Thanks Everett. Hopefully someday we'll get a TDW (or other
company) tech guy on this list just to fill-in details and give
practical advice. Hot tapping/stoppling is fascinating, is there
an original inventor of the technology?
April's message count for this list was 29, May was 312. OK, so Ralph posted a lot, but hey!
Paul
> Flow requirements on in-service piping repairs, depends upon
several
> variables. API-570 does address this issue, but it also refers
to their
> companion standard API-RP 2201 (no surprise). The 2201 std. does
tell you in
> detail why in some cases you would want low flow rates and/or
higher flow
> rates. My Sept. 1995 version of 2201 Sect. 3.3 explains this
very well.
> Maintaining flow on metal thickness less than 1/4" minimizes
overheating of
> the liquid contents, burn through caused by elevated metal
temperatures and
> fluid thermal expansion in closed systems. But higher flow rates
increase
> the weld cooling rate and the risk of cracking. And they go on
talking about
> various ranges of metal thicknesses etc.. API 570 sect.
'Repairs,
> Alterations, and Rerating of Piping Systems', tells you the
patch size and
> configuration requirements among other things.
> ----- Original Message -----
> From: Paul Bowers <pbowers@pipingdesign.com>
> To: <PipingDesign@yahoogroups.com>
> Sent: Thursday, May 31, 2001 9:35 PM
> Subject: Re: [PipingDesign] Repair of Piping In-Service
> > > AWS Pipeline Welding and Inspection (page 77), ASME B31G and
the
> > API 570 is
> > > your best source on this subject. One of the FAQ's is why
does
> > one have to
> > > ensure a flow when welding on a live line (say to install a
> > patch to fix
> > > leak or do a hot tap or stopple plugging). Almost always,
the
> > answer is that
> > > it helps to cool the weld area. I don't agree. What says
you?
> >
> > That's always been my understanding.
> >
> > Paul
Received on Sat Jun 02 23:56:00 2001
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