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Leak Testing, Transformer Tanks, Assemblies: 695 MVA

09/29/2014 2:13 AM

Could anybody in the transformer manufacturing industry advise me what the best method would be to test transformer tanks and parts thereof.I am new in this industry. At this stage we only test the transformer assembly when completed with oil inside with the active parts with vacuum overpressure. The capillary action of warm oil is more than than those of liquid penetrant, because also with the compressive force associated. The completed transformer weight is about 150 tons. I recommended that we excecute a soap leak test in the fabrication workshop before sandblast and paint. I did some research, and found companies in this industry are following this procedure.

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#1

Re: Leak Testing, Transformer Tanks, Assemblies:695 MVA

09/29/2014 1:10 PM

Hydraulically. You don't want the thing to rupture and throw bits everywhere. Anyways, your outfit should have a procedure to follow that has been reviewed by your indemnity insurance contact. Did you ring that individual or do you want me to do it for you?

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#2
In reply to #1

Re: Leak Testing, Transformer Tanks, Assemblies:695 MVA

09/30/2014 2:04 AM

How do you want to fill transformer tank the size of a olympic swimming with hydraulic oil which wil contaminate the virgin oil? there is procedure in place to test as per ASME V111 ug 98, 100(UW 50), seems you dont have experience in this industry, but thanks for the comment( myself a fabrication/welding inspector, IPE, NDT technician level 1 RT,evaluator and registerd radiation worker, PT, UT, MT level 2, and IIW welding technologist with an excess of 38 years welding technology experience, with the last 15 years as quality manager). Varous dicciplines is under my auspices now from designers etch.

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#3

Re: Leak Testing, Transformer Tanks, Assemblies: 695 MVA

09/30/2014 11:13 AM

Consider using a leak-down method where you pressurize the tank with a gas at a known pressure, and subsequently remeasure the pressure at intervals. Also, refer to the Nondestructive leak testing handbook.

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#4
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Re: Leak Testing, Transformer Tanks, Assemblies: 695 MVA

10/01/2014 3:35 AM

Thanks Welderman for this advise, what would you suggest then to find the tiniest pinhole(piping porosity) to detect possible leaks, cost effective equipment. Where do i source the Nondestructive leak testing handbook. Have an awesome day!!

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#5
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Re: Leak Testing, Transformer Tanks, Assemblies: 695 MVA

10/01/2014 9:20 AM

My 3rd edition is ISBN 1-57117-0171-5 . I suggest ou check with American Society for Nondestructive Testing,

My 3rd edition copy is ISBN 1-57117-071-5. Suggest you contact American Society For Nondestructive Testing, Inc. There are different methods used for detecting leaks than locating leaks. The leak-down method is good for detecting the presence of leaks but is a go-no-go test that won't help to pinpoint their location. The soap bubble test can pinpoint locations, but lacks sensitivity. The helium sniffer test is sensitive, but can be affected by background noise in a closed container. There can also be a concern as to whether a quantified leak is the result of one large leak or several small leaks in parallel. You may also be concerned about virtual leaks. I suggest you will be best served if you determine the sensitivity you require before you investigate detection and locating methods. I'm thinking that for oil leaks, a leak rate limit of 1E-5 Atm cc He/sec would be about right, but you will need to make that determination.

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