Well Integrity Technical Section

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  • 1.  SSSV leak rate acceptence 15 scf/min for gas. what are the basis?

    Posted 05-29-2024 06:11 AM

    What is the reasoning behind the 15 scf/min SSSV leak rate acceptance criteria? is it a calculated value at certain conditions or based on experiments?



  • 2.  RE: SSSV leak rate acceptence 15 scf/min for gas. what are the basis?

    Posted 06-02-2024 06:49 AM

    Mohammad

    I am not on the API committee and so I can't say for certain but I will try and let them correct my answer. 

    Both the Surface Safety Valve API RP 14H and the downhole Subsurface SV API RP 14B have the same criteria for gas of 0.43 cu mtr/min or 15 scfm.  On a surface fire a 15 scfm would be a small jet fire.  These can be calculated and rated for risk.  Even without calculations this small fire would not be enough to destroy a platform and heat could be managed with water to protect the structure.  This means this is viewed as a 'tolerable' leak rate. For consistency the same criteria was used for both safety valves.

    Why 15 scfm vs 20 scfm, I do not know. And what was the criteria for leak rate the Committee recognized was too high? 

    I hope this helps. Let me know if any questions.



    ------------------------------
    Dan Gibson
    aka The Well Doctor
    Completion & Well Integrity Advisor
    Houston, Texas
    ------------------------------



  • 3.  RE: SSSV leak rate acceptence 15 scf/min for gas. what are the basis?

    Posted 06-02-2024 10:00 AM
    Is it possible that at some point in the past that 15 scfm was a lower
    limit of a measuring device available at that time?
    Regards

    Olli Coker


    Original Message


  • 4.  RE: SSSV leak rate acceptence 15 scf/min for gas. what are the basis?

    Posted 06-03-2024 03:51 AM
    Edited by Quinton D'Souza 06-03-2024 03:53 AM

    As far as I can recall one of the basis for allowable leak rate.

    "Christmas tree valves allowable leak rates are based on the size of a leak which, if ignited can be doused by a single person with a hand held fire extinguisher without PPE".


    Original Message


  • 5.  RE: SSSV leak rate acceptence 15 scf/min for gas. what are the basis?

    Posted 06-03-2024 12:57 AM
    Edited by Philip Wodka 06-03-2024 12:57 AM

    To supplement Dan's response, I here quote a previous input from Paul Hopmann in 2016: "Valves have no specific defined leak rate apart from ESD valves they are defined in API 6 AV and refer to API 14 B that quotes 15 SCF or 400 cc of of hydrocarbon liquid. These Rates are based on the risk of a leak on an offshore platform and would generate a flame of 1.5 meters that is able to be extinguished by a person wearing proper PPE and a portable fire exthinguiser.". Paul was the team leader for the IOGP workgroup writing the ISO 16530-1 standard.