STATISTICAL ANALYSIS OF PIPE GIRTH WELD EXPERIMENTAL RESIDUAL STRESS DATA

Thermal and mechanical processes during welding introduce complex three-dimensional distributions of residual stress. Management of residual stresses represents a major challenge for engineers in order to achieve safe and reliable operation of existing engineering plants. Consideration of how such stresses vary through the wall within welded components is critical in structural integrity assessments. Development of more accurate and realistic weld residual stress profiles through statistical analysis of high quality measured data is highly desirable. This cannot be achieved without adequate interpretation of measured weld residual stress data through the development of an appropriate framework. At previous PVP conferences such a framework was detailed. However, the framework was used to analyse and interpret welding residual stresses measured in highly controlled test specimens of simple geometry. This paper represents the extension of the framework to interpret real plant weld residual stress data. Specifically, the results of residual stress measurements on nine pipe girth welds are analysed statistically with the objective of providing a justifiable residual stress profile. The measurement results were obtained using different measurement techniques from different laboratories. The extension to real life data, unsurprisingly, reveals some unanticipated difficulties compared to the simple test specimen previously considered.