure, contact weld or misalignment
Measures to ensure continued effectiveness could have included
- The selection of robust components to withstand the harsh environment
- Arrangements for regular inspection and maintenance to prevent failure
- , Protection from the environment and adverse weather condition
- Effective supervision and management to prevent misuse and interference
- Careful Circuit design to minimize the risk of earth faults causing failure to danger,
-
74-IC 06 - 06 The 1963 International Labour Organisation’s Convention 119 (C119) concerns the Guarding of Machinery. Part 1 considers
general provisions; Part 2 concerns the sale, hire, transfer and exhibition of machinery and Part 3 the use of machinery.
(a) OUTLINE the categories of machinery covered by Part 1 of the convention. Marks-2
(b) GIVE TWO examples of transmission machinery (exposed moving parts) specified in Part 2. Marks-2
(c) OUTLINE the requirements for the use of machinery as specified in Part 3. Marks-6
a. Categories of machinery such as
- Power driven and manually operated machinery, ; New or old machineries
- Road and rail vehicles during locomotion with safety of the operators in mind
- Agriculture machineries with respect to the workers connected with the machinery
b. TWO example of transmission machineries:
- Belts and pulleys; Fly wheels; Gearing ; Chain and shafting
c. The requirement of part 3 of the convection apply to an employer and/or his/her prescribed agent who should be aware
that using machinery without guards is prohibited by law and there is therefore an obligation on them to secure
compliance with the law’s requirements.
As such an employer should not require a worker to use to use machinery without guards in position nor make guards inoperative
on machines that may be used by a worker. Too, has an obligation both to use and not misuse the guards provided.
July 2010
END OF UNIT 6

53
IC 7 : Mechanical Handling (Jan 2012 No Q)
75-IC 7 - 07
R – LAQ3
a) OUTLINE the causes of instability in fork lift trucks (FLT).
b) DESCRIBE the different stages of training which FLT operators should undergo if they are to be able to use a variety of fork lift
trucks.
c) GIVE three situations in which refresher training for fork-lift truck drivers would be appropriate.
a. The causes of stability in fork lift trucks - The lateral and longitudinal instability.
Causes of lateral instability could be due to:
- Driving laterally on slope (factors; angle of slope, elevation of load); The poor condition of tyres or incorrect tyre pressure.
- Driving over the uneven and soft ground ; Speed travelled on corners; Having an insecure load; Hitting low obstruction (e.g.
Kerb);
Causes of longitudinal instability included:
- Overloaded vehicle; Incorrect positioning of load on forks;
- Load slipping forward (often as a result of the mast not being tilted back);
- Driving with load elevated or changing tilt; Travelling with loads forward down slope, or reversing with load up slope;
- Sudden braking or striking an overhead obstruction
b. Training should include the following stages:-
(i) Basic training (ii) Specific job training, relating to the FLT to be used (iii) Familiarization training at the workplace, under
supervision.
Basic training covers: The skills and knowledge relevant to the type of fork lift truck; The risks arising from FLT operation;
Maintenance and Checks. This is undertaken off site or in a dedicated area.
Specific training covers: Knowledge and operating principles of truck to be used; Use of truck in conditions met in the workplace;
On-site rules; Work to be undertaken and Safe systems of work. This should also be undertaken off site or in a dedicated area.
Familiarization training is undertaken on site and covers: The application of skills already learned; Familiarisation with the site
layout and Local emergency procedures.
a. Refresher training would be appropriate where operators:
- Have not used trucks for some time; Have been involved in an accident or near miss;
- Have developed unsafe working practices; Where there has been change in working practices or environment;
- Subject to company policy have regular refresher training.
- Operators who are only occasional users would probably require refresher training more frequently than those who
operate fork lift trucks on a daily basis.
July 2012
ETA 63,
NEBOSH
N
76-IC 7 - 11
R – SAQ2
OUTLINE the factors that a competent person would need to take into account when deciding the frequency of examination of
lifting equipment – 10
Or, OUTLINE the factors that a competent would need to take into account when deciding how frequent the thorough
examinations should be and IDENTIFY the documents the documents that would be need for such an exercise.
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54
The factors which need to be taken into account:
- The age of equipment or the date of manufacture
- The standards to which the equipment has been designed and manufactured
- The manufacturer’s design criteria and the quality conformity of the materials at the time of manufacture
- The schedule and recommendation on testing , inspection and maintenance
The documents:
- Maintenance and inspection records ; previous thorough examination records;
- Details of factor of safety or any proof tests
- History of use – records to identify the extent of use, the type of load lifted, and the type of environment operated in
- Repair record, accident and break down history
- Records of modification, alterations and any replacement parts fitted;
- The history of similar items of equipment to give comparative data
77-IC 7 – R –
SAQ1
IC 5 – 3
(a) OUTLINE the factors that may cause an agricultural Tractor to Overturn. Marks-6
(b) OUTLINE the measures that may be necessary to minimize the risk of a tractor overturning. Marks-4
b. The factors affecting the likelihood of an agriculture tractor overturning includes:
- The need to travel on slops / ramps (gradients) ; The direction of travel on gradient
- The condition and pressure of tyre; The width of wheel
- Travelling over the uneven and soft ground ; Speed travelled on corners
- The stabilities of attachment such as trailer and loads
- The effects of such attachment on center of gravity and on the lateral stability
c. To minimize the risk of overturn:
- The identifications of steep gradients and the restrictions for driving on such gradients
- The maintenance of vehicle and tyres; fitting wider wheels
- Restrictions on travelling on uneven and soft grounds; Slowing down the speed on the corners
- Fitting counterbalance weight ; fitting roll over protections for cabins ; fitting seat belts
- Training for the drivers
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55
78-IC 7 - 05
R – LAQ1
a) DESCRIBE the factors that may cause instability of a Mobile Crane. (cause of topple / overturning)
b) OUTLINE the measures that should be taken to reduce the likelihood of overturning during a lifting operation.
a. The Factors affecting crane stability can be related to its Load, lateral and longitudinal stability and general stability:
Incorrect initial selection of the crane;
Load:
- The load may be too heavy ; Exceeding the safe working load; have an off set center of gravity
- The load may not be adequately secured causing shock loading or become snagged
Lateral and longitudinal stability
- Sloping ground, soft ground or voids or uneven ground; Unstable ground that is incapable of bearing the weight of the
crane and its load;
- Adverse weather conditions (Excessive wind etc); Slewing or hoisting too fast; Not fully extended outriggers
- Ignoring rated capacity indicator alarm
General stability
- Travelling under load on gradients
- Extending the jib under loads; Travelling too fast under load
- Incorrect slinging Incorrect operation of the crane (for example in the non-use of outriggers); Mechanical failure
- Obstructions being struck by the crane
- Incorrect tyre pressures; incorrect tyre types
b. The measures that should be taken to reduce the likelihood of the crane overturning during a lifting operation can be divided
into Engineering control, Procedural controls, Behavioral control
Procedural Control:
- A lifting plan or method statement should be prepared;
- The selection of the crane with respect to its safe working load and reach
- Checking the existence of current test certificates for cranes and all lifting tackles;
- Ensuring the regular thorough inspection and maintenance of the crane and appointing a competent person to
supervise the lift;
- The lifting area should be cordoned off and should be segregated and warning signs should be displayed
Engineering control: should include,
- Ensuring ground conditions are appropriate for positioning the crane
- The out rigger should be fully extended with spreader plate underneath
- Avoiding contact with overhead services and other buildings or structures;
- Using adequate lifting gear
- Speed limiters, over-hoist limit switch and rated capacity indicator and alarm system
- Visibility can be improved by use of mirrors or CCTV;
- Take account of weather conditions and an anemometer should be ensured to identify the strong wind
Behavioral controls such as the competence and training of the driver, slinger , banksman and supervisor
ETA 60,
Jan 2007
N
79-IC 7 - 03 A mobile crane is to be used to erect a telecommunications aerial on the roof of a three-storey office building.
DESCRIBE the precautions that should be taken in order to minimise risks both to employees involved in the work and to other
persons who may be affected by the operation. Marks-20
July 2007

