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Anonymous Poster

Hydrostatic Testing of Tanks

07/14/2009 12:00 PM

Hydrotest is completed for an atmospheric tank constructed. However, after the hydrotest, we had to weld numerous 10mm thk support plates which was previously not welded to the tank bottom plate. Is re-hydrotesting of the tank necessary?
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ronseto
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#1

Re: Hydrostatic test of tank

07/14/2009 12:23 PM

I would say a retest is not needed. By atmospheric, do you mean the tank is not under internal pressure? If there is no differential pressure, a test is not necessary. Testing is only required if the tank is a pressure vessel. Leakage is detected by visual means.

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Anonymous Poster
#2
In reply to #1

Re: Hydrostatic test of tank

07/15/2009 12:50 AM

Thanks ronseto. It is a storage tank with max operating pressure of +100/-25mmH20. The pad plates are welded on the bottom plate and did not cross the bottom plate weld seam. Could we say that since there is no heat input to the existing weld seam, and low pressure there will be no chance of leakage?

If we refer to API 650 para. 7.3.6, we are not to do any welding after hydrotesting.

But if we refer to API 653 para. 12.3, re-hydrotesting is only required for major repairs.

How can we make a conclusion from here?
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PWSlack
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#3
In reply to #2

Re: Hydrostatic test of tank

07/15/2009 10:05 AM

If the welding were, perhance, to have affected the structural integrity of the tank and the tank had later failed while full of the process fluid, the indemnity insurers could easily walk away from the problem.

DO A RETEST AFTER WELDING.

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phoenix911
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#4

Re: Hydrostatic Testing of Tanks

08/04/2009 4:49 PM

nothing was said if this was a certified vessel

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