Hydrogen Pipeline In-line Inspection Case Study

Abstract There is a growing network of hydrogen pipelines operating in the United States: 1,600 miles (2,575 km) are already in place. Throughout their lifecycle, hydrogen gas pipeline assets need to be inspected periodically for safety and integrity of supply. Magnetic flux leakage (MFL) has been used for decades as an in-line inspection (ILI) technology. Because MFL tools must be durable and robust, their design has relied on well-established materials such as high strength alloy steels and rare earth permanent magnets. These materials are especially susceptible to hydrogen embrittlement, which occurs when a material is mechanically stressed while being exposed to hydrogen. Successfully inspecting hydrogen-carrying pipelines while reducing the risk of hydrogen embrittlement requires the use of alternate materials and methods to develop a capable ILI tool. This white paper will discuss the challenges of this unique inspection environment, which were resolved through innovative ILI tool design and focused pipeline operation during the inspection process.