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Pressure Vessel Pneumatic Leak Testing Blast Radius

Pressure Vessel Pneumatic Leak Testing Blast Radius

Pressure Vessel Pneumatic Leak Testing Blast Radius


I'd like to know if it is necessary/practical to use ASME PCC-2 Mandatory Appendix II - Stored Energy Calculations for Pneumatic Pressure Test for pneumatic leak testing of equipment that has already been hydrotested in the shop.

  • Loop Reactor with flanged/gasketed joints.
  • MAWP: 740psig
  • Material: Carbon Steel
  • Reactor components have been hydrostatically tested in shop

  • The site would like to pneumatically leak test the reactor with N2 to 638psig to prove flanged/gasketed joints are properly sealing before introducing hydrocarbons. We were asked to provide a blast radius for the test. Per PCC2, this will result in a radius of over 600'.
    1. Is it necessary to define a blast radius when hydrostatic testing has already been completed successfully?
    2. In terms of potential consequences, is there a difference between this proposed leak test and starting up an identical, existing pressure vessel at 638psig (in N2 service) after maintenance has disconnected and reconnected flanges?
    What I'm getting at is if a vessel has been hydro-tested, what is the point of setting up a blast radius for a pneumatic leak test? The integrity of the materials have already been tested, and in my mind the only risk is for a blown out gasket (and maybe N2 displacement of O2 if personnel are nearby). If a blown out gasket is that much of risk, then shouldn't we always have a blast radius barricaded off when starting up equipment after maintenance has disconnected/reconnected flanges?

    What am I missing here?

    Thanks, Will

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