Application of IOGP S-616 Annex U for Qualification of HFW Pipe: A Case Study

Abstract High-Frequency Welded (HFW) line pipe stands out as a preferred manufacturing method, renowned for its efficiency, precise dimensional control, and robust mechanical properties. However, historical challenges have emerged, particularly related to undetected flaws in the weld bond line and suboptimal heat treatment practices. In a significant development, the International Association of Oil and Gas Producers (IOGP) introduced the S-616 Specification Revision 2 (August 2022), titled “Supplementary Specification to API Specification 5L and ISO 3183 Line Pipe.” This collaborative effort by 12 Oil&Gas companies establishes standards for line pipe procurement, introducing Annex U to address the qualification of HFW pipe-mills. This article showcases the successful application of IOGP S-616 Annex U in the qualification of Corinth Pipeworks S.A. (CPW) HFW pipe mill. Qualification, initiated by steel production at Arcelor Mittal, Fos, incorporates specific internal controls to ensure coils possess consistent properties and minimal segregation levels, supporting weld line soundness. CPW’s mill qualification involves producing line pipes under five combinations of squeeze/pressure, and HFW heat input. These conditions, including optimal and variable parameters, create a production envelope. Line pipes undergo automatic ultrasonic inspection and destructive testing. Based on the specific qualification process outcome, it is concluded that the application of IOGP S-616 Annex U ensures the reliability and safety of HFW line pipes.