Confined space

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Confined space

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  2. 2. Confined Space Safety out LineCourse objective :contains the requirements for practices and procedures to protect employees in general industryfrom the hazards of entry into permit-required confined spaces (i.e., permit spaces). Thestandard requires employers to develop a written confined space entry permit program andprovide employee training.WHO SHOULD TAKE THIS CLASS?Employees who may enter confined spaces with potential hazards are required to receiveconfined space safety training.Result Expecting after completing this training course students will be able to: • Identify the hazards commonly found in confined spaces, including atmospheric hazards and physical hazards. • Identify the roles and responsibilities of the Entrant and Attendant as defined by OSHA for various personnel during confined space operations. • Understand the use and need for a confined space permit. • Understand basic emergency activities during a confined space emergency, including the hierarchy of rescue. 2
  3. 3. Index tableContents Page No. Suction one ( theoretical ) 51.0 Confined Space Overview 62.0 Hazards and Risk Factors 72.1 Hazard Categories 82.2 Risk Factors 93.0 Flammable Atmospheres 163.1 Causes 163.2 Chemical Toxicology Overview 183.3 Toxic Atmospheres 214.0 Hazards 234.1 Physical Hazards 234.2 Mechanical Hazards 234.3 Importance of Safe Work Procedures & Training 234.4 Importance Creating a Confined Spaces Entry Program 245.0 Risk Assessment & Management 285.1 Ensure Risks Are Known & Control Measures Are Followed 305.2 Importance of a Full Assessment 305.3 Training 315.4 Isolation 325.5 Lock-Out Energy Sources 335.6 Exposure to Product and Hazardous Substances 335.7 Clear or Neutralize Hazardous Substances 345.8 Physical Hazards 345.9 Climatic Factors 355.10 Electrical Hazards 355.11 Access and Egress 355.12 Hazardous Atmospheres 386.0 Emergency Procedures 426.1 What To Do When Work Ceases 437.0 Permit To Work 437.1 Steps of A Permit System 437.2 Advantages of Permits To Work 447.3 Usage 448.0 Job Hazard Analysis (JHA) 498.1 Analysis 498.2 Preventive Measures 509.0 Hazards Evaluation 519.1 Selecting Hazard Evaluation Techniques 3
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  5. 5. Day 1Saturday 18 Sep. 2010 5
  6. 6. Suction (A) Understanding The confined space Theoretical Process CONFINED SPACE1. OVERVIEWConfined spaces may be encountered in virtually any occupation; therefore, theirrecognition is the first step in preventing fatalities. Since deaths in confined spacesoften occur because the atmosphere is oxygen deficient or toxic, confined spacesshould be tested prior to entry and continually monitored. 6
  7. 7. Many workplaces contain spaces that are considered "confined" because theirconfigurations hinder the activities of any employees who must enter, work in, and exitthem. For example, employees who work in process vessels generally must squeezein and out through narrow openings and perform their tasks while cramped orcontorted. The term "confined space" is used to describe such spaces. In addition,there are many instances where employees who work in confined spaces faceincreased risk of exposure to serious hazards. In some cases, confinement itselfposes entrapment hazards. In other cases, confined space work keeps employeescloser to hazards, such as asphyxiating atmospheres or the moving parts ofmachinery. The term "permit-required confined space" (permit space) is used todescribe those spaces that both meet the definition of "confined space" and posehealth or safety hazards.A Broad DefinitionThe various definitions of a Confined Space as cited in standards, codes andregulations may differ slightly but basically they refer to:Enclosed or semi enclosed areas where access and egress may be restricted and/orhazardous conditions may occur while workers are engaged inside.Some definitions also include the following provisions: • Space of a size to enable a person to enter the space and perform assigned work; and • Space not designed for continuous occupation.HAZARDIn relation to a person, means anything that may result in injury to the person or harmto the health of the person.RISKIn relation to any injury or harm, means the probability of that injury or harm occurring. 7
  8. 8. What Makes Confined Spaces Hazardous?A confined space by its definition is an enclosed space or enclosure. This createshazards through reduced air circulation and ventilation. This provides the opportunityfor local concentrations of hazardous or flammable substances to increase to unsafelevels and/or for oxygen levels to decrease to unsafe levels.A confined space is defined in terms of the limited means of entry and exit. This refersto situations where rapid escape, especially rapid egress or where disabled orimpaired persons are involved, may be impeded. These limitations may be due to: • The design of the space (e.g., such as a valve inspection pit where a ladder is required for entry/exit); and • The size, shape and location of the means of entry and exit (e.g., a 1 meter diameter hole at the base of a tank).These design factors may not necessarily be hazardous in themselves (i.e. they do notdirectly cause injury/disease) but they do have the effect of increasing the risk ofserious injury resulting as a consequence of exposure to a hazard. This would includesituations where: • Rapid escape is not possible (e.g., employee working at the bottom of a storage tank. The tank has not been isolated and fills rapidly with water. The employee is not able to reach the access ladder in time); and • Rescue is impeded.Examples of Confined SpacesSome examples of confined spaces include manholes, sewers, boilers, tunnels, pipelines, wells,fuel tanks, ballast tanks, storage tanks, tank cars and tank trucks, vats, process vessels, septictanks, sewage lift stations, vaults, silos, bins, and ventilation and exhaust ducts. Some of theseare easily recognized as confined spaces, while others may not be generally considered as such.For example, deep empty swimming pools, deep trenches, deep open top tanks, pits and roofspaces. 8
  9. 9. 2. HAZARDS AND RISK FACTORSDistinction Between Hazards And Risk FactorsA distinction may be made between the hazards in a confined space (for example,those conditions, substances and materials which are capable of causing death, injuryor harm to health) and those elements which effect the risk of death, injury or harm tohealth. These elements are commonly referred to as "risk factors". Oxygendeficiency, for example, can be considered to be a hazard in a storage tank. Thepresence of decaying organic matter using the same situation could be considered tobe a risk factor as it would increase the likelihood of oxygen deficiency taking place.2.1 Hazard Categories 9
  10. 10. The types of hazards involved have been grouped into the four categories below.There is, of course, considerable scope for overlap. Carbon monoxide, for example, isboth highly flammable and highly toxic. Such hazards are discussed however, in thecontext in which they pose the greatest risk. Carbon monoxide therefore, is primarilyconsidered to be a hazardous substance, being highly toxic. It will burn atconcentrations above 12.5 % but will cause death within minutes at concentrationsabove 1.28 %.1. Oxygen DeficiencyOxygen deficiency is a common cause of death in confined spaces. This can occurthrough the dilution of oxygen levels due to the presence or introduction of other gasesor by chemical reactions which absorb the oxygen within the confined space.2. Flammable AtmospheresThe small spaces involved and lack of ventilation, can lead to concentrations offlammable substances (i.e. dusts, mist, gases) increasing to hazardous levels. Thesubstances involved can include: • residual material within the space (e.g., fuel and solvents); • by-products of chemical reactions (e.g., strong bases such as caustic soda react with metals such as aluminum, chromium and zinc to produce hydrogen gas); and • solvents used in the cleaning of the space (e.g., alcohols and toluene) and contaminants leaking into the space (e.g. LPG or Propane).3. Hazardous SubstancesThe small spaces involved and lack of ventilation can lead to concentrations ofhazardous substances increasing to life threatening levels. The substances primarilyinvolve residual materials within the space and substances used in work processes(e.g., solvents).4. Physical and Mechanical Hazards.Confined spaces such as chemical tank trucks, process furnaces, and industrialboilers may be of irregular shapes and divided into smaller sections by walls, tubes,and baffle plates. They may house both fixed and portable equipment includingstirrers, mixers and agitators. Lifelines may also be severed on projections or tangledup on interior obstacles like conduits, cable hangers and mechanical fittings. The taskof assessing these convoluted spaces for atmospheric hazards is much more difficultsince toxic gases and vapors may become trapped in hard-to-reach pockets. 10
  11. 11. 2.2 Risk FactorsThe above hazards, and their associated risk factors, are fully discussed below. Therisk factors involved in confined spaces are discussed in terms of: • nature of the contents of the space; • by-products of chemical reactions involving substances within the space; • work that is performed within the space; • leakage from any conduits that run through the space; and • introduction of contaminants (below ground tanks). Day 2 Sunday 19 Sep. 2010 11
  12. 12. 2.2.1 Oxygen DeficiencyPhysiology of RespirationThe human body is a biological engine in which the lungs act as both an air intake andexhaust. When air is drawn into the lungs, oxygen passes from the alveoli (the air sacswithin the lungs where gas transfer occurs) into the bloodstream and carbon dioxidepasses from the bloodstream into the alveoli. This process of gas transfer is known asdiffusion.Diffusion operates on the principle that a gas will move from an area of highconcentration to one of low concentration until equilibrium is established (i.e. theconcentration is equal in both areas). When air is drawn into the lungs theconcentration of oxygen in the air is higher within alveoli than in the capillaries thatflow around them. Oxygen then passes from the alveoli into the blood. Conversely, theconcentration of carbon dioxide in the blood is higher than in the air. Carbon dioxidethen passes from the blood into the alveoli. During exhalation the carbon dioxide isthen expelled. 12
