Procedure for welding on natural gas pipeline?

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Where could I find a procedure for welding on a natural gas pipeline?
I know very little about welding but my maintenance manager asked me
if I could do some research and find something on the topic. Any ideas
where to look? Thanks.

Re: Procedure for welding on natural gas pipeline?



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Procedures for welding any piupelines varie from region to region...your
best bet is to contact your local gas company as they have written
procedures for repair etc... Jim



Re: Procedure for welding on natural gas pipeline?


Good point. Thanks!



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Re: Procedure for welding on natural gas pipeline?



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I agree, but, IMHO the correct party to contact is the OWNER of the
pipeline.  They SHOULD know the regulatory structure they operate under, as
well as the materials and approved procedures for their lines.

Good luck, YMMV.



Re: Procedure for welding on natural gas pipeline?


Several of the local welders I know are going under re-certification check.
They are not informed as to what the next pipeline will contain but suspect
it is most important to contain without possible leak.  These are all well
seasoned and just back from a job.  These go off to states at all corners
of the country to weld as the line is being put in.  I have another friend in
Ohio.

Martin

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Re: Procedure for welding on natural gas pipeline?



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One time, a gas line was ruptured near my worksite.  It was a three or four
inch line IIRC.  I was into welding at that time, and asked how they were
going to fix it.  The guy said they would OA weld it.  I was surprised.

Steve



Re: Procedure for welding on natural gas pipeline?



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Surprised why?
--
As we enjoy great advantages from the inventions of others, we should
be glad of an opportunity to serve others by any invention of ours;
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Re: Procedure for welding on natural gas pipeline?



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Because I had just returned from years of seeing pipeline welded with arc
welding.

Steve



Re: Procedure for welding on natural gas pipeline?



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I was also surprised when I found out how much natural gas pipeline is
gas welded.
Turns out it is common practice for welding residential lines 3" and
smaller.
Larger stuff is stick or TIG welded.

Re: Procedure for welding on natural gas pipeline?


I am interpreting the OP as asking about welding onto a live natural
gas pipeline.  This is sometimes done, for example to install a new
branch connection by "Hot-tap" (i.e. tapping into the line while it is
"hot" [operating]) or for repair of localized corroded areas.

There is specialized equipment associated with this.  The best known
company for the associated equipment and providing this service is TD
WiIliamson (Tulsa, OK).  Some experienced gas companies just buy the
equipment from TDW and do their own hot-taps.
The attachment welds are typically fillet welds connecting the special
pieces (e.g. a "hot-tap split tee fitting" for making a new branch
connection or a split sleeve for reinforcing an area with excessive
corrosion) to the outside of the existing pipe.

API 1104 actually has a special section on this type of welding.  It
is "Appendix B - In-Service Welding" which provides details of how
such welding is to be qualified.

The trick for the welding is to:
a) Make sure the pipe wall thickness is great enough and the welding
parameters are "low enough" to prevent burning through to the inside
while simultaneously
b) making sure the welding parameters are "high enough" so that the
welds are not excessively hard (because the flowing fluid on the
inside makes the welds cool much faster than normal).

This is a real balanacing act and there is actually a computer program
(VERY expensive) that allows to you to determine the two effects
listed above for various welding conditions.

So,
1) Yes, welding onto live, operating gas pipelines can be done.  It is
done "routinely" by a number of pipeline operating companies but
requires a significant amount of expertise, engineering, and welder
experinece/training.
2) There are a number of technical articles on this subject (several
have been published in the Welding Journal).  There has been a lot of
technical research into this subject.

[Yes, this is actual "hands-on" knowledge rather than just repeating
information.  I have been involved in a number of hot-taps myself.]


Tom

Re: Procedure for welding on natural gas pipeline?


I've watched a gas crew do this on a 4" steel pipe to make a stub that
is fitted with a valve and adapter to plastic pipe. It even comes with a
nifty fitting to allow the operator to run a hole saw into the live
pipe, pull the saw back, seal it off, disconnect the hole saw assembly
and start in on welding the stub.

This is NOT something that I want to do .............  EVER!  It's in
the same category as working 8KV lines with just your gloves.

snipped-for-privacy@austin.rr.com wrote:
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Re: Procedure for welding on natural gas pipeline?



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My uncle and a neighbor were killed doing a hot tap at a steam generating
plant in Las Vegas in the early seventies.  Randy Haren and Dick Wilson.
RIP.

It always doesn't go by the book.

Steve



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Dick was a member of the Tulsa local, and had been all his life.  Had worked
all over the world.

 



Re: Procedure for welding on natural gas pipeline?



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In the US we use the API-1104 standard for most petroleum and natural
gas pipelines.


API = American Petroleum Institute.

If it is a high pressure pipe, as in above 600 psi, you have to go to
ASME code.

The American Society of Mechanical Engineers covers Pressure Vessels
and Pressure Piping.

Just so you know, these codes are not free or cheap.
The API-1104 book is around $300 and the ASME books come in 10 volumes
and cost over $1000.

Re: Procedure for welding on natural gas pipeline?


Thanks for the info!


On Wed, 28 Oct 2009 22:22:18 -0700, Ernie Leimkuhler

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