2. UNIT I
INTRODUCTION
Evolution of modern safety concepts
Fire prevention
Mechanical hazards
Boilers and Pressure vessels
Electrical Exposure
3. Industrial Safety
Industrial safety is primarily a management activity which
is concerned with
Reducing
Controlling
Eliminating hazards from the industries
or industrial units.
Management of
Events
Protection of
employees
By minimizing
hazards
6. Contd….
Shear Point
Crush Point
Pull – in Point
Burn Point
Wrap Point
Free wheeling parts
Stored Energy
Thrown Objects
7. Mechanical Hazards
Mechanical hazards are those associated with power-
driven machines whether automated or manually
operated.
In an industry, people interact with machines that are
designed to drill, cut, shear, punch, etc.
If appropriate safeguards are not in place or if workers
fail to follow safety precautions, machines can cause
major human injuries.
Also machines can cause damage to the property and
machines can also harm the environment.
8. Safeguarding from Mechanical
Hazards
Machine safeguarding is to minimize the risk of accidents
of machine operator contact.
The contact can be either
• A direct Contact with Moving part.
• Contact with chips, chemical and hot metal splashes, and
circular saw kickbacks.
• Caused by the direct result of a machine malfunction.
10. Safeguard Requirements
• Be secure and durable.
Safeguards should be attached so that they are secure.
• Protect against falling objects.
Objects falling onto moving machine mechanisms increase the risk of
accidents, property damage and injury. It should be prevented.
• Create no interference.
Safeguards can interfere with the progress of work if they are not
properly designed. So worker may be disable it due to work deadline.
• Allow safe maintenance.
Safeguards should be designed to allow the more frequently performed
maintenance tasks
11. General Precautions
Operators should be trained and supervised to ensure
that they dress properly for the job.
Shortcuts that violate safety principles and practices
should be avoided.
Other employees who work around machines but do not
operate them should be made aware of the emergency
procedures.
13. Boilers and Pressure vessels
• A pressure vessel is a closed container designed to hold
gases or liquids at a high pressure substantially different
from the ambient pressure without bursting.
• A boiler is a tank to hold a liquid (often water) so that it
can be boiled by a heat source.
• Boilers often have to withstand high pressure, in which
case they would also be considered a pressure vessel.
15. Safety valves
• Provide a measure of security for plant operators and
equipment from over pressure conditions.
• To relieve pressure.
• Located on the boiler steam drum
• Automatically open when the pressure of the inlet side
of the valve increases past the preset pressure.
• All boilers are required to have at least one safety valve
16. Safety valve
POP – Open Completely at a
specific pressure
BLOWDOWN – Remains open
until a specified pressure drop has
occurred
17. Gauge glass
• Allows the boiler operator to
see the water level in the boiler.
• named gauge cock valves
• secure the boiler water and
steam from the gauge glass.
• Another valve located in line
with the gauge glass is used to
blow the gauge glass down.
18. Water Column
• A hollow vessel having two
connections to the boiler.
• The top connection enters the
steam drum of the boiler
• Enters the shell or head at
least 2 inches below the
lowest permissible water
level.
• To steady the water level in
the gauge glass
• Equipped with high- and
low-water alarms that
sounds a whistle to warn the
operator.
19. Blowdown Valves
• Located on the water column and on the lowest
point of the water spaces of the boiler.
• Used to remove scale and other foreign matter
• To control concentration of dissolved and
suspended solids in boiler water.
• The surface blowdown is located at the
approximate water level so as to discharge
partial steam and water.
• The surface blowdown removes foaming on
the top of the water surface and any impurities
that are on the surface of the water.
20. Types of Boilers
Water-tube boilers
products of combustion surround the tubes through which the
water flows.
Straight tube boiler
Bent tube boiler
Fire-tube boilers
products of combustion pass through the tubes and the water
surrounds them.
Scotch marine boiler
vertical-tube boiler
horizontal return tubular boiler
firebox boiler.
21. Boiler Emergencies
Low water
High water
Serious tube failure
Flarebacks
Minor tube failure
Broken gauge glass
22. Safety Precautions
• Protection against toxic or explosive gases
• Ventilating fan
• Workers should not be inside the waterside of the boiler
when pressure is being applied to test a valve that has
not been under pressure.
• Workers should wear protective clothing when making
boiler water tests.
• External air leaks. Cracks, blisters, or other dangerous
conditions in joints, tubes, seams, or blowoff connections
• Deposits on their heating surfaces and for grease or
other foreign matter in the water.
