Influence of girth welding material on thermal and residual stress fields in welded lined pipes

An experimental and numerical investigation on the thermal and mechanical response of a lined pipe (compound pipe) under welding is presented. The welding process consists of a single-pass overlay welding (inner lap-weld) and a two-pass girth welding (outer butt-weld). The influence of the filler material of the girth welding has been examined thermally and mechanically as it is a key factor that can affect the quality of lined pipe welding. To this end, a three-dimensional non-linear finite element model based on the ABAQUS code has been developed and successfully validated against small-scale experimental results. This study was conducted on two specimens of lined pipe joined together by a girth welding deposited either by mild steel or by austenitic stainless steel. Furthermore, in this study, a pre-heat treatment required to produce lined pipe specimens has been taken into account. Strains and residual stresses have been measured by means of high temperature strain gauges, residual stress gauges and the X-ray diffraction technique along the inner and outer surfaces of the welded lined pipe whereas the thermal history has been recorded by thermocouples. The findings point out that replacing the girth welding mild steel by austenitic stainless steel has a significant effect on the residual stress results but no influence on the thermal history results. Two identical welded lined pipes connected by single-pass weld overlay and two-pass girth welding, dimensions in mm. [Display omitted] •The temperature fields are not affected by changing the girth welding material.•Replacing the girth welding to austenitic stainless steel shorten the length of residual plastic strain on the outer surface.•Beyond the fusion zones, the residual stresses are not influenced by changing the girth welding material.