  13. 13. Inadequate amount of Oxygen can lead to simple asphyxiation and deathThe amount of oxygen carried by the blood depends primarily upon the concentrationof oxygen within the inhaled air. This is shown by the graph below.As the airborne concentration of oxygen decreases, the amount carried by the bloodinitially shows only a gradual decrease. When the airborne oxygen concentration is10.5 % (i.e. 50 % of normal), the blood is still carrying approximately 85 % of itsnormal level. However, when the airborne concentration falls below 8.4 %, there is amarked decrease in the amount of oxygen carried. The resultant effect upon the bodyis shown in the table below. Oxygen Symptoms Concentration 21 % None (normal oxygen level) 13
  14. 14. 15 % No immediate effects 14 % Fatigue, impaired judgment 10 % Dizziness, shortness of breath, deeper and more rapid breathing 7% Stupor (State of unconsciousness) sets in 5% Minimum amount that will support life 2%-3% Death within 1 minuteAs the table above indicates, oxygen concentrations down to approximately 16 % canbe tolerated. However, this is at the expense of increased demands upon thecardiovascular system. An oxygen concentration of 15 % for example, will show noimmediate effects, but the load upon the cardiovascular system is equivalent to aworkload of three kcal/min.The blood normally holds reserves of oxygen. The blood returning to the lungs (torelease carbon dioxide) still carries over 40 % of the oxygen it held initially. This is whyyou can hold your breath for around 3 minutes without adverse effects. Your body isable to consume this "reserve store" of oxygen. However, if you were to continue tobreathe in an atmosphere containing very low levels of oxygen (where the air drawninto the alveoli has a lower concentration of oxygen than in the blood flowing aroundthem), the diffusion process would operate in reverse. With every breath you take, youwould be expelling oxygen instead of absorbing it. Consequently, your "3 minutereserve" would be depleted extremely rapidly.These points highlight some of the more insidious aspects of oxygen deficiencywithin confined spaces: • If the oxygen depletion is a gradual one, the initial effects may go unnoticed due to their gradual onset. When the symptoms reach a noticeable level, impairment may rapidly follow. • If a person enters a confined space with extremely low levels of oxygen, collapse can occur extremely rapidly as the person exhales oxygen. • If the work performed within the confined space requires less exertion than the effort required to escape from the space, then by the time the employee realizes there is a problem, it may be too late.2.2.2 Causes of Oxygen DeficiencyProcesses Involved 14
  15. 15. A decrease in the oxygen levels can occur through one or more of the followingprocesses: • combustion; • chemical reaction; • dilution; • displacement; and • adsorption.a. CombustionOxygen may be consumed through activities that involve the use of open flames (e.g.,welding, torch cutting, brazing) and by, for example, the operation of compressors andpumps.An additional hazardous substance hazard may also be created through incompletecombustion. This may lead to the creation of carbon monoxide as a combustion by-product. This gas interferes with the bloods ability to transport oxygen and can createproblems even with normal oxygen levels. A Carbon Monoxide level of 0.003% may beconsidered unsafe.b. Chemical ReactionRelevant chemical reactions include the following:c. CorrosionCorrosion is a chemical reaction that involves the conversion of a metal to a metaloxide. Iron pipe-work, for example, in the presence of moisture and air, will rust andcorrode. In other words, the surface of the iron and the oxygen in the air will combineto form rust.d. FermentationFermentation is a reaction usually involving the decomposition of sugars or starchesinto alcohol and carbon dioxide. This can occur in fermentation vats for beer or winemaking, or in silos containing grain that may be subjected to moisture or wetconditions.e. DecompositionThe breakdown of organic material (either in the space or from contaminants such asleaves washed into a drain) involves the absorption of oxygen and the production of 15
  16. 16. carbon dioxide. Where sulfur containing materials are present (e.g., in sewers)Hydrogen Sulfide gas (H2S) may also be produced.f. DilutionThe introduction of other gases into an enclosed space can dilute the oxygen levels.This can occur through venting from conduits, from the presence of gases used topurge the space or from leaking gas cylinders.ExampleA faulty valve on a nitrogen purge line is causingnitrogen to leak into an unused chemical storagetank (dimensions 2.5 m x 2.0 m x 2.0 m) at the rateof 0.5 liter per minute.In very general terms, the oxygen concentration in the tank can be calculated usingthe formula: 2,100% O2= ( --------------------------) x 100 (10,000 + (0.5 x t))where:10,000 = total volume of the tank (in liters) 2,100 = volume of Oxygen within the tank (i.e. 21 % of 10,000) 0.5 = rate of leakage (in liters per minute) t = number of minutesAfter approximately 360 hours, the Oxygen level would be at 10%.After approximately 44 days, the Oxygen level would be 5%.g. DisplacementGases that are heavier than oxygen will over time settle at the bottom of the space,thereby displacing the oxygen within the space. These gases can include residualcontents, chemical by-products (e.g. grain fermentation) or other gases entering thespace. Below-ground spaces are of particular concern in this respect.h. AdsorptionIn some situations, oxygen may bind with the surface of a material within a confinedspace. Example of newly constructed water filtration tanks partly filled with a slurry ofactivated carbon and water from which the water was drained off and the tanks 16
  17. 17. sealed. The following morning two workers entered one of the tanks to smooth out thecarbon bed and adjust the interior sprinkler mechanism. When they did not appear atlunch time, co-workers went looking for them. Their bodies were found on top of thecarbon bed. Subsequent tests showed that 24 hours after closure, the oxygen levelshad dropped to 12%. Other tanks in the area were checked. Some which had beenclosed for several days showed oxygen levels of only 2%.Investigators discovered that the dry, activated charcoal had no effect on the oxygenlevel. However, the damp carbon, which had previously been considered to be a non-hazardous material, had apparently selectively adsorbed ambient oxygen.3. FLAMMABLE ATMOSPHERESLEL AND UELAll flammable vapors, gases and dusts have a minimum concentration below whichpropagation of flame does not occur on contact with a source of ignition. This is knownas the lower flammable explosive limit (LEL). There is also a maximum concentrationof vapor or gas in air above which propagation of flame does not occur. This is knownas the upper explosive limit (UEL). A gas is explosive only between its LEL and UEL.For example, methane is explosive only when mixed with air in a concentrationbetween 5% and 15%. Because air is only 21% oxygen, most concentrations are quitelow. Consequently, when mixed with air many of these gases rapidly drop below theminimum level. In confined spaces however, this dilution may not occur. This can bedue to: • the small size of the space involved; • the lack of air flow; and • the gas concentrating in the bottom of the space (if it is heavier than air) or the top of the space (if it is lighter than air).3.1 CausesFlammable atmospheres can arise in the following situations:a. Inadequate Venting of ContentsOne of the most frequent causes of explosions in confined spaces is inadequateventing. For example, if a tank that has a capacity of 100,000 liters and has only been99% vented, this means there is still 1000 liters of the product, for example, petroleumvapors, which could settle and form an explosive mixture.b. Cleaning Agents and Solvents Used In Work ProcessesMany activities conducted in confined spaces involve cleaning and refurbishing. Suchprocesses may require spray painting or cleaning by use of solvents, both of which 17
  18. 18. can be of a flammable nature. For example, a painter had just finished spraying theinterior of a 21-foot long by 11-foot diameter horizontal tank. He passed a ladder andportable electric light through the manhole to a second man standing outside. Thisemployee had just laid the ladder down when he heard a muffled explosion. Turningtowards the tank, he saw flames inside and noticed that the painters clothes were onfire. After being pulled out of the tank, the painter explained that he inadvertentlybumped his spray gun on a second lamp inside. When the bulb broke, it ignited thepaint vapors. The painter died in hospital three days later.c. Chemical Reactions of Materials Within SpacesStrong bases such as Caustic Soda, react with some metals such as aluminum,chromium and zinc to produce hydrogen gas. The toxic effect of a combination of two chemicals may be far greater than the sum of the toxic effects of each.d. DecompositionDecomposition of organic material has already been noted in the Oxygen Deficiencysection. This can lead to the formation of methane and hydrogen sulfide. If theconfined space contains strong bases or acids, these may react with metals toproduce hydrogen gas. If the space is enclosed at the top, this could lead to theformation of a pocket of hydrogen. For example, an aluminum ladder placed into aincompletely empty tank of caustic soda, or hydrochloric acids used as a strippingagent on iron pipe work.e. Leakage of Cylinders and ConduitsLeakage of cylinders can occur as a result of the nature of the work being performed inthe space. For example, cylinders containing LPG or propane gas may be used for hotwork and if they have faulty seals, there may be the accidental release of their gaseswithin the space. Existing conduits and pipes, on the other hand, may leak theircontents due to fatigue or corrosion that has occurred over time.f. ContaminantsFlammable products such as petroleum and LPG are heavier than air. Consequentlythey can flow below ground level confined spaces. 18
  19. 19. An example of the above occurred when a sewer contractor, who was installing aninterceptor line, experienced an explosion and fire caused by an accumulation of LPGin the soil. The LPG had leaked from storage tanks and accumulated on the watertable. As the ground water seeped into the excavation, the LPG accumulated in theditch atmosphere, as well as in the open-ended sewer line. A spark from the backhoeprovided the ignition.g. Elevated Oxygen LevelsElevated oxygen levels occurring through leaking pipes or cylinders can affectflammability levels and cause things to combust more readily. As the level of oxygenincreases above 21% the following occurs: • flammable substances ignite more readily; • they burn at lower concentrations; and • they burn more rapidly.Potential sources may include oxy-acetylene cylinder sets, and where oxygen issupplied through pipe-work.3.2 Chemical Toxicology OverviewDose-Response Relationships  The toxicity of a chemical is defined by the amount (dose) of the chemical that will produce a response. The greater the dose, the more severe the response will be.  There is a balance between toxicity and dose;  Dose is the AMOUNT of something you are exposed to, or come in contact with;  The less the toxicity, the greater the dose you can tolerate without ill effects;  The greater the toxicity, the less dose you can tolerate without becoming sick. 19
