Influence of the type of pipeline integrity assessment on the effectiveness of repairs

Abstract

Assessing the integrity of corroded pipelines has long been and continues to be a concern for the industry. Over the years, several modifications to the original method have been proposed and adopted. In recent years, various methods for evaluating metal loss corrosion defects have been developed based on test data and safety factors. This article presents a comparison of the methods for evaluating corroded pipelines and comments on these different methods. The study is limited to corrosion defects and metal losses in pipelines exposed to internal pressure. The choice of points and methods of repair depending on the severity of the defects, or the degree of damage to the pipeline, can only be decided after having examined: a)The consequences of the unavailability of the pipeline on the transport program, b)The economic aspect; (the desired transportation capacity, as it is the desired maximum service pressure thatwill condition the repair plan, The following types of repairs are encountered: Repair without production stoppage, Repair with production stop. The presentation deals with the case of the study of a 164 km section of the OB1 pipeline linking Haoud El Hamra to Bejaia, 660 km long. The ERF calculation results (Estimated Repair Factor, following table) according to 2 criteria used (ASME B31G and modified B31G, gives us the opportunity to make a lot of comments as well as the opportunity to use the improved RSTRENG criterion