Learning from the Causes of Failures of Offshore Riser Emergency Shutdown Valves

Riser emergency shutdown valves (RESDVs) are an essential risk reduction measure for offshore installations and are a legal requirement under the Pipelines Safety Regulations 1996. The RESDV should isolate the topsides from the well and subsea pipeline in the event of an emergency shutdown, to reduce the inventory for loss of containment or when required for maintenance. RESDV failures, whether arising from a test or a real demand, are reportable to HSE under the RIDDOR regulations and a preliminary survey found approximately 180 cases of failure in a seven year period. Given the criticality of RESDVs to offshore safety, it was determined that the reasons for these occurrences should be investigated with a view to focussing inspection topics and identifying areas for future improvement across the industry.