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Hydrostatic Tests

12/10/2007 12:25 PM

Hi Im Working on my tesis, its about Hydrostatic Test, I already have a lot of information about it, but I cant find some one.

How can I determinate the duration of the test?

I already read the ASME B31.3, 31.8, API 1110, API 5L, but the duration (hours or minutes) I didnt found it :S


If you have an other information that can support me in my thesis, I will be glad with you.

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#1

Re: Hydrostatic Tests

12/10/2007 12:39 PM

EduardoF1,

As far as I know, the duration of a hydrostatic test depends upon the internal volume of the pipeline or vessel undergoing the test.

The larger the volume, the longer the test.

I have seen hydrostatic tests run for 30 minutes, as well as for 24 hours.

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Just my $0.02.

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#2
In reply to #1

Re: Hydrostatic Tests

12/10/2007 1:04 PM

I agree (and gave you a "good answer" vote).

I have seen time durations specified in some code documents, but times do vary quite a bit. I do not have any specific references, but for fire protection piping check NFPA, and check various plumbing codes for hydrostatic and vacuum testing of sewers.

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#3

Re: Hydrostatic Tests

12/10/2007 7:14 PM

The duration depends on the type of enclosure to be tested and if a pressure short time creep has to be detected or not. Under pressure the vessel will deform and this can have influences on seals or other components. The time under pressure must give those components to react.

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Member

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#4

Re: Hydrostatic Tests

12/11/2007 1:02 AM

Hello,

The test time should hinge on the material being tested and to a big extent, the porosity or the absence of it. Hollow steel for example does not need to be left over time as water is incompressable and steel is not porous. If there is a leak in the steel vessel then the leak will be certainly obvious on introduction or elevation of the water pressure. Ceramics though needs a little standing time. An idea would be to introduce a reacting catalyst to the outside of the vessel being tested to detect water presence during the test. I take it that you are doing leak tests and not expansion tests.

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#5

Re: Hydrostatic Tests

12/11/2007 2:35 AM

For pipelines designed, fabricated and inspected in accordance with ASME B31.4 "Pipeline Transportation Systems for Liquid Hydrocarbons & Other Liquids", the hydrotest duration shall not be less than 4 hours. Please refer to Para. 437.4.1(a).

For any pipeline, I recommend a duration for 24 hours, and a pressure and temp. recorders must be used, taking into consideration the type of liquid used for hydrotest to avoid freezing it in winter.

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#6

Re: Hydrostatic Tests

12/11/2007 2:56 AM

u may ref OISD standards. in GAIL, natural gas pipelines, i recall, it was for 24 hours.

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#7

Re: Hydrostatic Tests

12/11/2007 10:02 AM

Thanks everybody! :D

In the company where Im doing my thesis, they do some hydrostatic test to short section "spools" his lenght is no more than 2m (6.56 ft) doing a test of 1 hour.

But 4 hours its OK by ASME B31.4.

There is an other point, before reach the 100% of test pressure you must gradually increase the pressure into a determined time, this because if you set 100% in 1 step, this will cause the pipe yield (or expand) a little producing a pressure drop (thats what somebody explain me). So, you must set 10% by 5 minutes, 30% another 5 minutes, ... 60%, 100%... also 5 minutes each one. But In ASME and API I didnt find that, and you must know for my thesis I must say "this is according to [standard code]" all must be correctly supported. Anybody knows where I find that? Any Standard? or Book?


Thanks a lot.

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#8

Re: Hydrostatic Tests

12/12/2007 2:28 PM

You don't need to do it in small increments, just crank it up to the 110% of rated charge and see what happens....

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#9

Re: Hydrostatic Tests

12/13/2007 2:54 AM

EduardoF1,

Well, the above comments are quite satisfying for your thesis to go forward. However, please take a review for the following.

1. it is not only how to perform the hydrotest but the method of doing the test

2. think about why there is a requirements of hydrotesting?

3. you have to learn the properties and technical data of the materials so that you will understand the limitation of hydrotesting.

4. bear in mind that all fabrications/manufactured devices or vessel/tanks has its reference code of standards. from that standards, you will find the requirements for testing such as ex-ray test of welds, hydrotesting or even air test, verification of materials, etc., etc....

from that info, you will learn nearly to complete understanding why there is hydrotesting requirements.

those people above who voluntary comments on your questions, are highly professional to guide you....

jojie

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#10

Re: Hydrostatic Tests

12/20/2007 3:20 PM

Under ASME B31.3 you do not perform a hydrostatic test. Instead you do a mechanical leak check. There is no time requirement, the only time dependant function is that you must inspect for leaks. If it takes 30 seconds to check for leaks or 16 days to check, it doesn't matter.

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#11
In reply to #10

Re: Hydrostatic Tests

12/22/2007 8:10 AM

Hydrostatic test or leak test is essential in accordance with ASME B31.3, only there are cases where you can't proceed hydrostatic test, and you can proceed pneumatic leak test in lieu of the hydrostatic leak test. Please refer to ASME B31.3, Para. 345:

345 TESTING

345.1 Required Leak Test

Prior to initial operation, and after completion of the applicable examinations required by para. 341, each piping system shall be tested to ensure tightness. The test shall be a hydrostatic leak test in accordance with para. 345.4 except as provided herein.

(a) At the owner's option, a piping system in Category D fluid service may be subjected to an initial service leak test in accordance with para. 345.7, in lieu of the hydrostatic leak test.

(b) Where the owner considers a hydrostatic leak test impracticable, either a pneumatic test in accordance with para. 345.5 or a combined hydrostatic-pneumatic test in accordance with para. 345.6 may be substituted, recognizing the hazard of energy stored in compressed gas.

