From: erickson@atlas.cs.nps.navy.mil (David Erickson)
Newsgroups: misc.consumers.house
Subject: Re: Gas piping question
Date: 5 Oct 92 20:51:22 GMT
Reply-To: erickson@taurus.cs.nps.navy.mil (David Erickson)
Organization: Naval Postgraduate School, Monterey CA


I've lost the original posting, but the question was about adding a
connection for a gas dryer to an existing gas line.

I did this once, and it was an easy do-it-yourself job.  It does take a
few tools that may not be in the average homeowner toolkit:

	a pipe threader
	a pair of high quality BIG pipe wrenches (e.g. 18" & 24" RIGID)
	a pressure gauge with a schrader valve (so that you can pressure-
		test the system with a bicycle pump after you've finished)

along with a hacksaw, some pipe compound, a tape measure, etc.

First step was to get the permit.  This was actually useful, because
the inspector made me map out the entire gas system existing, then
helped me to size the new connection.  I didn't realize that gas is 
supplied at a very low pressure, so the pipe usually starts out at a
large diameter and decreases as the pipe fans out to supply each
appliance.  You can't just make a new connection wherever is convenient,
since it may affect the supply to an existing appliance, and the code
makes the assumption that all appliances might be used simultaneously.

The next step is to shut off the gas and purge the gas line.  Disconnect 
the line at the meter and let it sit for a while.

Then, cut the line at the point you want to make the connection, remove
the cut ends, and replace them with a combination of a left-hand,right-
hand nipple, a left-hand,right-hand bushing, a tee, and a couple of
regular nipples.  Use a liberal amount of joint compound.  Diagram follows:


     ------|                                                 |-----
           |-------------------------------------------------|
           |-------------------------------------------------|
     ------|                    / \                          |-----
                                 |
                                 |
                             cut here


                               |--|
                               |  |
     ------|     |----|      |-|  |-|                        |-----
           |-----|    |------|      |------------------------|
           |-----|    |------|      |------------------------|
     ------|     |----|      |------|                        |-----

             1     2     3      4        5

1 & 5 are regular threaded pipe, 2 is a left-right threaded bushing,
3 is a left-right threaded nipple, 4 is a tee.  Assemble 1,5,4 & 2, then
thread 3 into both 2 & 4 simultaneously.  It will draw them together, so
make sure it is the proper length, otherwise it can damage something.

If the connection can be made close to the meter (or by replacing an existing 
connection which is to be abandoned), you can avoid the left-right threaded
fittings.

Now, finish the installation by running the line from the tee to the dryer,
and install a shut-off valve.

Pressure test the system (pump it up to 10 psi and let it sit overnight -
it should not have dropped more than a half-pound or so).  If you have a
leak, mix some liquid soap and water, and squirt it onto each joint and
look for bubbles until you find the problem joint.

-Dave Erickson