  20. 20. High Toxicity - Low DoseFor example, acetone is a highly toxic chemical. However, you could work safely withit, if you were outside or in a well-ventilated room where your dose would be very low.As the chart below shows, your hazard potential for working with acetone in a well-ventilated room would be low.Low Toxicity - High DoseExample: Nitrogen gas has a low toxic rating. It is found in great amounts in the air webreathe. However, if you were in a confined space that had only nitrogen gas in it (avery high dose), you would soon die because of the lack of oxygen. As the chartindicates, your hazard potential for working in a room filled with nitrogen would behigh.Affecting Factors  The Amount Entering the Body. (D)  The Length of Time.(D)  The Rate of Absorption into the Blood.  The Physical Nature of the Chemical. (T)  The Chemical Nature of the Chemical. (T) 20
  21. 21.  The Age of the Individual.  The Health of the Individual.Measuring the Toxicity  PARTS PER MILLION - ppm  PARTS PER BILLION - ppb  PARTS PER TRILLION - ppt  LETHAL DOSE - LD50  LETHAL CONCENTRATION - LC50  THRESHOLD LIMIT VALUE - TLV  IMMEDIATELY DANGEROUS TO LIFE AND HEALTH – IDLH  PERMISSIBLE EXPOSURE LIMIT - PELLETHAL DOSE - LD50The LD50 is the amount of a material that, when administrated to laboratory animals,kill half of them. The expression is made in milligrams of the substance administeredper body weight of the animal expressed in kilograms (mg/kg).When extrapolated to humans, the lethal dose of an average person who weighs wkilograms is LD50 x w.LETHAL CONCENTRATION - LC50The LC50 is the concentration of a material that, normally express as parts per million(ppm) by volume, that when administrated to laboratory animals, kill half of themduring the period of exposure.THRESHOLD LIMIT VALUE • The TLV is the upper limit of a toxin concentration to which an average healthy person may be repeatedly exposed on an all-day, everyday basis without suffering adverse health effects. • Gaseous substances in air, the TLV is usually express as parts per million (ppm). • Fumes or mist in air, it is expressed in milligrams per cubic meter (mg/m3). • TLV values are set by the American Conference of Governmental Industrial Hygienist (ACGIH). • PEL: Permissible Exposure Limit. Set by OSHA 21
  22. 22. • TLV (TWA) is an 8-hour time-weighted average believed to be the average concentration to which most workers can be exposed during an 8-hour workday, day after day, without harmful effects. • TLV (STEL) is a 15 minute “short term exposure limit” should not be exceeded at any time during the work day.Ceiling (C) is a maximum concentration never to be exceeded even instantaneously. • An IDLH level represents a maximum concentration from which one could escape within 30 minutes without experiencing any escape-impairing symptoms or any irreversible adverse health effects.IMMEDIATELY DANGEROUS TO LIFE AND HEALTH - IDLHIDLH levels are published for many substances by OSHA and NIOSH.In practice, when the concentration of a toxic substance in a given area is known,IDLH levels may be used for determining whether self-contained breathing apparatusis needed when entering the area. If the concentration exceeds the IDLH level,positive- demand, self-contained breathing apparatus should be used. EXPOSURE MODEL LC50 T LD50 I TLV M PEL E SAFE EXPOSURE 03.3 Toxic AtmospheresToxic atmospheres may be defined as atmospheres that contain substances that havethe inherent ability to cause harm to the body. In confined spaces toxic atmospheresmay result from: • Products • By-Products; and • Work Processes. 22
  23. 23. a) Products As per flammable atmospheres - inadequate venting or purging or toxic products may be introduced into spaces in the form of solvents used as cleaning agents. b) By-Products By-products of chemical reactions, involving contents, can occur. For example: Hydrogen sulfide is formed in sewers. It is both highly flammable and toxic by inhalation. Nitrogen oxide toxicity can occur in grain silos. Nitrogen oxides can be generated in such processes and locations as intermediates or as rejected waste products. As these oxides may undergo inter-conversion by decomposition, interaction or reaction with oxygen, they are rarely released pure into the atmosphere, but occur as mixtures, the composition of which depends upon the source and the local conditions. Carbon dioxide may be produced from or through fermentation. For example, a worker entered a molasses pit through a 53 cm manhole and immediately called out for help. Two other men entered in response to the workers cry. All three were fatally overcome. Measurements made 10 days later showed that the atmosphere in the pit contained 1% oxygen, 3% carbon dioxide and 5,000 ppm ethanol, strongly suggesting that the molasses had fermented. c) Work ProcessesWork processes that may involve solvents, or may generate welding fumes andcarbon monoxide, may result in very hazardous or toxic work environments.SolventsTwo teenage boys died after being overcome by fumes from a degreasing vat atNoble Park, Victoria, in September 1981. The solvent being used was the highly toxicmaterial trichloroethylene. Both boys were in their first jobs, and they were given thetask of cleaning out the sludge from the bottom of the vat. They were given noinstruction, or warning of the toxicity of the material.Welding FumesWhen welding is performed in confined spaces, appropriate and sufficient mechanicalventilation must be provided and maintained to keep fume concentrations withinacceptable levels. Contaminated air must be exhausted from the work space anddischarged clear of the source of intake air. 23
  24. 24. Carbon MonoxideToxic atmospheres resulting from carbon monoxide can occur if proper work processplanning is not employed. For example, in Australia in 1974, two men died fromcarbon monoxide poisoning when they operated a petrol-driven pump inside a watertank. The operation of such a pump is, of course, quite safe in the open, but extremelyhazardous in a confined space.4. HAZARDS4.1 Physical HazardsExamples of physical hazards include energized electrical conductors, movingmachinery and temperature extremes. Unlike most atmospheric hazards which areinvisible, many physical hazards can be detected by our senses. For example, we cansee unguarded machinery and feel the effects of temperature extremes. Although wecannot actually see electricity, we can infer potential electrical hazards from things likeflexible electrical leads, switch-gear and exposed electrical components.4.2 Mechanical HazardsMechanical hazards may be present in confined spaces both as fixed and portableequipment. Commonly encountered fixed equipment includes mixers, agitators blenderblades, fans and stirring augers. Conveyors may also be found in spaces where solidmaterials such as grain or fertilizers are handled, processed or stored.4.3. Importance of Safe Work Procedures & TrainingIt is therefore essential that personnel at workplaces where confined spaces may beencountered be trained to identify potentially hazardous situations and able to callupon skills or skilled operatives to assess and implement safe procedures prior to workcommencing. It must also be emphasized that wherever practicable all alternatives toconfined space entry must be considered.The skills and training referred to extend from early identification and assessment ofpotentially hazardous situations through to appropriate emergency and rescueprocedures. This lecture covers the requirements for Emergency Response but doesnot include detailed information on Rescue Techniques, as this is a specialist field. 24
  25. 25. The importance of early identification of potentially hazardous situations is illustratedby accident records that show more than half the fatalities associated with confinedspaces occur among ill prepared personnel attempting to rescue co-workers indistress. This indicates that both workers and would-be rescuers have encounteredunexpected hazards that they were not adequately trained to identify and deal with. Italso indicates that systems of work and procedures were either inadequate or notadhered to.4.4 Importance Creating a Confined Spaces Entry ProgramIt is essential that persons having control of workplaces where work in confinedspaces may be necessary ensure that personnel are competent to readily identify suchsituations and are provided with clear and precise guidelines in the form of a confinedspaces entry program that must be enforced.The confined spaces entry program should include provision for Entry Permits thatdetail the type of work to be conducted and the results of a risk assessment that mustbe completed prior to entry.Small or enclosed spaces of some description can be found in many workplaces butmost are not a risk to persons engaged there during normal operations. Problemsdevelop where a combination of difficult access and egress occur with the possibility ofexposure to hazards such as those described in the first lecture of this series.It is important, however, to recognize that confined space does not necessarily meansmall-enclosed space. A combination of difficult access with a risk of exposure to aphysical hazard or suspect atmosphere (such as might be found in a ships hold, apowerhouse boiler or a bulk oil tank at a refinery) would be deemed a confined spacesituation.Common problem areas for hazard identification are explained below.4.4.1 Unfamiliar HazardsProblems could occur where building or maintenance work is being completed andemployers find themselves faced with non-routine situations and hazards that staff arenot trained to identify or address. These problems can be exacerbated wherespecialist contractors are engaged who may introduce new hazards to an installationthey have little knowledge of.Physical Shape of the Work-Site ChangesWork in confined spaces may be difficult to monitor within workplaces (such asconstruction sites and shipyards) where numerous industrial processes andprocedures are being conducted at the same time as the physical shape of the worksite is constantly undergoing rapid change. 25
