Gas turbine tripped due to an indication of gas inside the enclosure

Cause & Consequence

• Uncontrolled release of a flammable gas or liquid

Incident Location

Fixed Installation

Incident Activity

Production operations

Specific Incident Equipment

Bleed valve on double block and bleed

Lessons Identified

No reason for the plug being removed and the valve being opened could be found from the recent works scope.

Plug possibly removed during commissioning to connect a test instrument and not replaced

Plug possibly was not tight when fitted and vibrated out along with the valve vibrating open. No plug found on the floor, however during the check on additional instruments post incident, another nearby DB&B had a loose bleed plug.

It was also found during the investigation that the Engineering work pack for a recent controls upgrade showed instrumentation had open ended tubing fitted to the vent ports, but no caps were fitted. Caps / plugs must be fitted to open ended ports.

Incident Recommendations

Bleeds plugs and vent ports to be checked on instrument lines which have had recent invasive work.

Bleed plugs fitted to instrument lines during a recent controls upgrade are to be checked to ensure they are still secure 2 months after the incident.

Discuss the incident with teams to highlight the importance that if a line is left open as a vent then it must be added to the isolation certificate. The importance of making sure that plugs / caps are fitted to all bleed ports should also to be discussed.

Ensure a bleed plug check is completed on all future instrument engineering scopes.

Bleed plugs must be fitted in accordance to manufacturers recommendations.