Compressed gas cylinders are used to store gases for use in various processes and applications. These cylinders usually store gases at extremely high pressures and gases contained in these cylinders vary from extremely flammable (i.e. acetylene) to extremely inert (i.e. helium). If handled properly compressed gas cylinders are safe. However, handled improperly the same cylinders can present a severe hazard to workers and equipments. To prevent injury and property damage, compressed gas cylinder must always be stored, handled, used and maintained properly.
COMPRESSED GAS CYLINDER HAZARDS
Explosion: Cylinders with their high internal pressure could explode when exposed to damage from falling, exposure to extreme heat, electric currents, vibration, corrosion, strong chemicals or anything that can cause weakness or failure in the cylinder.
Crushing: Cylinders are heavy and awkward to handle. Proper procedures must be followed when using, transporting and storing compressed gas cylinders so they won’t fall or tip over and cause injury. Stored pressure inside the cylinder could also propel the cylinder like a rocket if allowed to escape at an uncontrolled rate (e.g. cylinder valve is broken or the cylinder gets punctured).
Fire: Cylinder valves can leak, causing their contents to discharge. Flammable gas could accumulate in an area and cause fire and explosion. To minimize hazards from leaks, store compressed gas cylinders in well ventilated area.
Gas Inhalation: Inert and hazardous gases could also cause health hazards if not stored and used properly. Inert gases like CO2 could displace oxygen in the area and cause inhalation problems. Harmful and toxic gases must only be used when appropriate Personal Protective Equipments (PPE) or appropriate engineering controls are available to protect the workers. These gases must also be stored when not in use in a well ventilated area to prevent accumulation of these harmful gases.
TYPICAL INDUSTRIAL GASES AND THEIR USE
- Acetylene – mainly used in oxy-acetylene flames for cutting mild steel and for welding.
- Oxygen – industrial grade oxygen are mainly used in oxy-acetylene flames for cutting and welding. Medical grade oxygen is mainly used for respiration.
- Argon – industrial grade argon gas is used primarily for applications such as arc welding, steel making, heat-treating and electronics manufacturing.
- Nitrogen - compressed nitrogen gas is commonly used as a purge gas in most of the industries to achieve an oxygen free or toxic free area and for safe repair and maintenance.
- Carbon dioxide - carbon dioxide is used by the food industry, the oil industry, and the chemical industry. It is used in many consumer products that require pressurized gas. It is also used in life jackets for quick inflation. CO2 is also used in fire extinguishers, especially those designed for electrical fires. CO2 fire extinguishers also work well on small flammable liquid. It is also used as welding gas.
- Compressed gas cylinders must be stored upright and properly secured with a chain, a strap, or a cable, above the midpoint but below the shoulder of the cylinder, to a stationary building support or to a proper cylinder cart to prevent it from tipping or falling.
- Cylinders shall be capped when not in use or when not connected to a system.
- Completely close the valves and keep the valve protection devices, such as caps or guards, securely in place.
- Store cylinders in a dry, well-ventilated area at least 20 feet from combustible materials.
- Do not keep cylinders in lockers. If the valve leaks, a dangerous explosive or asphyxiating buildup of flammable or toxic gas inside the locker.
- Install proper precautionary signs, such as “Flammable Gas”, “Oxidizer”, or “Toxic Gas”. It is also a good practice to label the storage area with the name of the gas stored in the cylinder for easy identification.
- Place cylinders in a location where it will not be subjected to mechanical or physical damage and it will not be exposed to heat or electrical circuits to prevent explosion or fire.
- Store empty cylinders and full cylinders separately.
- Oxygen cylinders must be stored at least 20 feet away from flammable gas cylinders or or by a noncombustible barrier at least 5 feet (1.5m) high having a fire-resistance rating of at least 1/2 hour.
- Gases belonging to the same hazard class can be stored in the same area. Inert gases are compatible with all other gases and may be stored together.
- Do not store cylinders longer than one year without use.
Most accidents or injuries involving cylinders happen while moving or handling the gas cylinders.
- Use the right equipment, correct procedures, and sufficient number of persons to lift and move cylinders to avoid personal injury and cylinder damage.
- Wear the proper PPE while handling compressed gas cylinders (i.e. safety shoes, safety glasses and gloves).
- Do not drag or roll cylinders. Transport cylinders with a properly designed cart, hand truck or properly designed cylinder cage for the transporting cylinders and make sure valve protection devices, such as caps or guards, are in place.
- When using a crane to lift cylinders, be sure to use proper cradles, nets, boats, or special platforms designed for this purpose to prevent cylinders from accidentally falling. NEVER lift cylinders with web slings wrap around the body of the cylinder.
- Ropes, chains and slings shall not be used to suspend cylinders, unless cylinder was designed for such.
- Do not lift by the protective cap or guard or use magnets to lift or move them since valves could be damaged.
- The cylinders shall not be painted so that physical damage on the cylinder will be visible. Painting of cylinders will only be done by the manufacturers or suppliers after the cylinders have been inspected and tested.
- Handle cylinders carefully when loading or unloading cylinders. Avoid dropping or banging them to prevent damage.
- Forklift trucks fitted with appropriate cage designed for the purpose shall be used for unloading cylinders from delivery trucks.
PROCEDURE FOR USE
- Keep cylinders upright and away from heat, sparks, fire, physical damage, or electrical circuits to avoid rupture.
- Use only in a well-ventilated areas to avoid gas accumulation.
- Do not bring cylinders into a confined space to avoid inhaling the gas and possible suffocation from the accumulation of flammable, toxic, or reactive gases.
- Users shall read, understand, and follow all cylinder markings and labels to avoid misuse.
- Before connecting a regulator, stand to one side, away from the “line of fire”, and momentarily open the valve and then close it immediately. This procedure, called “cracking” the valve, is done to clear the valve of dust or dirt that could enter the regulator.
- Open valves slowly by hand to avoid gauge damage. If a specific tool is required to open the valve, leave it in position so that the flow of gas can be stopped quickly in an emergency.
- Lift and move cylinders carefully to avoid dropping or falling.
- Close the gas cylinder valves when not in use such as during breaks, lunch, or end-of-shift to avoid leaks.
- Never apply or allow oil or grease on the cylinder fittings or regulators/gauges, particularly those containing oxygen, to avoid fire or explosion. Pure oxygen and oil can be explosive.
- Storage is not required for single cylinders of fuel gas and oxygen ready for use with regulators attached secured to a proper cart.
PROCEDURE FOR MAINTAINANCE
- Protect the markings on cylinders that identify the contents, and mark the full/empty status on cylinders. Mark all empty cylinders.
- Don't use the recessed top of the cylinder as a storage area for tools or material.
- If cylinders are leaking, isolate them outdoors and away from sparks or heat. Report it to your supervisor, request the gas supplier to send qualified people to take care of the problem – don’t try any repairs yourself. Tag leaking cylinders.