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Join Date: Jul 2012
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Pipeline Hydrotest

07/08/2012 1:44 AM

i was asked one question that can we avoid hydrostatic test for pipeline constructed according to B31.4 or B31.8. there is no chance to carry out HT and pipeline is around 100 KM long. what are the test can we carry out in lieu of HT ?

Is it acceptable to start operation of pipeline wihtout doing HT ?

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Guru

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#1

Re: pipeline hydrotest

07/08/2012 5:00 AM

1-why not pressurize the line from valve to valve with a gas, then use an instrument designed to find gas leaks?

2-are you an idiot?

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#9
In reply to #1

Re: pipeline hydrotest

07/09/2012 3:38 AM

Sorry. Regarding your question #2, "are you an idiot"? I now believe that the answer is YES!!!!!!!!!!!!

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#2

Re: pipeline hydrotest

07/08/2012 5:08 AM

Better not put it in my back yard.

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#3

Re: pipeline hydrotest

07/08/2012 6:16 AM

No!

Ok, one exception. If the operating pressure is kept below 14.7PSIG, you can run it.

You're not really serious, are you?

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#4

Re: pipeline hydrotest

07/08/2012 7:57 AM

After looking through my "crystal ball" (from the Wizard of Oz, BTW) I foresee multiple catastrophic failures occurring along this pipeline if HT is not done......

IF it is specified by the Engineer of Record, then you do it without question and argument, unless you want to be held in Non-conformance of the Contract Document requirements....also, in the event of failure(s) you will be held liable on many levels!

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#5

Re: pipeline hydrotest

07/08/2012 8:43 AM

We are fortunate to share a planet with you and your professional organization........... whom obviously has the superior ability to plan ahead.

Kudos....

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#6

Re: Pipeline Hydrotest

07/08/2012 10:56 PM

You were very eager to take the job and advance payment and work all along 100 km pipeline fabrication. Now when it comes the s**t part you think you can get away without doing the HT?

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#7

Re: Pipeline Hydrotest

07/08/2012 11:05 PM

SORRY TO ALL, i did not mean actual condition.

this is the question asked by an expert to me during an interview. ofcourse i gave same answer as 'NO'. but really wanted to know the options. if we can do 100% RT on all weld joints than is it possible to avoid pressure testing (HT or Air test) ? as we are doing only RT on Tie-in joints as golden joints?

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#8
In reply to #7

Re: Pipeline Hydrotest

07/09/2012 3:32 AM

OK. Here's a little thought experiment.

  • Fill it with water and give it a squeeze to a predetermined test pressure. Something goes bang and water leaks out. There may be some local problems though the environmental damage will be minimal.
  • Instead of filling it with water, fill it with liquefied natural gas and give it a squeeze to the same pressure. The same thing goes bang and it leaks. In the immortal words of David Coal Coleman, "What happened next?"

Simple, isn't it?

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#10

Re: Pipeline Hydrotest

07/10/2012 4:39 AM

The question is 100% RT or UT on all welded joints of pipeline can eliminate requirement of any kind of Pressure test (liquid/gas or other) ?

The answer will depend on the whole purpose of Pressure Test means is it only to check welded joint integrity or complete pipeline system ?

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#11
In reply to #10

Re: Pipeline Hydrotest

07/23/2012 5:09 AM

100% RT or UT on well joints of pipeline does not eliminates the requirements of hydrotest while 100% RT with UT can eliminates hydrotest requirement as it is done for the golden joint but its too expensive and time consuming as field joint coating can not be applied and backfilled till the resulats are on.

Second question aswer would be, hydrotest is the way of checking the weld joint integrity plus also relives the resudial stresses associated with weld joints and pipeline laying stress.... called as strength stress.... which is done for 4 hours with 1.4 times design pressure.

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#12
In reply to #11

Re: Pipeline Hydrotest

07/24/2012 11:48 PM

@2226

great answer. but where it is written that RT with UT will eliminate HT requirement in pipeline. i need reference please.

pipeline we are doing HT at 1.25 DP not 1.4 DP ?

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#13
In reply to #12

Re: Pipeline Hydrotest

07/31/2012 3:11 PM

There is no were written about this but this is the only way u can check and conclude that hydrotest is not required... as it is done for the golden joints. we do not have any option.

Regarding the 1.4DP and 1.25DP it depends n the pipeline class that has been defined in ASME B31.8. I belive its 1.4DP for liquid pipeline....Correct me if I am wrong....

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