Njord RBMs are used to mitigate buckling in seabed pipelines. Buckling occurs during start-up and shutdown sequences as the thermal fluctuations cause pipelines to expand and contract, leading to problematic buckling along its length.
Traditionally non-rotating cylindrical buoyancy modules have been installed along sections of the pipeline to reduce the weight and friction in that section and promote controlled bending. However in certain conditions the modules have displaced seabed material to build ridges (berms) that have then restricted the lateral movement that the modules were installed to promote.
With that in mind, Trelleborg developed Rotating Buoyancy Modules that roll on the seabed that thereby reduces lateral friction, berm creation and allows repeatable and predictable pipeline behaviour, eliminating rogue buckles and reducing axial walking in the pipeline. As a consequence it allows for project cost reduction as a lower quantity of buoyancy modules are used to create ‘safe buckling zones’.