This includes: a thorough steam or caustic cleaning (or a solvent or water washing, depending on the
combustible's solubility) followed by purging and inerting with nitrogen or carbon dioxide, and using
protective equipment as recommended in A6.0. Waterfilling just below working level may substitute for
A container with unknown contents should be cleaned (see paragraph above). Do NOT depend on
sense of smell or sight to determine if it is safe to weld or cut.
Hollow castings or containers must be vented before welding or cutting. They can explode.
Explosive atmospheres. Never weld or cut where the air may contain flammable dust, gas, or liquid
vapors (such as gasoline).
Compressed Gas Equipment. Standard precautions. Comply with precautions in this manual, and those
detailed in CGA Standard P-1, PRECAUTIONS FOR SAFE HANDLING OF COMPRESSED GASES IN CYLINDERS,
listed 6 in Standards index (para. 4-4).
Regulator relief valve is designed to protect only the regulator from overpressure; it is not intended to
protect any downstream equipment. Provide such protection with one or more relief devices.
Never connect a regulator to a cylinder containing gas other than that for which the regulator was
Remove faulty regulator from service immediately for repair (first close cylinder valve). The following
symptoms indicate a faulty regulator:
Leaks - if gas leaks externally.
Excessive Creep - if delivery pressure continues to rise with downstream valve closed.
Faulty Gauge - if gauge pointer does not move off stop pin when pressurized, nor returns to stop
pin after pressure release.
Repair. Do NOT attempt repair. Send faulty regulators for repair to manufacturer's designated repair
center, where special techniques and tools are used by trained personnel.
Cylinders. Cylinders must be handled carefully to prevent leaks and damage to their walls, valves, or safety
Avoid electrical circuit contact with cylinders including third rails, electrical wires, or welding circuits
They can produce short circuit arcs that may lead to a serious accident. (See para. 4-3.3.)