56
The measures that should be taken to reduce the likelihood of the crane related Risks affecting employees involve in work, during
a lifting operation can be divided into Engineering control, Procedural controls, Behavioral control
Procedural Control:
- A lifting plan or method statement should be prepared;
- Checking the existence of current test certificates for cranes and all lifting tackles;
supervise the lift;
Engineering control: should include,
- Ensuring ground conditions are appropriate for positioning the crane
- The out rigger should be fully extended with spreader plate underneath
- Using adequate lifting gear
- Take account of weather conditions and an anemometer should be ensured to identify the strong wind
- The need to follow safe roof work practices such as the provision of edge protection or the use of harnesses.
Behavioral controls such as the competence and training of the driver, slinger , banksman and supervisor
The precautions for others who might be affected by the operation.
- The lifting area should be cordoned off and should be segregated and warning signs should be displayed
- Providing sufficient personnel on site to control access of the public to the area;
- The provision of adequate signing and traffic control;
- Liaison with the local police and
- Planning the lift for a time of day when few people would be in the vicinity.
80-IC 7 - 02 a) OUTLINE a range of hazards associated with the use of mobile elevating work platforms (MEWP’s). 5
b) OUTLINE the general requirements for the safe use of MEWPS. 5
a) Range of hazards associated with MEWPs
- Instability of vehicle; Contact with overhead lines or other obstructions; Trapping; Impact hazards
- Fall from height of person or materials; Being struck by other vehicles; Mechanical failure
- Exposure of employees to adverse weather conditions.
b) General requirements for the safe usage of MEWPs
Procedural Control:
- Selection and training of operators; Controlling working areas by the use of barriers and signs and
- Regular inspection and servicing of the equipment;
Operational Control
- Maintaining stability by the use of fully extended and locked outriggers on firm ground
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57
- Correct positioning of the MEWPs to prevent over-reaching and proximity to dangers such as overhead lines;
- Prohibiting the transfer of persons or materials to or from the platform while it was in a raised position;
- Guarding scissor mechanism to prevent trapping
- Preventing falls from the platform by the use of suitable hand rails and safety harness
- Precautions to avoid fall of materials: Avoiding overloading of work platform; Usage of lanyard with hand tools;
Providing head protection where appropriate;
- Following the safe working limit; Preventing the use of the equipment in adverse weather conditions;
81-IC 7 - 08 In order to inspect the insulation condition on pipework 4m above ground level, it is proposed, in the absence of MEWP to utilize a
personnel cage lifted to the required height by a FLT.
OUTLINE the factors to be considered to ensure safety in the performance of this task.
The factors associated with the design of the equipment:
- The cage must be of adequate design and construction for the intended task
- The cage width should not exceed the width of the truck; The cage must be provided with handrails and toe-guards
- Its total weight including that of personnel and equipment to be carried should not be more than 50% of the rated safe
working load of the FLT; Allowable SWL should be clearly marked in the cage
- Guards should be fitted to afford protection against moving parts on the mast of the truck
Measures while carrying out the tasks:
- The FLT should be positioned on the firm and leveled ground with the mast vertical and the parking brake applied
- The cage must be securely fixed to the forks and
- The driver should remain at the controls of the truck at all the times and
- FLT should not move when the cage was elevated.
- Barriers should be positioned round the working area to protect against the possibilities of collision and passers by being
struck by falling materials
- Employees in the cage should wear safety harness.
Jul 2007
N
82-IC 7 - 04 As a Health and Safety Officer you are asked to give advice to a lift supervisor regarding a proposed lifting operation. The lift
requires the use of two cranes working together (a tandem lift).
OUTLINE the elements of a safe system of work that you would expect to see in order that the lift may be conducted safely. 20
- A prime requirement would be that the proposed lifting operation should be planned by a competent person and be
closely supervised in accordance with the level of risk involved.
- Checking the existence of current test certificates for cranes;
supervise the lift; Crane operators and banksmen would have to be competent
- The availability of the correct lifting equipment together with the availability of test certificates and reports of statutory
examination of cranes
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58
- A risk assessment would need to be carried out which should address matters such as: The weight, shape and center of
gravity of the loads and Availability of lifting points
- The positioning of cranes and, Any available resting place for loads and The numbers of times the lifting operation will
be carried out
- Ensuring ground conditions are appropriate for positioning the crane - firm ground away from trench work or other
excavations and overhead and underground services
- The out rigger should be fully extended with spreader plate underneath to ensure stability
- The precaution to be taken to cordon off the area for the lift.
- The weather condition and the environment in which the lifting equipment will be used to be considered while taking
safety precautions - an anemometer should be ensured to identify the strong wind
- The lift should be under the control of a competent person with knowledge, training and experience of tandem lifting
- Calculation should be carried out by a competent person to decide whether the cranes would need to be de-rated and
the lift should be carried out in such a way that the agreed individual safe working load of either crane is not exceeded.
- Effective means of communication using standards method of signaling would have been ensured between crane
operators and banksmen
83-IC 7 - 09 The jib of a large mobile crane has failed during a lifting operation.
DESCRIBE, with sketches where appropriate, the range of issues and evidence that an investigation team will need to examine in
order to determine the reasons for the failure.)
The issues that an investigation team would need to look at relate broadly to
• The crane,• The lift being performed and • The forensic evidence from the accident scene.
In terms of the crane, the team would need to identify
- The type of mobile crane being used, Its SWL and other operational criteria,
- Its design characteristics (e.g. use of counterbalance, outriggers, etc) and its configuration for the task.
- Maintenance and certification records, and lifting history, would provide some relevant information
With respect to the lift, relevant factors would include
- Details of the load (weight, centre of gravity, slinging method, etc),
- The type of lift (e.g. static, slewing, lift and travel, drag and lift) and
- The site conditions (e.g. wet, windy, sloping, presence of obstructions / excavations, etc).
- The lifting plan, witness statements and visual inspection should provide useful information on these factors.
The training records of the driver, slinger, rigger and banksman may also need to be inspected.
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59
The team would then need to look at the forensic evidence in order to determine
- The type of failure (e.g. buckling, brittle, ductile),
- The integrity of the jib (looking for evidence of alterations, repairs, corrosion, cracks, missing bolts, etc) and
- The settings and functionality of controls, switches and alarms.
84-IC 7 - 12
R – SAQ3
Problem associated with the over hoisting of overhead cranes, whereby the crane hook is hoisted beyond its upper limit and rope
fails, have been recognized for many years. OUTLINE
I. The mechanism that are most likely to be associated with this kind of failure 4
II. The technical and procedural control that can be implemented to prevent such failure 6
i. The mechanism that are most likely to be associated with such type of failure are as follow:
- Winding drum exerts torque on the hoist rope
- Exceeds tensile stress on rope
- Rope exceeds its elastic strain energy and Fails plastically.
- Elongation of strands resulting ductile failure
- Previous occurrence weakened rope
ii. The technical control that could be implemented:
- Designing in an adequate factor of safety
- Ensuring that there is substantial design which is over-engineered
- A torque limiter on the winding drum involving a trip or
- Other overload device will prevent over hoisting from occurring
- Procedural control: thorough examination by competent person; an effective maintenance schedule; daily pre-use checks
- Checking the upper limit trips and recording findings
85-IC 7 - 10
R – LAQ 2
A company is planning a move from premises containing a 'manual' warehouse to one in which the warehouse contains
automated order picking and automated guided vehicle (AGV) goods transfer facilities.
IDENTIFY and DESCRIBE the risks which might be reduced by such a move, together with the new factors or increased risks which
might arise from the changes.
The risk that might be reduced by the move from premises containing a “ manual” warehouse to one in which the warehouse
contains automated order picking and automated guided vehicles (AGV)good transfer facilities are as below”
- There will be no requirement for “manual handling” or FLT use with attendant training required
- There will be no need for pedestrian and vehicle segregation or
- Work at height to access racks above ground level
- Lighting and heating of the warehouse will be minimized
- There will be reduction in noise exposure
- There will be less likelihood of raking collision or risk to pedestrian
- Finally , if the diesel FLT were originally in use , there will be now lower source ignition source
-
Jul 2006
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60
New factors that might be introduced include:
- Unusual behavior from the automated vehicles, which might cause dropped loads or ejected materials
- Software faults that might occur and very difficult to detect
- The AGV will require proximity sensors to prevent pedestrian contact and there will be risk of AGV collisions
- The possibility of signal interference; which will affect the operation of the vehicle
- Order picking machine will need to be adequately guarded and maintenance work require isolation of the equipment and
operation under PTW
- An additional risk is unexpected startup of equipment
- Finally, there will need to be a battery charging routine for the AGV and need for increased fir detection in an unmanned
warehouse.
END OF UNIT 7

