A METHOD OF WELDING AND A SYSTEM THEREFOR

摘要

A method of welding in which an inert gaseous shield at a welding zone is provided by a mixture of gases of different densities. The proportions of the individual gases in the mixture are controlled to ensure that the density of the gas mixture is about the same as the density of the surrounding atmospheric air. Cryogenic means (100) may be used to form a condensed gas plug in a pipe (104) or the like to be welded.