The scope
A long-standing operator in the North Sea approached Jee for support in understanding the condition and reliability of a critical 30 inch emergency shutdown valve installed on their import line. The valve had been in operation since the early 1990s and its location meant that any replacement would require significant engineering time and major offshore intervention.
The client needed a clear assessment of potential failure modes, an understanding of any emerging degradation and clarity on whether the valve could continue operating safely within its expected service life.
The client selected Jee due to our decades of experience delivering subsea and pipeline integrity assessments and our track record in systematic reliability studies including FMECA. Our team was familiar with both aging infrastructure challenges and the operator’s own risk management processes, which helped streamline the study.
The solution
Jee carried out a full failure modes, effects and criticality assessment on the valve hardware, hydraulic actuator, hydraulic power unit and control cabinet. This work involved:
- breaking the system into all component parts for structured analysis
- identifying all possible failure modes, their causes and their local and global effects
- assessing likelihood and consequence using the operator’s risk matrix
- reviewing existing safeguards such as leak testing, maintenance routines and enclosure protection
- determining which components carried medium or high-risk levels that required action
- assessing which risks were time dependent and which were not
- identifying opportunities to reduce risk through improved maintenance, inspection, spare holdings and potential redesign of certain modules
The study involved two multidisciplinary workshops and detailed technical review of historic data, performance test results and design documentation.
Conclusion
Jee’s assessment confirmed that no intolerable risks were present and that many components exhibited low or very low risk ratings. Some components showed medium or high-risk levels that required planned risk reduction, including flange connections, valve internals, hydraulic filters and pressure control components.
Importantly, corrosion related failure of major components was found to be unlikely within the remaining service life due to very low corrosion rates in the system. Time dependent wear on seats and the valve ball was considered possible over several years although performance testing to date showed leak rates well within standards.
The client benefited from a clear, structured roadmap of recommended actions including enhanced inspection options, improved maintenance intervals, spare component strategies and consideration of modern valve monitoring systems. The study provided confidence in continued safe operation and enabled the operator to plan future interventions efficiently and with reduced risk.
For more information or to download our Integrity Management capability statement, visit www.jee.co.uk/integrity-management
To contact our Head of Integrity Management, Graham Wilson, email graham.wilson@jee.co.uk, or call +44 (0)1732 371 371.
Jee Ltd
