Abstract: A purge gas unit establishes an enclosed zone for purge gas within tubes or pipes having portions which are to be joined by welding. The purge gas unit includes a first bladder to be positioned on one side of the welding location and a second bladder positioned on the other side of the location. A purge gas supply tube extends through the first bladder and has an opening near the second bladder through which purge gas is supplied to the weld zone or space between the bladders. A vent tube extends through the first bladder and communicates with the weld zone near the first bladder and with a space beyond the first bladder. A safety cable also is attached to the second bladder and extends at least substantially through the first bladder, with the cable enabling the purge unit to be removed from the tubes after welding. The bladders can have annular chambers with central passages through which elongate members can extend. The bladders, in another embodiment, can be substantially flat when not inflated.

Abstract: A purge gas unit is provided for establishing an enclosed zone for purge gas within a tube or pipe having portions which are to be joined by welding at a predetermined location relative to the length of the tube or pipe. The purge unit includes at least one cone to be positioned on one side of the location where the welding is performed and a second cone positioned on the other side of the location. A purge gas supply tube is connected between the cones and has at least one opening therebetween through which purge gas is supplied to the weld zone in the pipe or tube between the cones. The gas supply tube extends through one of the cones beyond the weld zone defined between them and is connected to gas supply means.

Abstract: An improved purge unit is provided for establishing an enclosed zone around a weld area for retaining an inert gas. The purge unit is particularly advantageous when welding a branch pipe or pipe connection to a main pipe or header. The purge unit has a cone-shaped member which is inserted into an opening in the header through the branch pipe or connection and is then expanded to establish the enclosed zone around the inside of the weld area. An inert gas is then supplied through the purge unit into the zone and the cone-shaped member is subsequently collapsed and withdrawn after the weld is complete. An expandable tube is employed to expand the cone-shaped member and has a rod extending therethrough and connected to the member to provide greater stability for the purge unit.

Abstract: A purge unit is provided for establishing an enclosed zone around a weld area to receive an inert gas. The purge unit is particularly useful when a branch pipe is to be affixed to a main pipe or a header. The purge unit is inserted into an opening in the header through the branch pipe or connection and is then expanded to establish the enclosed zone around the inside of the weld area. An inert gas is then supplied to the unit into the zone to cover or blanket the inside of the weld area. After the weld is complete, the purge unit is collapsed and withdrawn through the opening and through the branch connection so as not to leave any material within the main pipe which could cause contamination.

Abstract: 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.