Isolation Block Valves on PSV....what is ASME BPVC S8 Appendix M5.3 asking for in item G, I

[JaredNOVA]

Working on a project for isolation block valves and wanted to be sure I fully understood the requirements before I started.

Under M-5.3 the first few line items are pretty self explanatory its when I get to item (g) that I become confused at what the standard is asking.

My interpretation is the code:

Item G: is requiring you perform a review/"analysis" of all pressure sources for the vessel assuming no relief exists (i.e. because the block valve is closed) and determine the maximum pressure level.....(I don't get involved with relief calculations but would a relief valve design basis be acceptable for this analysis requirement). Does anyone have an explanation of what exactly those that wrote this were looking for?

Item I: This is the one that really got me.....So its saying all other components but provides no definition of what all the incorporates is it just the inlet piping for the relief, flanges for the relief piping, or does it mean the vessel and if it means the vessel does it mean all the nozzles, and if it means the nozzle does it mean the inlet/outlet piping for the vessel. Any clarity would be much appreciated.

Anyway if there is anyone out there that could provide me with anymore clarity on either one or all of these items and specifically what ASME was desiring that would be much appreciated. I am a huge standard person as I feel it is needed to drive industry but when I come across things like this that in my opinion make it hard for the end user to interpret what exactly they were wanting if no one in your company sat on the committee, sometimes it is disheartening.

Side note I reached out to quite a few professionals who under the impression I got where not doing anything above a relief calculation to meet these requirements under Appendix M.

To summarize I guess I am really just confused on their definition of what the "analysis" is and what "Other system components" consisted of.

Thanks for any help in advance.

 

[met11]

I want to bump this one, because I searched around for an answer for a good bit of time and came up with nothing as well. Now I'm curious for an actual answer, as this is something we constantly specify, but that our clients have to deal with. The only thing I could find was a code interpretation:

Interpretation: VIII-1-04-97
Subject: Section VIII, Division 1 (2004 Edition); Appendix M, M-5.7, Responsibilities
Date Issued: June 15, 2006
File: BC05-1136
Question: M-5.3(i) of Section VIII, Division 1, Appendix M states that when a stop valve between a
pressure relief device and the equipment it is protecting is closed, the user shall ensure that the other system
components are acceptable for the potential levels of pressure established in M-5.3(g). Is it required by the
rules of Section VIII, Division 1 for the user to ensure that other system components are acceptable for
potential levels of pressure if the stop valve(s) is closed when the measures in M-5.7(b)(3)(b) are implemented?
Reply: No.