INERT GAS PURGE UNIT HAVING FLEXIBLE, EXPANDABLE MEMBER

摘要

The invention provides a purge unit for establishing a closed zone for an inert gas around a weld area. The purge unit is particularly adapted for use where a branch pipe is welded to a main pipe or header. The purge unit is inserted into an opening in the header and is then expanded to establish the closed zone around the inside of the weld area. An inert gas, in a volume much less than otherwise required, is then supplied through the unit into the zone to cover or blanket the inside of the weld area. After the weld is complete, the purge unit can be collapsed and withdrawn through the opening so as not to leave any material within the header which might cause contamination.