  26. 26. Structural Steel Skeleton in a ShipyardInadequate Hazard IdentificationIn the practical sense, it is important to maintain a focus on the risk factors associatedwith the work site and the work to be conducted rather than rely upon strictinterpretation of one or other of the various definitions of a confined space. Experiencehas shown that hazardous situations can be ignored due to misinterpretation ofdefinitions that cause workers to incorrectly assume there to be little or no risk.One such situation occurred where an upholsterer was overcome by vapors whileapplying surface coatings in a below decks cabin of a boat. No special precautionswere taken as the situation was not considered a confined space due to the cabinbeing a regular workstation under normal operating conditions (contrary to mostdefinitions of a confined space). A risk assessment should have caused the risk ofexposure to vapors to be considered and appropriate ventilation provided. Theappropriate interpretation of definitions should have been that the cabin was not aregular workplace or workstation for an upholsterer applying potentially hazardousproducts to large surfaces. Confined Space in a Boat Cabin under Construction 26
  27. 27. The Hazard Develops Over TimeMany projects in industries such as steel fabrication may start as simple steelskeletons but gradually develop into enclosed tank like structures that ultimatelybecome confined spaces. Such projects include the hulls of ships and the bodies ofroad and rail tankers. Confined Space created during Construction of a Ships HullThe tendency for workers in these industries is to overlook the hazards or ignore therisks as the confined space is formed. Although the enclosed spaces may inthemselves not pose any significant risk, the introduction of metal work processessuch as cutting and welding into such spaces does. These are also typical areaswhere confusion arises if a focus is maintained upon the definition of a confined spaceas opposed to assessing the risk as the project develops.It should be noted that operations to repair such units that have previously been inservice face increased risks due to the unknown or uncertain nature of the internalenvironments resulting from the products carried. Road Tanker damaged by a Blast during Hot Work 27
  28. 28. Similarly, the construction of fibreglass units such as boats and swimming pools maycommence as open structures and develop into potentially hazardous confined spacesas construction nears completion. Toxic and flammable vapors from the fibreglassprocess may collect where workers have restricted means of egress. Fibreglass Boat Hull under ConstructionEvery Situation Requires Hazard IdentificationIn industries or utilities such as water supply and sewerage management, work inconfined spaces such as inspection pits and sumps is commonplace. The recognitionof such a place of work as a confined space may be well understood and accepted buteach situation still requires formal hazard identification as a start to the assessmentprocess. It may be that the hazards that deem one such installation to be a confinedspace may differ from those to be found in another and complacency or assumptionson the part of workers can lead to tragedy. This is especially important wheremovements of air are likely as hazardous atmospheres can form in pockets andenvelop unsuspecting workers operating in tunnels, trenches and pits that formintegral parts of larger systems. It is also not uncommon for fumes from internalcombustion engines or escapes of natural gas to accumulate in below ground spaces. Open Pit over a Sewer on a Construction Site 28
  29. 29. 5. RISK ASSESSMENT & MANAGEMENTWhat is a Risk Assessment?  An assessment of the risk is nothing more than a careful examination of your work area with regard to what could cause harm to people.  To weigh up whether the precautions in place are sufficient or if more may be required. The aim is to eliminate or reduce the risk to an acceptable level.  A risk assessment is the systematic identification of potential hazards in the work place by personnel as a first step to controlling the possible risks involved.In safety, management terms the evaluation of risk involved in a given process oractivity centers around the following questions.  What is the hazard (potential to cause harm)?  What is the likelihood of exposure (in the given circumstances occurring)?  What is the likely outcome (taking into account any existing controls)?HazardsLook for hazards that could result in harm in your area, activity, process or equipmentthat you are using.Hazards may be physical, chemical, biological or ergonomic in nature.Physical hazards include the potential to harm posed by inadequate or excessivelighting, temperature, noise/vibration, pressure, humidity and radiation.Chemical hazards are associated with those solids, liquids, gases etc, with thepotential to cause injury or harm to those exposed.Biological hazards are more specialized but include moulds, fungus, spores etc.Ergonomic hazards are the potential to harm due to poor workplace design.The consideration of the man/machine interface e.g. computer workstations, lifting andhandling, slipping and tripping.How do you perform a risk assessment?There are eight steps to performing a satisfactory risk assessment 1. Focus for assessment 2. Identify activities 3. Identify hazards 4. Who at risk 5. Evaluate risk 6. Review controls 7. Record Decisions 8. Review Regularly 29
  30. 30. How do you assess risk levels?Risk levels are categorized in a numbered format. Each hazard is given a rating andthis is multiplied by the probability that these hazards will occur, as shown in thefollowing equation.Risk level = Hazard severity x Likelihood of occurrencePotential hazards in the workplace • Portable and fixed electrical appliances • Tools and equipment • Handling of materials • Trailing cables • Access and egress • Fire exits • Heating and ventilation • Sanitary conveniences • Chemicals • Cleaning substances • Dusts & powders • Biological hazards (bacteria, viruses, etc.) • Repetitive actions • Working alone • StressIdentified HazardsThe following hazards have been identified in the operation of This Corporation:Assessed Hazards • Burns from fire • Inhalation of smoke or chemical • Burns from electrical/gas plant • Cuts from plant • Ingestion of Chemicals • Contact with electricity • Blood borne pathogens • Airborne harmful substances • Handling of hazardous materials & spillage 30
  31. 31. Consequence Probability 1 2 3 4 5Safety & Common or Known to Could Not likely PracticallyHealth repeating occur or “It occur, or to occur impossible occurrence has “I’ve heard happened” of it happening” 1 1 2 4 7 11 2 3 5 8 12 16 3 6 9 13 17 20 4 10 14 18 21 23 5 15 19 22 24 255.1 Ensure Risks Are Known & Control Measures Are FollowedOnce a confined space and the associated hazards have been identified, it is essentialthat systems and procedures be followed to ensure that workers are not exposed tounacceptable risks. It is also necessary to ensure workers are aware of such risks andunderstand procedures and their responsibility to comply with them.Experience has shown that many employers and workers fail to implement appropriatesystems for safe work in confined spaces because they fail to recognize the risks orfind it convenient to ignore precautions where productivity or worker comfort may becompromised. The policy must be, "If in doubt, do not enter!"5.2 Importance of a Full AssessmentHaving identified a confined space situation it is necessary to assess the risks andconsider the means by which those risks can be eliminated or minimized. Assumingthat entry is unavoidable, it is essential, due to the degree of risk, that consideration begiven to the hierarchy of control when selecting appropriate control measures ratherthan simply relying upon personal protective equipment.Although few confined spaces situations will include all the hazards and risk factorscovered in the two lectures in this series, it is vital that the possibility of them occurringbe considered. It is also vital that the assessment includes consideration of the natureof the plant or installation being worked upon as well as the work to be conducted andany interaction that may occur.5.2.1 Special Precautions May Be Necessary 31
  32. 32. Special precautions may be necessary, especially where potentially hazardous surfacecoatings are to be applied or hot work of any kind is to be conducted. Such specialprecautions should be documented on the Entry Permit or an appropriate Hot WorkPermit that should be issued where any process is to be employed that wouldintroduce a source of ignition.5.2.2 Determine the Degree of RiskIt is also important during the assessment phase to realistically gauge the degree ofrisk and to ensure that the control measures to be implemented are practicable. Whereworkers and employers fail to gain a real understanding of the hazards and risk factorsinvolved there can be as much a tendency to over compensate, as there is tounderestimate the control measures required. This can cause workers to beencumbered with unnecessary personal protective equipment during the course ofexacting operations.5.2.3 Select, Train & SuperviseIt is also necessary during the assessment phase to consider the suitability orotherwise of the personnel who will be required to conduct the work. The physicalcapabilities and fitness of individuals needs to be considered, as does the level oftraining. A Responsible Person should be appointed to supervise the work, and certainpersons should be authorized to conduct essential duties.5.3 Training5.3.1 Confined Spaces Entry ProgramIt is essential that persons involved with confined space entry receive appropriatetraining in all aspects of the work including an understanding of all relevant systemsand procedures. A confined space entry program should coordinate and document thetraining and skills development of workers and should include hazard identification andrisk control, use of equipment and individual responsibilities. Training should alsoinclude emergency response and first aid.5.3.2 Responsible Person Must be AppointedA Responsible Person should be appointed (often the supervisor) to take overallresponsibility for the confined space work. This person should have a totalunderstanding of all aspects of the work, be trained to use all equipment and becompetent to coordinate operations in the event of emergency.5.3.3 Observers Responsible For Emergency Response 32