61
IC 8 : Electrical Safety
86-IC 08 - 5
R-SAQ 2
“A”
Direct contact with live parts of an electrical supply within a workplace can result in serious injury or death.
OUTLINE a range of control measures that may prevent or limit the effect of such contact. Marks-10
Technical control measures include:
- Isolation should be first choice, working dead and locking off all source of power
- All conductors and live parts ( such as cables, bus bars, connections) to be protected by insulation,
- Preventing contact with live part can be achieved by the use of barriers at usual direction of access or
- Full Enclosures to prevent contact from any directions
- Unintentional contact to be prevented by deputing skilled persons under continuous and direct supervision.
- Usage of RCDs – residual current devices can limit the effect of direct contact with live part , reduce the risk from
electrical shocks
- Use of fuses or circuit breakers to protect against over current
- Restricted access control to switch rooms and switchgear cabinets.
- The provision of mats and use of appropriate tools.
- Correct identification and labeling of electrical systems, 'Live indicator' lights.
Procedural control measures included:
- Safe systems of work and Risk assessment ; Procedural measures such as Implementation of PTW, LOTO
- Design of systems to include lock off and diversion; Appropriate training, competency and authorization,
- Operating procedures such as live working only when justified / reasonable
- Periodic testing for earth continuity and impedance loop testing,
- Control of third parties and employees bringing in own electrical equipment;
- Planned preventative maintenance of electrical systems and equipment;
- Warning Signage and Personal protective equipment.
July 2012
Jan2010
July2007
87-IC 08 - 6
R-LAQ2
“A”
OUTLINE the precautions that should be taken when construction work is to take place under or near overhead power lines
that will remain live during the work. Marks-10
The possibilities of re-routing the cables if practicable otherwise the local electricity supply company would need to be
approached for advice on the precautions to be taken. This will include –
Controlling the access:
- Advice on maximum working at heights and horizontal distances permitted near the overhead lines. /
- The safe clearance distance should be ascertained from the Distribution Network Operator (DNO) or local electricity
supply company
- Establishment of physical limiting equipment fitted for the maximum height and vertical reach of the plant.
- Subcontractors and those which could penetrate the safe distances would have to have physical limiting equipment
fitted with.
- Safe routes where plant could travel and operate would have to be marked, barriers and solid goal posts erected.
- These arrangements would need to be monitored on a regular basis to ensure they remained intact and in place, and
appropriate warning signs displayed.
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62
Controlling the work
Where field work is taking place it may be impractical to erect barriers and goal posts around the overhead lines - these are more
appropriate for use at gateways.
The following precautions may also be needed to manage the risk:
 Clearance – the safe clearance required beneath the overhead lines should be found by contacting the Distribution
Network Operator (DNO);
 Exclusion – vehicles, plant, machinery, equipment, or materials that could reach beyond the safe clearance distance
should not be taken near the line;
 Modifications / physical restraints – Vehicles such as cranes, excavators and tele-handlers should be modified by the
addition of suitable physical restraints so that they cannot reach beyond the safe clearance distances, measures should be
put in place to ensure these restraints are effective and cannot be altered or tampered with;
 Maintenance – operators of high machinery should be instructed not carry out any work on top of the machinery near
overhead power lines;
 Non-conductive equipment, eg wooden ladders would have to be used.
 Training – workers and subcontractors should be briefed on hazards associated with the work and the safe system of
work to be followed. Drivers of visiting vehicles should also be informed.
 Emergency procedure: procedures for dealing with an emergency would be necessary and information on these
procedures would have to be passed on to workers.
 Supervision – access for plant and materials and the working of plant should be under the direct and high level
supervision of a suitable person appointed to ensure that safety precautions are observed.
88-IC 08 – 4
“A”
A worker has received an electric shock from a 240 volt portable drill whilst installing a set of wooden shelves.
(a) OUTLINE the physical effects the worker may have suffered from the accident. Marks-5
(b) IDENTIFY the emergency action that should have been taken immediately after the accident. Marks-5
(c) OUTLINE the precautions that could have been taken to prevent the accident. Marks-10
a) Physical Effects of Electric Shock
- Fibrillation of the heart muscles with possible cardiac arrest/ affecting its ability to pump blood
- Respiratory failure – resulting in reduced supply of oxygen to the brain
- Muscular contraction or spasm causing Involuntary grip that can prolong current flow making it worse
- Burns to tissue and eventually cardiac arrest followed by Death.
- The possibility of secondary injuries – such as falling from ladder if this was being used
b) Emergency Action
- The first step to not touch the causality directly but
- Isolate the source of power or using a non-conductive instrument to push the victim clear;
- Wrap the causality in the insulating material, Checking for breathing and pulse; (ABC)
- Administering CPR (mouth-to-mouth resuscitation) if needed;
- Placing the victim in the recovery position and Contacting the emergency services.
c) Precaution: Equipment selection, Technical precautions and organisational issues
Equipment Selection:-
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63
- The use of battery-powered hand held tools; Reducing the Voltage to 110 V by using step down transformer; Properly
earth / Usage double-insulated tools; Conformity with standards.
Technical / Procedural Precautions:-
- The use of residual current devices (RCD) would have isolated the supply on contact with a live conductor.
- Equipment should be inspected and maintained to ensure that components (plugs, sockets, cables etc) are free of
damage, Using correctly rated cables and fuses,
- Pre use Inspection by the operator
- and testing of portable appliances and electrical systems,
- Housekeeping standards, and the provision of information, instruction and training - particularly in relation to systems of
work and pre-use checks.
89-IC 08 - 2
“B”
With respect to an electricity supply operating at 240v:
(a) OUTLINE the factors that determine the severity of the effects of an electric shock. Marks-6
(b) for EACH of the following protective devices outline their principles of operation:
(I) Residual Current Devices; -3; (ii) Fuses; -3 (iii) 110v Centre Tapped To Earth Reduced Voltage Systems. -3
(c) OUTLINE other design features of electrical systems intended to improve safety. Marks-5
a) Factors that determine the severity of the effects of an electric shock
- The voltage (440 V, 220V, 110V); The type of Current (AC / DC)
- The body resistance of the individuals with reference of age and gender
- The amount of moisture / perspiration on the body ; The type of footwear worn
- The route taken by the current through body; the speed of action taken by any protective measures
- Environmental Conditions – such as the floor material and presence of water
b) I) Residual Current Devices:
 RCD is designed as shock limiting device not for system protection, RCD operates on earth leakage faults.
 RCDs work on the principle "What goes in must come out". They operate by continuously comparing the current
flow in both the Phase (supply) and Neutral (return) conductors of an electrical circuit.
 Any difference in the current passing though Phase and Neutral will triggered the switch to cut off electrical supply
and preventing severe electric shock.
 The device should operate within 30 to 50 milliseconds of the fault being detected
ii) Fuses: A fuse is a device placed in the live side of a circuit,
 designed to cut off the power supply to the circuit automatically within a given time
 If the current flow in the circuit exceeds a given value and produce sufficient heat caused to melt the fuse which is
designed to do so at a predetermined temperature.
 Or. The fuse is thin wire which blow / melt by overheating due to overload / exceeding the amount of current in the
circuit.
 It prevents the overload of an electrical system and overheating of electrical wiring.
 However, its speed of operation is generally too slow to protect people from electric shock.
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64
iii) 110v Centre Tapped To Earth Reduced Voltage Systems:
 One of the better ways of reducing the risk from electricity is to reduce the voltage, Achieved by the use of a step
down transformer.
 A common reduction is to 110 volts and a transformer used to achieve the reduction is described as centre tapped to
earth
 In such transformer, the secondary winding is earthed to its centre
 Thus ensuring only 50% that is 55 volts as the maximum voltage from live to earth involved in an electric shock.
c) Other design features of electrical systems intended to improve safety.
 The selection of suitable cables and placing them out of reach wherever possible to avoid damage;
 The provision of effective means of isolation to ensure the secure disconnection and
 Separation of electrical equipment from every source of energy;
 The use of earthed systems and class 1 equipment or double insulated class 2 equipment;
 The use of circuit breakers and The introduction of earth free zones.
90-IC 08 - 12
“B”
a,b are
Similar IC08-
2
a. OUTLINE the dangers against which protection is provided by a fuse in an electric circuit and explain how such protection is
achieved. 3
b) With respect to UK mains voltage electricity, DESCRIBE the methods and devices other than fuses designated to improve
electrical safety. 11
c) DESCRIBE the Precautions which should be taken when maintaining or repairing electrical systems 6
a) Protection is provided by a fuse: A fuse is a device placed in the live side of a circuit,
 It prevents the overload of an electrical system and overheating of electrical wiring.
 It is designed to cut off the power supply to the circuit automatically within a given time
 If limits the over current, and achieve this by the heating effects of electric current which melt the metal link (fuse) if the
current flow in the circuit exceeds a given value.
 Blow / melt of fuse cause to Breaks the circuit and remain broken until the fuse is replaced.
b. The methods and devices designated to improve electrical safety.
i. Miniature circuit breakers, ii. Residual Current Devices and, iii. Reduced low voltage systems.
i. Miniature Circuit Breakers included that they:
 Are reliable and Are a system protection system
 Involved close tolerances for designed current flow and speed of operation;
 Provide visual detection following operation; Need to be reset after fault detection;
ii. Residual Current Devices (RCDs) or earth leakage circuit breakers (ELCBs) are:
 Designed as shock limiting device not for system protection, Operates on earth leakage faults.
 RCDs work on the principle "What goes in must come out". They operate by continuously comparing the current
flow in both the Phase (supply) and Neutral (return) conductors of an electrical circuit.
ETA 69,
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65
C is
Similar to
IC 08 –16
R – SAQ1
 Any difference in the current passing though Phase and Neutral will triggered the switch to cut off electrical supply
and preventing severe electric shock.
 The device should operate within 30 to 50 milliseconds of the fault being detected
iii. Reduced low voltage systems such as 110v/50v/25v with transformer supply centre tap to earth consist of:
 One of the best ways of reducing the risk from electricity is to reduce the voltage, Achieved by the use of a step down
transformer.
 A common reduction is to 110 volts and a transformer used to achieve the reduction is described as centre tapped to
earth
 In such transformer, the secondary winding is earthed to its centre
 Thus ensuring only 50% that is 55 volts as the maximum voltage from live to earth involved in an electric shock.
 Earthed systems and class 1 equipment, or double insulated class 2 equipment
c) DESCRIBE the Precautions which should be taken when maintaining or repairing electrical systems
- Identifying the apparatus to be worked on; Obtaining system drawings and information;
- Considering whether working can be done “dead” and if so;
 Isolation should be first choice, and locking off all source of power should be done under the Permit to work
system
 Earthing of conductors at the point of work
 Testing system for dead: Any test instruments should be checked against reference source before testing the
system for dead.
 Testing the Test instrument: The test instrument should be re-checked before testing the system for dead
 Correct identification and labeling of electrical systems, 'Live indicator' lights.
- If however it is unrealistic to work dead then a safe system for live work includes:
 There should be safe system of work:
 Barriers to prevent access to live conductors; Full Enclosures to prevent contact from any directions
 Screening any conductors near to work if it is reasonable for them to be live;
 Testing live conductors through holes for test probes; Using suitable test equipment;
 Having testing arrangements in place for testing equipment - before and after;
 Consideration of insulating PPE; insulated tools; non-conductive mats
 Adequate working space and adequate lighting
91-IC 08 - 14
“C”
Areas involving flammable gases and vapours are classified by legislation surrounding the existence of Dangerous Substances and
Explosive Atmospheres according to the probability of occurrence of flammable atmospheres.
a) EXPLAIN the purpose of classifying areas in this way AND distinguish between each zone class.
b) DESCRIBE the types and principles of protection required for electrical equipment in relation to flammable atmospheres.
Part a requires the Explanation of the Zone Classification system contained in legislation (e.g. the UK Dangerous Substances
and Explosive Atmospheres Regulations 2002 (Regulation 7 and Schedule 2)
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66
a) The purpose of the zone classification system is to ensure that only suitably designed equipment and protective systems are
used in areas where a flammable atmosphere may arise.
The criteria for designating an area as Zone 0, Zone 1 or Zone 2
- In Zone 0, flammable atmospheres are present continuously or for long periods.
- In Zone 1, they are likely to occur in normal operation, while in
- Zone 2, they are not likely to occur in normal operation but if they do, they are present for a short period only.
b) The principles of specific protection methods such as – needs description
- Intrinsic safety,; Flameproof, Pressurised, Encapsulation,
- Non-sparking, Oil immersion and Powder filling.
Additionally,
- The use of recognised design standards,; Earthing of conducting surfaces and
- The need to comply with the legislative (DSEAR) requirements as to which category of equipment may be used in the
different zone-classified areas
92-IC 08 – 1
/ 10
R – LAQ1
“C”
Small electroplating companies often have poor standards of health and safety, made worse by the presence of conductive and
corrosive fluids, and humid corrosive atmospheres
a) DESCRIBE the types of fault that may be found in fixed electrical systems under such conditions. 10
b) OUTLINE the information relating to fixed electrical systems that will be required prior to a survey by a competent person. 10
a. The types of fault that may be found under such conditions in a fixed electrical system.
- Poor earthing and a lack of earth continuity
- Damaged socket and switchgear;
- Covers missing from junction boxes
- Inadequate excess current protection such as the fitting of fuses with incorrect ratings
- Means of isolation in poor condition and Badly sited and incompetent workmanship in the original installation.
Additional problems caused by the atmosphere include
- Exposed live conductors due to damaged or perished insulation
- The equipment not selected appropriately for use in wet and corrosive conditions.
- Corrosion of system parts such as access grilles and transformer casings and
- Short circuits caused by the ingress of fluids
- Makeshift connections and alteration done by incompetent person
- Cables not protected by conduit or conduit damaged
- Inadequate working space and cramped access to equipment
b. The type of information required by a competent electrician prior to carry out a survey would include:
- An inventory of the equipment (log)with details of its type and manufacturer
Jan 2011
Jan 2009,
Jul 2007
N

