+3 votes
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Gas alarms activated without any gas leak

asked Mar 24, 2014 in Safety by lulopez (2,220 points) | recategorized Mar 24, 2014 by lulopez
What can be the root causes of a gas alarm going off without any gas leak on a FPSO?
commented Mar 25, 2014 by Normandy (21,040 points)
Have you check to see if all gas detectors are in good working condition?
commented Mar 25, 2014 by lulopez (2,220 points)
Yes, all gas detectors were checked and they are in good working order.

2 Answers

+3 votes
answered Mar 25, 2014 by Normandy (21,040 points) | selected Mar 25, 2014 by lulopez
 
Best answer

Then it could be any of the following causes:

  • A combination of condensed Hydrocarbon vapors, and no-wind conditions probably allowed a slug of condensate to be discharged directly above the HVAC air intakes at the aft of the FPSO.
  • Undispersed Gas/Condensate released from Cargo tank vent pipe
  • Incorrect location of vent for crude containing residual gas (HAZID/HAZOP)
  • Inadequate design of condensate removal system (HAZOP)
  • On/off control of tank venting higher quantity of gas (Controls Philosophy)
  • Vent pipework design allowed condensate slug to form (Piping Design)
  • Operating without normal conditions – Production mode with Condensate removal system shut down was not formalized

​Anyone else has more to share or comment?

+3 votes
answered Mar 25, 2014 by pasmith (3,320 points)

The followings may also contribute to the gas detectors going off:

  • If FPSO was deployed to a field producing crude oil with a higher condensate fraction
  • Failure to recognize or assess the risk posed with the condensate removal package out of service and effect of cargo venting
...