Mr. Ehrfurth,
Mr. Christopher Wright had forwarded your subject inquiry on to the "PipingDesign" group, and it has received some reply on this forum. I would just like to add that while I don't have direct experience in hot-tapping chilled water lines by any method, nor for that matter with Power Piping Code etc. dictates specifically concerning same, I believe at least iron and even steel "water" lines in general have been wet-tapped or hot-tapped (and even under pressure) perhaps for some decades with various types of mechanical tapping sleeves or saddles, tapping valves and construction equipment and procedures utilizing such devices (basically without welding). While practical application of such items/procedures is of course some dependent/limited on the actual size ratios and piping material of line and branch etc. connections, as well as by variables of extreme temperature or pressures etc., it would appear that where this could be done with secure results it would at least basically eliminate many or all of the issues/concerns brought up it appears by welding/operations. Of course, it appears if such lines are "insulated", the insulation must be dealt with in either tapping approach. I believe there are even some specialized construction firms that advertise substantial expertise in tapping operations with some or all of these approaches, and I suspect you could bring up these firms and the aforementioned devices with a few key words and a good search engine on the Web.
Randy Conner
Research Department - Technical Division
American Cast Iron Pipe Company
1501 31st Avenue North, Birmingham, AL 35207
P. O. Box 2727, Birmingham, AL 35202
ph 205-325-7946
fax 205-325-8095
-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=7KUfycKqvOAWNCE1hRsjlSgQaYk4fLclIXWqbmTzwBwXMoNs35DdwKMwKPkf87Sr3cBfgzFc8Dj06py2ERfWAY7DQA2cqw">PipingDesign@yahoogroups.com</a> [mailto:<a href="/group/PipingDesign/post?postID=7KUfycKqvOAWNCE1hRsjlSgQaYk4fLclIXWqbmTzwBwXMoNs35DdwKMwKPkf87Sr3cBfgzFc8Dj06py2ERfWAY7DQA2cqw">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
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=rdY1tbHu6cuoXdJEEKdu_fe5jDymDxLEtuKadBoaJYvUHywcCL41uBUz1nUtwuZA4aoUD6xRmI69PWagusEeoxR7ZRc">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=3Trz2JLhqx5BmmFMwJQYMjoPAZ71RovDeA-uCui8hLCeV6cub-fzbuEHeTRoSKda-PWinmsdfCdopoU">chrisw@skypoint.com</a> | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania1864)
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