67
- Details of the operating voltage and current of system
- IP classification including the measures of protection against the ingress of water and foreign body
- Records of circuit diagram and manuals for equipment together with details of modifications, interconnections and
any protective devices
- Circuit identification and what each supplies and control
- Means isolation and its location; earthing arrangements; the type and size of cables
- Operation of protective devices such as over loads
- Previous inspection reports
93-IC 08 –
11
“C”
Similar –
IC 08 - 17
R – LAQ3 (b)
a) OUTLINE the factors related to construction work that can increase the risks from electricity on a construction site.
b) Describe the control measures that may be used to address the problems outlined in (a).
a. The factor related to construction work which increases the risk from electricity
- The working environment (including the weather), Water, Damp,
- Soil or mud;
- Damage by activities; Severing / abrasion of cables due to nature of work;
- Equipment supply by contractors (whose standards might vary); The possible temptation to use long trailing cables;
- Damage by vehicles; the difficulties in managing a range of people and activities on site.
b. A strategy to ensure electrical safety during construction activities in relation to the provision and use of electricity on the site
will need to include the following
- Provision for safe system of work and adequate precautions for any persons working on the electrical system
- Proper planning and assessment of the requirement for electricity on site
- Acknowledgement that the supply is temporary and local distribution will grow with the project, therefore cable
routeing will be an important consideration
- Regular testing and reassessment of the fixed supply by the competent person
- Suitable cable and equipment for site environment which is robust and adequately protected
- Protective devices such RCD (residual current device) , fuse , insulation arrangements and double insulation
- Provision and strategy of the adequate system earthing
- Reduced low voltage system using 110 V step down transformer or use a battery operated equipment
- Conspicuous marking of temporary and existing supplies both overhead and underground
- Selection inspection and testing of portable equipment
- Control and co-ordination of any portable equipment brought onto site
- Provision of training and instructions for supply users
- Ensuring that installation and work on the electrical system is only carried out by competent person.
ETA 86,
Jul 2006
N
94-IC 08 –
15
R – SAQ3 (b)
a) IDENTIFY the particular aspects of a working environment that may increase electrical risks.
b) OUTLINE the means by which protection is afforded by, and the limitations of, the following:
I. INTRINSICALLY Safe Equipment; II. FLAME Proof Electrical Equipment.
I. The particular aspects of a working environment that may increase electrical risks.
ETA 75

