hydrostatic test duration for b31. 3 prefabricated spools 3

[unclebensrice]

Dear all,

Our company made an order for thousands of prefabricated pipe spools. The purchase order stipulates that the spools shall meet b31.3 criteria. The fabricator says he can only pressure test the spools for 1 minute as opposed to the requisite time of 10 minutes as per b31.3. Can this reduced test time be accepted ? Thanks.

 

[LittleInch]

you still need to ask how the supplier is intending to test open ended spools, especially those with elbows on. Straight pipe he might be able to clamp between moveable end stops like they do in the pipe mill, but once you've put an elbow on it you can't. I suspect he will be using plugs in which case I can't see how he can't couple up a load of spools at once and the hydro them all together?? BTW what is the hydro pressure / size of these "spools" Makes a difference to understand what we are talking about.

It could be that he can actually joint together spools by plugs and other devices and test more than one at once.

However when I saw the phrase - B31.3 designed for flow lines, with elbows in the line, I started to realise that things are not as they should be. B31.3 is designed for pipe inside plants, not flowlines.

1 minute or 10 minutes is in your hands as the owner / purchaser to waive or not as required. What you need from the fabricator is a written waiver request and then you can approve or not taking into account the consequences (time, cost etc) of your decision. Hand it to your "boss" to countersign whatever you decide.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[DekDee]

Little Inch,
This is how the supplier intends to test

"The spools are not flanged at the ends. They are made up of api 5l pipe pup pieces welded to b16.9 elbows mostly. The fabricator would like to avoid joining multiple spools together by welding just to leak test then cut them separate again to him it's a waste of material not to mention extra welding and cutting."

This is why I have been going on and on about the ridiculous waste of time and money because someone doesn't understand what a piping system is.
It seems to be falling on deaf ears so I will give up,
Cheers,
DD

 

[LittleInch]

Dekdee,

That is why the supplier doesn't want to weld lots of the spools together. I cab see his point. What I asked was how does he intend testing a spool with open end(s)?? Unless he puts something in the way the water will just shoot out the end no?? Perfectly reasonable question to me.

The current answer from uncle ben is "the coupled system will be filled with water and then after the pressure is raised". I'm asking how does he raise the pressure. If he can do it for one spool why can't he do it for 10 of them at the same time and then test 10 for 10 minutes instead of 1 for 1 minute each?? Then every one will be happy.

so far no answer.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[weldstan]

unclebensrice,
Since the P.O. required the hydrotest strictly per B31.3 and the fabricator accepted the work without exception, he must comply. What he is asking may well be reasonable and will, more than likely, assure scheduled delivery. It is up to you as the Purchaser to weigh his request. If the pipe is ERW and its quality suspect, you should consider the request. If you suspect the fabricator's weld quality, you might consider a longer hold time to assure finding leaks from tight discontiuities. If you really suspect the fabricator's quality, you should not have awarded the Order or you should provide full time inspection if its price was low enough.

 

[unclebensrice]

Hello gentlemen,

Apologies for this belated response it's the weekend here. So just to answer some of your questions again:

- I already asked the supplier to submit a more detailed procedure on pressure testing and whether he will be using end stops/plugs/weld to connect and seal off the ends and submit a brochure if he will be using a specialized pressuring device.

- we should be using api 1104 for pipelines I agree but they're using b31.3.for everything here perhaps because it's more stringent.

- fabricator submitted a written waiver request justifying his case by contrasting the little holding time needed for api 5l pipes and valves tested under api 598 to the extensive 10 min time needed for the spools.

- I know what a piping system is and that 345.1 is for piping systems and that testing the piping system in the field once is enough but like I said the purchase order states b31.3. 3 pressure testing and this is needed in our case because the spools are made abroad and we need a guarantee they're all good. Thanks for the patronizing tone on that one hehe.

- the spools will be made from seamless pipe.

- maybe this fabricator has one pressuring machine that's why he wants less time on the hydrotest.

Thanks again all of you guys for your time aND all your helpful comments.

 

[unclebensrice]

Test pressure is 430 psi

 

[MITProfessor]

Gentlemen,

The code does not mandate shop hydrostatic testing of piping components nor piping subassemblies as is. hydrostatic testing of components is covered under relevant manufacturing standards.

"As a special case" in the event where the owner needs to hyrotest, 345.2.3 allowed under "special provisions" to (additionally) test individual component and subassemblies. In this case, the same should be additionally identified as a special requirement.

 

[unclebensrice]

In one of the interpretations of the code,namely Interpretation 21-11, it says that a pressure test of less than 10 minutes by the pipe manufacturer will not satisfy b31.3 code requirements of paragraph 345.

Also the purchase order for these spool stipulates/additionally identifies b31.3 pressure testing so that's your special provisions clearly stated.

Thanks.

 

[weldstan]

If the 430 psi test pressure produces a stress across the circumferential welds < 20% of the SMYS and I suspect it's less than 15%, you are wasting time and money. The Supplier is simply looking at saving about 4 weeks time in testing and the costs thereof; however, exception was not taken to the P.O. requirements and you are justified in maintaining the original requirements.

 

[unclebensrice]

The b31.3 code is a design code not a manufacturing code so its test pressures are are going to ve understandably much less than let's say api 5l. Even api 5l is at 60% or 70% SMYS. I think the intention of b31.3 pressure testing is to verify the workmanship or integrity of the weld not the strength ; that the welds don't leak and are free of discontinuities; kind of like what RT is to WPQs. The strength of the weld is verified through PQRs by the mechanical tests.

Thanks.

 

[moltenmetal]

Again, hydrotest on plain end pipe is a waste of time. What duration it is done for is not really worth worrying about, because you're going to have to re-test when the completion welds are done anyway. From a cost and quality perspective IMHO the bigger issue is the addition and removal of the cap they will probably weld onto the pipe to accomplish the test- unless they're planning to use an expanding plug in the end of the line to do so. That is probably fine with plain end pipe but how well is it going to work on elbows, as someone else has already queried? Surely any method they use to do this is going to take more than 10 minutes per spool to set up, so what's the dif between 1 and 10 minutes under test?!

 

[StoneCold]

You are better off to re-negotiate that you will waive the hydrotests at the shop if they will assume responsibility for any defective welds that show up in the field. Then just back charge them for any bad welds that have to be fixed in the field. If there quality is good you both win.

Regards
Stonecold

 

[LalitMohanKothari]

Our company made an order for thousands of prefabricated pipe spools. The purchase order stipulates that the spools shall meet b31.3 criteria. The fabricator says he can only pressure test the spools for 1 minute as opposed to the requisite time of 10 minutes as per b31.3. Can this reduced test time be accepted ? Thanks.
Just think this way also
“As during shut down the time is very short and so many loops having only one pipes ….during that time we don’t perform hydro test and do NDT for tie in joints .
Sometime loop is very small and we do NDT only for 2 or 3 joints …this time hydro may be waived by client or depend upon the situation at site.
This saves a lot of time also.
For doing of spool hydro test you can make a string and do partial welding which is is common practice to perform hydro….even ….this way we are doing old pipes hydro testing then why not for new pipe.
1 minute is not enough for any process pipe .”
Thanks & Regards,
Lalit Mohan Kothari
“Dreams and dedication makes powerful combination “
TUV NORD

https://www.google.co.in/?gws_rd=cr&ei=OhrBUpbJKISLrQeAr4HABw#q=lalait+mohan+koathari++corrosion