Transition Temperature Determination for Thick Wall Line Pipe

The applicability of Drop Weight Tear Test specimen to evaluate the ductile to brittle transition temperature of thick wall pipes (30 mm and 40 mm wall thickness) has been investigated by comparing West Jefferson tests at different temperatures and laboratory data. The traditional API pressed notch specimen has been used with full and reduced thickness, together with chevron notch and weld notch starters. The different crack initiation methods have been examined with the goal of providing an easier test specimen, with reduced fracture energy. The 85% shear area transition temperature indicated by the different test specimen show a reasonable similarity, but the higher costs of preparation of the alternative notch geometries limit their adequacy in substituting the traditional pressed notch specimen. Good agreement has been found between standard DWTT specimen and full-scale test transition temperature. The results of this program together with literature data, confirm the validity of the DWTT specimen to measure the ductile to brittle transition temperature for thermomechanical rolled linepipe steels of thickness up to 40 mm. The reduced thickness specimens conservatively predicted full scale behaviour.