HC Leak from Compressor Cylinder Head

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Alert ID: 
Description of Task: 

HC Leak from Compressor Cylinder Head

Gas was detected by a maintenance technician working near the VVP of an adjacent compressor. The investigation revealed that gas was passing the o-ring on the cylinder head arrangement. A small blister on the o-ring indicated where the gas was released. Checks of the bolt torques indicated a slight under tension on some of the bolts.

Lessons Identified: 

• O-ring was not properly installed but the system passed a pressure test

• Installation in congested area may have caused problems

• Bolt under tensioning allowed gas to pass at discrete location on the o-ring

• Torque wrench was in certification but calibration was suspected as incorrect


• Care needed when installing o-rings in congested areas as they may be misaligned or become damaged.

• Check calibration of torque wrenches regularly

Information source: 
Contact Details: 
Step Change in Safety
Specific Equipment: 

Variable Volume Pocket o-ring seal

Incident consequence: 
Hydrocarbon release
Production operations
Fixed Installation
Cause of accident or incident: 
Uncontrolled release of a flammable gas or liquid