FW: Fwd: [STM] Hot Tapping of Chilled Water Piping

From: <Jim>
Date: Fri May 05 2006 - 16:30:00 EDT

I have seen them run the thermostat on the chiller up to 50 degrees or greater and make the weld. You will still get cooling but you be above the preheat temperature. You should not have flashing due to water flow in the system and if you do have flashing the surge tank should absorb the brief pressure change.

-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=3KUNOyQsih5ckavu6UUpnxmGkRzqnJMmQDU_hqVz8aei_swyGDqx5PJPU8i6FCeqzdY-umuvVszA1UWHPfX2KwzKR9IVgIY">PipingDesign@yahoogroups.com</a> [mailto:<a href="/group/PipingDesign/post?postID=3KUNOyQsih5ckavu6UUpnxmGkRzqnJMmQDU_hqVz8aei_swyGDqx5PJPU8i6FCeqzdY-umuvVszA1UWHPfX2KwzKR9IVgIY">PipingDesign@yahoogroups.com</a>] On Behalf Of Christopher Wright
Sent: Thursday, May 04, 2006 10:39 AM
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=r3QtozTKom1fFAo69_zBn-0hBCYXQgyMRnMClhU8rUXxHjJyZqkgQA8M4-_-poOH45Lw6UC2ZkRI99Yt1APx1M6K4LAC">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 <a href="/group/PipingDesign/post?postID=ddnUPVs_26M6pfDPWkMp7l0Dkumqth6ZiovRMfbEIxU-eCfbkzW4CJfR4qT3EvwPolUsb-M05z2ZE3UD">chrisw@skypoint.com</a> | 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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