Confined Spaces – Part 1 An Overview of the WISHA Confined Spaces Standard
Purpose of This Module This two-part module provides basic information for employers about the hazards of confined spaces, how to control these hazards and what WISHA requirements apply when employees enter confined spaces. Some employers may elect to contract out confined space work. In those cases, employers are obligated to fully inform contractors of the confined space hazards at their facilities. This overview does not replace the confined spaces standard. For the complete WISHA confined space rule requirements, see Confined Spaces Chapter 296-62 Part M.
Confined Spaces Overview Part 1 of this overview will cover the following: How to identify a confined space, Confined space hazards, How to control or eliminate the hazards.
Identifying the space What is a confined space? A confined space is an enclosed space that: • is large enough to get whole body inside, is not designed for human occupation, has limited or restricted entrance or exit. It must have all three characteristics to be a confined space.
Identifying Confined Spaces Examples of confined spaces Manholes & Sewers Tanks Boilers Grain storage bins Other examples include vaults, pipelines, tank cars, and ship holds
Hazards of Confined Spaces Basic Principles Confined spaces can be deadly. Some confined spaces are more hazardous than others. Confined space conditions can change rapidly from no hazards to life-threatening hazards. Some confined spaces are so hazardous, a written permit system is required for entry. The hazards of confined spaces can often be controlled or eliminated before entering. For a description of an actual confined space fatality,click here.
Hazards of Confined Spaces What are the main hazards of confined spaces? • Hazardous atmospheres • Engulfing materials • Entrapment • Moving parts • Electricity
Hazard of Confined Spaces When is a confined space so dangerous a written entry permit system is required? • When there is an actual or potential “hazardous atmosphere” or • when the space contains loose material that can engulf a person, or • when the space is configured in a way that can trap a person, or • when there is any other recognized serious safety and health hazard.
Hazard Identification A “hazardous atmosphere” in a confined space has one or more of the following: Flammable gas, mist or vapor Flammable dusts Oxygen content below 19.5% or above 23.5% Air contaminant concentrations that would cause death, incapacitation, or permanent health problems You must do air monitoring to determine if a hazardous atmosphere exists.
Hazard Identification Hazardous Atmospheres – Flammable Gases, Vapors and Dusts Flammable gases, vapors or dusts will ignite from a spark or flame if above a level in the air called the “lower flammable limit” (LFL). Gas or vapor levels higher than 10% of the LFL are considered hazardous and the confined space cannot be entered until levels are reduced. Amounts above 10% of the LFL are usually toxic as well. LFL is sometimes called “LEL” – “lower explosive limit”
Hazard Identification Example of flammable gas levels - Methane Air 0% Air 100% Too Rich Too Lean Boom! Methane 100% Methane 0% 5.3% LFL 15.0% UFL An open flame or a spark will cause an explosion when methane amount is between 5.3% and 15%, the upper flammable limit (UFL).
Hazard Identification Hazardous Atmospheres – Oxygen Deficiency A reduction in oxygen is caused by tank rusting, microbe activity, or replacement by another gas. Lack of oxygen can cause a person to immediately collapse and die. Normal air contains 21% oxygen. A space with oxygen content below 19.5 % is considered “oxygen deficient”. 19.5% 21% 0% Oxygen content Oxygen deficiency exists
Hazard Identification Effects of Oxygen Deficiency % OxygenSymptoms 19.5% - 16% Fatigue, mild impaired coordination 16% - 12% Increased breathing rate and pulse; impaired coordination, perception or judgment 12% - 10% Further increased breathing rate, blue lips, mental confusion 10% - 8% Fainting, nausea, vomiting, mental confusion within few minutes 8% - 6% Collapse, death within 8 minutes 6% - 0% Coma within 40 seconds, death Using an “inerting gas” like nitrogen, to counteract flammable vapors will result in an oxygen deficiency.
Hazard Identification A word about oxygen-enriched atmospheres A confined space with oxygen amount above 23.5% is considered “oxygen-enriched”. The source of extra oxygen is typically from leaking oxygen cylinders used for oxy-acetylene torches. Oxygen above 23.5% is a fire or explosion hazard. Green tanks contain oxygen
Hazard Identification Hazardous Atmospheres – Toxic Chemicals • At very high levels, most chemicals in the air can be immediately life-threatening or cause permanent bodily harm. • At lower levels, chemicals in the air can still cause harm. PEL • Most chemicals have “permissible exposure limits” (PELs) which will cause harm if exceeded. • Even non-toxic or low-toxic chemicals can replace oxygen if levels are high enough.
