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Welding Instructions

Providing that certain precautions are taken, and welding does not present major difficulty. Inert shielded arc processes (TIG) are particularly appropriate to the welding of these alloys.

The following procedure has been established for assemblies in tubes and accessories with a thickness of 1.5 to 10 mm welded by the TIG process.


To weld under proper working conditions, the welding set should be equipped with a pre-gas, pre-arc, and arc fall system.

General Welding Conditions

  • Direct current with direct polarity (the electrode is connected to the negative pole).
  • Electrode: it is made of thorium tungsten or zirconium tungsten.

Its state of cleanliness is most important, influencing the quality of the weld and the stability of the arc.

The diameter of the electrode is dependent on the welding current:

Diameter mm Current mm
1 25/70
1.6 60/150
2 100/200
3 200/300

To achieve a perfectly stable arc and obtain a maximum heat concentration it is advisable to work the electrode as close as possible to the maximum supportable current.
Protective gas : neutral argon protection is generally sufficient. Torch flow 8 to 12 l/mn.

Filler Metal

Specifications for filler metal are:
Aws specification: A.5.7.ERCuNi BS EN ISO 24373
Cu630% Ni filler metal is recommended for both alloys.
The parent metal filler rods should always be perfectly degreased.

Preparation of Joints

In general, all types of joints can be used.

For tubes and accessories with a thickness less than or equal to 2 mm, it is not necessary to make a chamfer but it is desirable to break the internal square corner to favor penetration.

For tubes and accessories with a thickness greater than 2 mm, a chamfer of around 30° to 40° is recommended.

welding instructions