Pipeline Riser emergency shut down valves - Inspection issues and recommendations
Offshore inspections in 2006-7 focused attention on Riser Emergency Shut Down Valve (RESDV) inspection and testing. The inspections showed that, typically, testing, records and practice were managed relatively poorly.
Regulation 19 and schedule 3 of the Pipelines Safety Regulations 1996 (PSR) require RESDVs to be capable of adequately blocking the flow and this must be achieved with a valve that is suitable and is maintained in an efficient state, in efficient working order and in good repair. The Piper Alpha disaster highlighted the critical nature and functions of riser emergency shut down valves.
Key Items Causing Concern
- Unclear lines of responsibility between the pipeline operator and the installation duty holder.
- Quality and standard of inspection/testing practice and records management, not always consistent with the standards expected for safety critical equipment.
- Missing data and records.
- Inconsistencies between hard copy and computerised records.
- Testing practices and equipment not always in accordance with written procedures.
- Inconsistency in units used for leak test performance and test results makes equivalence difficult to reconcile – sometimes no units are recorded.
- Leak tests undertaken at pressures significantly lower than the maximum allowable operating pressure with limited or no extrapolation of results.
- Records do not make it apparent whether test results meet performance standards.
- Little evidence of the use of trend analysis from leak test and closure results.
- Limited evidence of Warning or Action levels being used to allow for suitable maintenance and repair planning before failure.
- Valves failing to meet performance standards on initial demand test (but being repeatedly re-tested until standard met) and then continuing to be operated normally without review or adjustment to future performance standards or frequency of testing.
- Evidence of operators adopting an operational risk assessment approach to validate continued operation without a fully functional RESDV.
Recommendations - Pipeline Operators should
- Review riser emergency shut down valve inspection and testing procedures and management systems.
- Undertake a formal reassessment of the adequacy and effectiveness of existing arrangements.
- Identify and implement any improvements necessary.
HSE Intervention Priorities
HSE wrote to all pipeline operators in December 2007 requesting them to complete the recommendations listed above and to provide a summary of their findings to HSE before March 2008.
Continue communication and intervention work to help reinforce the adoption and use of recognised good practice for the inspection and maintenance of RESDVs.
Targeted intervention of RESDV integrity management arrangements and practice, including coverage of associated verification issues.
Issue Date: 19 February 2008
Gas and Pipelines Unit