Hydrocarbon Releases Found From well Slot Flow Transmitter Pipework

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Alert ID: 
Description of Task: 

Hydrocarbon Releases Found From well Slot Flow Transmitter Pipework

During maintenance on wellhead, the SSSV hydraulic master and wing valves were opened. The choke was opened to 25% (the 6" production block valve downstream of the venturi was closed), pressurising the system to a CITHP of 233bar. During a local inspection of the plant, a gas leak was noticed coming out of 1 leg of the 3/8" 'T' piece fitting to the DP cell and pressure gauge. There was also a separate gas leak at the seal point of the isolation valve integral to the manifold block. The local gas detection did not activate.

Lessons Identified: 

Metallurgical analysis discussion stated that austenitic stainless steels are particularly susceptible to stress corrosion cracking in the presence of aqueous chlorides at elevated temperatures.


  • Confirm all other fittings in the same service are gas tight and show no signs of deterioration
  • Take further samples of the population of fittings to gauge whether a system issue – completed and found to be isolated case
Information source: 
Contact Details: 
Step Change in Safety
Specific Equipment: 

Pipework & Fittings, Valve, Wellhead

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