PSV Setting for Pneumatic Testing Of Pipe

[UW1981]

We are update our pneumatic testing procedures for B31.3 piping systems to better comply with ASME PCC-2 Article 5, section 6.2 - which is the best defined pneumatic testing procedure I have seen. However, the PSV setting recommendation for PCC-2 is different than ASME B31.3 345.5.2. The question is.....which PSV setting is the most appropriate to use....the B31.3 (which is a bit problematic since you need to use a pilot PSV at test pressure higher than 500 psig due to the "50 psig above test pressure" limit to avoid simmering of the PSV) or PCC-2, which when followed is a very conservative test procedure?

I appreciate your thoughts/comments.

B31.3 Section 345.5.2 Pressure Relief Device. A pressure relief device shall be provided, having a set pressure not higher than the test pressure plus the lesser of 345 kPa
(50 psi) or 10% of the test pressure.

PCC-2 Section 6.2 Pneumatic Pressure Test of Pressure Vessels or Piping
(h) Overpressure relief protection shall be provided.
The set pressure of a pressure relief device should be not more than the greater of
(1) the test pressure plus 70 kPa (10 psi), or (2) 110% of the test pressure

 

[moltenmetal]

In my opinion, a pneumatic test which is carried out with a leaking or simmering PSV is not very useful. You're presumably doing a pneumatic rather than hydrostatic test for a reason and hence want the test to be valid- hence I'd lean toward the PCC-2 requirement.

The use of the word "shall" in the B31.3 wording is problematic then- you would be taking exception with a mandatory requirement of the testing section of B31.3 . It is not unknown for people to do so, though. If a pneumatic test is carried out in such a way that anything other than an equipment failure results in a challenge to the relief valve, you're doing it wrong (i.e. your testing procedure and associated training needs work).

 

[jte]

I've stayed off this forum for a few years now, but a friend called my attention to this thread so... I'm back.

I can't tell you that following B31.3 is better or worse than following PCC-2. To a large extent my thoughts revolve around more specific circumstances such as jurisdictional requirements and risk issues. For example, is B31.3 required by local law, or are you using B31.3 because your company chooses to since it is a recognized standard? Is the plant in the middle of a populated area or remote with good ability to control how many people are in the area in the vicinity of the test? I have a bias towards PCC-2 over the construction codes, but that is not a reason in and of itself to make a specific, all-inclusive recommendation.

One thing I will suggest to UW1981 is to not publish the new update to your pneumatic testing procedures just yet. If you are referring to things like PCC-2 Article 5.1 section 6.2(h) etc. then your references will be all messed up after the 2018 edition gets published. For section 6.2 specifically, a new clause (f) is being inserted in between the current (e) and (f) with the result that your reference to (h) will need to change to (i). Your procedures will likely be impacted as well by the new last sentence to (e). So, if you can, hold off on this revision until say early 4th quarter this year. I don't have a set schedule for the new edition to hit the streets but I'd expect some time in third quarter.

 

[UW1981]

Moltenmetal, thank you for the response and perspective.

JTE, any chance I can get a preview of the language changes in 6.2.....you have my curiosity tweaked! Also, we have had some questions come up with regard to using the pressure increase procedures listed in PCC-2 for new construction. For pneumatic testing above 1,000 psig, you can end up with as many as 9 steps. Since the pneumatic testing procedure in B31.3 is vague with regard to number of steps and hold time, you could do the same test to 1000 psig in three steps - and, of course, this would be the preference of the construction folks. However, I have a hard time arguing that the PCC-2 procedure is not now RAGAGEP for new piping, even though PCC-2 is for repairs.....after all, many companies now use the stored energy and safe distance recommendations from PCC-2....if they don't use the step procedure, it would appear you putting yourself out on the limb. Thoughts/comments?