Opinions- hydrostatic test data

[Eric Myers]

Hi all, I'm looking for a second (or more) set of eyes on some pipeline test data. The pipe in question is approximately 600ft of 24", mostly exposed except for a 30' section.

Here is a chart of pipe temperature and pressure for the last hours of the test.

Some of my own observations:
[ul][li]Recorded pipe temperature reached a low of 59F at .4 hours, and rose back up to 60F near the 2 hour mark. I'm guessing the pipe reached an actual low around the 1.25 hour mark and temperature started climbing back up after that. Per my own understanding, it would be generous to say that the lowest pressure should have been 386F if everything was okay, and should have started climbing from there.[/li]
[li]As pipe temperature climbs, pressure continues to drop until 3.2 hours on. The temperature is 64F at this time, and my calculated pressure is around 468 psi. Actual recorded pressure is 362 psi.[/li]
[li]At the end of the test, pipe temperature has risen 10 degrees F, but the pressure has only now gotten back up to what it was at the time the temperature started going up.[/li][/ul]

Is anyone aware of a way that the data could look like this without it indicating a leak?

 

[LittleInch]

" mostly [highlight #FCE94F]exposed[/highlight] except for a 30' section"

" The pipe is mostly [highlight #FCE94F]buried[/highlight]. "

Which one??

But I don't think you could "prove" anything from those readings - far too "jumpy" data.

I don't know what 49 CFR 195 E says so unless you can post a particular section then I don't think you can get very far.

If you really want to say something to the end client you could and need to stick to the facts, not opinions.

So something like

"For your information, I was asked to review and certify the leak? test results on pipe xxx to 49 CFR 195 E. I was unable to do so as the data supplied in terms of temperature and pressure variations could not be used due to large variations and time delays between the two. I could not ascertain whether there was a leak or not and have advised XYZ construction ltd of my opinion in this matter."

Then you've let them know you're not happy and if they want to brush it under the carpet then they will and if they don't then you'll get a call.


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

 

[Eric Myers]

Sorry- it is mostly exposed except for 30'. Post edited to correct that.

If I can't end up with conclusive results that this couldn't be something other than a leak, then I will confine the communications just to the contractor. I am going to chase the question about initial water temperature when I get some time, to make sure it doesn't point to something absurd.

 

[1503-44]

I'd just say "insufficient test time, results inconclusive", unless you want to consider the time prior to stabilisation. If you can prove that the injections were to maintain pressure during temperature drop in the absense of leaks, then that would be OK. Start at the end of the test and work backwards until you get the 4 or 8 hour duration. I guess you have a visual report? So 4 hrs is ok with that.

https://www.govregs.com/regulations/title49_chapterI-i1_part195_subpartE

§195.303 Test pressure.
The test pressure for each pressure test conducted under this subpart must be maintained throughout the part of the system being tested for at least 4 continuous hours at a pressure equal to 125 percent, or more, of the maximum operating pressure and, in the case of a pipeline that is not visually inspected for leakage during the test, for at least an additional 4 continuous hours at a pressure equal to 100 percent, or more, of the maximum operating pressure.

§ 195.310 - Records.

https://www.govregs.com/regulations/title49_chapterI-i1_part195_subpartE_section195.310

Gas

https://www.govregs.com/regulations/expand/title49_chapterI-i1_part192_subpartJ_section192.505