68
“C” - Where the environment exposes equipment to mechanical damage such as impact, stress, abrasion, wear, or vibration;
- Working outdoors where equipment is exposed to changes in the weather;
- High / low temperatures;
- Contaminants (water or corrosive atmosphere);
- Flammable atmosphere (vapour, gas or dust).
II. The protection afforded by
Intrinsically safe equipment: is based on
- The restriction of electrical energy within the equipment and connecting wire
- Consequently, there is insufficient energy to cause a spark or heating effect to act as a source of ignition.
- However, faults (Capacitive or inductive effects) may raise energy levels above the safe limit. Such kind of equipment
specified for “Zone 0” areas.
Flame proof equipment:
- It allows flammable atmosphere / Explosive mixture to enter the equipment, but the apparatus is placed in an enclosure
which is able to withstand the pressure of an internal explosion and prevent the ignition of any flammable atmosphere
that surrounds the equipment.
- Consequently, the ignition of any flammable atmosphere surrounding the enclosure is prevented
- Flame proof equipment may not be suitable for use with combustible powders or dusts, and may require special
measures for water proofing / to prevent the ingress of water.
- Such kind of equipment specified for “Zone 1 and 2” areas.
95-IC 08 –16
R – SAQ1
“D”
OUTLINE the precautions required when work is to be carried out on an 11 kV electrical supply transformer.
General Precautions
- 11 kV is an high voltage and working with such high voltage is full of dangers therefore, The training and competence of
operators and supervisors are utmost important
- For this, an authorised senior employees to be deputed having similar experience
- The transformer rooms should be locked and entry should be restricted
- The work should be done under close supervision following PTW
- No lone working should be allowed and all operators should remove all personal jewellery such as watches, rings, chains
which may be conductor.
- The working environment should have enough space and sufficient lighting
Live working: live working should be allowed on extreme circumstances when dead work is not practicable, best practices
dictates that live work should be permitted when dead work is unreasonable and it is only reasonable to work live. Following
precaution should be taken
- There should be safe system of work: using insulated tools, non-conductive mats, PPE gloves and glasses
- Barriers to prevent access to live conductors; Full Enclosures to prevent contact from any directions
Dead working: precautions include.

69
- Isolation should be first choice, and locking off all source of power should be done under the Permit to work system
- Earthing of conductors at the point of work
- Any test instruments should be checked against reference source before testing the system for dead.
- The test instrument should be re-checked before testing the system for dead
- Use of fuses or circuit breakers to protect against over current
- Correct identification and labeling of electrical systems, 'Live indicator' lights.
96-IC 08 - 17
R – LAQ3
“D”
Construction work is to take place in a rural area where electrical power for the site is to be gained from an existing 11 kV
overhead supply that cuts across the site on wooden poles.
OUTLINE the control measures to ensure electrical safety in relation to:
a) The overhead supply; 6 b) The provision and use of electricity on the site. 14
a) Overhead supply: The possibilities of re-routing or burying the cables if practicable and contact with the local electricity supply.
If the OVERHEAD supply remains, then precautions for work near overhead lines need to be implemented , This will include –
- Safe routes where plant could travel and operate would have to be marked, barriers erected.
- Minimum distance parallel from power line / Horizontal distances permitted near the overhead lines.
- No storage of materials within 6m of line.
- Solid goal posts or tunnels where access routes pass under power line.
- Height restrictions for plant (rigid posts, signs); use of banksman and appropriate warning signs
- Appointment of responsible person to oversee the measures and appropriate training and information for operatives
b) The provision and use of electricity on the site: - A strategy to ensure electrical safety during construction activities in relation
to the provision and use of electricity on the site will need to include the following
- Provision for safe system of work and adequate precautions for any persons working on the electrical system
- Proper planning and assessment of the requirement for electricity on site
- Acknowledgement that the supply is temporary and local distribution will grow with the project, therefore cable
routeing will be an important consideration
- Regular testing and reassessment of the fixed supply by the competent person
- Suitable cable and equipment for site environment which is robust and adequately protected
- Protective devices such RCD (residual current device) , fuse , insulation arrangements and double insulation
- Provision and strategy of the adequate system erathing
- Reduced low voltage system using 110 V step down transformer or use a battery operated equipment
- Conspicuous marking of temporary and existing supplies both overhead and underground
- Selection inspection and testing of portable equipment
- Control and co-ordination of any portable equipment brought onto site
- Provision of training and instructions for supply users
- Ensuring that installation and work on the electrical system is only carried out by competent person.
ETA-page
80, JAN
2007 N
IC 8 - 8 OUTLINE what should be considered when preparing a scheme for the systematic examination, testing and maintenance of Jan 2011

70
“E”
portable electrical appliances. Marks-10
- The importance of producing an initial inventory of the equipment to be examined and tested including its source
such as in-house, contractors or workers and ensuring that each item was provided with a unique means of
identification.
- Then it would be necessary to determine the appropriate type and frequency of inspection for each item based on
factors Affecting the level of risk such as
o Type of appliances,
o Any protective systems provided such as earthing, double insulation or reduced voltage
o The age and usage of appliance
o The environment in which it was used such as in corrosive atmosphere where more frequent testing may be
required
o The experience and the competence of the user
- Additionally, Historical data and manufacturer’s recommendations need to be considered
- Finally, criteria for each type of examination and test would have to be laid down which would include issues such as
o The competence of the tester
o The calibration and maintenance of test equipment
o The formats of records to be kept on the results of the tests and
o Examinations and systems to identify and take out of use equipment that was found to be faulty.
Jan 2007
N
97-IC 8 - 9
“E”
IDENTIFY the factors that may determine appropriate intervals for the inspection and testing of portable electrical equipment.
It is good practice (law in some countries e.g. UK - The Electricity at Work Regulations 1989) that all systems, including portable
electrical equipment, should be maintained so far as is reasonably practicable to prevent danger.
Any factors that increase the probability of damage to the equipment, and hence an increase in the level of risk, point to the
need for more frequent inspections. Such factors might include:
- Its frequency of use; The environment in which it is used that could lead to mechanical damage,
- Exposure to adverse weather conditions or Exposure to environmental contaminants;
- The frequency of connection or disconnection;
- Whether it is transportable or static;
- The robustness of the equipment and its accessories (cable and plug); and
- The number of users and their competence.
- Voltage at which it operates, Whether it is double-insulated and
- Its criticality to the processes of the organisation; The age of the equipment,
- Its breakdown history and Any recommendations from the manufacturer should be considered.
ETA –
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END OF UNIT 8

