Valve packing and/or body/bonnet leaking during Hydrotest (ASME B31.3=

[Adry_77]

thread292-412114

I always considered that leakage through something which is not a piping joint, i.e. a valve packing, does not automatically constitute a failure of the test. I have usually taken note of these kind of leakage and repaired (e.g. changing body/bonnet gasket) after test. My approach has always been accepted even by the most demanding clients.

On my current project, I am facing a problem with our Notified Body (third party required by European Directive for some piping systems category). He is trying to reject some big and very high pressure test due to observed leakages from valves' packing and body/bonnet joints on Small bore valves.

Unfortunately I can not find any detailed information about these cases neither in ASME codes nor in the relevant interpretations.

Could somebody help me? HT procedures of major oil companies could also help

Thank you in advance

Adry

 

[XL83NL]

Okay, in order to help you I need a few more details.

What is your design code?
I assume your work falls under the PED 2014/68/EU and requires CE marking? What is the category of the spool?
Are the valves welded in or flanged to the spool?
Do you have a EU declaration of conformity for the valve that leaks?

 

[Adry_77]

Hi XL83NL,

Design code ASME B31.3 ed. 2012
PED/97/23/EC
CE marking of the piping system category III shall be according to "module G".
Apart from some additional requirements (e.g. more stringent requirements for impact test), the No.Bo. has approved, since the engineering phase, design, fabrication, erection and test purely according to ASME B31.3 with ASTM materials.

The subject test packages contain category 3 PED lines.

Yes we have declaration of conformity. Actually we have CE marked valves for any service and they have all been purchased as category III. In addition, for any valve we have shell and seat leak test certificates according to API 598 (also for size and rating for which it is not required by API 598).

The valves are welded ends.

Ciao

 

[XL83NL]

Please note you have to work to PED 2014/68/EU; 97/23/EC has been repealed and is no longer active.

Upon review of the PED and it's guidelines, PED does not really specify in detail what the hydrotest constitutes, i.e. what the acceptance criteria are, how it should be performed, etc..

I would start the discussion with your nobo that you have bought PED certified valves, which already have satisfied PED ESR (Essential Safety Requirements). Putting the pipe spool and valve together is making some sort of assembly, one may argue. The only additional thing you (need to) do, is verify if the ESR's are met for the new weld you made on this previously certified pressure accessory, i.e. the valve. Only the weldconnecting the valve to the spool need be hydrotested acc PED and B31.3, is my opinion. And thats what I would argue. The valve has already shown conformance to the PED for it's internals etc.

PS: you are using an outdated version of B31.3; better switch to 2016 edt (for any new jobs).

 

[Adry_77]

XL83NL,

Thanks a lot for your support.
The No.Bo.'s point is that they have approved design, fabrication and testing according to ASME B31.3 and he can not find any evidence if the subject code allowing any leakages from connections (other than welds) during the test execution.

We are using ASME B31.3 ed 2012 becuase it was the current edition when the contract was signed. We always state in the contracts that the applicable codes and standards are the current editions at the time of contract signature. By the wary, it is another point in my favour because ed. 2012 takes into account also the Pressure rating ratios in the Test pressure calcultaions, therefore, in many cases (including the disputed ones) we tested at a pressure higher than the one calculated according to edition 2014 of the same design codes.

Ciao

 

[XL83NL]

Hi Adry, your notion of using the applicable edition during signing of contract is correct IMO. Thats how we do it to.

As far as I can tell, the formula's for the test pressure in the 2016 and 2012 edt of B31.3 are the same. The formualtion in the 2016 is written shorter, however with less symbols.

Seems to me your NoBo is looking for something he can reject, rather then having a meaningfull discussion if it should be rejected. B31.3 2012 may have some details on this, but not much I guess. There are other threads on similar topics here @ eng-tips.com

http://www.eng-tips.com/viewthread.cfm?qid=327710

http://www.eng-tips.com/viewthread.cfm?qid=369574

http://www.eng-tips.com/viewthread.cfm?qid=85788

Ultimately, your spools need to fullfill the PED. B31.3 is just a way to get there. It's not the bible for the PED, so to say.
So, what you could do is look in EN 13480 (part 5 I think) for the acceptance criteria in there; as it is a harmonized standard, work under that code presumes conformity with the PED. Look specifically for this subject, leakage in valves. You may then argue with your NoBo that, since B31.3 is not clear on this topic but EN 13480 is, the requirements of EN 13480 can be used as additional measurement for your case to show conformity with the PED.

 

[MGZmechanical]

Hi, in EN 12266-1 pressure test for valves it says that at pressure test (1,5 times the design pressure) no leakage is allowed through the body and at 1,1 times the design pressure is must be tight at the packing. For me the body to bonnet joint is part of the body and it should be tight at 1,5·PD.
The EN 12266 it's an harmonized standard with the PED.

https://ec.europa.eu/growth/single-...ds/harmonised-standards/pressure-equipment_en

regards

 

[XL83NL]

Yes but the OP doesn't (probably) have valves acc. that EN standard. So that flag is probably off.