Hello,
Regarding you query for the structural integrity of
joint after welding, you need to heat the weld for
stress relieving and to refine the grain structure.
The duration will be more than designated period for
post weld heat treatment; as mentioned in the code
like ASME BPVC sec IX or equivalent for that
material being the designated temperatures can not
be achieved for line flooded with chilled water.
There will be flashing of water while taking the hot
tapping. Normally while carrying out this work
pressure in the line is decreased to minimum flow
requirements. Any way you need to carry out the
further heat treatment as per above para.
Regards,
A K Nashine
> -----Original Message-----
> From: <a href="/group/PipingDesign/post?postID=Qggsnh32nvy9-sYyFCFyCgtjvsEjnEuIKBUEtMs-uoB3AfyeuQoYloH0LZkJsdfVj-fxFi33lhK78RPDsMPOUQ0SSBg">PipingDesign@yahoogroups.com</a>
> [mailto:PipingDesign@yahoogroups.com] On Behalf Of
> Christopher Wright
> Sent: 04 May 2006 20:09
> To: Pipingdesign
> Subject: [PipingDesign] Fwd: [STM] Hot Tapping of
> Chilled Water Piping
>
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>
> I saw this on the steam list. If anyone has any
> ideas for Ehrfurth
> maybe you could e-mail him direct
>
> Begin forwarded message:
>
> > From: "Ehrfurth, Jay - DOA"
> <Jay.Ehrfurth@Wisconsin.gov>
> > Date: May 4, 2006 8:35:29 AM CDT
> > To: "steam-list@lists.cc.utexas.edu"
> <steam-list@lists.cc.utexas.edu>
> > Subject: [STM] Hot Tapping of Chilled Water Piping
> > Reply-To: <a href="/group/PipingDesign/post?postID=NgRJOeiouDg8KHFYIj1yO2vSX-zGUrufIYXtKSzNJVQ6ok921Cj3kNE4lu-533gnkpJCULfiK4c-v8RS7-YCWlO1q3g">steam-list@lists.cc.utexas.edu</a>
> >
> > My question pertains to hot tapping an in-service
> chilled water line.
> >
> > Since this is not a Power Piping Code welding
> scenario our
> > specifications require welding certs from the
> National Certified Pipe
> > Welding Bureau. The welding procedure
> specification submittal
> > indicates on the WPS and associated PQRs a minimum
> preheat of 50degF.
> > Our chilled water system runs around 40-42degF.
> Has anybody run into
> > this issue when needing to hot tap into their
> system?
> >
> > Some of my other concerns are:
> > - As to welding on a flooded pipe with a
> temperature less than the
> > preheat temperature what should be my concerns
> with the
> > structural integrity of the weld?
> > - What concerns should I have about flashing the
> water in contact with
> > the weld?
> >
> > Thanks,
> >
> > Jay Ehrfurth
>
> Christopher Wright P.E. |"They couldn't hit an
> elephant at
> chrisw@skypoint.com | this distance" (last words
> of Gen.
> .......................................| John
> Sedgwick, Spotsylvania
> 1864)
> <a href="http://www.skypoint.com/~chrisw/">http://www.skypoint.com/~chrisw/</a>
>
>
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Received on Tue May 09 23:26:00 2006