Can 1/2" black gas pipe be buried ?

We just bought a home which was built in 1994. There is a 3/4" black gas line which goes about 100' underground to our pole building. We have a modine heater in there. ( Hot-Dawg )model.
Everything works fine. When the gas line comes out of the ground near the pole building the pipe is gray colored with some kind of metal "jacket" around it. I dug down a few feet near it.
It appears to have this "jacket on it the entire run. I know it's metal becasue a magnet will stick to it. What about rust and corrosion ? The line starts from our basement 3/4" black sch 40.
When it enters the pole building it is 1/2". Is this correct for code requirements ? ( Green Bay, WI ) Thanks Tony.

 

Tony: Are you sure it is 3/4" Schedule 40 PVC? Or is it Iron pipe? What you probably see is a plastic coating on the black pipe to retard rusting. Personally I don't think it helps all that much. I would prefer to see coated copper lines in an underground situation. It is more flexible and doesn't rust.

 

Larry, Thanks for the response. It is Black pipe 3/4" running underground out to the pole building. I would think that over time it may rust. My magnet sticks to the pipe at both ends.
Is there such a thing as plastic gas line ? I've seen yellow flexible gas line but I assume it is metal inside. Thanks !!

 

The gas line you see the guys burying beside the road is plastic, but it is impermeable to gas, whereas pvc is not. I, like you, don't like steel underground, but if it ain't broke, don't fix it, and don't bother digging it up if it doesn't leak. The yellow gas line you see is really copper clad in yellow plastic to identify it as gas. It also keeps down on abrasion.

 

You mentioned BLACK iron pipe. This of course is completely unacceptable, and it probably rusted through while you were waiting for a reply to your post!

Then you mentioned GRAY jacket. This sounds like it could be galvanized steel pipe. Galv. used to be approved for underground use, but it will rust through after several years, and most codes do not approve it today.

Someone mentioned copper. This is a very local issue. Any area which has high sulfur content in their gas, the local codes will prohibit the use of any copper on natural gas.

 

Galvanized pipe is never used on natural gas, as the pipe contains galvanization on the inside as well, and can flek off and clog up orifices.

 

Larry
I "used" to believe galvanized could not be used for gas lines until I moved to Florida. It was code where I lived (Ocala). When I first saw it at a McDonalds I couldn't believe it but it tied in to the meter (inlet and outlet).
There are new plastic gas lines that are being installed but you have to take a course and pass a test to be able to install them. They have special fittings and tools. I have never seen black pipe allowed underground.

 

I can't belive this conversation, there are literally hundreds of thousands of miles of "black pipe"' installed underground.

There have been "black iron" pipes (actually steel pipes with the black oxide from the mill) in service underground for close to 100 years with little or no failure.

Certainly there have been steel pipes with no protective coatings that have failed in one way or another with less than ten years in the ground. Most distribution and service gas piping installed today is with special plastic piping but the main transmission piping is still made of steel pipe, albeit with a plastic coating and the welded joints are specially wrapped and sealed against corrosion. Transmission lines also often have "impressed current" systems to retard corrosion.

Even plastic service piping usually transposes to steel piping when/where coming above ground as the steel is far more resistant to damage than is plastic.

 

furd,
I agree that there is steel pipe underground. It has Extrucoat covering and all joints are welded. How many home gaslines do you see that are installed in this manner? Homeowners do not realize that there are codes that go along with the installation of underground gas lines. They also have anode bags to limit corrosion that are attached with a Cad welder.

 

I would have never thought it would have been a code issue to use galvanized for gas. I have seen orifice failures and the culprit turned out to be flecks of galvanization from inside the pipe. Oh, well, learn every day, or stagnate. Thanks for the heads up.

 

Chandler,
Florida had some of the strangest codes in plumbing I ever saw. Plus, they changed from county to county by quite a bit.

 

actually, the pipe you're seeing coming up from the ground, off of the black pipe, is some form of trac pipe. Its a flex gas line with a plastic yellow coating on it specifically designed for gas, so yes, a magnent would stick to it. The other plastic pipe that Larry was talking about is different, thats for huge lines run underground and its not coated with copper on the inside, its pure plastic and put together with "push-type" fittings, not my first choice, but I guess whatever works.

Also, Im not from where you all are, but its not a bad idea to run sched. 40 black underground, and especially if youre going to make the transition from black to omegaflex (or whichever trac pipe it may be).

I hope I helped some of you. =]

 

Old thread, but for FWIW, check with the local AHJ; metallic underground gas pipe is usually required to be buried 12", factory coated, and the joints need to be coated with approved gas pipe paint primer and hand wrapped spirally with approved plastic tape.

 

Aha, these are exactly what I'm looking for.

Do you have any brand names for the gas pipe paint primer and the plastic tape?

Thanks,

- Ted

 

The flexible pipe that you see in these kinds of installations (TracPipe, Gastite, Gasflex, etc.) is a type of CSST (Currogated Stainless Steel Tubing). It is not magnetic since it is stainless steel. Just because you aren't getting a magnet to stick to it does not mean it is non-metallic.