Application of ultrasonic testing for welding defects

Abstract

The main purpose of the following study was to carry out a broad research on ultrasonic testing on welding defects. The research problem investigated during this dissertation was the applicability, relevance and importance of Ultrasonic Testing (UT) in finding welding defects. Both internal and surface welding defects were taken into consideration with the findings reported in the final stages of the dissertation. Welding is a critical process and is used extensively within the maritime sector, which led to the following study being conducted. Ensuring high quality welds is a must in the maritime sector to ensure that the metal structure being assembled is fit for purpose and safe. Hence, the research question addressed throughout this dissertation was whether welding defects can be revealed by UT and how the UT results are obtained. The procedure taken to address this research question was via a comprehensive literature review, together with some additional relevant theory. Apart from UT, other NDT methods were also discussed which were deemed to be relevant and necessary for the ongoing analysis in the dissertation. According to the literature review and theory investigated, the following part of the dissertation consisted of practical case studies with a detailed explanation on how to obtain the final UT results. The procedure involved was heavily discussed including the prior calibrations that must be done, the necessary understanding of the nature of the welding defect and the decisions taken during the actual testing in order to obtain correct or relevant results. Major findings and trends, found as a result of the analysis carried out, were documented and recorded. Different conclusions were drawn up depending on the nature of the welding defect investigated. In order to find and analyse all type of welding defects, it was concluded that other or a combination of NDT methods must be used in order to fully capture the location, size and type of welding defect.