Purge welding - from which the name Purgetech is derived - is a technical and specialised process.
Each parent metal is fused together without the use of a filler wire. To enable a clean, full penetration weld to be achieved all areas of molten metal must be isolated from exposure to oxygen during the weld process.
This is accomplished by closing off the section of pipe and introducing a flow of argon gas through a carefully placed inlet, thus “flushing out” or “purging” all the oxygen from the pipe.
Once all the oxygen has been removed, the join can then be TIG welded from the outside with a single continuous fusion weld, ensuring the molten weld pool penetrates fully to the inside of the pipe.
The appearance of a quality purge weld is that of being welded from both sides.