71
IC 9 : Element IC9 Safety in construction and demolition
98-IC9-01 OUTLINE the advantages and limitations of the following types of fall protection devices AND give a suitable application for EACH:
(a) Safety Harnesses/fall arrest; Marks-5
(b) Safety Belts/fall restraint; Marks-5
(c) Safety Nets; Marks-5
(d) Air Bags. Marks-5
July 2012
July 2010
Jan 2008
99-IC9-05 A scaffolder is lowering scaffold poles from the third floor of a scaffold tower to a colleague below using a pulley wheel
and rope. Next to the scaffold tower there is a shop entrance. The scaffolder on the ground floor places the scaffold poles
horizontally onto the back of a vehicle parked on a busy road. The scaffolders have already received information,
instruction, training and suitable supervision.
OUTLINE the additional practical measures that could minimize the risk of injury to the scaffolders and members of
the public during this activity. Marks-10
 The pulley wheel and rope were ; -the required statutory inspections of such tools
 The SWL of pulley was not exceeded;
 Correct slinging techniques and rigging on the scaffold poles and use guide ropes where necessary.
 Toe-board and handrails would need to be fitted on the upper platform to protect both the scaffolder on that floor
and public below.
 Suitable safety harness should also be worn by the workman on the upper floor as fall protection
 Attention should be given to nearby hazards such as obstruction and power lines
 Signs and barriers to be erected at ground level to prevent public access to the lowering areas.
 There could be a danger of passing traffic and the placing of cones would help to prevent a collision with the lorry.
 Finally both workman should be provided with hi vi clothing, gloves and head protection
Jan 2012
July 2009
100-IC9-02 An independent scaffold is to be used as a working platform to carry out repairs to a two-storey building.
a) OUTLINE factors which should be considered in order to confirm that the scaffold is safe to use. Marks-15
b) IDENTIFY the inspection requirements for the scaffold. Marks-5
a) Below factors to be considered to confirm that the scaffold is safe to use
 The scaffold must be designed in accordance with recognized standard
 The scaffold should withstand the intended load such as Bricks, Construction materials, tool and workers
 Must be erected by competent scaffold erectors
 The use of sound scaffold materials and fittings to be ensured
 The scaffold must be erected on firm and leveled ground avoiding all voids and drains
 The scaffold must be provided with base plates and sole boards
 Scaffold structure to be “Square” and plumb, sprit level can be used for this purpose
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July,
2007

72
 The platform must be fully boarded , secured without any gaps, overhang and wide enough for the work to be done
 The scaffold must be tied with the building ensuring no vertical or horizontal spacing greater than 8.5 m
 The platform should be provided with suitable guard rails – such top rails, mid rail, toe guard and brick guard
 The use of diagonal and longitudinal bracings
 Safe means of access to each work platform ensuring the ladder extended at least one meter above the platform
 Appropriate method of waste removal such as garbage chute to be ensured
 Suitable means for raising and lowering construction materials through hoist or closed container
 If the scaffold is erected in a position where there is likely to be movement of vehicle and collision is certain then the
protection must be provided to prevent damage from any such collision. /
 It should also be provided with an exclusion zone at its base to prevent it from being struck by passing traffic.
b) The inspection requirements for the scaffold
 Must be inspected by a competent person after erection
 Then at interval not exceeding 7 days
 After any alteration ; after any damage ; after inclement weather condition
101-RRC –
IC9-SA-Q2 OUTLINE the key technical and procedural measures required to ensure the initial and continued stability of an independent tied
scaffold to be erected against a multi storey building in a city Centre. 10 marks
 Technical: Recognized Standard, Withstand the intended load, Suitable for use, Sound scaffold materials, Leveled ground ,
Base plates /sole boards, Adequately braced, Outriggers if required, Tied in the building, Traffic protection – light,
Demarcation etc.
 Procedural: Erected by competent person; Inspection Requirements; inspection and supervision (Daily checks / Defect
reporting)
102-RRC –
IC9-SA-Q3
OUTLINE the design and procedural issues that are relevant to the safe use of a scaffold hoist tower on a construction site.
Design:
 Selection – capable of lifting loads (size / weight)
 Enclosed – ensure that hoist ways are enclosed to avoid any unauthorized obstructions
 Hoist to be fitted with Interlocked gate at the ground and Over run device
 Gate and hand rail at each landing and the hoist Platform must be close to edge of landing – avoiding gaps
 Loads should be secured on the platform and the hoist Platform should be enclosed to prevent people and material
falling from height
 Marked with SWL / maximum numbers of person and never be exceeded the limit
Procedural:
 Erected by trained and competent person; secured to the supporting structure; erected on suitable base
 Operators clear views of all landings; Operator trained and competent
 Through examination after erection / repair / alteration
 Inspection after 6 month, regularly weekly checks; result recorded

73
103-IC1-04 It has been found necessary to repair the explosion venting system at the top of a 15 metre high grain silo on a farm. Fixed
external and internal access will be required for fitters / welders.
Prepare a summary of the essential precautions to be taken before and during the repair work.
Essential precautions to be taken:
- Planning and organizing the work,
 Considering that all work should be covered by a detailed method statement and risk assessment;
 One person to be nominated in charge; All workers to be briefed on general and specific risks, etc;
 Contingencies for bad weather and emergencies
- Preparing the silo
 Emptying it; Ensuring the supply to the silo is isolated and locked off;
 Ensuring all residual grain is removed or dust-damped before hot work commences; Suitable lighting ensured
- Consideration of specific issues relating to confined spaces
 Controlling entry to silo with permit-to-work; Suitable access and egress;
 General ventilation and Atmospheric test; Breathing apparatus (SCBA)
-
Jul
2006N
- Consideration of scaffold and working at height:
 Competently erected platform; - Edge protection and Handrails; Harnesses (if needed), and Protection of fragile
sections of the silo top; and Regularly inspected ladders , hoists
- Hot work : Hot work permit; ventilation of fumes; check for flammable dust; siting of gas cylinders; fire watch and
extinguishers
- Protection of the working areas by: Excluding non-essential personnel, Erecting barriers and Use of appropriate warning
signs.
104-IC9-04 An independent tied scaffold to a new ten-storey office block has collapse into a busy street
a) OULINE the factors that may have affected the stability of the scaffold 8
b) DESCRIBE the main principles of scaffold design, erection and use to ensure the stability of such scaffold 12
a. Just reverse of ANS of IC9-02 (a)
 Factors that may have affected the stability of the scaffold
 The original scaffold erected without confirming any recognized standard
 The scaffold erected without calculating the intended load that can fail to withstand.
 Erected by incompetent / untrained workers
 Inadequate scaffold materials : The use of incorrect or damaged fittings such as non-load bearing couplers or those
affected by corrosion
 The unsatisfactory bearing capacity of the ground on which the scaffold was erected
 The scaffold foundation being undermined either by surface water or by site works such as excavation;
 The scaffold erected without base plates and sole boards
 Standards which were out of plumb or bent, no “square” maintained
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N

