×
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

Relief Valve outlet Pipe size

Relief Valve outlet Pipe size

Relief Valve outlet Pipe size

(OP)
Hey Everybody:

Does ASME Code require that the outlet of a conventional spring operated relief valve be larger than the inlet? I have seen a few NB marked valves that are 3/4" x 3/4", but the ones I am looking at our 3/4" x 1". My client currently has a coupling reducer on the outlet, turning it into a 3/4" x 3/4". I assume if we show that minimal back pressure occurs (less than the 10% overage rule of thumb) it would be ok to do this.

RE: Relief Valve outlet Pipe size

It would be possible to have the inlet and outlet pipes of the same size. It depends of the length of the discharge pipe. If there is not a discharge pipe, the flow of the valve is determined by its nozzle diameter that always is less than the inlet/outlet piping size. If there is a discharge pipe you must calculate that the valve plus the pipe have equal or more capacity than the valve.
casflo

RE: Relief Valve outlet Pipe size

jgibbs22,

The only size restriction I am aware of for Section VIII, Division 1 vessels ("U" stamped ones), minimum size of inlet of PRV should be not less than 1/2" NPS. Outlet sizes is defined by flow capacity of PRV and could be either the same size or one size bigger.

Regards,
Kurt

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