  33. 33. Observers must be appointed and trained to the same level as the persons enteringthe confined space, as they are responsible for emergency response and are usuallypart of the rescue team. In many instances, the observer is also a skilled worker andmay change positions at breaks or shift changes. This alternating of roles, wherepracticable, helps to build trust and commitment between team members.Observers should be capable of being in continuous communication with those in theconfined space. They should also be able to observe those in the confined space ifpracticable. They should also operate and monitor equipment used to ensure safetyduring entry and work in a confined space. In addition, if necessary, they shouldinitiate rescue procedures.5.3.4 Emergency Response TrainingAppropriate training should also be provided for those associated with the provision ofequipment and worker support even though they may not personally be required toenter or work in the confined space. Rescue workers require specialist training andalthough they may not necessarily be part of the team conducting the actual work theymust be available in the immediate area in case of emergency.Practice drills and rescues are also an essential part of confined space training. Theprocedures must be well rehearsed and followed at all times to ensure those reactionsare automatic. Each practice drill should be assessed and procedures modified toaddress any problems identified. Stand by personnel must be trained to adhere toapproved procedures and not rush to the aid of a co-worker in distress.5.4 Isolation5.4.1 Isolate or Disconnect Pipes & DuctsAll plant, equipment and sources of energy connected to the confined space must betotally isolated or disconnected. All connecting pipes or ducts must be physicallydisconnected, blanked off or otherwise sealed. It is not adequate to simply shut offvalves, as it is not uncommon for them to leak. Where the closing of valves is the onlyoption then two in the same line must be locked out with a bleed between them toensure no equalization of pressure should one leak.ExampleWorkers at a fruit processing factory were exposed to steam that was introduced intoholding tanks where they were working when valves connecting the tanks to otherparts of the production line opened unexpectedly.5.5 Lock-Out Energy Sources 33
  34. 34. All sources of electrical energy and connections to remote equipment associated withthe plant being entered must be isolated and locked out. Particular attention must bepaid to any automatic start up or shut down procedures, especially where computersare utilized in control systems. Any sources of mechanical energy or mechanicaldrives such as agitators, gears or shafts etc. must be identified and eitherdisconnected or otherwise disabled. Other components that may be free to move andthereby constitute a risk to workers must be chocked or locked out.ExampleA worker was crushed when working on a semi-automatic brick-pressing machine thatwas activated by a remote limit switch. The main press had been isolated from thepower supply but a secondary unit that forced raw material into the press had not.Further information on lock out and isolation procedures can be found in the lectureLock-Out and Tag Out in the Risk Control section of this series.5.6 Exposure to Product and Hazardous SubstancesImportance of AssessmentWhere maintenance, repair or refurbishment of plant or an installation is to beconducted it is essential that assessment be made of the risks associated withpossible exposure to product from that plant prior to entry. Workers required to enter aconfined space or an enclosed area must be made aware of any potential hazards andequipped with appropriate knowledge and equipment to tackle those hazards shouldthey be encountered.ExamplesWorkers were overcome when exposed to toxic fumes at a chemical plant when theyentered a large open pit to complete maintenance work. No assessment had beenconducted to determine the product that had been held in the pit and no testing of theatmosphere conducted even though hazardous substances were the products of theplant.A product that is not necessarily hazardous in itself may become so in a confinedspace. There have been situations where workers have been overcome by oxygendeficiency caused by displacement of air by food derivatives when entering vats atfood manufacturing plants, mistakenly confident that any atmosphere associated withfood would have to be harmless. 34
  35. 35. Typical Confined Space in a Food Processing Plant5.7 Clear or Neutralize Hazardous SubstancesWhere risk assessment identifies substances remaining in plant and systems underrepair, provision must be made for appropriate cleaning or purging. Areas wherehazardous substances may be found should be placarded and additional informationshould be sought from management records and Material Safety Data Sheets toensure that all hazardous properties of the product or substances are cleared orneutralized.5.8 Physical Hazards5.8.1 Consider the VicinityThe physical hazards that workers may be exposed to in confined spaces are manyand varied and include environmental factors. Consideration should also be given toany work or treatment being conducted on the exterior of the confined space or in thevicinity.5.8.2 Barricade, Sign-Post & Deal with Physical HazardsWherever possible the area or plant in question should be roped off or barricaded andsign posted to indicate that confined spaces work is being conducted. Receivers orholding tanks in production lines or process plants must be totally isolated fromassociated machinery and allied processes and procedures. Where railway rollingstock is being entered, wagons should be parked on side rails with points locked out orthe rails to the work area scotch blocked to prevent accidental shunting. Roadtransport units should have barriers at each end to prevent other units fromaccidentally bumping. Trenches or pits should be cordoned off to prevent traffic ormachinery from approaching. Where entry is required to furnaces or boilers,precautions must be taken to ensure workers are protected from possible falls of dustand debris or damaged linings such as refractory bricks, etc. 35
  36. 36. 5.9 Climatic FactorsPossible exposure to environmental factors (such as extremes of heat and cold, orwater entering the work site) must be considered. Where possible, enclosures shouldnot be exposed to the heat from the summer sun as internal temperatures can soar,giving rise to the risk of heat stress for workers or possible release of toxic fumes.Similarly, precautions should be taken wherever possible to ensure that internaltemperatures are not allowed to fall, or rain water enter the confined space due toexposure to adverse weather conditions. It is especially important to consider suchenvironmental factors where workers may be required to enter spaces associated withstorm water or drainage that could be subject to flash flooding.5.10 Electrical HazardsAll sources of electrical power provided for the confined spaces work must be lowvoltage where possible or provided with earth leakage protection that is situatedoutside the confined space. It is recommended that portable electric hand tools bedouble insulated. In some situations it may be necessary to provide an electricity killswitch for the observer so that all power can be instantly isolated in the event ofemergency.5.11 Access and EgressRequirementsTwo aspects of access and egress must be considered where confined space entry isrequired. 36
  37. 37. 5.11.1 Normal Access & EgressThe first is for safe controlled passage under normal or routine conditions whereworkers are aware and prepared for unavoidable restrictions. The need for swiftevacuation in the event of emergency or alarm must be taken into consideration at thistime. Confined Space Access Platform showing Emergency Chute5.11.2 Rescue of Injured WorkersThe second area of consideration is the rescue of an incapacitated worker. Althoughrescue procedures are not included in this lecture it is vital that consideration be givento the potential difficulties that may be encountered should such a situation eventuate.At this stage the need for a safety harness and a means of lifting or removing anincapacitated worker from the confined space should also be considered.5.11.3 Prevent Falls During Access & EgressRisks associated with restricted access and egress include falls from heights, falls intodepths or voids, restricted openings and/or obstacles within the path of workers.The risk of falls is common where access is required to large vessels or structures withinspection ports or hatches at or near the top. Difficulties can be caused not only bythe need to gain access to the point of entry from the outside but also from the inside.Although suitably erected and secured ladders may suffice for some simple tasks,such as inspection in low risk areas, they are not sufficient where equipment isrequired to be ported or in foreseeable life threatening situations that may requirerescue or assistance. The risk of injury from falls must also be considered whereworkers are required to enter sunken areas or where breaks in the level of floors arelikely to be encountered. 37
  38. 38. Where access is required at heights for other than the simplest operations it isessential that a working platform or scaffold of some description be considered. Thisshould provide for a secure point of entry for those entering a confined space as wellas a safe workstation for those observing and monitoring operations. Such workplatforms would also facilitate the transfer of equipment in and out of the confinedspace and provide a secure base for any emergency or rescue procedure.5.11.4 Size of Openings for Access & EgressRestricted openings can cause major problems for confined space workers, especiallywhere access must be gained through hatches or ports designed for product ratherthan personnel. Any such opening to be used for access and egress of workers mustbe of a minimum size that may vary with the requirements of local regulations. It is vitalthat any such means of access is assessed with due consideration of the physicalcharacteristics of all personnel that may be called upon to enter and any foreseeablesituation that may arise. It is not acceptable to simply utilize an opening that canaccommodate only the smallest worker or workers in a non-stressful situation. In manysituations, it can be virtually impossible to retrieve an unconscious worker through anaccess way that was difficult to negotiate when conscious.5.11.5 Consider Creating a Temporary OpeningThis vital area is one where the hierarchy of control must be considered. Workers areoften exposed to unnecessary difficulties associated with access and egress whenother simple measures, such as the provision of a temporary hatch or opening, couldvery easily be provided and closed upon completion of the work. Secondary openingssuch as these would also provide for improved ventilation and in some situationsimproved light. Temporary Access Hatch in the Hull of a Ship 38
  39. 39. 5.11.6 Ensure All Obstructions Are IdentifiedObstructions within confined spaces must also be considered prior to entry. Whereinspection from the outside is not sufficient to give clear indication of obstructions thenplans or advice from those with knowledge of the installation should be obtained. It isnot acceptable to allow a worker to enter a confined space with little or no knowledgeof the interior and assume they will find their way around. If information cannot beobtained that will allow for knowledgeable assessment to be made prior to entry, thenother means of completing the work must be considered or additional precautionsimplemented.5.12 Hazardous AtmospheresHigh Risk to WorkersThe internal atmospheres of confined spaces may be flammable, toxic, oxygendeficient or oxygen rich, which may give rise to risk of fire and explosion or impairedphysical capability for persons entering. The composition of atmospheres can alsochange very rapidly especially if residues or deposits are present or the space noteffectively isolated.The result of explosive ignition in a confined space can be catastrophic and has beenknown to blow tanks apart. The risk of workers encountering atmospheres hazardousto life is also very real and all possible measures must be taken to test and make safeor ensure that airline respirators are utilized.5.12.1 Use Gas Detector to Monitor AtmosphereThe first stage of assessment is to consider the use or product to which the area hasbeen subjected. It is also essential that records be maintained of any cleaning orpurging procedures that have been conducted. It is also vital to ensure that no closedor hidden compartments have been neglected or overlooked.It is also necessary, in all but the mostobvious situations where a hostileatmosphere is not a consideration, to testthe atmosphere prior to entry. Testingmust be conducted at least daily or at thestart of each shift and be monitoredcontinuously whenever workers are inside. 39
  40. 40. Common Gas DetectorA gas detector of some description will be used tomeasure the levels of various flammable gases andoxygen present in the atmosphere. Most gas detectorsare equipped with alarms that activate when oxygenlevels fall below 19% or climb above 21%, which is thenormal safe range for human respiration. The type ofgas detector or monitor usually used in such situationsalso sound alarms when hazardous levels of carbonmonoxide occur, or concentrations of flammable gasesthat exceed 5% of the lower explosive limit (LEL) aredetected.LOWER EXPLOSIVE LIMIT (LEL)It is important to understand that the LEL is the lowest concentration of flammable gasin an atmosphere that will sustain combustion. The alarms on gas detectors areusually set to activate at 5% of that level, as is required by most standards and codes,not when flammable gases reach 5% of the total atmosphere. Steel Tank Destroyed by a Blast during Confined Space workMonitoring Is Still Required Even If Gas Free Certificate IssuedWhere confined spaces have been purged or cleaned, usually with steam, it is oftenthe practice to issue a Gas Free Certificate. Such Certificates should only be taken asan indication that a unit or space has been cleaned and should not be taken as aguarantee that the internal atmosphere will continue to be safe. Testing and monitoringis still essential. 40
  41. 41. Day 3Monday 20 Sep. 2010 41
  42. 42. 5.12.2 Take Appropriate Precautions When TestingIn larger confined spaces, or where movement of air islikely, it will be necessary to test the atmosphere atextremities or in connecting areas if they cannot beisolated.A common mistake by workers about to enter confinedspaces is to test the atmosphere only at the point of entry.Another common mistake is to test at point of entry andthen enter to test extremities without appropriateprecautions being taken. This can cause them to actuallyfind the hazardous atmosphere for which they are testingbut to not be prepared or protected when they encounter Confined Space workerit. This is especially true where heavier than air gases with Airline Respiratorcollect at the bottom and extremities of enclosed areas.It is vital that where there is any possibility of encountering a hazardous atmospherethen full protective measures, such as airline respirators that can guarantee a safesupply of respirable air, must be used until the atmosphere is proven to be safe.Eliminate Cause If Monitoring Detects DangerWhere contamination is detected at any time after an atmosphere has been declaredsafe it is essential that steps be taken to determine the cause and appropriate actiontaken to eliminate the source. It is not acceptable to simply purge and re-enter whentesting equipment indicates the contaminant levels to be reduced to acceptable levels.If Safe, Provide Mechanical VentilationWhere the atmosphere can be guaranteed to be safe, mechanical ventilation shouldbe provided to maintain a flow of fresh air during the period of occupation. The supplyof fresh air must also be adequate to purge any contaminants from the work processesbeing conducted.If Unsafe, Apply Hierarchy of ControlWhere the atmosphere cannot be guaranteed, appropriate protective measures mustbe maintained but with the hierarchy of control being considered at all times.5.12.3 Monitoring and ObservationWhat the Observer Must Do 42
  43. 43. Where an enclosed workplace is identified to be a confined space, no person is toenter unless an observer is appointed and positioned at the point of entry. Theobserver must be identified on the Entry Permit and must attend at all times theconfined space is occupied. He or she must have received appropriate training in allaspects of the work in hand and understand how to use, read and interpret anyequipment being used to monitor the internal environment. They must also beconversant with emergency procedures and in constant communication with theoccupant of the confined space.6. EMERGENCY PROCEDURESProvision must be made for rescue of the occupant should an emergency arise, andprocedures and equipment must be appropriate for the hazards likely to beencountered. The rescue personnel will therefore by necessity need to be trained andequipped to at least the same level as the occupant in relation to safe work in confinedspaces.Where more than one person is likely to be working in a confined space the provisionfor rescue must take this into consideration. Where several confined spaces occur inclose proximity, for example, where three tanks or boilers are being constructed nextto one another, one designated rescue team may be appropriate. However, should anemergency arise in one it will be necessary for work to cease in all confined spaces 43
  44. 44. and personnel evacuated until the emergency is over and the rescue team is againfree to respond.6.1 What To Do When Work CeasesWhen work ceases for breaks or end of shift, all sources of potential hazard must beremoved from the space and the area rendered safe. Equipment such as spraypainting guns or potentially hazardous products such as paints or surface treatmentsmust be removed. Gas lines for cutting and welding equipment must be turned off andremoved. At the end of a shift all electrical supplies would normally also be turned off.However, during short breaks the low voltage electricity would usually be maintainedfor lighting, as would any equipment for the monitoring of the internal atmosphere.Upon completion of the confined space work, it is necessary for all personnel to beaccounted for and entry permits to be signed off and submitted to the responsibleperson.7. PERMIT TO WORKA permit to work is formal written authority for persons, usually trades-persons, tocarry out work including maintenance on plant, a building or an item of equipment. Thepermit to work is issued by an authorized person. This person must have a clearunderstanding of the equipment, be aware of any hazards that may be involved and betrained in the operation of the permit to work system.The permit is a written statement by the authorizing person that hazards associatedwith the task have been identified, assessed and necessary control measures put inplace. Any special precautions to be taken by the trades-person are clearly definedand the authorizing person states if it is safe to carry out the task.A permit to work does not include instructions to the trades-person on how to performthe work for which they are specially trained, nor is it a reflection on their competency.7.1 Steps of a Permit System 1. The job is identified and authorized person is consulted. 2. Plant or item is prepared for maintenance and is inspected by authorized person. 3. Permit prepared and precautions are entered. 4. Permit discussed with trades-person at the work site. 5. Permit is to be signed by authorized person and trades-person. 6. Original of permit is kept open in the supervisors office and the job copy of permit is on the job with the trades-person. 7. Original of permit is signed off by trades-person. 8. Original of permit signed off after inspection by authorized person. 9. Job completed, or permit ended. 44
  45. 45. 10. Original of permit is filed for reference. 11. Job copy of permit discarded. 12. Regular auditing of the originals, and other action including training if required.7.2 Advantages of Permits to WorkA well prepared Permit to Work system can make maintenance safer in many ways,some of which are: • It prevents an unauthorized person from initiating a job, a permit can only be issued by a person authorized to do so. • A trades-person will have confidence that those hazards affecting his personal safety have been considered and assessed before work is started. • A permit to work provides a plan to carry out the work safely. • It forms a basic checklist that enables the tradesperson to concentrate on the job and to avoid the need to make snap decisions under pressure. • Clear lines of responsibility are identified. • The likelihood of confusion is reduced due to the need for the permit to work to be fully discussed with and countersigned by the tradesperson at the work site. • The permit to work system lets all affected people know that work is to be carried out on an item of equipment or plant. • The chance of work beginning by contractors without proper instruction is reduced. • The risk of someone trying to operate the equipment whilst it is being worked on is greatly reduced. • The permit to work is a permanent record of precautions taken prior to maintenance work being carried out.7.3 UsageA Permit to Work is to be used with work involving any of the following: 1. Contractors - Any work involving contractors on site is to be covered by a Permit to Work. Contractors may or may not be familiar with the site and a permit to work provides a formal method of assessing any Health and Safety issues that the contractor and the site management may have to consider in relation to the task involved. 2. Hot Work - Hot work includes welding, flame cutting, brazing, grinding or any activity likely to produce heat or sparks. Permits are not required for safe areas designated for such work such as welding bays in maintenance workshops. 3. Confined spaces - A confined space is an area that is substantially enclosed. A permit to work is required in all circumstances involving this type of work. A safety person who is familiar with the plant, the activity and who has been 45
