Repairing Corrosion Resistant Alloy Clad Pipelines: The Weld or Connect Choice

Abstract The use of subsea Corrosion Resistant Alloy (CRA) clad pipelines is increasing nowadays, and there are plans to increase even further their laying to develop large reservoirs and transport high temperature, high pressure, highly corrosive fluids. This tendency calls for the development of solutions capable of facilitating a safe and reliable repair intervention, which are going to be presented hereafter. This paper aims at comparing traditional welded solutions, such as above water repair methods and underwater hyperbaric welded solutions, with the novel options offered by subsea connectors purposely developed for CRA clad pipelines. These connector solutions ensure continuity of containment of the corrosive fluid by means of engineered non-elastomeric, metallic seals, and are qualified according to the most demanding DnV rules, thus allowing the comparison on a pure operational perspective. Repair connectors for CRA clad pipelines are robust and qualified solutions, and their installation shall follow the same sequence as legacy elastomeric-seal repair connectors, with minor additional preparation required. From a pure intervention perspective then, a dedicated comparison of each step will be provided, thus emphasizing the reduced demand in terms of installation spread, specialized divers as well as tailor made welding procedures requiring constant update and recertification. From a timeline perspective, repair connectors offer valuable alternatives for all such cases where time is really of the essence, such as in the business interruption scenario post intervention. Finally, an assessment of spare pipes is also provided, showing how the pre-selection of an optimized repair solution can effectively reduce the pre-investment needed for spare pipes, especially in subsea congested areas. Technology development is constantly evolving for the benefit of the energy industry: while CRA clad pipeline repair solutions have been already shown in certain occasions with focus on the technology qualification, a competent and complete assessment of the wide-reaching benefits of such technology has never been presented, and this would be extremely valuable for the Arabian Gulf area.