×
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

Section VIII Safety Valves

Section VIII Safety Valves

Section VIII Safety Valves

(OP)
Hello All,

My company makes jacketed pressure vessels where the jacket and inner chamber are filled with steam.  One of our designs takes steam from the jacket and uses that as the steam source for the inner chamber.  This is the only source of pressure for the inner chamber.  The jacket is rated for 45 PSIG internal and the chamber is rated for 45 PSIG external and 30 PSIG internal.  Can we install one safety valve on the jacket and not have one on the inner chamber?  The argument is if the jacket safety is set to 30 PSIG and the jacket is the only source of pressure then the chamber is inherently already protected.  As always, thank you for the help!

Best,
Steris

RE: Section VIII Safety Valves

What Code is being used to manufacture your vessels... and have you reviewed that Code?

Patricia Lougheed

******

Please see FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

RE: Section VIII Safety Valves

you have not defined if the two vessels are in direct communication with each other without intervening valves or flow restrictions, or if there is any exothermic process occurring or means of pressurizing the internal vessle via some other connection.

RE: Section VIII Safety Valves

(OP)
We are making them in accordance with Section VIII and there is a valve separating the two vessels.  There are no exothermic processes or other possible sources of pressure other than the jacket.  I understand that a strict interpretation of the code will require a safety, however can a case be made that only one safety is needed?

RE: Section VIII Safety Valves

Absolutly not.  The vessels can be isolated from each other. thus a PRV is required on each vessel.

RE: Section VIII Safety Valves

Duweg6 is right. The inner vessel could be filled with condensate , isol valve closed, and if the outer jacket heats up the inner vessel then a thermal releif valve , at a minimum , is needed at the inner vessel. You would need to calculate the worst case of thermal relief, and there may be other scenarios possible that may need to be considered.  

RE: Section VIII Safety Valves

(OP)
Hi all -
I completely understand the arguments and the intention of the code.  What I don't understand is that a few of our competitors use only one safety and I'm not sure how they are able to get away with it.  Their process flow and piping is roughly the same as ours.  I feel like there is an exception somewhere but I don't know where.

Thanks again!

-Steris

RE: Section VIII Safety Valves

(OP)
Hi All -

I think I found what I was looking for.  There is an exception in Appendix M-5.5 as allowed by UG-125(g) & UG-135(d)(2).  I hope that is able to help someone else.  Thanks again for all your help!

Best,
Steris

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