Titanium, stainless steel and other corrosion resistant alloys (CRAs) need to be shielded with an inert gas during welding to protect the molten weld pool from combining with oxygen and nitrogen from the surrounding air. Without some sort of protection, any of the welds made will oxidise and can form metallurgical defects that could result in weld joint failure.
Without this protection, welds will oxidise and can form metallurgical defects that may cause weld joint failure. Both TIG (GTAW) and Plasma (PAW) welding torches are fitted with gas cups that the inert gas flows through and protects the molten weld metal around the arc. The problem with this is that as the weld torch travels further along the weld seam, the welded metal is still hot enough to oxidise as it is exposed to air. Therefore in most cases the oxidation has to be removed to reduce the risk of weld failure. In order to eliminate the air from combining with the remaining hot metal, a trailing shield can be fitted to the welding torch.
Huntingdon Fusion Techniques Limited (HFT) offers a complete range of shields that cover most welding geometries of the above named materials. There are lightweight radiused models that cover all diameters of pipes and cylindrical vessels as well as flat models that better suit sheet metal or other flat applications. There is even an internally radiused model for those welders that have to weld inside a large diameter pipe or chamber.