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Arc Welding Processes



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Methods of Arc Welding:

SAW (submerged arc welding):

For this process, welding power may be AC or DC. The welding current ranges from 250 amps for 2.4 mm wire to 2000 amps for 9.5 mm wire. Weld quality is high, meeting ASME Boiler & Pressure Vessel Code and Piping Code requirements (ASME IX ).Welding is in flat and horizontal positions only. For one inch plate, single V weld the electrode diameter is 5/16 inch, the speed is 10 inches per minute.

GMAW (Gas metal arc welding)

The welding power sources is either DC or AC. Normal electrodes used is up to 1/8 inch diameter. Normal amperes required is from 50 to 225. For carbon steel inch thick, number of passes required is 2. Required filler wire diameter is 1/16 inch. Protection from wind may be required.

SMAW ( shielded metal arc welding)

In this process, covered electrodes are used. You may use AC or DC power source. This method is mostly used for mild and alloy steel and stainless steel. The electrode is clamped in an electrode holder which has a cable leading to the power source. The work is electrically grounded. The electrode tip is touched to the work to establish the circuit, and then retracted about 1/16 of an inch. Arc voltage ranges from 20 to 40.
Current ranges from 20 to 500 amps.

GTAW (gas tungsten arc welding)

This process employs a tungsten electrode which is not consumable. Shielding is obtained from a gas, e.g. helium or argon or gas mixtures. Pressure may or may not be used. Filler metal may or may not be used. This process is also called TIG welding.
When shielding is obtained by the use of an inert gas like helium or argon, this process is called Inert Gas Tungsten Arc Welding. The arc is generated between the work and the tungsten electrode which is not consumed. The filler metal must be added from an external source, usually as bare filler rod. GTAW is best for making root weld of high quality, for example when joining two lengths of pipe.

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