Field Instruction Storage, Handling, Transport and Disposal of Sulphur Hexafluoride (SF6) Gas

Transcription

1 6.14 Storage, Handling, Transport and Disposal of Sulphur Hexafluoride (SF6) Gas Purpose Describe the minimum requirements for safe handling, storage, maintenance, repair, transport and disposal of equipment containing SF 6 gas. Safety Aspects and Implications SF6 gas is colourless, odourless, tasteless, non-toxic and non-combustible. However, SF6 gas can be a risk to human health due to toxic by-products and its potential to displace oxygen in confined spaces. DANGER Sulphur hexafluoride (SF6) gas is five times heavier than air. Escaped SF6 gas will displace oxygen at ground level, especially in confined spaces. If SF6 gas is present, it could present a danger of asphyxiation due to oxygen deficiency to anyone working in enclosed areas, including a vehicle s cab or cargo-carrying area. Environmental Aspects and Implications SF 6 gas is a greenhouse gas with a global warming potential 23,000 times more than carbon dioxide. Instructions Follow the manufacturer s instructions and the SF6 Safety Data Sheet (SDS) to handle, store, maintain, repair, transport and dispose of SF6 filled equipment. Ensure that SF6 does not leak into the atmosphere. Safety Before commencement of work, a risk assessment must be carried out using the Risk Analysis Procedure (OSH ), to identify and document the hazards and risks associated with the task and ensure appropriate control measures are implemented. It is important that, appropriate control measures must be identified, documented and implemented to lessen or control the identified hazards. When working with equipment containing SF 6 gas, wear personal protective equipment (PPE). See FI 2.6 Worksite Clothing / PPE requirements, in this manual. The minimum PPE is Level 1, in addition to specialist PPE according to the task (see AS 2791 High-voltage switchgear and control gear Use and handling of sulphur hexafluoride (SF 6) in high-voltage switchgear and control gear, Annex E). This may include: SF6 coveralls with hood disposable gloves (preferably nitrile or neoprene) CS10 # Page 1 of 5

2 full-face respirator fitted with organic vapour canister, e.g. filter 510 or gas filter against organics. Alternatively, a suitable respirator and chemical type industrial goggles may be used safety footwear covers. A Confined Space Entry permit is required when working in confined spaces Wherever there is high volume SF6-filled equipment, the following requirements must be met. If any enclosure, e.g. cable trenches and pits, near the equipment has been identified as a confined space, permanent exhaust fans must be installed to evacuate gas from the confined space. Fit exhaust fans with an inlet pipe extending to the lowest level of the space, ensuring the removal of SF6 from the work area is to an open or well-ventilated area. If the equipment is in an enclosed or partially enclosed area, the area must be adequately ventilated before doing any work. Handling and Recovery Anyone working with equipment containing SF6 gas must: be trained and found competent to operate SF6 evacuation and filling devices follow the safety recommendations contained in the SF6 MSDS ensure that the gas does not come in contact with heat, sparks, open flames or other ignition sources as it can produce toxic by-products. During planned maintenance or repair work, use a SF6 evacuation and filling device to reclaim and process SF6 and return the withdrawn SF6 into the equipment being maintained or repaired. A circuit breaker must be evacuated and filled according to the manufacturer s instructions. Any SF6 that is recovered but not returned into equipment must be returned to district depot stores. Maintenance on SF6 equipment must be done in a ventilated area. Neutralise by-products, e.g. with hydrolysed lime, and extract with a Hazmatrated vacuum cleaner. Storage The storage compound for SF6 cylinders must be: well ventilated and preferably located outdoors free from fire risks and away from sources of heat and ignition kept clear and access restricted to authorised personnel only clearly labelled as a cylinder store and the appropriate hazard warning signs displayed CS10 # Page 2 of 5

3 Smoking and naked flames are not allowed near the cylinder storage compound. Cylinders must be: clearly labelled as containing new or used gas separated into groups of new (i.e. full cylinders), used (i.e. partially full cylinders) and empty arranged so that oldest stock is used first stored upright and correctly secured to prevent toppling. The cylinder valves must be tightly closed and, where appropriate, valve outlets capped or plugged. where possible, standing on an open galvanised steel grid to reduce corrosion of the cylinder base periodically checked for general condition and leakage. Transporting The following transport requirements must be followed. Before loading the vehicle: ensure that the cylinders are manufacturer-approved, and free from defect or modification remove any regulators or other equipment the cylinder must not be transported with these attached firmly tighten (do not over-tighten) the cylinder valve handwheel and check that it is properly closed. Use the valve outlet sealing nut when available. carefully check for gas leakage using leak detection fluid (see your gas supplier). Cylinders must not be transported in the cab of the vehicle. Never transport a cylinder if a leak has been detected during loading. Do not remove any valve protection device (if fitted) during transport. Because ventilation and cooling decreases considerably when the vehicle is stopped or parked: do not leave cylinders for long periods (more than 1 hour) in the sun (heat build-up) do not store in closed vehicles parked overnight (gas leak) unload the cylinders immediately upon arrival at your destination. Cylinders must be removed from the vehicle and secured upright before attaching regulators and subsequent use. Transporting cylinders in a utility vehicle In addition to the requirements already listed, there are special requirements to follow when transporting SF6 gas cylinders in a utility vehicle under 3.5 ton gross laden weight. The total weight of the cylinders must not exceed 250 kg. CS10 # Page 3 of 5

4 Vehicles without a canopy preferred method Transporting cylinders upright against a headboard is the preferred and safer method. Restrain the cylinders by containing them in a purpose-built frame (preferably) or lashing them to the vehicle body. Secure tightly with at least two horizontal straps, as shown below. Vehicles with a canopy If transporting cylinders lying down in a utility vehicle that has a canopy, do the following. Ensure that the area where the cylinder is stowed is very well ventilated. Place the cylinders: on a purpose-built cradle (preferably) or chocks on the deck, as shown in the diagram below lengthwise on the deck with the base blocked against the headboard or another strong part of the load and with the valves facing rearwards. Secure tightly with at least one strap to prevent the cylinders from rolling or sliding, as shown below. For more information, see BOC Guidelines for gas cylinder safety 2008 Australian edition at: CS10 # Page 4 of 5

5 Disposal Recover all the remaining SF 6 before disposing of SF 6-filled equipment. Neutralise all failed or decommissioned equipment previously filled with SF 6 before disposal, salvage or repair. Treat all of the following as controlled waste : failed or decommissioned equipment containing SF 6 gas by-products SF 6 gas requiring treatment for re-use References Occupational Safety & Heath Act 1984 Occupational Safety & Health Regulations 1996 SHMS OSH Job Risk Analysis (JRA) Procedure SHMS OSH Personal Protective Equipment SHMS OSH Vehicle and Journey Management Procedure Field Instruction 2.5 Other Personal Protective Equipment Field Instruction 2.6 Worksite Clothing / Personal Protective Equipment Requirements Field Instruction 2.23 Job Hazard and Risk Management (JRA) Field Instruction 5.8 Handling and Transporting Loads AS (High-voltage switchgear and control gear Use and handling of sulphur hexafluoride (SF6) in high-voltage switchgear and control gear) - SDS BOC Guidelines for gas cylinder safety 2008 Australian edition: CS10 # Page 5 of 5