How to Seal ends of gas conduit through slab?

[haygood]

Hi. Nice forum. This stuff is great.

I'm putting a slab for a shed in my backyard up against the house. There is a gas line underground in that area that comes out of the ground and disappears into the brickwork. This is a slab-on-grade home in Texas.

The gas line is really in horrible condition at and below ground, so I'm going to replace it all the way to the meter. Yes, my shoulders are getting sore.

Before I can put a slab over it, I understand that I need to run the new gas line in a conduit. The ends of the conduit need to be "sealed". How do I seal them?
The conduit will terminate with a vertical section right next to the brick wall of the house. This end will be inside my shed, which will use fences on 3 sides, so it won't be a "tight" structure because of the gaps between each picket. Can I terminate the conduit under ground beyond my new slab for the shed, or do I need to run it until the gas pipe comes up at the meter, another 40 or so feet away? How do I seal these ends?

Any other suggestions are welcome.

Also, I'm not certain, but I think the meter is galvanized, but I've got black pipe in the house. Which should I use and are there any considerations for where I join black pipe to galvanized? (galvanic corrosion in general, I get, but how to prevent it in this case?)

Thanks!

[HayZee518]

black pipe and galvanized are almost the same - the base material is iron or steel. electrically in active. dissimilar metals are active - zinc/copper, brass/copper etc. when running a gas pipe through concrete it must be sleeved. lazypup has all the answers for gas pipe etc. the sleeving can be sealed with expanding foam. [urethane]

[LazyPup]

Dielectric couplings are only required when joining copper to ferric iron pipe. You may directly connect black iron pipe to galvanized iron pipe.

To make the sleeve you should install sched.40 PVC or ABS pipe that is at least two nominal trade sizes larger than the desired pipe.

On the exterior end of the pipe and within 3' of the slab you install a vent opening.

To make the vent you install a Tee with a riser going up above grade. On the top of the riser you may use a 1/2bend (180 deg elbow) or two 1/4 bends back to back as illustrated in the attached drawing. The open end of the vent MUST point downward and it must be a minimum of 4" above finished grade or in regions subject to snowfall it must be a minimum of 4" above the height of the average snowfall.

From the tee on the end you should install a short section of pipe to insure that when you put the foam it it will not go into the tee and restrict vent flow.

The exterior end of the pipe and all interior openings MUST be sealed.