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contactfarhan
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Acceptance Criteria for Hydrostatic Test of Pressure Vessels

10/30/2011 7:48 AM

Dear Folks, i am new in this forum and its very nice to see all the discussions made in this forum. i want to raise a Question for all you people expert advice that:

Q) Is there any criteria for temperature reduction during holding time that we can accept for both new construction and in-service?
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lyn
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#1

Re: Acceptance crieteria for Hydrostatic Test of Pressure vessels

10/30/2011 9:30 AM

Depends on what specification you are working to. What controls the design, construction and inspection of the vessel?
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pritam
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Re: Acceptance Criteria for Hydrostatic Test of Pressure Vessels

10/31/2011 1:23 AM

Normally temperature variation of water pumped inside the pressure vessel for hydrostatic test during the test period is negligible, so temperature correction is not suggested. However, if your test period is longer and you expect significant temperature variation, seek guidance from expert testing agencies.

As per my experience, about 0.075 litres of water is to be pushed per cubic meter of vessel to raise pressure by 1 bar. Cubical expansivity of water is 0.214 litre/cu.m, so variation of temperature may cause variation in test pressure by 2.85 bar/deg.C.
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pritam
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#3
In reply to #2

Re: Acceptance Criteria for Hydrostatic Test of Pressure Vessels

10/31/2011 3:18 AM

Small correction in my own comment:

Unit of cubical expansivity of water shall be corrected as 0.214 litre per cu.m per deg.C instead of 0.214 litre/cu.m.
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drbobwoolery
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#7
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Re: Acceptance Criteria for Hydrostatic Test of Pressure Vessels

10/31/2011 9:45 AM

That 75 mL per bar would increase as the vessel approached its yield strength. Diligent hydrotesting of pipelines includes not only holding test pressure for 8 or more hours, and in some cases, spiking the pressure to the full SMYS, but then running a measurement pig to demonstrate that none of the pipe stretched beyond specifications. Enbridge had around 10% of joints on one line stretch over 1%. Those that were over 2% were replaced.

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contactfarhan
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#4

Re: Acceptance Criteria for Hydrostatic Test of Pressure Vessels

10/31/2011 5:06 AM

Noted. Thanks for the expert advice....it will be nice to more threads...
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contactfarhan
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#5

Re: Acceptance Criteria for Hydrostatic Test of Pressure Vessels

10/31/2011 5:10 AM

In addition to this "Can anyone explain how during holding time how much pressure drop is allowed in order to accept the test, e.g, if a system to be tested at 100 Bars, during holding time if pressure drops to 90 bars will it be acceptable or simply no leak is acceptable at all.
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pritam
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#6
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Re: Acceptance Criteria for Hydrostatic Test of Pressure Vessels

10/31/2011 7:53 AM

There should be simply no leak. In case of any leak observed, system is to be depressurised, leak is to be rectified and test to be repeated.
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RVZ717
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#8

Re: Acceptance Criteria for Hydrostatic Test of Pressure Vessels

10/31/2011 2:56 PM

Pressure Vessels are designed to strict standards/codes. All the information you need is outlined in the ASME pressure vessel code book.

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avatarkings
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#9

Re: Acceptance Criteria for Hydrostatic Test of Pressure Vessels

11/02/2011 3:17 AM

acceptance criteria for hydrostatic test depends upon the quality of the vessel in standards which are given to it like iso standards,bis standards,jis standards,din standards etc.
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