74
 Unauthorised alteration of the scaffold
 Overloading either with materials or because waste chutes became blocked
 Impact by a load suspended from a crane or by a road vehicle
 Severe weather conditions including high winds
b. Similar to IC9-02
105-IC9-06 A worker suspended in a fall protection harness is at risk of suffering from suspension trauma with the potential for serious injury
or death
OUTLINE the precautions an employer could take to reduce the risks to the worker in this situation. Marks-10
- Initial selections of the harness, particularly its shock absorbency and
- Manufacturing of harness must complying with recognized standards
- Implementation of plans to prevent prolonged suspension in the fall protection harness
- If the prolonged suspension occurred then drawing up of procedures for carrying out rescue and providing treatment as soon
as possible
- Suitable trainings for all employees who are in need of using fall protection and those involved in rescue; determining
o the correct use and wearing of fall protections; suitable anchorage; free fall height
o How suspension trauma occurs ; The method of reducing risk while suspended
o The procedure that should be followed in a rescue operation
- The procedures for rescue should contain
o Contingency based actions - The worker should be trained to pump their legs frequently
o The need for rescue workers to elevate the victim’s legs and rescue them in the direction of gravity to avoid negative
hydrostatic force
o The need for continuous monitoring of the suspended worker for sign and symptom of suspension trauma
o Ensuring the victim receives appropriate first aid treatment once rescued such as supplementary oxygen
administered by trained personnel
o The need to call for medical assistance if the worker is unconscious in harness suspension
o Monitoring the worker after rescue and ensuring evaluation by a healthcare professional.
- It is essential that the signs and symptoms of suspension trauma are recognised it includes
o Light headedness; Palpitations; Poor concentration; Fatigue, Nausea; Dizziness; Headache
o Sweating, Weakness; Paleness; Breathlessness; Usually low heart rate and blood pressure
Jan, 2010

75
106-IC9-07 The International Labour Organisation’s Standard R175 and its associated Code of Practice sets out general principles for ‘Safety
and Health in Construction’. Minor repairs need to be carried out to the sloping roof of a large two-storey property. A scaffold is
to be erected in order to gain access to the work area.
Using the guidance in R175, OUTLINE the precautions necessary for carrying out the repairs. Marks-20
To carry out the repairs, the precautions under the guidelines of ILO R175 are as below
- Scaffolds; b. Ladder access; c. Roof edge protection; d. General workplace precautions
Scaffolds: necessary precautions include:
 The scaffold must be designed in accordance with recognized standard
 Scaffold is of adequate size and strength; Must be erected by competent scaffold erectors
 The use of sound scaffold materials and fittings to be ensured
 The scaffold should be stable: The scaffold must be tied with the building ensuring no vertical or horizontal spacing greater
than 8.5 m
 The platform must be fully boarded , secured without any gaps, overhang and wide enough for the work to be done
 The platform should be provided with suitable guard rails – such top rails, mid rail, toe guard and brick guard
 Adequate means to be provided to restrict the access when it is not in use
 The scaffold must be inspected – Prior to first time use; At regular intervals; After alteration and interruption in its use;
After exposure to extreme weather condition
Ladders: necessary precautions include:
 Ladders must be secured at top and bottom; the ladder extended at least one meter above the landing platform
 Workers using ladders must always ensure the three point of contacts while ascending / descending
 No one should take any tools or materials in hand while using ladders for climbing,
 Arrangements should be made for lifting tools and materials to the working area by means of a hoist or gin wheel.
 Properly secured roof ladders should be used for work on a sloping roof with protection provided around those areas where
fragile material may be present.
Jan 2011
Roof edge protection: necessary precautions include: Sufficient guard rails to be provided to protect workers from falling from
eaves or roof edges. If it is not practicable to provide guard rails, and workers could fall from a distance of 2 m then other means
of fall protection such safety harness, safety net must be used
General workplace precautions: necessary precautions include:
- Extra care must be taken while working near to overhead power lines; The provision of garbage chute for debris removal
- The use of PPEs such as hard hats, safety boots, eye protections, gloves and high visibility clothing. Adequate welfare facilities
107-IC9-09
similar
01-IC1 - 01
A three-storey building is situated with one side fronting on to a pedestrian walkway.
The building is to undergo extensive maintenance to the external fabric which includes a sloping roof.
a) OUTLINE the safety aspects of the work that will need to be considered before work starts.
b) DESCRIBE, with sketches, the means of providing safe working places for those working at height.
a. 01-IC1-01
- 1-Selection of contractor; 2– Risk Assessments, SSW, method statements; 3– Access and egress; 4– Correct use of ladders;
5– Edge Protection / Fall protections; 6 – Means for transporting tools, materials; 7– Garbage chute; – 8 Competent
ETA-page
81, Jul
2006N

76
employees; 9 – Plant and equipment; 10– Precautions for possible contacts with hazardous substances such as tar, asbestos;
11. Utility supply – gas / electricity; 12– PPE (knee pad etc) ;
13 – Additional measures / protection of pedestrian: Barriers, Signs at ground, Arrangement for vehicle movement –
Restricted access / security, Traffic control / flagman.
14-welfare facilities; 15. Emergency arrangements.
108 - IC9-13
similar
02-IC1 - 02
OUTLINE the health and safety issues to be considered when planning the demolition of a two-storey detached house in a street of
occupied houses. (10) ETA 88
Safety issues for demolition: 1-Selection of Demolition contractor (competency) 2– Risk Assessments, SSW, method statements
3– Access and egress 4– Correct use of ladders 5– Edge protection / fall protections 6.Identifications / insulations of buried
services (EWG), 7. Inspection, examination and maintenance of plants / equipment 8 – Means for transporting tools, materials 9–
Garbage chute – 10 Competent employees 9 – Precautions while handling gas cylinders 10– Identification, Precautions for
possible contacts with hazardous substances such as lead paint, asbestos, 11. Protections of adjoining property 12– PPE 13 –
Additional measures / protection of public: Barriers, Signs at ground, Arrangement for vehicle movement – Restricted access /
security, Traffic control / flagman.
You are the Safety Advisor to a company that installs satellite dishes. The dishes need to be secured to the external walls of
buildings and this involves work at height. Due to limited access around these buildings and the typical heights involved (3 to 5 m)
ladders are the only practicable way of carrying out the work. Workers are on their own when carrying out the work.
(a)DESCRIBE the safety precautions that could reduce the risk of falls from height when using ladders. -14
(b)OUTLINE the emergency procedures you would implement in the event of accident or illness for this type of lone working. -
6
July 2011
END OF UNIT 9

77
Element IC10 Environmental pollution and waste management
July 2012
No “Q”
109-
IC 10 - 04
A large manufacturing company wants to minimize its emission of greenhouse gases.
Identify the activities of the company that may lead to the release of greenhouse gas emissions into the atmosphere. 10
There is a wide range of ways in which activities can contribute to global warming, either directly or indirectly.
Included to:
- Combustion of fossil fuels (oil, LPG, gas and coal) leading to release of carbon dioxide and other relevant gases through
heating systems;
- Transportation emissions (CO, CO2);
- Consumption of electricity generated from fossil sources and process use of fossil fuels;
- Use of cement and bricks in construction leading to release of carbon dioxide from calcium carbonate in cement
manufacture or greenhouse gases from energy used in manufacture;
- Use of chemicals deriving from fossil fuel sources;
- Disposal of waste to landfill leading to methane emissions;
- Emission of VOCs used as process solvents or from fuels;
- Emission of HFCs and chlorinated / fluorinated hydrocarbons;
- Peat consumption and deforestation removal leads to a reduced capacity to absorb carbon dioxide naturally
Jan 2012
July 2007
110 - IC 10 –
03 – R SAQ
3
A company produces waste in the form of a hazardous sludge / mud.
Disposal of the waste is currently via a licensed contractor to a landfill site but this is becoming increasingly costly.
OUTLINE the various options that the company might consider to reduce the cost and environmental impact of dealing with the
waste. 10
• Identification of recycling opportunities at all stages of the process;
• Substitution of process materials for ones that give rise to a non-hazardous waste;
• Improving production efficiency in order to produce less waste;
• Treating waste on-site to reduce quantity (e.g. De-watering);
• Treating waste to reduce hazardous properties (e.g. Sediment tank in dewatering
process to reduce the hazardous waste mixed with water before disposal);
• Mixing the waste with other waste streams to neutralize hazardous property
• Selecting waste contractors that can process the sludge;
• Seeking opportunities to exchange waste streams with companies that can use waste as raw material;
• Exploring other disposal means (e.g. Incineration, liquefied waste to sewer, etc) or even
• Exploring the possibility of becoming licensed / approved to save costs.
Jul 2008

