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TIG WELDING

Edge preparation

Copper alloys (Cunifer, Yorcalbro) Material thickness mm

Type of joint

Welding current, Horizontal

Tungsten electrode mm ø

1

90–100

1.6

100–115

1.6

100–115

1.6

2

115–130

1.6

3

170–200

2.4

190–220

2.4

190–220

2.4

NB: When welding Stainless steel and Cunifer, backing gas must be used inside piping.

In order to avoid surface oxidation, pipes of stainless steel must be purged with inert gas sufficiently to remove all oxygen inside the pipe in the weld area. The usual way to achieve this is to seal off a small length of the pipe on each side of the weld groove. This restricted volume is then purged with a suitable inert gas, sufficiently to remove all oxygen. The ideal concentration of oxygen is below 25 ppm, as this is insufficient to oxidize stainless steel.

Backing gas tool for larger pipe dia.

Gas in

Backing gas tool for small dia. pipe

Gas in

Gas out

4.02

Out trough free opening

The most common gas to use is Argon or Formier gas (90% N2 and 10% H2) 399