(c) Where the owner considers both hydrostatic and pneumatic leak testing impracticable, the alternative specified in para. 345.9 may be used if both of the following conditions apply:

(1) a hydrostatic test would damage linings or internal insulation, or contaminate a process which

would be hazardous, corrosive, or inoperative in the presence of moisture, or would present the danger of

brittle fracture due to low metal temperature during the test; and

(2) a pneumatic test would present an undue hazard of possible release of energy stored in the system,

or would present the danger of brittle fracture due to low metal temperature during the test.

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#12
In reply to #7

Re: Hydrostatic Tests

05/14/2008 7:54 PM

Hi:

Could you send me information about hydrostatic test? I would like to learn about it. Documents in Spanish or English will help. My email is: manfredo4@yahoo.com

Thanks a lot.

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#13
In reply to #7

Re: Hydrostatic Tests

05/14/2008 10:53 PM

Dear EduardoF1,

"if you set 100% in 1 step, this will cause the pipe yield (or expand) a little producing a pressure drop (thats what somebody explain me"

Only we like to avoid sudden stressing of the pipe material, so we like to raise up the pressure step by step. But there is no a problem related to pressure drop, where during hydrotest you have to inject a liquid to raise up the pressure. Drop in pressure is a problem related to flowing of the fluid (dynamic), where our case is static.

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#14
In reply to #5

Hydrostatic Tests during winter time at low ambient temperatures

10/06/2008 2:18 AM

Do you have any procedure on how to hydrotest piping during winter time with an ambient temperature from 5 till -40 degrees Celsius?

Is it only by adding some antifreeze in the water test, or I have to sort out a different system?

Thanks

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#15
In reply to #14

Re: Hydrostatic Tests during winter time at low ambient temperatures

10/06/2008 3:10 AM

Sorry, I don't have a procedure for hydrotesting at this very low temp. Only it is allowed to use antifreeze mixed to liquid of test. And ASME code recommends (in these cases) to proceed a pneumatic test in lieu of hydrostatic to avoid freezing of liquid inside your piping system.

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#16
In reply to #15

Re: Hydrostatic Tests during winter time at low ambient temperatures

10/07/2008 4:03 AM

Abdel Halim, I've checked in ASME B31.3 but it's written that we can proceed with Pneumatic test inlieu of Hydrotest.

Can you please tell me where can I find this paragraph, thanks.

Regards

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#17
In reply to #16

Re: Hydrostatic Tests during winter time at low ambient temperatures

10/07/2008 5:06 AM

Per ASME B31.3,

Par. 345 Testing

(b) Where the owner considers a hydrostatic leak test impracticable, either a pneumatic test in accordance with para. 345.5 or a combined hydrostatic-pneumatic test in accordance with para. 345.6 may be substituted, recognizing the hazard of energy stored in compressed gas.

(c) Where the owner considers both hydrostatic and pneumatic leak testing impracticable, the alternative specified in para. 345.9 may be used if both of the following conditions apply:

(1) a hydrostatic test would damage linings or internal insulation, or contaminate a process which would be hazardous, corrosive, or inoperative in the presence of moisture, or would present the danger of brittle fracture due to low metal temperature during the test

(2) a pneumatic test would present an undue hazard of possible release of energy stored in the system, or would present the danger of brittle fracture due to low metal temperature during the test

345.5 Pneumatic Leak Test

345.5.1 Precautions. Pneumatic testing involves the hazard of released energy stored in compressed gas. Particular care must therefore be taken to minimize the chance of brittle failure during a pneumatic leak test. Test temperature is important in this regard and must be considered when the designer chooses the material of construction. See para. 345.2.2(c) and Appendix F, para. F323.4.

345.6 Hydrostatic-Pneumatic Leak Test

If a combination hydrostatic-pneumatic leak test is used, the requirements of para. 345.5 shall be met, and the pressure in the liquid filled part of the piping shall not exceed the limits stated in para. 345.4.2.

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#18
In reply to #17

Re: Hydrostatic Tests during winter time at low ambient temperatures

10/09/2008 11:49 PM

Dear Abd El Halim,

I've found that answer and I would like to know from you if it's applicable in my case or not:

ASME B31.8 allows static tests with air up to 70% of SMYS. I've tested lines longer than your 10,000 ft with air with excellent results. You didn't say the diameter of your line or the test pressure, but as long as you keep the hoop stress below 70% of SMYS and your area classifications are consistent with ASME B31.8 air tests you can save yourself a lot of pain and suffering by just doing the test with gas (either air or an inert gas). All of the calculations are in ASME B31.8 or you can look at my web page for a document that pulls the issues into one package.

There are people in these forum that will tell you that I'm giving you irresponsible advice, and that the total stored energy in an air test is just too great to be risked. ASME disagrees with that assertion, and I've done dozens of big static tests with air with great success by following all of the rules.

Regardless of your final choice of test media, be very careful of the temperature that you put into your calculations. Eastern Canada in April can be pretty chilly and cold temperatures shift the brittle-failure curve dramatically.
David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com

My Questions are:
1) If yes, how do I recalculate/convert the pneumatic test pressure from the Hydrostatic one?

2) If I will have to use Ethylene Glycol as my only solution my question is:
As the bulk modulus of water/antifreeze mixture is different from that of water alone, the volumetric expansion coefficient will be different.
How do I calculate the pressure/temperature variation?

Thanks

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Users who posted comments:

Abdel Halim Galala (5); aironyx (3); Anonymous Poster (1); EduardoF1 (1); gajendrasingh01 (1); jojie_oak (1); Lagoon Explorer (1); manfredo4 (1); nick name (1); Ried (1); The JMAN (1); vicini (1)

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