Hydrotesting software

[IanMiller]

As I am sure many of you are aware, after hydrotesting a pipe a series of calculations must be completed to correlate the actual pressure trends with calculated effects of thermal expansion, pipe wall expansion durring high pressures ect. I was wondering if anyone knew of a software package which might help with this process. Or a technical paper that would better outline the assumptions which should be made in this type of analysis so I could attempt to write my own program.

Ian Miller

 

[CRG]

It seems like you are describing a leak test. If that is the case, consider:

% of entrained air in system.
Thermal expansion/contraction of piping system.
Thermal expansion/contraction of fluid, both air and the test medium.
Compressibility of the fluids, both air and the test medium.
Deformation of the piping system from pressure.
Constraints of the piping system, above ground system or below grade system.

Think Superposition Theorem for the calculations.

There is a company that specializes in this type of work; however, be careful if you contact them. Do not, divulge any hints as to the project you are working on because they are your competitors and they will aggressively try to make your client their client.

 

[IanMiller]

CRG,
Thank you for your response, it was very informative. As I dive deeper into this problem the The more confused I become.

The systems I am pressure testing are burried ductile iron pipelines. I'm just examining our methods and I have found some proceedures I do not understand the basis of. For instance DOT requires that the test have a minimum pressure of 125% of the operating pressure, however there is no standard for the maximum the pipe can be tested at. Should the maximum be the SYMS of the pipe? Also what qualifys the test as a pass? Given the estimates made durring measurement and calculations would a .02% drop in pressure signal a leak or just error in the test? One competing pipeline allows the engineer to raise the final temperature 1 degree above indicated to get the pressures to balance. What basis this is from I have no idea. So far I have been unable to find any documentation that answers these concerns from API, ASME, ASTM, or DOT.

Thank you

Ian Miller

 

[CRG]

IanMiller, you should be confused. Follow the recommendations found in the ASME B31 codes (B31.1, B31.3, B31.4, etc) to establish pressure criteria for hydro-test. As for the interpretation of the test results, I recall the pass/fail criteria to be quite vague in the ASME codes. There are a lot of variables to be considered when you use your results to ascertain a potential leak.

The test is intended to verify the ability of the piping system to safely contain the design pressure. Lately, the hydro-tests have been used to ensure that the systems are tight and free from leaks as well. Here is where the problems of test interpretations arise.

A good discussion of this topic is available from

http://www.vistaleakdetection.com/

Please recall the advice I gave you in my last note.

 

[scotta]

Yes, there are several factors involved and the best way in my experience to "feel confortable" that the pipeline is not leaking is to extend the test time... Hydrotests should be as described by CRG; a "strength" test at a factor times design or max allowable operating pressure, and a leak test - typically at a somewhat reduced pressure and over an extended time whilst monitoring temp fluctuations.

A good ref for pipeline(hydrocarbon) hydrotesting with some explanation as to correlations for water temp, temp probe accuracy, un/restrained systems, guidance on a accepatble pressure variation dependent upon pipeline installation area etc can be found in the Australian Standard for hydrotesting pipelines, refer AS 2885.5, or the equivalent Canadian Standard

Hope this helps

 

[eugenp]

Ian,
You can refer to DEP Shell where you will find a comprehensive methodology which will give the answer for all your questions.
Regards,
eugenp

 

[IanMiller]

Thanks for all the great information. Vista Research confirms many of the doubts I was having about the accuracy of hydrotesting as a leak detection method. Has anyone had any experience with the company or its products, especially in large diameter (24&quot high pressure (200psi) applications. I worry about the systems ability to filter out the noise from the highly turbulent flow we see in our pipelines.

Eugenp,

You mentioned a DEP Shell. What is it and where could I find it?

Thank you
Ian Miller

 

[eugenp]

Ian,
DEP is an abbreviation from Design and Engineering Practice available from SHELL Corporation. If you want send me an e-mail to eugenp@yahoo.com and I will send you a copy (PDF file) of relevant specification related to pipeline hydro-test.

Regards,
eugenp

 

[IanMiller]

Eugenp,

I tried to write you at your yahoo address, but it was returned. Please forward the PDF file to datsun661600@hotmail.com .

Thank you for all your help.

Ian Miller

 

[vendora1]

Dear eugenp,
I would be very appreciated if you could send me the file also.
my email is:
setak@parsiannet.com

Best Regards,

 

[odem]

Dear eugenp,
I would be very appreciated if you could send me the file also.
My email is:
lduncan@opeinc.com

Regards,
Odem

 

[portharcourt]

Dear Eugenp,
I will also appreciate if you send me the pdf file at maduforoprospect@yahoo.co.uk.
Many regards and thanks
Portharcourt

 

[Salzilla]

Dear eugenp,
I would be very appreciated if you could send me the file also.
my email is:
sal.chirico@honeywell.com

 

[aybee]

Dear eugenp,
please send a copy of the DEP shell doc tried the other email but it was rejected...eckybo2001@yahoo.com

 

[VLD]

Dear eugenp,
I would be very appreciated if you could send me the file also.
My email is:
vdurst@ncra.coop

Thanks,
VLD