[opendtv] Re: Steel pipes for gas!

  • From: "Bob Miller" <robmxa@xxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 31 Oct 2006 12:07:08 -0500

On 10/31/06, Craig Birkmaier <craig@xxxxxxxxx> wrote:

At 5:24 PM -0800 10/30/06, John Willkie wrote:
>We know that gas lines break during earthquakes (Northridge '94,
>magnitude 7.1), and although it's been a few decades, I remember
>attending San Diego City Council meetings where building code
>upgrades were discussed, including keeping the requirement for steel
>gas lines.  Haven't paid much attention since then.

Hmmmm...

If I were concerned about the potential of breaking a gas line, I
would probably prefer the plastic lines now being installed. There
are three general problems that can cause gas leaks:

1. Construction crews that do not properly locate utilities before
digging. We've had two such incidents with gas lines in the past year
or two here in Gainesville. I doubt that steel has any advantage over
plastic when a back-hoe snags a line.

2. Corrosion.  Plastic is the hands down winner here. The
installation procedure uses ultrasonic welding techniques, which make
the joints as strong or stronger than the plastic pipe.

3. Earthquakes, sinkholes, etc. When the ground starts to shift,
which would you rather have, a pipe system that is flexible and can
bend, or one that is rigid? We are not talking about plastic water
mains or sewer pipes, which typically have segments that plug-in to
one another with gaskets or glue. Gas mains are thick wall plastic
with ultrasonic welds.

Regards
Craig

Was thinking the same thing.

Also what is the issue with using a plastic pipe as to transmission?
Would the signal leak from such a pipe buried underground or would it
stay in the pipe? John suggest that it would have to have metal in the
plastic.

If you have to have metalized plastic I guess that would eliminate the
main attraction of gas line broadband where ever plastic is deployed
since you would have to dig it up and replace it with a metalized
version.

Bob Miller


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