Good stainless steel practice is the basis for welding duplex and superduplex grades. However, some issues from the generalized ‘good practice’ rules must be emphasized where as other issues need only the same attention as when welding 300 series stainless steels.

This paper discusses good ‘duplex and superduplex‘ stainless steel practice. Issues around, for example, welding procedure design, heat input and interpass temperature are discussed.

The practical application of the rules is all important. The first step is to educate the work force into thinking ‘duplex’, i.e. not just another grade of stainless steel. Specification and practical fabrication issues, as applied to reactor and pressure vessel fabrication, are described. Welding procedures are given, together with the results of procedure qualification tests and production test plates.