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TIG WELDING

Shielding gas

Shielding gas is necessary for the TIG process. The gas which must be chemically inactive (inert), has several functions in the TIG process: • To provide the atmosphere needed

for ionization, ensuring a stable arc and suitable heat transfer.

• To protect the hot tungsten

electrode against the oxidizing effect of the air.

• To protect the molten pool

against contamination and oxidation from the air.

R510 regulator with flow meter in order to adjust gas flow in l/min.

• To protect the hot end of the filler

metal rod from oxidation.

• To protect melt pool and electrode

during cooling after the arc is broken.

Argon has proven to be the most suitable gas for this purpose. It is a colourless and odourless inert gas, heavier than air, non-toxic and nonflammable. It is obtained from air which contains approximately 1% argon.

For the TIG process, a purity of 99,95% is commonly used.

It is necessary to adjust the gas flow and a regulator with flow-meter is therefore needed.

4.02

Onboard a ship it is necessary to have a flow-meter that functions correctly also when positioned out of vertical. The Unitor R510 gas flow regulator for argon is specially designed for this purpose and has a capacity of 0–32 l/min. Note that when welding stainless steel it may also be necessary to use backing gas to protect the backside of the weld from the oxidizing effect of the air.

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Argon is supplied in 10 or 50 litres 200 bar gas cylinders.

A separate gas supply (cylinder, regulator and hoses) should be used for this purpose.