  46. 46. briefed as to the action to take in the event of a problem arising is to be present at all times a person is within the confined space. The plant must be isolated of all the services to the enclosed space and consideration must be given to the activity being carried out. For instance, hot work may require special extraction and or breathing apparatus. The temperature of and the time duration a person may be in the enclosed space should be considered and specified on the Permit to Work. If fumes are known to have existed, they must be tested to be clear before entry is allowed.4. Pressure Vessels - Any activity involving welding a pressure vessel should be covered by a permit to work and must be carried out only by a suitably coded welder. Maintenance activities involving work on pressure lines may need to be considered for permit to work where there is a hazard to personnel working which cannot be covered by a sites normal isolation practices or safe systems of work.5. Work at Height - Any work involving access to roofs and or trenches must be covered by a permit to work. Work within the factory where there is a risk from falling objects that would endanger personnel or equipment should also be covered by a permit to work.6. Chemical or Highly Flammable Areas - Work on chemical lines or tanks should be covered by a permit to work where that work is not a routine task covered by a safe system of work. Lines should be isolated from the supply, emptied and decontaminated as necessary. A permit is to be used where electrical equipment is to be used in chemical areas where highly flammable chemicals are present. For example - drills.7. Electrical Systems - Where there is a hazard to personnel working which cannot be covered by a sites normal isolation practices or safe systems of work. All 11kV working must be covered by a Permit to Work.8. Safety and Emergency Systems - Where there is a hazard to personnel working which cannot be covered by a sites normal isolation practices or safe systems of work.9. Lone Working - Where a person is to work alone within an area of the site away from other personnel who can reasonably be communicated with then a permit to work is to be issued. The person and checkers are to be briefed on the procedure for lone working.10. Lock-Out – Tag-Out.11. Cold Work.12. Blasting. 46
  47. 47. 13. Internal Combustion Engines Inside Company Buildings.7.3.1 Permits Issued For Hot WorkBefore authorizing the issue of a HOT WORK PERMIT, factors such as the followingmust be taken into account. 1. Emptying and cleaning the equipment of flammable material. 2. Isolating from sources of hydrocarbons by means of disconnection, blanking, insertion of blinds. No reliance should be placed on closed valves. 3. Sealing off sewer and drains within a radius of 75 feet (23 meters). 4. Clearing away any flammable material in the work area. 5. Location and earthing of welding or other equipment being used. 6. Degree of risk and potential sites of accidental release of hydrocarbons in the area. 7. Provision of fire-fighting facilities and the need for stand-by fire attendant, if necessary. 8. Testing by means of a combustible gas detector to ensure gas-free condition of the equipment and surrounding area. 9. Frequency of repeating gases free testing or the need for use of portable continuous gas detector with visual and audible alarms. 10. Containing and extinguishing weld sparks and molten slag. 11. The presence of substance such as lube oils and bitumen may give off vapours when heated. 12. Adjacent areas where work is taking place which may affect this work area.7.3.2 Permit Issued For Cold WorkA COLD WORK PERMIT must be obtained to cover general work, which is not regardedas hot work. 47
  48. 48. The COLD WORK PERMIT is required to cover such work as cold cutting and tapping,wire brushing, de-scaling, scaffolding, chemical cleaning, air driven power tools, entryinto sewers, deep drains, chambers, or buildings which may have contained toxic gas ordust etc. Before authorizing the issue of a COLD WORK PERMIT, factors such as the followingmust be taken into account.1. Is equipment, plant and location free of oil, gas and vapour?2. Has equipment been depressurized?3. Are the equipment, plant and location, electrically isolated?4. Are there adjacent areas where work is taking place which may affect this workarea?7.3.3 Welding On Live EquipmentThis action covers welding on equipment which is in service and where the equipmentcannot be depressurized and freed of gas/oil so that it can be covered only by a PERMITissued for Hot Work.WELDING ON LIVE EQUIPMENT includes welding of stubs into lines or vessels prior todrilling for hot tap for welding brackets on tanks and patch work.Occasions may arise when there are good reasonsfor carrying out welding work on pipelines, vessels, tanks or other equipment whilst innormal operations, e.g. in an emergency where there may be a greater risk in shuttingdown equipment than in carrying out live welding under carefully pre-planned andcontrolled conditions.Apart from the normal safety precautions to be observed when carrying out hot work, orhot work on live equipment, additional precautions are necessary.Welding should not be done on any equipment containing pure oxygen or compressedair (unless the air has been filtered to remove oil mist and chemicals if heating woulddecompose the chemicals and form an explosive mixture, caustic soda or a combustiblemixture).Immediately prior to commencement of welding or hot work on live equipment, a suitablyqualified person should check that the PERMIT conditions are adequate to ensure thenecessary control and should himself be present at the start of the job and thereafterkeep in close touch at frequent intervals with the senior man on the job.7.3.4 Excavations 48
  49. 49. Poorly planned excavations can result in damage to underground services, such aselectrical lines, natural gas lines, water lines, sewers and drains.The consequence of damaged service lines is often complete shutdown of operationsresulting in major business losses.Permits are written to prevent damage to underground equipment and services.Excavations may expose hazardous materials, which have leaked and arecontaminating the soil.Permits ensure that procedures to protect workers from exposure to toxic substanceshave been identified.Permits are written to ensure that necessary equipment is present and in good workingorder.7.3.5 Internal Combustion EnginesInternal combustion engines produce poisonous gases such as carbon monoxide, andoxides of nitrogen.Permits ensure that procedures are followed that will prevent equipment emissionsfrom contaminating air inside buildings and confined spaces.7.3.6 Lock-Out –Tag-OutLockout Is Defined as:The Placement of a Lockout Device on an Energy Isolating Device, in AccordanceWith an Established Procedure, Ensuring That the Energy Isolating Device and theEquipment Being Controlled Cannot Be Operated Until the Lockout Device IsRemoved.Is used for energy isolation  Hydraulic  Pneumatic  Mechanical  Radioactive  Thermal  Electrical  Chemical 49
  50. 50. 8. JOB HAZARD ANALYSIS (JHA) • JHA is a procedure which helps integrate accepted safety and health principles and practices into a particular operation. • In a JHA, each basic step of the job is examined to identify potential hazards and to determine the safest way to do the job.Four basic stages in conducting a JHA are:1.Selecting the job to be analyzed.2.Breaking the job down into a sequence of steps.3. Identifying potential hazards4.Determining preventive measures to overcome these hazards.8.1 AnalysisSome of the More Common Hazards:A. Caught In • Rotating PartsB. Contact With • Electrically Energized Parts, • Hot Surfaces, • Chemicals; Corrosive, Skin Absorbable, or Inhalation Hazardous, • Sharp Objects, • Cutting or Grinding Surfaces. 50
  51. 51. C. Struck By • Overhead Lifts, • Overhead Work or Loose Debris, • Chains or Cables under Tension, • Crane or Sling FailureD. Fall From or Into • Holes in Working Surfaces, Platforms, Scaffolds, • Missing or Loose Guardrails, Open Platform Gates or Chains, • Inadequate Tie off Points and Lanyard Length.E. Slip or Trip • Objects Projecting Into Walking Path, • Debris on Walking Surface or Loose Surface Material, • Uneven Surfaces, • Slick Surfaces, Oil, Water.Briefly, ask: • Can any body part get caught in or between objects? • Do tools, machines, or equipment present any hazards? • Can the worker make harmful contact with objects? • Can the worker slip, trip, or fall? • Can the worker suffer strain from lifting, pushing, or pulling? • Is the worker exposed to extreme heat or cold? • Is excessive noise or vibration a problem? • Is there a danger from falling objects? • Is lighting a problem? • Can weather conditions affect safety? • Is harmful radiation a possibility? • Can contact be made with hot, toxic, or caustic substances? • Are there dusts, fumes, mists, or vapors in the air?8.2 Preventive MeasuresIn order of preference: • Eliminate The Hazard • Contain The Hazard • Revise Work Procedures • Reduce The Exposure 51
  52. 52. 9. HAZARDS EVALUATION A Hazard Evaluation (HE) study is an organized effort to identify and analyze the significance of hazardous situations associated with a process or activity. Specifically, HE studies are used to pinpoint weaknesses in the design and operation of facilities that could lead to accidental chemical releases, fires, or explosions. Understanding of risk requires addressing three specific questions:• What can go wrong?• How likely is it?• What are the impacts? RISK UNDERSTANDING What are How likely What can The Is it? Go wrong? impacts? FOUNDATION FOR RISK ASSESSMENT Historical Analytical Knowledge experience methods and intuition Aspects of Understanding Risk 9.1 Selecting Hazard Evaluation Techniques A successful HE program requires tangible management support; sufficient, technically competent people (some of whom must be trained to use HE techniques); an adequate, up-to-date information database; and the right tools to perform HE presented in these guidelines has been applied in the chemical process industry and is appropriate for use in a wide variety of situations. 52
