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.

[Mustangous]

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.

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

I know this post is old, but I figured i'd just reply to this because the pic and great explanation is already here.

I just have a quick question, I am running a new 1-1/2 gas line from my house to a pole building before I pour the floor. The pole building is facing perpendicular to the house. I am running the PE pipe from the house, across my yard, under the garage and coming up the back of the building on the exterior (125').

So my question is, since i am not coming up into the inside of the building, do i have to seal both ends of the sleeve and have a vent as per that drawing? Or do i have to do the same as the drawing?

Thanks guys for your time, great website!
Troy

[HayZee518]

what's a PE pipe?
do you really need an 1 1/2 inch gas pipe? You must have one heck of a heater!
Is your house feed 1 1/2"?

[Mustangous]

what's a PE pipe?
do you really need an 1 1/2 inch gas pipe? You must have one heck of a heater!
Is your house feed 1 1/2"?

pe is polyethelyne gas pipe. its almost like a pex for gas.

Sorry, There will also be a 120k btu furnace for the building. Building is 34x60. I was originally going to run an 1-1/4 gas line till i saw the btu ratings of the tankless instant hot water heats. Smallest one is 180K btu's.

As for the size of the pipe, I think its because of the length of the pipe is what dictates the size.There are online calculators I used for my btu's being used. Someone correct me if im wrong, but I think that its because natural gas is very low pressure. maybe the pipe acts like a tank? I only have 3/4 coming out of my meter, but I have 1-1/4 running to my 150K btu water heater for my radiant floor heat and was required by my building inspector.

btw, My inspector isnt really answering my above question. He says he can design it for me... lol So thats why I am searching the web.

[pushkins]

Technically yes, the reason here is that even though your not entering the building the pipe used as a sleeve must be able to vent WITHOUT filling with water from rain or dirt etc.... hence the 180 degree elbow.
When you just come up out of the ground and transition to only PE as it bends 90 degrees and enters the building the only option to seal the pipe is spray foam (fire stop can also be used) this blocks any gasses, moisture etc....from exiting the conduit, therefor the need for a vent in the line.

Of course your building inspector does have the last say on this BUT he/she cannot fault or fail you for installing as per code (like Lazypups diagram)

[Mustangous]

Technically yes, the reason here is that even though your not entering the building the pipe used as a sleeve must be able to vent WITHOUT filling with water from rain or dirt etc.... hence the 180 degree elbow.
When you just come up out of the ground and transition to only PE as it bends 90 degrees and enters the building the only option to seal the pipe is spray foam (fire stop can also be used) this blocks any gasses, moisture etc....from exiting the conduit, therefor the need for a vent in the line.

Of course your building inspector does have the last say on this BUT he/she cannot fault or fail you for installing as per code (like Lazypups diagram)

Great, thanks for the response. This helps me out a lot! Its nice feeling confident about what your gonna do is right.. lol Don't want to do things twice and pay for extra material if i don't have too..

Thanks again!