ABSTRACT
With the onset of satellite field developments, the lengths have increased, in some instances to tens of kilometres. They are of relatively small diameter so they possess sufficient negative buoyancy not to require a concrete weight coating. The term “riser” is applied to a section of mainly vertical pipeline that connects the pipeline on the sea floor to the processing facilities on the platform. Confusingly, the term riser applies to both pipes that take fluids up to the processing facility (“import” risers), and to the pipes that take fluids down to the seabed section of the pipelines (“export” risers). The methodology will be non-conservative since it ignores the reality that if the coating breakdown is uniform (as supposed), the pipeline adjacent to the anode will take disproportionately more current than more remote parts of the line. However, this concern can be offset by the knowledge that other design parameters are intentionally conservative.
