Schleswig-Holstein Netz (SHN), a German distribution system operator, manages electricity and natural gas networks, including two parallel 12-inch natural gas pipelines crossing a canal.

Constructed in the early 1980s, these pipelines cross the canal via a utility crossing culvert, entering, and exiting through vertical shafts and terminal buildings owned by the local port operator.

The system’s complex geometry, including vertical drops, tight bends, and dense surrounding infrastructure poses significant challenges from an inspection and internal and external condition monitoring perspective, particularly surrounding the management of corrosion threats. These uncertainties, combined with the increasing age of the assets, drove SHN to seek a novel inspection solution to ensure that operational risk could be maintained within acceptable thresholds.

From a traditional ‘free-flowing’ in-line inspection perspective, a key limitation is the absence of launcher and receiver infrastructure, which renders conventional ILI methods such as free-swimming or bi-directional tools impractical. Additional constraints include non-passable features, such as tee-branches, the operational requirement to keep at least one pipeline in continuous service, and the impracticality of reverse flow or liquid/nitrogen-based propulsion methods.

To overcome these challenges and address the active integrity threats, a self-propelled robotic inspection system was developed, capable of performing magnetic flux leakage inspections independently of flow conditions or pressure. This paper details the specific adaptations made to the robotic platform, to enable safe and controlled navigation through the system’s complex geometries. The comprehensive upfront technology validation program focusing on mechanical passage and measurement performance aspects in relation to the credible pipeline integrity threats is then presented. Finally, the paper discusses the key integrity management benefits that were realized by deploying the novel inspection system within the SHN pipelines.