Hazard Identification Hazardous Atmosphere – Toxic Chemicals The most common toxic chemicals in confined spaces fatalities are hydrogen sulfide and carbon monoxide. Other toxic chemicals can include welding fumes, vapors from liquid residues in storage tanks, or chemical products used in the confined space. Chemicals can quickly reach toxic levels in the air of a confined space, especially gases, solvent vapors or sprayed products.
Hazard Identification Hazardous Atmospheres–Hydrogen Sulfide (H2S) Hydrogen sulfide gas is commonly found in sewers. It can be instantly fatal at higher levels in a confined space. Disturbing sewage sludge can release more hydrogen sulfide gas. 2000 600 1000 30 200 100 H2S in ppm Smell strong odor Loss of smell Death in minutes Coughing,red eyes Unconscious in 30 min. Instant collapse
Hazard Identification Hazardous Atmospheres – Carbon Monoxide (CO) Carbon monoxide comes from operating internal combustion engines in or near confined space. Propane-powered engines also emit carbon monoxide. Fatal levels of CO are quickly reached in confined spaces. Propane-powered manlift in a large tank The PEL for CO is 35 ppm. To see the effects of CO, click here
Hazard Identification What are the Hazards of Engulfing Material? Engulfing materials include liquids or loose solids such as grain, sand or other granular material. People cannot escape when caught in moving loose solids and usually suffocate. Workers often get engulfed when in-feed or out-feed lines are inadvertently opened or activated.
Hazard Identification What is Entrapment? The space is configured in a way that can trap a worker, for example, sides sloping towards the center Gravel hopper with sloping internal sides
Hazard Identification Other Recognized Hazards Electrical lines, steam lines or hydraulic lines Mechanical hazards (moving parts) Hazards caused by the work (welding, painting etc.)
Controlling the Space The hazards of a confined space can be be controlled in the following ways: • Prevent employee entry. • Remove or reduce hazards in the space first, before a person enters. • If hazard cannot be controlled, you must use a written permit system to enter safely. See Part 2 for more information on a written permit system.
Controlling the Space Warning employees and controlling access Post warning signs at the entrance of confined spaces. Limit employee access to confined spaces by using entry barriers or locks. Make sure that unauthorized workers do not enter the confined space.
Hazard Control How To Control Hazardous Atmospheres Drain or pump out liquid contents, if any. Blank off all in-feeding lines. Air test and ventilate. Continue ventilating constantly. If possible, remove any sludge from outside the confined space. Exit space if conditions deteriorate.
Hazard Control Hazardous Atmospheres Dangers It is difficult to eliminate hazardous atmospheres in most sewers lines. Tank sludge or sewer sludge can release toxic gases during cleanup. Toxic or flammable gases can exist in pockets or layers.
Hazard Elimination How To Eliminate Physical Hazards Lock-out moving parts Blank or block steam pipes and product in-feeding pipes. De-energize electrical parts or wiring
If Hazards Can’t Be Eliminated If hazards cannot be completely eliminated, there are only two options: a complete written permit system, or “alternate procedures.” Both require training of employees. See Part 2 for more information on entry procedures.
Additional Information More information is available on WISHA webpage This presentation is just an overview and does not cover all requirements. For more information on how to put together a confined space program for your workplace, go to: http://www.lni.wa.gov/wisha/publications/App/Document/ConfSpac.doc For additional assistance, you can call one of our consultants. Click below for local L & I office locations: http://www.lni.wa.gov/wisha/consultation/regional_consultants.htm
Confined Space Quiz Question 1 Which of following are considered confined spaces? • A sewer manhole • A sub-basement vault with only one door • A 20 foot deep ditch • A 30-gallon drum
Confined Spaces Quiz Question 2 When can a hazardous atmospheres be fatal? • When there is not enough air • When there is 2% methane • When there is 10% oxygen • When there is no ventilation
Confined Spaces Quiz Question 3 Which of the following is not a good way to control hazardous atmospheres? • Ventilate for two hours before entering • Drain or pump out liquid contents • Air test and ventilate continuously • Remove any sludge from outside the space