Safety precautions must always be practiced when working with compressed gases.
By Jerome E. Spear
Compressed gases pose a unique hazard. Depending on the particular gas, there is potential exposure to physical and mechanical risks associated with high pressure as well as chemical dangers associated with the gas itself. As a result, gas cylinders require special precautions for their storage and handling.
Compressed gas and equipment is addressed in specific OSHA standards (29 CFR 1910.101; 29 CFR 1926.350) for both general industry and the construction industry. Other relevant standards are established by the Compressed Gas Association.
There are hundreds of different types of materials that may be stored in a compressed gas cylinder—oxygen, fuel, refrigerants, inert gases, and poison gases among others.
The compressed gases used most commonly are acetylene and oxygen. Acetylene is highly flammable. Oxygen, although not a flammable gas, supports combustion by making fires burn more intensely. These two gases, as well as other compressed gases, if released suddenly, can cause a cylinder to become a missile-like projectile.
Proper Storage and Handling
Serious accidents may result from the misuse or mishandling of compressed gas cylinders. Only trained employees should be assigned to handle them under pressure.
Acetylene cylinders must be separated from incompatible cylinders. Flammable cylinders must be kept separate from oxygen cylinders by at least 20 feet when not in use or by a 5-foot-high fire-resistant partition, according to OSHA standards.
The cylinders should be stored with the valve end up— and this is especially true for acetylene.
Chains or other restraints should also be used to prevent cylinders from falling or being knocked over.
The storage area should be dry and well ventilated as leaks can cause oxygen to be displaced and, depending on the contents of the cylinder, create a flammable atmosphere or toxic environment.
Cylinders are not designed for temperatures in excess of 130°F, so they should not be stored near sources of heat such as radiators or furnaces.
Acetylene storage rooms should have no other occupants and should not contain any oxidizing agents or sources of ignition. Fire extinguishers should be readily available throughout the storage area—and of course, smoking should be prohibited.
Oxygen cylinders should not be stored near combustible or flammable products, including hydrocarbon fuels or petroleum
Always consider gas cylinders to be full, and handle and store them with appropriate care. Accidents have happened when containers under partial pressure were thought to be empty.
If the contents are emptied, the valve should not be left open, as contaminants can get inside the cylinder. Instead, positive pressure should be maintained inside the cylinder to prevent contaminants from entering the cylinder.
Because of their shape, smooth surface, and weight, cylinders are difficult to carry by hand. However, they should never be rolled or dragged. They should be transported on a hand or motorized truck and secured to keep them from falling.
When they must be transported any long distances, cylinders should be properly secured with special attention paid to protecting the valve stem from damage. Valve protection caps should be in place during storage and transport.
Do not lift cylinders by their cap and do not transport them with the regulator attached. They should not be lifted using magnetic devices. Where cylinders must be handled by a crane or derrick, they should be carried in a cradle or suitable platform and extreme care should be taken not to drop or bump them.
Using Cylinders Safely
The training requirements for gas cylinder usage fall under OSHA’s hazard communication training requirements. As such, it is essential to know and understand the properties, uses, and safety precautions of the gas itself before using the cylinder. This will also guarantee the appropriate Material Safety Data Sheet is nearby.
Always use the proper regulator for the gas in the cylinder and check the regulator before attaching it to a cylinder. If the connections don’t fit together, the wrong regulator is being used! Regulators are threaded differently by type and are standardized by the Compressed Gas Association to prevent accidents.
Do not use lubricants or allow oil or grease to come in contact with the cylinder or its valves—they may be incompatible with the gas contents in the cylinder.
Attach the regulator securely before opening the cylinder valve, and always use a cylinder wrench to tighten the regulator nut and hose connection. Open cylinder valves slowly. A cylinder without a hand wheel valve should be opened only with a tool provided or approved by the gas supplier.
Before making a connection to a cylinder valve outlet, crack the valve for an instant to clear the opening of any debris, and then adjust the pressure.
Do not open an acetylene valve all the way. Open just a quarter turn in case you have to turn off the fuel source quickly in case of a fire. Oxygen valves, on the other hand, should be opened all the way because there is a backseating valve on the oxygen cylinder that prevents the high-pressure gas from leaking out through the threaded stem.
Open the valves from the side. Always point the valve and opening away from yourself and away from anyone else in case there is a failure to the regulator, and the valve stem on the regulator fails and blows out.
Always check to make sure the cylinder is set to the correct pressure indicated for that gas. If you are using the right regulator, there should be indicators on the gauge with an operation range indicating where the pressure should be set. Acetylene is not stable above a gauge pressure of 15 pounds per square inch, so the gauge pressure must be kept below this setting.
Before a regulator is removed from a cylinder valve, close the cylinder valve and release the gas from the regulator. Cylinder valves should be closed when work is finished, even if the contents are empty.
Always inspect cylinders, regulators, and hoses before using. If you suspect a leak, you can lightly spray a soap and water solution around
the fittings, hoses, and other suspected leak areas. If the area “bubbles up,” a leak is present.
Cylinders, regulators, hoses, and fittings that develop leaks should be removed from service and properly tagged. Cylinders that develop leaks should be moved to a well-ventilated area and the supplier notified.
Other Safety Precautions
Never use oxygen in place of compressed air in pneumatic tools, oil-preheating burners, or to start internal combustion engines.
Compressed air or oxygen or any compressed gas should not be used to blow away dirt or dust from clothing. Particles can become airborne and strike the eyes; oxygen can be injected into a cut or injury and introduce air bubbles into the bloodstream. Clothing saturated with oxygen can become a torch if contact is made with a lit cigarette or an accidental spark.
Finally, respect the high pressure of compressed gas cylinders. A sudden release of pressure, such as from damage or failure to the valve stem, can gain enough momentum to break through a cinderblock wall—200 feet away!
Jerome E. Spear, CSP, CIH, is president of J.E. Spear Consulting and has more than 22 years of experience helping organizations prevent injuries and illnesses, control losses, and achieve regulatory compliance. He held the positions of technical, services manager with XL Specialty Risk Consulting and corporate industrial hygiene manager for Chicago Bridge and Iron Co., a worldwide steel fabricator and construction company.