×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

PSV test fluids.......

PSV test fluids.......

PSV test fluids.......

(OP)
Can anyone please advise how to determine what test fluid should be used to test the set pressure on a PSV. Any help or reference to standards would be appreciated.

RE: PSV test fluids.......

ASME Sec. VIII, Div. 1, Para. UG-136(d)(4)
requires New Gas or Vapor Service valves to be tested on Air, Liquid Service Valves to be tested on Water and Steam Service to be tested on Steam, unless the Steam Valve is too large or too high Set Pressure.  Then they may be tested with Air provided a compensation factor is applied.

NBIC, Para. RE-2010 requires the same as ASME Sec. VIII, Div. 1, for repaired Valves, with the exception of Steam service valves tested on Air. Only owner/users are granted permission to use steam to air correlation factors under the National Board "VR" Program.

J. Alton Cox
www.delucatest.com

RE: PSV test fluids.......

NOTE: For clarification, the capacity units on the PSV Nameplate may be useful in determining the appropriate Test Fluid.  Lbs/hr or PPH indicate Steam Service and require testing on Steam.  SCFM indicates Air/Gas Service and requires testing on Air.  GPM indicates Liquid service and requires testing on Water.

In some cases, the capacity may indicate a fluid other than the actual service.  If this is the case you should verify that the PSV is suitable for the application and then test it according to the actual service condition, steam, air or liquid.  If the PSV is not suitable for the application, it should be replaced or converted to the correct trim prior to testing.  Air service valves in Lquid service may not attain full lift at 10% overpressure and therefore may not provide the required overpressure protection.  Liquid PSVs in Air or Steam service may not have the proper internals to attain full lift on compressible fluids.  

J. Alton Cox
www.delucatest.com

RE: PSV test fluids.......

Another important point is that the test record needs to capture both the lift pressure and the reset pressure.  For PSV's intended for compressible applications doing a liquid test (not recommended by JAlton above for many good reasons, they're still done sometimes) makes it very difficult to see the reset point since it happens so quickly.

David

RE: PSV test fluids.......

Regarding Testing, for compressible fluids you really need sufficient volume to get a representative pop and reseat.  Low volume test equipment (less then 3.0 cu ft) typically will not provide reliable lift and blowdown data.  For incompressible (liquid) fluids, a J-Tube or Dip Tube design vessel is desirable.  Hydrostatic pump type test equipment is very difficult to determine set pressure using NB-18 criteria.

J. Alton Cox
www.delucatest.com

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources