Gas release from safety release valve

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Rating: 
Average: 3.8 (5 votes)
Alert ID: 
03716
Description of Task: 

Import gas had been introduced to platform after a considerable shutdown. A detailed gas-compression re-commissioning procedure was being followed.

During commissioning of an HP compressor, an individual involved in the commissioning operation identified that gas was emanating from the bonnet vent port of a 2 ½ “ safety relief valve.

The suction pressure of the HP compressor is controlled by a pressure controlling valve and the safety relief valve protects the HP compressor. Due to the 9 barg operating pressure of the HP flare system, the safety relief valve is of balanced bellows design.

Upon discovery of the leak, the decision was made to initiate a manual blow-down and this was carried out and completed a short time after.

Subsequent investigations have revealed that the leak was caused by a crack in the bellows which allowed HP flare-gas to escape via the vent port.

Lessons Identified: 

The bellows in balanced bellows relief valves have a finite life and as such should be treated as consumables.

Recommendations: 

Ensure that suitable and sufficient maintenance routines are in place for bellows in balanced bellows relief valves which are in line with manufacturers recommend max-life.

Contact Details: 
Andrew Howard, HSE Lead, Talisman Sinopec Energy UK.
Specific Equipment: 

2 ½ “ balanced bellows safety relief valve protecting an HP compressor.

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