Lenght of Time to do a pressure test?

[Bluecat46]

Can any point me in the right direction regarding, how long should you leave a system under pressure for a test?

In Process Piping by Charles Becht Chapter 14 states pressure to be held for at least 10 minutes or as long as it takes to examine the pipe.

EEMUA Guide to the pressure Testing Section 3.3 Test pressure to be maintained for not less than 30 minutes.

I guess really I am asking what is the general opinion to pressure testing time and is there any other documents that mention a time period.

 

[zdas04]

Both ASME B31.3 and ASME B31.8 have times, and they're different. Company policies (if longer than the code) will usually supersede. I used to regularly see company policies that required 24 hour tests, but not so much anymore. I see a lot of 3 hour tests. A lot of 1 hour tests. No real consistency.

I think the longer tests are trying to guard against creep in semi-resiliant piping from parting a weld or fitting connection, but I see them required in steel too.

It is really all over the map, and there is a lot more opinion than justification in the literature.

David

 

[eyec]

what you find in any Standard is considered the "Mnimum". different pressure media (hydro, pneumatic, helium, etc) present various hold times by company Specifications and criticality of the item being tested.

i have witnessed everyting from 5 minutes to 8 hours and know of instances of 24 hours for dye penetrant testing.

 

[pennpiper]

Getting to the "Hold Time"(*) is only part of the equation. In my experience if you are doing a "System wide" hydro-test the size and complexity of the system has a baring on the "Hold Time".
Before the Clock starts for the "Hold Time" you need to fill the system. To do this you need people to vent off all the high points.
How many high points are there and where are they? How many people do you have involved in this activity?

(*)
("Hold Time"= The number of potential leak points + the distance between the points * by the number of people to do the checking)

 

[zdas04]

penpiper,
Good points. When I'm designing a test, I generally define the things that have to happen between starting to fill and starting the clock on the test. One big reason why is that in the procedures I write the tester is not allowed to add test fluid after the test starts (and I define a minimum acceptable finish pressure to account for temperature drops, I allow them to bleed fluid to account for temperature rises).

David

 

[SNORGY]

Where I am at, we make it simplistic.

If you require proof of successful hydrostatic test as part of a QA/QC file that will withstand audit scrutiny by a Regulator, then you typically need to provide the test chart instead of just an affidavit that says, "Yep. We did it. It's all good." The test duration then becomes the length of time it takes to create a meaningful chart by the chart recorder, which is typically several hours, not ten minutes.

B31.3 says ten minutes or the amount of time it takes to examine each joint. Pipeline codes specify minimum durations much longer than that.

Regards,

SNORGY.

 

[Bluecat46]

Thanks everyone for their input it seem that this is a area that boils down to your site standards (difficult if your being asked to advise on the site standard we use the hold for 30 mins after system is filled on all pipework) however another question!

All the answers seam to be based on a pressure test for pipeline systems, what would be done if you are test a single spool of pipe i.e. after welding/dye pen?

 

[BigInch]

B31.3 isn't pipeline.
B31.4 liquid hydrocarbon pipelines, requires a strength test for 2 hours. Prior time to stabilize pressures and temperatures may vary considerably, as well as requirements for longer strength hold times as may be specified by the client.

In any case, if you want to know for sure, read your design code.

From "BigInch's Extremely simple theory of everything."

 

[dmfa200]

One thing to consider is ambient temperature especially outdoors in the sun.

Filling a spool with cool ground water and applying pressure before the spool has a chance to equalize with the ambient temperature will result in overshooting your test pressure.

Our inspector did not like to see pressures any more than 10% over the specified test pressure.

 

[duurai]

as per ASME31.3 Process piping are need 10 to 15 Minutes only
as per ASME31.4 Pipe line are need 2 hours....

 

[BigInch]

drrrai, You're 3 months late with a copy of the answers already given above.

What would you be doing, if you knew that you could not fail? Ans. Bonds and derivative brokering.