Underground gas line help?

[varmint]

What should have been a simple job got complicated yesterday: we finally got around to buying our own 120 gal. propane tank, and after they switched out the old rental tank, a pressure test showed an underground leak somewhere between from where the 1/2" copper line went into the ground and where it came out 120' latter, to a regulator set at the side of the house. the tank sits at the back of a shop building, where a second regulator supplies a propane direct vent heater. Having the tank there, and not at the house, works out better in many ways. The line was buried about 3' deep in a 16" wide trench with an electrical conduit and plastic water line about 10 years ago. Since the leak only showed up under a high pressure test, and I never suspected a leak otherwise, and we couldn't find it using a gas detector wand, looks like I will need to retrench and bury a new line next to the old one. Far enough away that I don't hit anything, of course. I am thinking I should pull it thru 2" PVC conduit? I have never trenched anything, and going across a well-established gravel drive concerns me- will a rental trencher handle that? The gas guys said to bury it 18" deep. A little research says that any concealed joint should be brazed- and since coils of type L copper come 60', I will need one joint. The original joint was a flare fitting, I recall, but its hard to imagine that coming open... still?
Comments/advice are welcome!

 

[tulenutn2o]

What should have been a simple job got complicated yesterday: we finally got around to buying our own 120 gal. propane tank, and after they switched out the old rental tank, a pressure test showed an underground leak somewhere between from where the 1/2" copper line went into the ground and where it came out 120' latter, to a regulator set at the side of the house. the tank sits at the back of a shop building, where a second regulator supplies a propane direct vent heater. Having the tank there, and not at the house, works out better in many ways. The line was buried about 3' deep in a 16" wide trench with an electrical conduit and plastic water line about 10 years ago. Since the leak only showed up under a high pressure test, and I never suspected a leak otherwise, and we couldn't find it using a gas detector wand, looks like I will need to retrench and bury a new line next to the old one. Far enough away that I don't hit anything, of course. I am thinking I should pull it thru 2" PVC conduit? I have never trenched anything, and going across a well-established gravel drive concerns me- will a rental trencher handle that? The gas guys said to bury it 18" deep. A little research says that any concealed joint should be brazed- and since coils of type L copper come 60', I will need one joint. The original joint was a flare fitting, I recall, but its hard to imagine that coming open... still?
Comments/advice are welcome!

My advice would be to have a propane service company come out and do it. Couple hundred bucks here. Figure the trencher, etc. and having it done becomes a deal. I ran mine in plastic at 30 cents a foot versus $1 plus. The trencher will chew right through that drive.No joints with the plastic either.

 

[MacLawn]

I ran mine in plastic at 30 cents a foot versus $1 plus. The trencher will chew right through that drive.No joints with the plastic either.

You used plastic for a gas line? Never heard of that...

 

[Egon]

Plastic gas line with the proper ends pre attached should work. Just ensure the pipe is good for your pressure.:thumbsup:

You used plastic for a gas line? Never heard of that...

Very common for lower pressure lines. It's what is usually used when the distribution lines are ploughed in with a Dozer.

 

[sweettractors]

The propane companies in this area, put the copper line about 3-4 inches under the ground. I am talking from the tank to the house. They do this manually with a grubbing hoe. Ken Sweet

 

[rjkobbeman]

You used plastic for a gas line? Never heard of that...

My natural gas line is run in plastic from the "main" at the street to my house. The run is like 1000'. The plastic line is approximately 1". The coupling from the plastic line to the galvanized pipe is underground... just under my meter. The galvanized section goes from the plastic to the meter. From there it is all standard stuff. I think the natural gas pressure is around 35psi in the plastic... before the regulator.

Hurricane Ike came through my area (southern IL) two days before the gas line trench was covered up. (Obviously not a hurricane when it got to us... but dump many inches of rain in a couple of hours.) It was all uprooted and the line was floating! Kind of freaked me out... but they came back and covered it back up. All has been well ever since.

 

[crazyal]

Around here the Natural gas guys just dig holes at each end and push the new line throuh the dirt. Takes them no time what so ever to do.

