CONFINED SPACE ENTRY Helen Verstraelen CONFINED SPACE DEFINITION

CONFINED SPACE ENTRY Helen Verstraelen

CONFINED SPACE DEFINITION § Is large enough and so configured that an employee can enter bodily and perform work; § Has limited or restricted means of entry or exit; § Is not designed for continuous human occupancy. § 2 categories: § With open top with a dept that will restrict the natural movement of air § Enclosed spaces with very limited openings for entry

EXAMPLES § § § § Cargo tanks Manholes Chain lockers Fuel tanks Ballast tanks Double bottoms Void spaces § § § § IG plant Pipes Trenches Pump rooms Sewage tanks Cable trunks …

POTENTIAL HAZARDS § § § § § Flammable atmosphere Asphyxiating atmosphere Toxic atmosphere Irritant atmosphere Mechanical hazards Communication problems Entry and exit problems Thermal effects Noise and vibrations Physical hazards

FLAMMABLE ATMOSPHERE § Arise from enriched O 2 atmospheres § Vaporization of flammable liquids § Chemical reactions § Concentration of chemical dust § Flammable gasses are often heavier than air and will seek lower levels § Gasses lighter than air will rise and develop a flammable concentration if trapped above the opening § Byproducts of work can generate explosive conditions § Welding § Combustible dust during cargo operations ( grain, fertilizers, chemicals…)

ASPHYXIATING ATMOSPHERE 1. Normal 20. 9% O 2 in air 2. Decreased O 2 % can cause: 1. 17%: increased breathing volume and higher heartbeat 2. 14 -16%: increased breathing volume, accelerated heartbeat, poor muscular coordination, rapid fatigue, intermittent respiration 3. 6 -10%: nausea, vomiting, inability to perform, unconsciousness 4. <6%: spasmatic breathing, convulsive movements, death within minutes

ASPHYXIATING ATMOSPHERE § Reduced O 2 level can be the result of: § Consumption of air § Combustion of flammable substances: welding, heating, cutting, … § Bacterial action: fermentation § Chemical reactions: rust formation § Rate of consumption influenced by number of people and the amount of their physical activity working in the space § Displacement of air § Gasses as Nitrogen or CO 2 are used to displace air or combustible gases and will result in an asphyxiating atmosphere

TOXIC ATMOSPHERE § Toxic atmosphere can be caused by: § Manufacturing process § The product stored: ex. removing decomposed organic material from a tank can liberate toxic substances, such as H 2 S § The operation performed in the confined space: ex. Welding § During cargo operation a mechanical or human error may also produce toxic gases § CO is a hazardous gas that may build up in an space after incomplete combustion of organic materials (wood, coal, gas, oil. . ) or microbial decomposition of organic matter. Dangerous at 200 ppm, fatal at 1000 ppm. Can not be tested with a combustible gas indicator, must be tested specifically

TOXIC ATMOSPHERE § Limit values: § TLV (Threshold limit value): concentration for a healthy person 8 hours a day during his whole working life. § TLV – STEL (Short term limit value): 15 minutes time weighted average, max 4 times a day, min 60 minutes between 2 periods § TLV ceiling: may never be passed

MECHANICAL DANGERS § Each piece of mechanical or electrical equipment should be manually isolated before entry into a CS to prevent inadvertent activation § The space should be completely isolated to prevent vapor leaks, flashbacks, … § Closing of valves is not sufficient. Physically disconnection or blanking is necessary. Testing of the blanked or disconnected lines in needed when re-entering gases may re-contaminate the space § Other areas of concern are steam valves, pressure lines and chemical transfer pipes

COMMUNICATION PROBLEMS § Communication between the in- and outside of the CS is very important § When visual monitoring of the worker is not possible because of the design of the CS or the location of the entry hatch, a voice or alarm-activated explosion proof type of communication system will be necessary § Suitable illumination of an approved type is needed to provide sufficient visibility for the job

ENTRY AND EXIT 1. The physical limitations of the entry and exit of a CS are directly related to the hazard of the CS 2. Precautions for safe entry and exit should be taken and standby equipment should be ready for rescue 3. Consider the following 1. Type of CF and access to the entrance 2. Number and size of openings 3. Barriers in the space 4. Time required for exiting in case of fire or vapor incursion 5. Time required to rescue injured persons

THERMAL EFFECTS § When the body temperature increases above 38, 5°C, workers are less efficient, and are prone to heat exhaustion, heat cramps or heat stroke § Special precautions must be taken in cold environments to prevent frostbite, or hypothermia § Protective clothing for both hot or cold environment will additional bulk to the worker and must be considered in allowing for movement in the CS and exit time

NOICE AND VIBRATION § Workers in CS are exposed to higher sound levels as the sound reverberates on the walls, thus increasing the risk of hearing damage (temporarily or permanent) § Even when it is not intense enough to cause hearing problems, it may still interrupt communication with the standby person at the exit § Whole body vibration may affect multiple body parts and organs § Segmental vibration, appears to be more localized in creating injury to the fingers and hands when using tools as pneumatic hammers or rotary grinders or…

ENTRY § The act by which a person intentionally passes through an opening into a permit required confined space. § Any part of the body passing through the opening is considered entry.

ENTRANT - SUPERVISOR § Entrant: The crewmember(s) who will physically enter the confined space to perform the work. § Supervisor: The officer responsible for coordinating the entry into the confined space. He is also directly responsible.

ATTENDANT § The crewmember who remains outside the confined space and monitors the entrant(s); guards the space against unauthorized entry; warns the entrants of any unusual conditions; and summons the rescue personnel if needed.

