Multipass welding of nuclear reactor components - measurements

During the process of welding high residual stresses and large deformations can occur. This is a problem in nuclear power plant components, and in many other engineering applications as well. Finite element calculations can be used to predict these residual stresses, and in the long run also to find welding procedures that diminishes the residual stress at sensitive areas. The present report describes measurements done during and after welding that can be used to validate such calculations. Stainless steel pipes of two different thicknesses have been studied, and each thickness has been welded by two different welding procedures, U-seam and OPTI-GAP. Measurements on one stainless steel plate welded by an X-seam are also included in the report. On all of the studied objects transient temperature measurements during welding were performed. After welding all of the objects were subjected to residual stress measurements by the hole drilling method. During welding of the thinner pipes and the plate transient strains were measured, and after welding of the thinner pipes neutron diffractions measurements of residual strains were performed