Gas Leak from Actuated Ball Valve Trunnion

Cause & Consequence

• Uncontrolled release of a flammable gas or liquid

Incident Location

Fixed Installation

Incident Activity

Production operations

Specific Incident Equipment

Actuated, 16” 300# trunnion mounted ball valve in 25Cr Super Duplex Stainless Steel. Trunnion fixed externally to ball valve body with capscrews. Plant Tag Number SDV-11379

Lessons Identified

• Installation specifications should take into account possible modes of failure and specify materials to mitigate the risk of occurrence
• An appropriate inspection technique/strategy should be in place which takes into account possible modes of failure during operation

Incident Recommendations

• Undertake a review of asset valve populations to identify those valves potentially at risk from Chloride induced SCC considering valve; operating temperature; design and materials of construction; location and potential for chlorides environment.
• Replace trunnion cap screws of valves potentially at risk with cap screws not susceptible to Chloride induced stress corrosion cracking
• Review company material / valve specifications and revise as required to recognise failure mode and specify materials accordingly
• Develop and implement a Long Term Strategy for valve cap screw inspection and replacement
• Review and revise the asset ALE strategy based upon learning from this incident