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  1. The Obturator

    What is "Free length" of springs in safety relief vavles??

    ASME does not certify. The National Board of Boiler & Pressure Vessels Inspectors (or their appointed representative), would certify a pressure relief device against the relevant ASME Code. To obtain such certification, the (valve) manufacturer will also have to have their production facilities...
  2. The Obturator

    What is "Free length" of springs in safety relief vavles??

    UG-136 Was valid in ASME VIII (2019) until the 2021 edition, when UG-136 (amongst other Pressure-relief Valve/Overpressure protection requirements), were transferred to the new ASME XIII Section specific for overpressure protection (which you originally referred to). ASME XIII (2023) is the...
  3. The Obturator

    Medium for calculation of PSV relief rate

    If your vessel is not a cylinder but a pressure vessel containing only gas or vapour, and you are sizing due to external fire, then the calculation method to determine the Pressure-relief Valve orifice size can be found in API STD 521 (2020) Paragraph 4.4.13.2.4.3 (Equation 9). This might be the...
  4. The Obturator

    PSV Inlet and Outlet Pressure Drop Calculation Question

    That article contains incorrect information. It is a situation yet again, on getting effective (API) and Actual (ASME) orifice areas and coefficients mixed up. Use only Actual areas and coefficients together or Effective areas and coefficients. Never an actual area and effective coefficient or...
  5. The Obturator

    Medium for calculation of PSV relief rate

    @goutam_freelance ASME VIII-1 Mandatory Appendix is long deleted and replaced by ASME XIII (2023) Mandatory Appendix IV. @Dulli2000 I believe you are trying to size a Pressure-relief Valve for a flow other than air? You might need to familiarise yourself with the requirements of Pressure-relief...
  6. The Obturator

    Friedel's Model (two-phase) and Noise Attenuation Questions

    API 521 Calculates Noise based on an open valve outlet discharging to atmosphere. I will mention that there are manufacturers who can supply dedicated safety valve silencers that are fitted to the outlet stream.
  7. The Obturator

    How to dump to 50% of vessel's design pressure

    The API 521 (2020) Paragraph 4.6.6 that you reference does end with the statement "Depressurising disposal systems are discussed in 5.3.3". Maybe have a read of that. Since you posted in the safety/relief valve forum, be also aware that Pressure-relief Valve manufacturers of old, did catalogue...
  8. The Obturator

    What is the drifference when recertification between PRV/PSV on HC and Steam valves

    Your question would be best posted in the safety/relief valve forum. First of all, ASME I safety valves do not come under API-526. ASME I safety valves are primarily steam boiler valves. The required characteristics of opening/closing etc., are more stringent. Although API-527 has a section...
  9. The Obturator

    Allowable Overpressure for Electric Steam Boilers per ISO-4126

    In a conventional design spring operated Pressure-relief Valve (with closed/pressure tight bonnet and cap), The allowable built-up back pressure is equal to the overpressure. This is a API-520 Pt 1 statement (5.3.3.1.3.). The ARI SAFE valve data sheet advises maximum 10% built up back pressure.
  10. The Obturator

    Allowable Overpressure for Electric Steam Boilers per ISO-4126

    10% maximum built up back pressure for this valve. 'Higher on request' say ARI. Data Sheet https://www.ari-armaturen.com/_appl/files_tb/files/900005-2.pdf
  11. The Obturator

    Allowable Overpressure for Electric Steam Boilers per ISO-4126

    The ARI SAFE is not an ASME I design. Not even ASME VIII, This is a German design based on TUV/AD Merkblatt A2 (aka a 'DIN' valve), but which conforms to the standard ISO 4126 in turn specified and compliant for boilers to EN 12953 FYI: I located a copy of EN 12953 where it refers the boiler...
  12. The Obturator

    Allowable Overpressure for Electric Steam Boilers per ISO-4126

    What is the valve brand and model number?
  13. The Obturator

    Allowable Overpressure for Electric Steam Boilers per ISO-4126

    You should be referring to the latest ASME I (2023), which does not change the subject, however the stated 6% is the maximum MAWP of the boiler (not the overpressure of the safety valve(s)). What was the design code of the boiler installed in Sweden and when was it built? Is it code ('V') stamped?
  14. The Obturator

    Foam Glass Insulation - fire case

    I might be off track here, but you might want to look at Table 5 in API-521 and see how the Environmental Factor 'F' is determined for use in calculation - I must admit your stated insulation is alien to me.
  15. The Obturator

    Allowable Overpressure for Electric Steam Boilers per ISO-4126

    ISO 4126 Limits overpressure to 10% maximum...you can utilise a ASME I design to be fully open at 3% overpressure if you so wish provided the valve design meets PED (if installation is in the EU). (There is an exception in PED to the 10% overpressure limit, but this applies to fire case only -...
  16. The Obturator

    Allowable Overpressure for Electric Steam Boilers per ISO-4126

    @Pavan Kumar You are yet again proliferating queries related to the same boiler subject over several posts and in different forums. This is your 3rd post that I know of the same boiler. Please stop this. You did not even comment on my earlier comments and questions. You also appear not to have...
  17. The Obturator

    Does dry gas PSV always need drainage on discharge pipe ?

    Although you state that this type of vent pipe is a typical design from CGA-G-5.5, it is not of a typical outlet pipe for Pressure-relief Valves meeting API-520,-521,-526, ASME VIII, XIII etc. Note I do not have CGA-G-5.5 to comment more on.
  18. The Obturator

    Does dry gas PSV always need drainage on discharge pipe ?

    We're going to need more info to advise on this. Maybe a sketch/photo? What is the valve type and size (inlet x outlet), set pressure, how is this 'gooseneck' attached and what material is it? (This goose could fly off very easily during valve opening). What API is basically cautioning you on...
  19. The Obturator

    Electric Boiler Question

    @Pavan Kumar - I take it this post relates to your other post in the safety relief valve forum Allowable Back Pressure per ISO-4216 Part9 It would have been better to consolidate this query into one posting so that all contributors to comments can have full visibility (I may have missed the...
  20. The Obturator

    Allowable Back Pressure per ISO-4216 Part9

    Just to be clear, ISO 4126-9 Paragraph 7.1 states "...The allowable back pressure, which is the sum of the built-up back pressure, and the superimposed back pressure, is typically specified by the valve manufacturer or national code or regulation". ie., As I stated earlier, back pressure is...

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