Cavity
Welding - Cavity welding is another approach to weld in a water free environment. In this process, the conventional arrangements for feeding wire and shielding gas are surrounded by a means for introducing cavity gas and the whole is surrounded by a trumpet shaped nozzle through which a high velocity water jet passes.
Cavity method avoids the need for a habitat chamber and it lends itself to automatic and remote control. The process is very suitable for flat structures where butt welds with a back up strip can be welded in the flat or overhead positions.
Cavity welding does not appear to be suitable for unbacked pipeline butt joints nor for lap joints which have accounted for the majority of underwater welding work.
