Structural integrity of circumferential welded joints in pipelines and risers

Abstract

The technological challenges for oil and gas drilling and production in the newly discovered Pre-Salt layer are enormous and have strongly motivated the development of more efficient and yet innovative offshore production systems capable to meet the complex and stringent design and operation requirements for ultradeep waters. Within this scenario, the riser system for oil and gas export from the well head to the floating production unit plays a key role in ensuring high levels of structural integrity and safe operation of the offshore infrastructure. This research plan addresses a numerical and methodological investigation of strength mismatch effects on the fracture behavior of circumferential welded joints for risers and pipeline systems. The approach is further extended to defect assessment procedures in such structural components based on the ECA methodology. A central objective is to develop more advanced and yet more accurate defect assessment procedures which are applicable to riser installation by the reeling method. The project is divided into 04 subtasks as follows: i) SET-SOL - Development of SE(T) fracture specimens applicable to fracture testing of weldments; ii) JCRISER - Evaluation of J and CTOD crack driving forces for welded joints in risers containing circumferential defects; iii) ACRSOL - Critical engineering assessments of welded joints in risers e iv) FRACTOOL - Development of the research code FracTool. (AU)