Riser ESDV leakage rate study

The purpose of this study was to conduct the annual tests on riser emergency shutdown valves (RESDV), in line with current legislation

Jee’s client has a presence in the North Sea and asked Jee to carry out tests on all RESDV to determine the time of closure and leakage rate when closed.  In 2008, one of these valves had been found to be approaching its’ currently specified maximum allowage leakage rate.

Jee conducted a study to determine the effect of seal degradation on leakage past the riser ESDV, accounting for energy losses in the system as the system passed the valve.

Key outputs were:

• Leakage rate of the valve when tested at MAOP, for varying levels of seal degradation (and hence gap between seal and ball valve interface)
• Assessment of an acceptable level of seal degradation whilst still maintaining the integrity of the RESDV, taking account of previous studies relating to the current maximum allowable leakage rate

• Re-assurance on the condition of the RESDV and whether remedial action was required, or if the allowable leakage rate could justifiably be increased
• Rapid turn-around of the study to enable prompt assessment of actions required