LOW IMPACT TEST RESULTS IN CARBON STEEL FLANGES, FITTINGS AND PIPING: END USER'S VIEW

摘要

Carbon steel components (Flanges, Fittings and Piping) have been reported with low impact test results. Some have failed during hydrotest and start-up as well as in-service. Steel grades that have shown problems complying with impact test requirements are ASTM/ASME A105, ASTM/ASME A234 Gr. WPB and ASTM/ASME A106. ASTM A350 LF2. These components according to some design-fabrication industry standards are not suitable for use even though they complied with applicable ASTM/ASME materials standards meeting the mechanical properties and chemical composition. Some analyses have led to identify key contributing factors to this low impact test results including Chemistry/Micro-alloying, fabrication approach and use of 100% re-cycle steels. This paper presents summarize findings from numerous reports of failure, testing data and selected approach when screening these materials prior to installation. Based on literature review the need for improvement in the approach for mechanical testing including fracture toughness testing for modern materials was identified.