Structural integrkity of api 5L X70-X80 steel grade pipeline for hihg pressure long distance transmission gas lines

摘要

In 1995 Snam,centro Sviluppo Materiali (CSM) and ILVALP started a joint research project aimed at developing the mateiral selection criteria for high pressure long distance natural gas pipelines.Within this scenario of large natural gas volumes transportation,the research focused on large diameter (up to 1422 mm),high thickness (up to 30 mm),high steel grade (API 5L X70 and X80) pipes,suitable for operting pressure up to 15 MPa.Specific objectives of the research were the definition and assessment of toughness requreiemtns.for the avoidance of brittle fracture initiation and long running ductile fracture propagation.The aim of the experimental activity was to verify the validity,for high strength steel pipes,of the current test methods,to reproduce full scale pipe ductile to brittle transition behaviour,and of the available predictive formula for shear fracture arrest toughness requriements.