78
111-IC 10 -
06
A
Animals are kept at a zoo where managers are planning to write a waste management policy. For the solid waste produced,
OUTLINE the issues that should be addressed by such a policy and associated procedures. Marks-10
OR, an urban zoo is drawing up a waste management policy that is to be structured in three sections in line with its health and
safety policy. Taking accounts of the type of waste produced, OUTLINE the issues that should be addressed by such a policy. 10
The issues that should be addressed for writing the waste management policy...
i. Statement of intent; ii. Allocation of responsibilities (organising); iii. Practical arrangements
i. The statement of intent would refer to
 The need to minimise the production of waste, by adopting 3 Rs: Reduce – Reuse – Recycle,
 To recycle the as much as possible,
 To comply with environmental legislation without putting at risk the health and safety of workers, members of
public, contractors or animals through the waste handling procedures
 And not put the H&S of employees, visitors/public, contractors or animals at risk through the waste management
procedure
ii. Allocation of responsibilities: An organisational structure which clearly defines responsibilities throughout the waste
disposal chain and includes managers, employees and contractors. Or responsibilities for achieving these objectives would
then have to be clearly defined and allocated to managers, workers and contractors
iii. Practical arrangements: these would include
 The separation /segregation of different type of waste
 The procedures to be followed in handling the types of waste such as animal faeces, soiled animal bedding, animal
carcasses, sharps, animal feed waste as well as paper and packing, sharps from veterinary treatment, horticultural
waste and waste from catering activities.
 The waste would have been clearly labelled and
 On site storage of segregated waste; Safe handling of waste to avoid risks arising from manual handling and
contamination.
 The arrangement section of the policy should refer to the use of a licensed waste disposal contractor.
 And final destination of the waste to a landfill site or incinerator.
July 2010

79
112 - IC 10 –
R LAQ 1
An industrial process produces residue in the form of a granular, hazardous waste that is transported from the site in skips.
DESCRIBE the procedures that should be adopted for the handling and storage of the waste on site, and its transport to a
disposal facility. 20
Handling:
- Define the nature of hazardous waste – assess the likely exposures / controls needed
- Means of conveying waste to skip; Means to prevent dust formation from the granular material
- Protect material in transit to the skip – sheeting / covering
- PPE – gloves, eye protection, respiratory protection; Prevent over loading of skips
Storage: the arrangement for the storage will depend on the quantities being stored
- Isolated ; labeling ; secure place ;vehicle access ; sign age
- Protection from contamination / weather
- Contain any run off
- Emergency planning: loss of containment, release of material
Transport:
- Pre notification to the relevant authority ; Consignment note procedure;
- Identification of a licensed disposal site
- Licensed carrier
- Vehicle :
o Information cards
o Emergency equipment
o Appropriate marking for waste being carried
o Security of the load / vehicle during transport
o Fit for the purpose of transporting hazardous waste
o Route to the tip
- Driver – adequately trained
-Appointment of advisor for transport of dangerous goods.

80
113-IC 10-
01
B
A catastrophic fire occurs in a warehouse which stores a substance which gives off toxic products. The warehouse has an integral
asbestos roof and it is situated near to a densely populated area. The fire burns for a day and completely destroys the building.
(a) IDENTIFY the environmental impacts related to this event, giving a probable source of EACH. Marks-5
(b) IDENTIFY the range of design features that could prevent or mitigate the environmental impacts of such an event at these
premises.Marks-5 (Remember Khalid Port, ERCO Refinery Fire and reconstruction of building)
a)
- Initial impacts on the environment would be the release to atmosphere of greenhouse gases (including carbon
dioxide, methane, and ozone), smoke and particulates such as soot.
- Asbestos fibres could be carried out by air and contaminate the locality
- The possibilities that toxic products could enter sewers and water course and also soak into the soil causing effect
on flora and fauna.
- Unless precautions were taken, fire fighting media could run off to water courses while clean up after the fire
- Waste product (Fully and semi burnt materials) and sludge (mud) could be deposited in landfill sites.
b) Design features that could have prevented or mitigated the impact on the environment include:
- Initial construction of the building with non-combustible materials and introducing compartmentalisation
- Using a roofing materials other than asbestos
- Providing fire proof coating on steelworks
- Using impervious (Fire resistance) materials in the construction of floor
- Providing a flameproof storage container for critical toxic substances
- Installing fixed fire detection and protection system;
- Fitting interceptors to the drains
- Constructing a bund around the warehouse (Like Khalid port site, refinery project after fire they constructed bund
wall around the oil containers / refineries)
- Using fire water catch tank or lagoon during the fire fighting operation and treating the residual solids before
consigning them to landfill sites.
Jan 2009
114 - IC – 10
– R SAQ 2
A landfill site has a range of static and mobile plant , all of which diesel powered and require refueling on regular basis. For this
purpose, diesel oil is transferred from large , onsite, bunded tanks to a bowser attached to the forks of a mechanical handler,
which then transport s the oil both around the site and occasionally via a public road to a neighboring site about 1 km away
OUTLINE the possible risks to Health, safety and environment from the refueling activities 10
- Spillage- during transfer from tank to vehicle / or to bowser
- Spillage during transportation of the bowser either on / off site
- Contact with the skins of operatives involved in the transfer of oil, and possible inhalation of diesel fuel
- Tank leakage during transfer, due to possible corrosion and collision
- Collision of vehicle during transport
- Mechanical hazard from the lifting mechanism
- Fire / explosion associated with the use of diesel

81
115-IC 10 Environmental pollution is a major concern in many industrial processes. A number of alternative strategies are available to
organisations to manage these risks.
Give the meaning of:
(a) Integrated Pollution Prevention and Control (IPPC); Marks-4
(b) Best Practicable Environmental Option (BPEO); Marks-3
(c) Best Available Techniques (BAT). Marks-3
a. IPPC applies to industrial installations and its main aim is to achieve a high level of protection of the environment taken as a
whole. It takes into account the whole performance of the plant and As it is ‘integrated’ includes
o Emissions to air, water and land, ; The generation of waste,
o The use of raw materials, ; Energy efficiency
o Noise ; The prevention of accidents and the restoration of the site upon closure
b. BPEO is the option which provides the most benefits or least damage to the environment taken as a whole at an acceptable
cost and in the long as well as in the short term. The option includes
o A range of methods such as kerb side recycling and green composting
c. BAT applies to certain pollution installations and its aim is to avoid or reduce emissions and their impact on the environment
as a whole. It takes into account
o The balance between costs and benefits to the environment so that the greater the environmental damage that
can be prevented. The greater the cost of the techniques that must be provided.
o ‘Available’ are those techniques that are readily procurable by any person,
‘techniques’ includes plants, systems, processes, monitoring measures and staff
Jan 2011
116-IC 10 -
02
The residents of a village have recently been affected by fallout of dust on their cars and property. They allege that the dust came
from cement works situated a few miles away.
OUTLINE the steps that should be taken by those responsible for the cement works in order to investigate whether emissions
from the works are the cause of the problem. Marks-10
In order to investigate whether the dust causing the problem emanated from the cement works, management would
• Need to carry out a desk study involving contact with the residents
• A research into historical records,
• Weather patterns, possible links with the prevailing wind direction and
• The existence of other potential sources of dust in the area.
• Check the plant for obvious faults and
• Carry out continuous monitoring of the emissions on site together with off-site background monitoring.
Jan 2008

82
• Analyze the dust collected from the village would also help to establish whether it matched that produced at the
alleged source.
Questions from:
1. Int. Exam. Rept. July 2012-Unit-IC
2. Int. Exam. Rept. Jan 2012-Unit-IC
3. Int. Exam. Rept. July2011-Unit-IC
11 x 6 = 66 - 9 (repeated) =
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