  53. 53. 9.1.1 What-If AnalysisThe What-If Analysis technique is a creative, brainstorming examination of a processor operation. Hazard analysts review the subject process or activity in meetings thatrevolve around potential safety issues identified by the analysts. Each member of theHE team is encouraged to vocalize What-If questions or specific issues that concernthem. The What-If Analysis technique can be used to examine virtually any aspect offacility design and operation (e.g., buildings, power systems, raw materials, products,storage, materials handling, in-plant environments, operating procedures, workpractices, management practices, plant security, and so forth). It is a powerful HEtechnique if the analysis staff is experienced; otherwise, the results are likely to beincomplete. What-If Analysis of simple systems can easily be conducted by one or twopeople; a more complex process demands a larger team and longer or more meetings.A What-If Analysis usually reviews the process, beginning with the introduction of feedmaterial and following the flow until the end of the process (or the boundary defined bythe analysis scope). What-If Analyses can also center on a particular type ofconsequence (e.g., personnel safety, public safety, or environmental safety). Theresults of a What-If Analysis usually address potential accident situations implied bythe questions and issues posed by the team. These questions and issues oftensuggest specific cause for the identified accident situations.Example:The ammonia and phosphoric acid react to form diammonium phosphate (DAP), anonhazardous product. The DAP flows from the reactor to an open-top storage tank.Relief valves are provided on the storage tanks and the reactor with discharges tooutside of the enclosed work area. 1. If Phosphoric acid feed rate is greater than ammonia, it result in off-spec – safe reaction 53
  54. 54. 1. If both flow rates increase, than the rate of energy release may accelerate, and the reactor, as designed, may be unable to handle the resulting increase in temperature and pressure. 1. If Ammonia feed rate is greater than Phosphoric acid, than unreacted ammonia may carry over to the DAP storage tank • Any residual ammonia in the DAP tank will be released into the enclosed work area, causing personnel exposure. Ammonia detectors and alarms are provided in the work areas. An example What-If question is: Sample page from What-If Analysis Table for DAP Process Example Process : DAP Reactor Analysts: Mr. Safety, Mr. Design Topic Investigated: Toxic Releases Date: 05/13/2004 What-If Consequence/Hazard Safeguards RecommendationThe wrong feed Potentially hazardous Reliable vendor Ensure adequate materialmaterial is phosphoric acid or handling and receivingdelivered instead ammonia reactions with Plant material procedures and labelingof phosphoric contaminants, or handling procedures exist.acid? production of off- specification product.The phosphoric Unreacted ammonia Reliable vendor Verify phosphoric acidacid concentration carryover to the DAP concentration beforeis too low? storage tank and filling storage tank. release to the work areaThe phosphoric Potentially hazardous Reliable vendor Ensure adequate materialacid is phosphoric acid or handling and receivingcontaminated? ammonia reactions with procedures and labeling contaminants, or exist production of off- specification product.Valve B is closed Unreacted ammonia Periodic Alarm/shutoff of ammoniaor plugged? carryover to the DAP maintenance (valve A) on low flow storage tank and through valve B. release to the work area Ammonia detector and alarm Flow indicator in phosphoric acid lineToo high a Unreacted ammonia Flow indicator in Alarm/shutoff of ammonia 54
  55. 55. proportion of carryover to the DAP ammonia solution (valve A) on high flowammonia is storage tank and line through valve A.supplied to the release to the work areareactor? Ammonia detector and alarm Hazard and Operability Analysis (HAZOP) The Hazard and Operability (HAZOP) Analysis technique is based on the principle that several experts with different backgrounds can interact in a creative, systematic fashion and identify more problems when working together than when working separately and combining their results. Although the HAZOP Analysis technique was originally developed for evaluation of a new design or technology, it is applicable to almost all phases of a process’s lifetime. The essence of the HAZOP Analysis approach is to review process drawings and/or procedures in a series of meetings, during which a multidisciplinary team uses a prescribed protocol to methodically evaluate the significance of deviations from the normal design intention. HAZOP Analysis technique is distinctively different from other HE methods because, while the other approaches can be performed by single analysts (although in most cases, it is better to use an interdisciplinary team), HAZOP Analysis, by definition, must be performed by a team of individuals with the specific, necessary skills. The primary advantage of the brainstorming with HAZOP Analysis in that it stimulates creativity and generates new ideas. This creativity results from the interaction of team with diversities backgrounds. Consequently, the success of the study requires that all participants freely express their views, but participants should refrain from criticizing each other to avoid stifling the creative process. This creative approach combined with the use of a systematic protocol for examining hazardous situations helps improve the thoroughness of the study. The HAZOP study focuses on specific points of the process or operation called “study nodes,” process sections, or operating steps. One at a time, the HAZOP team examines each section or step for potentially hazardous process deviations that are derived from a set of established guide words. One purpose of the guide words is to ensure that all relevant deviations of process parameters are evaluated. The following is an example of creating deviations using guide words and process parameters. Guide Words Parameter Deviation NO + FLOW = NO FLOW MORE + PRESSURE = HIGH PHASE AS WELL AS + ONE PHASE = TWO PHASE OTHER THAN + OPERATION = MAINTENANCE 55
  56. 56. Guide words are applied to both the more general parameters (e.g. react, mix) and themore specific parameters (e.g., pressure, temperature). With the general parameters,it is not unusual to have more than one deviation from the application of one guideword. For example “more reaction” could mean either that a reaction takes place at afaster rate, or that a greater quantity of product results.LIST OF TERMSAirline Respirator - A respirator through which compressed clean air from a sourceremote from the workplace is supplied to the wearer at a suitable pressure by meansof an airline or air hose.Attendant - A person designated by the department head in charge of entry to remainoutside the confined space and to be in constant communication with the personnelworking inside the confined space.Authorized Entrant - A person who is approved or assigned by the department headin charge of the entry to perform a specific type of duty or duties or to be at a specificlocation at the job site.Bonding - The joining of two or more items with an electrical conductor so that allends joined have the same electrical charge or potential.Entry - The action by which a person passes through an opening into a permit-required confined space. Entry includes ensuing work activities in that space and isconsidered to have occurred as soon as any part of the entrants body breaks theplane of an opening into the space.Entry Permit - The written or printed document that is provided by the employer toallow and control entry into a permit space and that contains the information specifiedin this program.Entry Supervisor - Department Head or the designated representative responsible fordetermining if acceptable entry conditions are present at a permit space where entry isplanned, for authorizing entry and overseeing entry operations, and for terminatingentry as required by this program. Note: An entry supervisor also may serve as an attendant or as an authorized entrant, as long as that person is trained and equipped as required by this program for each role he or she fills. Also, the duties of entry supervisor may be passed from one individual to another during the course of entry operation.Hazardous Atmosphere - An atmosphere that may expose employees to the risk ofdeath, incapacitation, impairment of ability to self-rescue (that is, escape unaided froma permit space), injury, or acute illness from one or more of the following causes: • Flammable gas, vapor, or mist in excess of 10% of its lower flammable limit (LFL). • Airborne combustible dust at a concentration that meets or exceeds its LFL. 56
  57. 57. NOTE: This concentration may be approximated as a condition in which the dust obscures vision at a distance of 5 feet or less. • Atmospheric oxygen concentration below 19.5% or above 23.5%.Hot Work - Any work involving burning, welding or similar fire-producing operations.Also, any work that produces a source of ignition, such as grinding, drilling, or heating.Hot Work Permit - The employers written authorization to perform operations (forexample, riveting, welding, cutting, burning, and heating) capable of providing a sourceof ignition.Immediately Dangerous to Life or Health - An atmosphere that poses an immediatethreat of loss of life: May result in irreversible or immediate severe health effects; mayresult in eye damage/irritation; or other condition that could impair escape from aconfined space.Lower Explosive Limit (LEL) - The minimum concentration of a combustible gas orvapor in air that will ignite if an ignition source is introduced.Material Safety Data Sheet (MSDS) - A document describing the properties andhazards of a substance including its identity, uses, ingredients, health hazards,precautions for use and relevant first aid and emergency procedures.OBSERVER – A competent person assigned to remain on the outside of, and in closeproximity to, the confined space. The Observer is sometimes called the Stand-by-Person.Oxygen-Deficient Atmosphere - An atmosphere that contains an oxygenconcentration of less than 19.5% by volume.Oxygen-Enriched Atmosphere - An atmosphere that contains an oxygenconcentration greater than 22% by volume.PPE - Personal Protective Equipment: Any devices or clothing worn by the workerto protect against hazards in the environment. Examples are respirators, gloves, andchemical splash goggles.PEL - Permissible Exposure Level: - Concentration of a substance to which anindividual may be exposed repeatedly without adverse effect.Purging - The removal of gases or vapors from a confined space by the process ofdisplacement.Standby Person - A person designated by the department head in charge of entry toremain outside the confined space and to be in constant communication with thepersonnel working inside the confined space. 57
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