Repairing corrosion defects of subsea pipe and the availability of repair method

The repair technology for subsea pipeline includes abovewater dry maintenance, underwater hyperbaric welding, lineup clamp repair, flange connection, on-line stoppling, leak clamps maintenance. The application scope, special equipments and personnel needed, detection requirements, shut-down duration of running, repair time, maintenance costs are compared and analyzed among the various technical methods. The evaluation procedures and methods for corroded subsea pipeline are given, including the methods with the partial safety factor-based and the allowable stress design-based, together with the original data and calculation process. Based on these considerations with the technoeconomic analyses from different repair schemes, the optimal repair scheme for the defects of corroded submarine pipeline is determined.