I have been caught with this one a few times and there are two ways I have
got round it:
Sometimes a branch line has a larger than necessary isolating valve. If this
is the case then sometimes it is possible to make a new connection
downstream is the branch valve. You do have to interrupt the branch flow for
a short time, but the remainder of the air system can remain in service.
Lock out the isolating valve to avoid an unpleasant surprise. If branch
interruption is not permitted, a rental instrument air set can help out.
Sometimes a temporary jumper pipe can be installed across two existing valves, and the line in between isolated by two more isolating valves.
On occasion, with water, I have welded a socket to the outside of a live pipe, fitted a ball valve and then drilled through the pipe wall using a gland around the drill stem. This is dodgy at best, and would be even more dodgy on air as there is a higher risk of blowout and getting metal cuttings in the pipe.
Think of the exercise as two problems; one to create a dead pipe section and the other to stab in a valve.
Cheers
Steve McKenzie
-----Original Message-----
From: regoldst [mailto:regoldst@attbi.com]
Sent: Wednesday, November 27, 2002 1:48 PM
To: PipingDesign@yahoogroups.com
Subject: [PipingDesign] Hot Tapping Plant Air and Instrument Air
I'm presently working in a Major Oil Refinery in the United States and I was told that you can't Hot Tap air lines due to the generaed heat problems and the Refinery won't allow clamp-on tees for Tapping, so I'm at a loss for ideas. Shutting down plant air and instrument air is out of the question and spare valved connections have been used, so I'm looking for ideas. I don't remember this being a problem in the past. Has there been a recent code change or have I been doing this wrong for the last decade or so?
Discussion List sponsor: Texas Flange - a good source for information on
industrial flanges, all they ask is for referrals for designs they help
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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Received on Tue Nov 26 20:24:00 2002
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