Precautions and Safe Practices for Welding - CONNECTING AND ADJUSTING SHIELDING GAS SUPPLY



Here is a list of steps and important things to check when hooking up cylinders. They are intended to help prevent possible injury or death to you and your fellow workers as well as prevent possible equipment and property damage.

Fasten the cylinders to be used in an upright position. If cylinders are not on a suitable cylinder cart, they should be securely chained or strapped to a workbench, wall, or post so that they cannot be accidentally knocked or pulled over.

“Crack” the cylinder valve. Stand at one side or rear of the cylinder outlet. Open the cylinder valve slightly for an instant, and then close it. This will clean the valve of dust or dirt which may have accumulated during storage. Dirt can damage critical parts of a regulator.

Always attach a regulator to the gas supply (and a flow meter when required). When a single cylinder is used, a pressure-reducing regulator must be connected at the cylinder valve. Normally in electric welding and cutting, a combination regulator- flow meter is used. Make certain that the regulator is proper for the particular gas, service pressure, and flow requirements. If the shielding gas is supplied at the proper working pressure through a piping system that is regulated from a large storage unit or bank of manifold cylinders, a flow meter may be connected at the work station.

Do not use adaptors unless you follow the instructions of a manufacturer. The various Compressed Gas Association (CGA) designated connections are designed for your protection. Refer to CGA pamphlet V-1.

Never force connections that do not ft properly. This can strip the threads on fittings and result in leaky connections. To prevent leakage, be sure the regulator nut is pulled up wrench-tight, not merely hand tight. Do not tighten the connections excessively.

Do not use lubricants or pipe fitting compound for making connections. Connections in apparatus are designed so that they can be made up clean and leak tight. Oil or grease in lubricants and compounds tends to gum up regulating equipment and torches. Lubricants and compounds can also contaminate the shielding gas, and in the case of oxygen service they can contribute to a catastrophic fire and personal injury.

Make sure the regulator pressure-adjusting screw is released by rotating it counterclockwise until it turns freely. This closes the regulator valve and prevents a sudden surge of pressure from possibly damaging components in the system. If regulator is equipped with a flow meter, be certain the flow control valve is closed by turning the knob all the way in (clockwise).

Stand to one side of the regulator or regulator/flow meter away from gauge face. SLOWLY open the cylinder valve. NEVER open a cylinder valve suddenly. Sudden surge of high pressure gas can weaken or damage critical components in the regulator.
Check all connections and joints for leaks. After making all connections, close torch or downstream valve and then turn in the regulator pressure-adjusting screw to the desired operating pressure (or just open the flow meter valve). Using a suitable leak test solution, check every connection and joint from cylinder to torch for leaks, Correct any leakage before starting operations.

Never tighten a leaky connection between a regulator and cylinder when under pressure. Close the cylinder valve; allow the trapped gas to leak out; and then tighten the connection.

Use correct pressure and gas flow. Always be sure you are using the correct gas pressure. Refer to the manufacturer’s instructions for the torch or apparatus being used. If operating properly, the regulator maintains pressure as set. The required flow rate will of course vary according to the type of job. Once set at the desired rate, a flow meter will give an accurate measurement of flow at all times.

As soon as you have finished working, or if you are going to disconnect the regulator or regulator-flow meter combination, do the following:
Close the cylinder valve.

Open the flow meter and torch valves to release all pressure from the hose and regulator.

When the gauge pressure drops to zero, close the flow meter valve.

This will prevent the occurrence of an accident caused by someone removing the

Regulator with the cylinder valve open, Double check by observing the inlet gauge

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