Deviation from ASME B31.3 Hydrotest Requirements

[Vikoll]

Dear Colleagues,
Could you please provide your expert opinion of whether deviations from the ASME Codes, particularly from hydrotest requirements in B31.3, are allowed at owner’s discretion?
My understanding always was that companies can deviate only from their own Standards and Specifications by issuing TDN (technical deviation notice), but not from ASME Codes. That means, unless Code provides wording “Subject to the owner’s approval, it is permissible...” (or similar), Code requirements must be followed.

I am working on 8” and 12” HDPE piping headers about 3-4 km long that are installed outside of plant battery limits and simply convey ground water from water wells to the pond. Existing P&ID for HDPE headers shows piping material class per B31.3 that requires section of HDPE line with valves, (that is not always open the atmosphere), to be hydrotested due to design pressure above 150psi. I suggested to designate lines outside of ASME Codes, build them per PPI and other applicable standards and have them service tested. Owner verbally agrees that these lines are not B31.3 or CSA Z662 and hydrotest is highly impractical and costly. At the same time owner insists that their procedures require lines to remain under B31.3 and suggests writing a TDN to waive hydrotest requirements. Does this make sense? Am I missing something? Why would ASME bother to issue Codes If everyone can write a TDN to waive Code requirements?
Thanks!

 

[mk3223]

If the Code is so true to cover every situation, it's to be an impossibly complicate manuals and procedures which no-one will understand.
On the other hand, the Owner is totally responsible for its facility which may be following the required Code or any TDN as suitable for its process and suggested by its SME. It includes one TDN with the specific condition as you described.

 

[Dhurjati Sen]

Dear Vikoll,

Only the owner can waive any leak test. Check Clauses 345.8 & 345.9 in addition to 345.1 of B 31.3

Actually, the owner is trying to use you (your deviations) (assuming you are the contractor's personnel) as a shield in case of any unforeseen event.

In any case, he cannot escape responsibility as he needs to approve those deviations. Also, B 31.3 puts the onus entirely on him in this regard.

Regards.

DHURJATI SEN

https://www.nace.org/people/dhurjatisen

 

[DekDee]

Vikoll,
Hydrotest requirements cannot be waived due to them being "impractical and costly" whether the Owner approves a deviation or not.
Hydrotest - it complies with B31.3
No hydrotest - it does not comply with B31.3
The exemptions are listed in 345.8 and 345.9 but I do not think these are applicable to your situation,
Regards,
Shane

 

[moltenmetal]

Water is generally Category D and the owner is permitted to waive the mandatory leak testing in favour of a service test.

If you're a contractor you need the owner's permission to waive the hydrotest.

A pneumatic test is a permissible alternative provided it can be done safely. With nonmetallic piping, pneumatic tests are generally frowned upon.

 

[DekDee]

Moltenmetal,
Please read the OP.
His design pressure is above 150 psi so it cannot be Category D,
Regards,
Shane

 

[LittleInch]

So these lines convey water from wells to the pond. so they are normally full of water.

How are these line suddenly " hydrotest is highly impractical and costly" ??

I really don't understand this.

Beware if you don't now that PE tends to creep under hydrotest pressures and you need to plot the decay curve.

B31.3 isn't the best PE design code as it still looks at it as a strange form of metal, which it isn't.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Vikoll]

LittleInch,
As I mentioned, the design pressure is above 150psi, but only because pumps can create that high dead head pressure if someone closes valve without shutting down pumps. Normal operating pressure is just about 100psi that makes this service category D under normal operating conditions. It is impractical and costly because installation is in Alberta where we have below freezing temperatures min 6 months in the year. For winter hydro-test we need to use glycol/water mixture. Given length of headers more than 3km, we will need a lot of glycol, we will need to install vents and drains. Drains are very difficult to install, as headers are supported from grade (no even sleepers). These headers are cut and moved/fusion-bonded at new locations every 5-6 months, so hydro test will be required every 6 month? If glycol is used, how to utilize it in environmentally friendly manner? How long it will take to equalize pressure in HDPE headers that expand under pressure? Does it make sense to do all this if 99% of time it is category D fluid
Paras 345.8 and 345.9 are not applicable to our installation. So back to initial questions: can the owner waive hydro-test by approving TDN? I see some say the owner can do this (I would like to know the basis for this) and others say, if the owner does this, the piping will not be complaint with B31.3. I leaning toward the letter one. Any other opinions?
Thanks to everyone for your support!

 

[TGS4]

Which of the various jurisdictions does this specific pipe fall under. AEB? ABSA? NEB?

 

[Vikoll]

TGS4, I believe these lines do not fall under any of listed jurisdictions

Thanks,
Vikoll

 

[TGS4]

I find that hard to believe. My understanding is that if there is pressure equipment in Alberta, and another entity isn't claiming jurisdiction, then it falls under ABSA. It would be a good idea to confirm this.

 

[Vikoll]

TGS4,
I truly appreciate your concern, but water at 20°C is not an expansible fluid, and as such, does not require registration with ABSA.
Going back to initial question and putting all other matters aside: if anyone else can provide the expert opinion on whether owner can deviate from B31.3 hydro-test requirements, that will be much appreciated.

