Helically wound tubes - making joints by welding in two stages

摘要

Helically wound tubes are welded from strip in an axially rotated and advanced forming cage. The edges of the strip are first provisionally joined by a discontinuous high speed arc weld made in the forming cage, and after cutting the tube into lengths, the final weld is made by arc welding at a lower speed outside the cage. Allows tubes of different dias. to be produced without long delays for resetting the appts.