R6 weld modelling guidelines: application to groove weld worked example

Weld modelling guidelines have recently been developed as part of a new section of the R6 integrity assessment procedure, which is used in the UK nuclear power industry. The intention is to improve the consistency of weld modelling procedures, the accuracy of predicted residual stress profiles and confidence in their use for defect tolerance assessments. The first issue of these guidelines is applicable to austenitic stainless steel joints produced using arc welding processes. The components of interest are mainly thick section nuclear pressure vessels and pipe welds where distortion is not the key issue. Recommendations made in the guidelines are largely based on residual stress analysis methods, validated by measurements on a range of weld mock-ups, developed over several years in support of British Energy projects. The guidelines themselves are divided into two main parts. The procedure itself defines the weld residual stress analysis steps and identifies the key modelling decisions to be made. A much larger section then follows, providing advisory notes on how to make key modelling decisions, with reference to supporting documents and three appendices. The purpose of this paper is to describe the application of the guidelines to a typical weld residual stress assessment. This is in the form of a worked example which details the step-by-step application of the guidelines and describes the key modelling decisions that were made at each step of the procedure. The worked example is for a three bead groove weld specimen. This specimen is an austenitic stainless steel plate with a groove running along the entire length of the plate. The groove is filled with three stringer weld beads.