CONFINED SPACE PERMIT § A Permit-Required 1. Contains or has the potential to contain a hazardous Confined Space is atmosphere; confined space 2. Contains a material that has one or the potential for engulfing an entrant; more of the 3. Has an internal configuration following such that an entrant could characteristics: become trapped or asphyxiated; or 4. Contains any other serious safety or health hazard.

EXAMPLE PERMIT

EXAMPLE PERMIT

CONFINED SPACE ENTRY PROCEDURE § § § Isolate the space Ventilate/Inert the space Conduct tailboard Complete permit Test the atmosphere Enter the space

ISOLATE THE SPACE FROM ALL HAZARDS § Close Valves § Double block & bleed, or blank flange § Empty the Space § Depressurize, vent & drain § Lockout/Tagout Equipment § Electrical sources § Rotating/reciprocating parts § Hazardous materials § Clean residue from the space

VENTILATE / INERT THE SPACE 1. Use mechanical ventilation 1. Fans or air horns 2. Ventilate at the rate of at least four (4) volumes per hour 1. Larger spaces require more ventilation 3. Make sure air supply is not contaminated 1. Ventilation air supply must be from fresh air uncontaminated with flammables, toxins, etc. 4. Inertion is needed when explosive gasses are present

TAILBORD BREEFING § Entire crew must attend § Attendants, entry supervisor § Review hazards of entry and work § Review PPE § Review procedure for contacting rescue § verify rescue available § Complete permit

COMPLETE ENTRY FORM § Permit must be correctly and completely filled out prior to entry. § Permit must be activated by Entry Supervisor’s signature to be valid. § No entry is allowed without a valid permit. § Permits are valid for up to 12 hours. § When work is completed, permit and tailboard form should be returned to safety. § Cancelled permits must be kept on file

TEST THE ATMOSPHERE IN THIS ORDER: § Check for Oxygen Content: § At least 19. 5% and less than 23. 5% § Check for Combustibles: § Less than 10% of the LEL § Check for Toxic Gasses: § Most commonly carbon monoxide (PEL <35 ppm) § or any other hazardous materials as determined by the use of the space.

OXYGEN / FLAMMBABILITY TEST § Oxygen: § Electrochemical principle. See Toxicity test with CO § Flammability: § Wheatstone bridge or IR: see “gas fires” for principles

TOXICITY TEST (CO example)

TOXICITY TEST (CO example) Electrochemical sensors detect gases by measuring the electric that is generated by chemical reactions (oxidation/reduction). The chemical reaction in the case of CO gas generation is : CO + H 2 O -> CO 2 + 2 H+ + 2 e(Detection principle), carbon monoxide is oxidized on the detection electrode, and hydrogen ions are generated. On the counter electrode, hydrogen ions (equal to the hydrogen ions on the detection electrode) react with oxygen from the air and generate water. The electricity generated by this reaction chain is proportional to gas concentration, thus the gas concentration can be determined by monitoring the generated electricity.

TOXICITY TEST § Tubes with absorbent material: § Airborne chemicals are trapped onto the surface of the absorbent. § Decolourisation takes place § Gas specific § 1 time use. Momentum measurement!!!

IMPORTANT NOTICE § Any time a limit is exceeded, no matter what the reason, all personnel shall immediately exit the space, and no others shall enter until atmospheric conditions are returned to safe levels. THERE ARE NO EXCEPTIONS TO THIS!

WHEN PERFORM ATMOSPHERE TESTING § Prior to every entry when the space is vacant; § After a 10 minute ventilation period (if ventilation is necessary); § At least hourly for permit-required confined spaces. § More frequently, if conditions or suspicions warrant.

Always test the air at various levels to be sure that the entire space is safe. Good Air Good air near the opening does NOT mean there is good air at the bottom! Poor Air Deadly Air

ENTER THE SPACE § An attendant shall be posted near the entrance for the duration of the work. He shall be in constant communication with the entrants while the job is in progress. § All entrants shall sign the sign in log when entering the space and sign out when exiting. § The attendant shall maintain the permit and sign in log for the duration of the work.

JOB FINISHED § Remove all personnel, tools, and debris from the space. Sign off the log. § Close the space. § Cancel the permit. § Review the job with the host employer (hazards, problems, other employers, etc. )

ATTENDANT RESPONSIBILITIES § To monitor entrants during the job and during entry & exit to help insure their safety. § The attendant may not abandon his post for any reason while personnel are in the space unless relieved by another qualified attendant. § To monitor atmospheric conditions in the space prior to and during entry. § To control access to the confined space. § To summon emergency assistance as needed. § To assess hazards in and around the space, and take action on the same. § To keep records of confined space work, such as air test results, personnel entry/exit, etc.

ENTRANT RESPONSIBILITIES § To assure that the space has been adequately ventilated, isolated, emptied, or otherwise made safe for entry. § To immediately exit a space, without question, upon word of the attendant, no matter what the reason. § To follow all safety rules and procedures that apply to the job. § To be familiar with the work to be performed and the procedures that apply to the job. § To use the appropriate PPE whenever necessary.

SUPERVISOR RESPONSIBILITIES § To assure adequate protection is provided to the entrants by verifying adequate lockout/tagout and that all hazards are securely isolated. § To support the attendant’s authority in controlling access to a confined space. § To verify that all personnel have exited prior to closing the space. § To assure that all personnel involved are aware of the hazards associated with the space. § To assure that rescue services are available prior to entry.