Differential Burst Pressure of Marine Pipelines as an Independent Layer of Protection

Offshore pipelines and risers are designed to different codes leading to different reliability targets, and different wall thicknesses. Pipeline design codes also differentiate between areas where people are present and those with no population or less environmentally sensitive. As a result, the offshore section of the pipeline (with “thinner walls”) could be considered to work as a structural fuse during an unforeseen pressure surge; if the pipeline bursts first, then the occupants of platform would be exposed to less risk than if the riser or pipeline in the vicinity of the platform were to fail. This implies that differential burst pressure could act as an Independent Protection Layer (IPL). This paper explores conditions that sections of a pipeline must satisfy in order to be considered as an IPL. A first order reliability method is outlined for determining the required target reliability. The application of this approach is described in a case study.