Thanks,
Vikoll

 

[racookpe1978]

You really do want the answer that we (collectively) are not giving you, don't you?

Water IS expansible at all temperature above 4 deg C. (Its greatest density is about 4 deg C, that is.)

 

[TGS4]

Nowhere had you stated that the fluid was 20°C. You need to hire an expert in the various codes. And provide them with ALL of the relevant information.

 

[Vikoll]

My bad, Gents, if I have missed important information. I sincerely thought, if I say that HDPE headers convey "ground water from water wells to the pond" that will provide some indication of fluid temperature. I did not want to make my post over-complicated with many numbers. Also, it is certainly beyond my expertise to address a difference in opinions between nuclear racookpe1978 and ABSA about how water becomes an expansible fluid when departures from 4°C and reaches 20°C.
Please let me go back to my initial question: "can the owner deviate from B31.3 hydro-test requirements if pipe is HDPE and located outside the plant battery limits, fluid is water at design temp. 20°C and design pressure 170psi-180psi, pipe has in-line block valves, so it is not open to the atmosphere, pipe is 2km-4km long, it is laid on a ground without any supports and restraints and almost all the time simply conveys seepage ground water from water wells to the pond? The design pressure can be reached only if submersible pumps are running against closed valves due to human (operator's) error"
Owner thinks that it is B31.3 piping just because piping material class says so(IMHO, mistakenly), but at the same time does not want to do hydro-test and for that reason suggest to wright a TDN.
If anyone has a good suggestion with a solid justification, please kindly provide your expertise, otherwise please let me close this thread and thank everyone for participation.

Thanks,
Vikoll

 

[DekDee]

Vikoll,
Suggest you close the thread.
Your design pressure is greater than 1035 kpa (150 psi) so your piping is rated Normal Fluid Service ( even if it is open to the atmosphere most of the time the code is only interested in design pressures).
As per B31.3 NFS you must hydrotest or your piping does not comply with the code.
Regards,
Shane

 

[LittleInch]

Ok, Let's remember what the code intro says. (My bold and italics)

"The Code specifies engineering requirements deemed necessary for safe design and construction
of pressure piping. While safety is the primary consideration, this factor alone will not necessarily
govern the final specifications for any piping installation. The Code is not a design handbook.
Many decisions that must be made to produce a sound piping installation are not specified in
detail within this Code. The Code does not serve as a substitute for sound engineering judgments
by the owner and the designer."

Now for me I struggle to understand all your issues as it isn't clear to me based on this post why you can't hydro ( doesn't take very long for B 31.3) or why you can't use alternative methods like air or a mixture of the two.

Also are you re-using this pipe? - "These headers are cut and moved/fusion-bonded at new locations every 5-6 months, " so you cut up the pipe, shift it then re-weld it?

However you can perfectly well write a document listing all the issues and then determining what is an acceptable method for your situation. E.g. what is the impact of a failure? Could you instead provide a relief system to lower your max pressure?

Strength tests are there to make sure the pipe and joints don't break, not a leak test.

Then analyse the requirements and the tests that you would do on the fusion welding and determine if this gives you enough coincidence that the risks of failure are acceptable.

Then send it to the client and get them to approve.




Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Vikoll]

Thank you, LittleInch, with your reference to the Code, I think we are getting closer to the answer. Actually, in my mind, the initial question was not of a technical matter, but rather about order of precedence, division of authorities and what governing body or document shall prevail.
I quite strongly believe that the owners cannot deviate from the Code unless they smartly use given to them opportunity to prove that such deviation is consistent with Code requirements such that design, fabrication, examination etc. are adequate and produce an equally safe and operable or even better outcome, refer to 300.3(c). Having said this, if one Code requirement (say hydro-test) is removed, the designer shall provide something equivalent instead to demonstrate that removing the hydro-test does not compromise the final design. As you mentioned, strength test or, say, wall thickness increase and/or additional inspection may provide a good basis for such deviation. But the owner cannot approve TDN just because they realize that one of the Code requirements is impractical and very expensive for given installation.
Another option I see is building theses lines outside of B31 Code that clearly not applicable to these lines, not to mention nuclear Code that racookpe1978 suggested to entertain.
Also, DekDee, may I suggest you to look at 345.1(d) about open to the atmosphere lines? If you think hydro-testing these lines will benefit design and create some special value, go for it, but you do not have to.
This type of discussion I was expecting not going into all kind of technical details.
Next time I will try to formulate my questions more clear and steer the discussion in proper direction.
I again want to thank everyone for participation.

Thanks,
Vikoll

 

[moltenmetal]

Rules- based code- and they do have that "rule" about the max pressure for water under Category D, which it embarrasses me that I forgot about. It's necessary to have a rule, for the people who use this code but do not possess the engineering judgment to know when a rule can be broken safely, or "bent" in favour of something else which will produce an adequately safe outcome for the specific circumstances. It's also sensible to break some rules when they can be broken judiciously- but then you can't be said to be following a rules-based code. No way around it.