I appreciate the message of SARE. We used the hot tapping in one of our
refinery expansion projects...for taking the tapping from hydrocarbon as
well as utility lines without shutdown the rest of the refinery.
As SARE's message explains it is a complicated process to be handled by the
specialists. If it is high-pressure lines, issue is further complicated. In
offshore platform because of the space limitations and other constraints
extra planning and care may have to be taken.
Hari
-----Original Message-----
From: SARE, RALPH H. [mailto:SARERH@YANPET.SABIC.com]
Sent: Saturday, September 29, 2001 10:33 AM
To: 'PipingDesign@yahoogroups.com'
Subject: [PipingDesign] Ho t Taps
Let us say that the break point of between the API Offshore Spec and ASME Code Piping is delineated on the piping drawing. For piping above water the procedure goes something like this (since you have forgotten to state specifics, i'll just give a general idea on how its done).
Material preparation
You will be needing a hot tap machine capable of cutting a 24" coupon like
the TDW 1200D. This monster weigh abot 2 tons. U will also require a full
branch split tee either a welded or bolted to match the flange rating of the
valve of your choice (weigh about 500kg) and of course a full port valve
meeting your req't (need to check out you line designation and piping class
spec for this).
Safety Precaution
There are certain risk involved here since u will be cutting a hole thru a
live line. To reduce risk donot perfrom hot tap on a pipng that contain
flammable gas and air mixture. For guideline on flammable and combustible
liquid u may refer to NFPA 321.
Inspection and Testing
Do make a full scan to check for the thickness of the pipe. Check also for
lamination. Normally done using s UT shear wave. This is to prevent "burn
thru" and to ensure that u have sufficient "meat" on the pipe to carry the
imposed load. I suggest you compute the max. permissible operating pressure
using the thickness measured.
Check available headroom (u will need a lot of space for a 24" hot tap)
.
Installation
Install the full branch splitt tee (complying of course with ASME)
preferably by welding.
Perform hydro prior to cutting of the coupon
Reduce pressure and temp. Maintained the flow
Install the hot tap machine and cut the coupon
Retract coupon, close valve and remove hot tap machine.
Intsall you new line and inspect tightness of joint.
You need a trained and qualified personnel to perfrom hot tap. My recommendation if ofr you to Hire the services of company who specialiced in hot tap. I hope this help.
> ----------> > > pipe on Offhore
> > > Does anybody know how to perform HOT TAP for 24"
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Your use of Yahoo! Groups is subject to the Yahoo! <http://docs.yahoo.com/info/terms/> Terms of Service. Received on Sat Sep 29 02:46:00 2001
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