High frequency induction welding of austenitic stainless steel for pressure vessel tubing

Abstract

A process for producing high pressure tubing from austenitic stainless steels. The process entails passing a continuous austenitic stainless steel strip through pre-weld rolls enclosed in a forming housing to produce a continuous tubular shape having opposing edges separated by a longitudinal gap. While the gap is maintained with a seam guide and a liquid-free gas mixture of an inert gas and a gaseous flux is directed at the gap and into an interior of the tubular shape, the tubular shape is caused to pass through a high frequency induction coil to cause heating of the opposing edges of the tubular shape. Pressure is then applied to the tubular shape with weld rolls to force the opposing edges together and form a continuous tubing having a continuous butt weld joint. The weld joint is then quenched with an inert gas without the assistance of a liquid coolant.