Developing a solid relationship with your gas cylinder supplier is essential to maintaining a safe workplace that complies with WHS legislation in Australia. Gas cylinders are classed as dangerous goods and Australian Standard AS4332-2004 - The storage and handling of gases in cylinders has specific requirements for how gas bottles must be both received and returned to suppliers.
Hazards surrounding compressed gases in cylinders
Gas cylinders present a complex range of hazards due to the combination of gas stored under pressure, the chemical properties and toxicity of the gases themselves, and the physical nature of the cylinders. Even ‘empty’ cylinders still contain residues of the gases held inside and their long slim design makes them vulnerable to drops, falls, or being knocked over.
You have a responsibility to ensure that all personnel (including suppliers and delivery drivers) understand the hazards associated with the gases in cylinders likely to be encountered on the premises. These are the hazards identified by AS4332-2004:
Pressure- the mechanical energy stored in a gas bottle is comparable with that of a motor car travelling at 180 km/h. Each cylinder has an incredible potential for damage if the cylinder is ruptured and explodes.
Flammability - when flammable gases leak into a confined space without being ignited, the concentration can quickly reach the flammable range and any small spark or ignition source (even static electricity) will cause an explosion.
Reactivity - some gases are highly reactive and can create explosions through a chemical reaction known as decomposition. When gases like acetylene become unstable (cylinders are shaken) or contact incompatible substances (copper) the gas begins to decompose — this generates heat and explosions.
Certain gases and their bottles are also vulnerable to corrosion, at the same time elastomeric components contained in storage and handling equipment can damage the cylinders through leaching, embrittlement, cracking or swelling. Damaged cylinders can create catastrophic leaks, contamination of gases, explosions and dangerous chemical reactions.
Toxicity - human exposure to toxic and corrosive gases is extremely dangerous. Gases are usually inhaled but they can also be absorbed through the skin. Once inside the body, the toxic agents can damage internal organs or quickly cause the death of your workers.
Asphyxiant Hazard - leaked gases displace the oxygen in the air. When oxygen levels drop below 18% there is a threat to life by asphyxiation. Gases like LPG which are denser than air tend to collect in low lying areas and quickly fill confined spaces.
Oxygen Enriched Atmosphere - when oxygen levels in the atmosphere increase above 21%, non-flammable substances can become flammable. This includes the clothing worn by workers. Ignition can occur from simple sources like heat, friction or static electricity.
Cold hazard - refrigerated gases or liquified gases that cool when depressurised can cause frostbite injuries and cold burns to workers who come in contact with the gas. The cold gases can also damage equipment creating brittle fractures or get stuck inside valves then rupture the fittings when heated.
Safely receiving cylinders
Gas cylinders should be thoroughly inspected on delivery and any cylinders which appear damaged, corroded or have loose/leaking fittings should be rejected and refused entry to the site. Develop a good relationship with your gas supplier and make sure their delivery team is trained to undertake the proper handling and unloading techniques.
The Standard has the following requirements when unloading cylinders and transferring them in the warehouse or worksite:
- Use mechanical handling devices like forklifts, pallet trucks or gas bottle trolleys when unloading and transferring cylinders
- Make sure the cylinders are always protected from being knocked over, falling or being impacted (use individual safety chains or cylinder restraints)
- Wear PPE applicable to the chemical and physiochemical hazards (thermal gloves, overalls, safety boots, eye guards etc)
- Never drop cylinders over the side of trucks or roll them along the ground (even for short distances).
- Keep cylinder valves closed and caps firmly in place.
- Loading and unloading areas must be designated NON-SMOKING and isolated from ignition sources, combustibles and sources of heat.
Storing and handling empty cylinders
Completely used or partially empty cylinders shall be managed with the same precautions as full cylinders. Empty gas bottled should be labeled and placed in a separate area ready for collection by your gas cylinder supplier.
Don’t forget that empty cylinders must still be:
- Treated the same way as full cylinders and not thrown about, rolled along the ground, or carried by the valve
- Segregated according to hazard class
- Stored upright with the valve closed and cylinder cap in place
- Individually restrained
TIP: Develop a great relationship with your supplier so empty cylinders are collected regularly and your overall stocks are kept to a minimum.
Returning gas cylinders to your supplier
The Standard has strict requirements for how gas bottles must be returned to the supplier —this includes both damaged and undamaged cylinders. Your duty of care to protect workers and contractors also extends to the delivery and collection team of your supplier, you must ensure that the cylinders don’t create a hazardous situation during transport.
Section 8.2 of AS4332-2004 requires that:
- Cylinders ready for pick-up by the supplier are kept in one safe area (most likely the cylinder store).
- Valves are tightly closed (without being over tightened) and cylinder caps are in place. Please take additional care to ensure any valves or plugs are secured on gas bottles that carry Class 2.3 toxic gases.
Damaged gas cylinders
Damaged cylinders must always be returned to the supplier, this includes corroded, fire-damaged or leaking cylinders. Contact your supplier in advance to notify them so that arrangements can be made.
The cylinders must be marked or tagged as damaged, then isolated to a safe, well ventilated area. Follow the instructions of your supplier for safely storing them and minimising leaks. Damaged cylinders must never be returned under normal transport arrangements, so you’ll need to give your staff correct instructions and training.
IMPORTANT: Always contact your supplier in advance for advice on disposal and recovery procedures.
For more information and accurate advice about storing and handling gas cylinders so your workplace complies with current WHS legislation in Australia, download our free eBook Gas Cylinder Storage: Compliance and safety requirements. It’s an excellent resource for WHS Managers or supervisors responsible for managing the Dangerous Goods held at your worksite. Download it today by clicking on the image below: