Oxygen-Fuel Gas Welding General Requirements

Mixtures of fuel gases and air or oxygen may be explosive, and employees must be protected from this hazard. No device or attachment facilitating or permitting mixtures of air or oxygen with flammable gases prior to consumption are allowed unless approved for the purpose, except at the burner or in a standard torch.

Under no circumstances is it acceptable for acetylene to be generated, piped (except in approved cylinder manifolds), or utilized at a pressure in excess of 15 pounds per square inch gauge (psig) or 30 pounds per square inch absolute (psia). The 30 psia limit is intended to prevent unsafe use of acetylene in pressurized chambers such as caissons, underground excavations, or tunnel construction. This requirement does not apply to the storage of acetylene dissolved in a suitable solvent in cylinders manufactured and maintained according to U.S. Department of Transportation requirements or to acetylene intended for chemical use. The use of liquid acetylene is prohibited.

Only approved equipment such as torches, regulators or pressure-reducing valves, acetylene generators, and manifolds are acceptable for use during oxygen-fuel gas welding. All welding cables and other equipment must be placed so that they are clear of passageways, ladders, or stairways.

Operators in charge of the oxygen or fuel-gas supply equipment, including generators, and oxygen or fuel-gas distribution piping systems, must be instructed and judged competent by their employers for this important work before being left in charge. Rules and instructions covering the operation and maintenance of oxygen or fuel-gas supply equipment including generators, and oxygen or fuel-gas distribution piping systems must be readily accessible.

When gas welding or cutting in confined spaces, the torch valves must be closed and the gas supply to the torch shut off at a point outside the confined area whenever the torch is not to be used for a substantial period of time, such as during lunch breaks or overnight. If possible, the torch and hose must also be removed from the confined space.

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