weldolet and hot tapping
weldolet and hot tapping
(OP)
Hello, there:
To hot tapping into and existing 18" line (Sch. 10. A53 Gr. B, UT shows the wall thickness is 0.25", 300 psig and 200F), using weldolet connection (instead of split Tee).
Please help:
To check whether the weldolet connection is safe , which code should be followed? where could I find the weldolet dimension to check area?
Any advice is appreciated.
To hot tapping into and existing 18" line (Sch. 10. A53 Gr. B, UT shows the wall thickness is 0.25", 300 psig and 200F), using weldolet connection (instead of split Tee).
Please help:
To check whether the weldolet connection is safe , which code should be followed? where could I find the weldolet dimension to check area?
Any advice is appreciated.





RE: weldolet and hot tapping
RE: weldolet and hot tapping
Suggest you ask your weldolet supplier for dimensional details of the weldolet so you can check out the area. Also the weldolet weld to the parent pipe should be pressure tested before you cut the hole in the parent pipe.
RE: weldolet and hot tapping
RE: weldolet and hot tapping
I have never seen Sch 10 CS piping used at these pressures. in fact I've never seen any Sch 10 CS in these sizes. The minimum has been Sch 20 with STD being the norm.
RE: weldolet and hot tapping
RE: weldolet and hot tapping
go to
http://www.ceejpublishing.com/Articles/0009.htm
luismarques
RE: weldolet and hot tapping
luismarques,
why do you say "generally safer to use a full encirclement fitting"? I don't see anything in that article that says one way or the other.
As to safety, codes etc.... where is the original line, and what is in it? As a start if it's a B31 pipe there's the code it was designed to, API 2201, and internal company standards, and of course, jurisdictional requirements.
in my (limited) experience, hot taps are generally taken very seriously, so choice of what to do and how to do it is often not a low leven engineering one. At the very least you need QC and saftey buy in before continuing.
SLH
orig message
0707 (Petroleum)
6 Aug 07 13:02
it is generally much safer, to use a full encirclement fitting on hot tap and line stop operations.
go to
http://www.ceejpublishing.com/Articles/0009.htm
luismarques
RE: weldolet and hot tapping
We don’t know the pipe code of the piping where twinbrooks wants to do the hot tapping.
I invite you to read the paper I post with a little bite of more attention.
“A full encirclement fitting will do a couple of things that a simple nozzle will not, it will assist to re-round thin-walled pipe, that may not be round, it will handle the horizontal stresses that the line stop head will place on the pipe, it will also handle the bending stresses applied by the line stop head. For all of these reasons, it is generally much safer; to use a full encirclement fitting on hot tap and line stop operations.”
luismarques
RE: weldolet and hot tapping
Is everybody in this forum really convinced that a welder assigned to the job of welding a weldolet to a pressurized Sched 10 pipe is absolutely safe while performing his job?
RE: weldolet and hot tapping
Twinbrooks, but for the benefit of those reading this
after the fact, I offer the following:
1. Is the hot tap the last resort? Is it feasible from
a process point-of-view? Some processes can not be hot
tapped. Some, although possible, may not be reasonably
safe. API RP 2201 is an good start in answering the many
questions that can arise.
2. One needs to confirm there are no issues with the
additional piping loads being applied to the existing
line. A pipe stress analysis would be prudent.
3. The existing pipe wall thickness (actual) needs to
be at least equal to the required thickness for pressure
plus a reasonable thickness allowance for welding. If
the actual thickness (preferably confirmed via UT for
example) is barely more than that required for pressure,
then loss of containment at the weld pool is a risk.
4. The configuration of reinforcement needs to be reviewed
and, if necessary, calculated. Full encirclement saddles
for size-on-size hot taps are an example where
reinforcement calculations should be performed.
Reinforcement of branch connections using weldolets are
not generally performed by anyone other than the fitting
manufacturer.
5. Assuming the welded branch is to be pressure tested
prior to the hot tap operation (the "punching" of the
hole), the required thickness of the existing pipe for
the pressure exerted on the OD (within the welded branch
connection) needs to be reviewed. One does not want the
existing pipe to fail while pressure testing the new
connection.
6. Use a reputable hot tap contractor who has experience
in all phases of the project: engineering, procurement,
fabrication, quality control, etc.
Hot taps can be done safely, IF the proper attention is
devoted to each step.
Jeff L
RE: weldolet and hot tapping
As far as min wt – you’ll need to do a UT to make sure there are no laminations and the thickness is what you thought and is safe welding. What is safe for wqelding depends on many things, including the material being welded, operating temp & press during welding, weld procedure, produict in the piupeline, etc. Generally though, you’ll want no loess than 5 mm/0.20 in.
And don’t forget flow during hot tapping. For gas, you’ll want to around of 0.4 m/s / 1.3 ft/s of velocity, much more & the weld will cool too fast, much lower & you’ll get heat accumulation.
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: weldolet and hot tapping
However, the welder would rather be swimming in a pond full of alligators. The split tee at least "feels" better.
RE: weldolet and hot tapping
check with bonney-forge for specs, they have reinforcing pads and all.
genb
RE: weldolet and hot tapping
Ziek
RE: weldolet and hot tapping
http:/
RE: weldolet and hot tapping
RE: weldolet and hot tapping
WHAT SIZE IS THE BRANCH??????