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Helicoil repair in pressure vessel Question
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Posted by: mito57

02/22/2005, 13:54:19

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I need to repair some tapped holes in a manway collar from a reactor. Does anyone has some experience in using HeliCoil inserts in pressure vessels? My main concern is if this kind of repair meets the ASME code. Anyone has done this in a pressure vessel before? Any comment will be appreciated.





Modified by mito57 at Tue, Feb 22, 2005, 13:55:10

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Re: Helicoil repair in pressure vessel
Re: Helicoil repair in pressure vessel -- mito57 Post Reply Top of thread Forum
Posted by: jdsmith

03/16/2005, 23:09:13

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Hi - just read your question. If the manway collar is welded to the reactor, as I have to assume it is, then it is part of the vessel and a code repair by a certified shop MAY be required. To me this is a gray area because you are not modifying or repairing a pressure retaining component (like a vessel wall or weldment).

If the manway flange is an ANSI flange, modifying it by enlarging the holes for Helicoils causes it to no longer meet the ANSI specifications. The ASME pressure vessel code requires either an ASNI flange or one designed according to Appendix 2 of the code.

If the manway was initially designed according to Appendix 2, the new calculations should be run.

Any shop with a "U" or "R" stamp should be able to do this for you and should also work with an Authorized Inspector (AI) who is the ultimate authority on construction and repairs. I would ask the AI.

Hope this helps,

Doug







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Re: Helicoil repair in pressure vessel Agree
Re: Re: Helicoil repair in pressure vessel -- jdsmith Post Reply Top of thread Forum
Posted by: mito57

03/17/2005, 08:46:28

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Thanks for your answer. Our repair shop is actually dealing with the Helicoil repair to se if it can be used. Our only option is this doesn't work is replacing the flange. As far as I know the Helicoil option will be available next year when the ASME PCC-2 document be published. This document is already approved but not published yet so it can't be used as a reference. I've found this link with a review of this document if you are curious.

http://committees.api.org/standards/CRE/sci/misc/docs/repairs-guidearticles.ppt







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Re: Helicoil repair in pressure vessel
Re: Helicoil repair in pressure vessel -- mito57 Post Reply Top of thread Forum
Posted by: ABTL

02/23/2005, 18:21:49

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What pressure???

Any repair has to be ASME certified in order to retain that stamp. I doubt very much if a helicoil is ASME approved. This sounds like a man cover that is accessed on a regular basis. If you want a strong repair that will last try full size threaded inserts such as a KAR Keensert or Jergans? insert. Use pipe dope on the threads.

Again, you will lose the certification unless you have an ASME certified shop do the repair.

If this is an important reactor or if anyone could possibly get hurt from a threaded fastener failure then definately call in the ASME certified shop for the repair







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Re: Helicoil repair in pressure vessel Smile
Re: Re: Helicoil repair in pressure vessel -- ABTL Post Reply Top of thread Forum
Posted by: mito57

02/24/2005, 08:16:39

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I know it has to be acertified repair an that's exactly my concern. Besides, Helicoils are regular used and approved for nuclear and aircraft applications. I have no room for Keenserts. The side of the tapped hole is only 1/4" away from the outside of the collar. I will have a ASME certified for the repair. I'm just tryng to know if HeliCoils are acceptable for ASME. The reactor works at 9 psi/FV and the cleaning opening is pointing to the ground. The bad holes are 4 out of 20, so the concern is not that a failure could hurt someone. The problem is that there is some leak because of the bolts which can't be tightened.
Helicoils will have more than enough strenght to withold the pressure. I've already calculated this but I'm not going to use it if I'm not sure they are ASME approved. So that's my question.






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Re: Helicoil repair in pressure vessel
Re: Re: Helicoil repair in pressure vessel -- mito57 Post Reply Top of thread Forum
Posted by: ABTL

02/24/2005, 16:38:43

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Just call your ASME certified repair shop and ask them.
I hope everything works out good for you.
Jim






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