Comparison of approaches to the frequency and size distribution of welding flaws

This paper reviews the need to know the frequency and height distribution of welding flaws for use in structural reliability assessments. Three different approaches for determining the frequency and height distribution of flaws are described and compared. These approaches are based on the use of flaw data from inspection, the modelling of the processes giving rise to flaw formation, and empirical correlation of flaw probability with welding parameters using expert judgement. The strengths and limitations of the approaches are discussed with regard to their potential application. The paper concludes that the use of empirical correlation based on expert judgement offers a good middle course between the use of flaw data from inspection and detailed modelling. It has the potential to be developed for risk informed inspection of a wide range of welding processes, materials, and flaw types relevant to the power, offshore, and oil and gas industries.