27. Electrical Hazards
Electrocution:
• Is fatal
• Meaning: to kill with electrical shock
• Results when a human is exposed to a
lethal amount of electrical energy
28.
29. Electrical Hazards
Arc Flash
Sudden release of electrical energy through air when
a high-voltage gap exists and there is a breakdown
between conductors
Gives off thermal radiation (heat) and bright, intense
light that can cause burns
Temperatures as high as 35,000°F
Arc Blast
high-voltage arcs can also produce considerable
pressure waves by rapidly heating the air and
creating a blast
30. Electrical Hazards
Fire:
• Most result from problems with "fixed
wiring”
• Problems with cords, plugs, receptacles, and
switches also cause electrical fires
31. Electrical Hazards
Explosions:
• Occur when electricity ignites explosive
mixture of material in the air
• Note:
o Electricity is source of these hazards
o All hazards are of equal importance
32. Examples of fatal accidents
• Case #1: Worker electrocuted when the ladder come in
contact with overhead power lines
• Case #2: Worker electrocuted when mast come in
contact with high voltage overhead lines
• Case #3: Worker changing energized ballast on light
fixture was electrocuted and fell to the concrete floor
while working from an 8' fiberglass stepladder.
33.
34.
35. Electrical Protection Methods
Power source identification:
• Mark all breakers accordingly for the circuits
they protect
• Mark all disconnect means accordingly for
the equipment they service
• Identify all voltages with proper labeling
36. Employer Requirements
Employer requirements to protect workers:
• Ensure overhead power line safety
• Isolate electrical parts
• Supply ground-fault circuit interrupters (GFCI)
protection
• Establish and implement an AEGCP
• Ensure power tools are maintained in a safe
condition
37. Employer Requirements
• Ensure proper guarding
• Provide training
• Enforce LOTO safety related work practices
• Ensure proper use of flexible cords and
power strips
• Ensure proper identification of power
sources
38.
39.
40. Fire Hazards
Conditions that favor fire development or growth
Fire hazards usually involve the mishandling of fuel or
heat
Fire or combustion is a chemical reaction between
oxygen and a combustible fuel
Source of ignition= Spark, flame and high temperature
are needed
41. Fire Triangle
• The triangle illustrates
the three elements a
fire needs to ignite:
heat, fuel, and an
oxygen
• The fire extinguishes
by removing any one
of the elements in the
fire triangle.
42. Source of Fire Hazards
Types of Fires
• Class A Fires
• Class B Fires
• Class C Fires
• Class D Fires
• Class K Fires
50. Fire Detection Devices
Smoke detectors
require a flow of air in
order to work well
Heat detectors
detect fires where there
is no smoke activated
by the significant
increase of temperature
associated with fire
Flame detectors
react to the movement
of flames.
Editor's Notes
Electrocution is fatal; it means to kill with electrical shock.
Electrocution results when a human is exposed to a lethal amount of electrical energy.
An arc flash is the sudden release of electrical energy through the air when a high-voltage gap exists and there is a breakdown between conductors.
An arc flash gives off thermal radiation (heat) and bright, intense light that can cause burns.
Temperatures have been recorded as high as 35,000°F.
Fire
Most electrical distribution fires result from problems with "fixed wiring" such as faulty electrical outlets and old wiring.
Problems with cords (such as extension and appliance cords), plugs, receptacles, and switches also cause electrical fires.
Explosions
An explosion can occur when electricity ignites an explosive mixture of material in the air.
Note that although electricity is the source of these hazards, and all of these hazards are of equal importance, this lesson focuses on eliminating electrical hazards.
Case #1: Two workers were moving an aluminum ladder. One of them was electrocuted when the ladder came in contact with overhead power lines.
Case #2: Worker was raising a mast on a water well drilling truck when the mast came in contact with high voltage overhead lines, electrocuting the worker.
Provide examples of accidents related to the type of work your audience does. Locate accident summaries on OSHA’s website. Go to: http://www.osha.gov/pls/imis/accidentsearch.html. Within the keyword field, enter a keyword to be searched against. For example, to obtain accident investigations involving electrocutions, enter the key word electrocuted. To view a list of key words, use the keyword list at the bottom of the Accident Investigation Search page.
Power source identification
Make sure that all breakers are marked accordingly for the circuits they protect.
Make sure that all disconnect means are marked accordingly for the equipment they service.
Make sure that all voltages are identified with proper labeling.
(AEGCP) assured equipment grounding control program.