OSHA has revised its acetylene standard. The agency said its new final rule replaces references to outdated industry standards with updated references reflecting current industry practices.

The revised standard requires that in-plant transfer, handling, storage, and use of acetylene cylinders comply with Compressed Gas Association Pamphlet G-1-2003, titled Acetylene. The revised standard also updates references for the provisions addressing piping systems, as well as acetylene generators and filling acetylene cylinders.

Acetylene is a colorless gas that can become explosive if liquefied, heated, compressed, or mixed with air. It is commonly used in certain plastics and is the most common gas used for fueling cutting torches. When mixed with pure oxygen in a cutting torch assembly, an acetylene flame can reach a temperature of 5,700 degrees F.

According to the MSHA Web site, use of acetylene creates special hazards in a workplace compared to other fuel gases. For example, the gas is chemically unstable, which makes it very sensitive to conditions such as excess pressure, excess temperature, static electricity, or mechanical shock. Exposure to any of these conditions can cause it to undergo a violent, explosive decomposition reaction. If this reaction or ignition occurs within the torch base or supply hose, it can propagate back into the storage cylinder causing it to explode violently. Acetylene is very easy to ignite and burns at a very fast rate, MSHA further notes. The energy from a static spark capable of igniting acetylene is lower than for any other fuel gas except hydrogen. The static charge developed by walking across a carpet floor on a dry day can be 1,700 times greater than that needed to ignite acetylene. When unburned acetylene gas is discharged from a torch, static electricity can be generated at the torch tip. If the tip comes in contact with a ground path, a static spark capable of igniting the gas can occur.