 

[rjkobbeman]

Around here the Natural gas guys just dig holes at each end and push the new line throuh the dirt. Takes them no time what so ever to do.

I think it comes down to cost and who is paying for it. I had to pay for mine and horizontal boring was expensive. Took them about an hour to dig a trench.

Here we are two years later and you can't tell where the trench was.

 

[bigtiller]

I would do a low pressure test and leave the gauges on for 20 minutes or more. Sometimes small things get moved around a bit with high pressure. By low pressure I mean 10 pounds because that is the working load of the line from the tank to the house. If you have the connections, I would even check it with 11 inches of pressure. You said you had no reason to suspect a leak before so I am thinking the high pressure test may have had a false positive.

 

[gauthier]

If you are going to have any connections[what ever form they maybe] tween tank and house,,before you cover it up,,you need to pressure it up with the propane[you could make a fitting and put on one end and check with air too],, take a coffee cup or something,mix some dishwashing liquid in it with water,,stir good,smear bubbles on fittings,or what ever,with a small paint brush.If there is a leak,you'll see it.

 

[scottie]

get the guy with the license and liability ins to do it. much cheaper in the long run.been doing this for years, and wouldnt trust an unlicensed install. Scottie

 

[tulenutn2o]

As long as you leak check and are ok with your work. I say don't get taken just because a guy has a license(tax stamp). Just a revenue generator. It is not rocket science ,nor is it hard to do. Just be more careful since it is combustible gas. Trench, put your line together and leak check before putting it under, cover it up and be done.

 

[AHNC]

I'm going to be doing the same with new water, power and gas services to my house in a common trench. If you run this line in copper, I would suggest that you use the coated copper. It is still flexible and the protective coating is good. The poly pipe is commonly used for underground gas nationwide. Flare connections, when properly done, are excellent, but you have to have a good flaring tool, deburr the pipe and make a good flare. As a rep in the gas, P/H, HVAC business it is the biggest installation error I see.

Whether you do this yourself, and it isn't rocket science, or have a contractor do it I would suggest that you install CO detectors and if you have a basement , a combustible gas detector. I'm in the gas business, very comfortable with it, and would not have a home without them. Cheap insurance.

Given the issues you've all ready had, and the proximity of the other piping, I'd have a properly equipped contractor or the gas company come in and knock this thing out.

 

[varmint]

When I had put this stuff in about 10 years ago, I was too cheap to put it in a conduit, or casing, and looks like it bit me. I will have to have one joint in the middle (120' of tube, and it comes in 60' coils) so I plan on silver soldering a coupling. I am going to pull it thru a 2" PVC schedule 40 conduit. I checked on the coated tube, but it will cost more than twice what I can get the regular type L tube for. I sort of know what happened- we had a serious road compactor go back and forth over the gravel drive, which was nice for the drive, but probably bad for the copper in the ground. If I had just buried it in sand....

When they pressure tested the old line, it started at 120 psi but went down fast. I watched them do it several times, trying to isolate the section of tube that was bad. Couldn't find the leak. I need to have one 90 degree bend in the trench, so I am planning on using two 45's to make the pull easier.
I will get a price from the gas company guy, but I think I know where that will take me.

 

[Egon]

Please remember that pulling a copper pipe through a conduit will create a nice spot for propane to accumulate if there is a leak.

 

[johnk]

If it doesn't leak at low pressure and leaks when more pressure is added I'd have to say it is leaking at a fitting. If it is solid underground I'd use a leakk detector solution or a soapy water mix at all your fittings including the gauges hooked up for the test. On plastic gas lines the ends are called pre-bent risers with a pigtail of plastic on one end with a stab joint similar to chinese fingers and on the other end above ground is redular pipe thread to connect to. A regular service line is tested at 100 PSI for 10 minutes. They usually have a max of 32#'s gas pressure on a mediun pressure main. Also if you run plastic any distance underground you should lay a tracer wire 10 ga or so in the ditch with the plastic so it can be picked up with equipment so you know where the plastic is. It should be attached to the metak end by your tank and th the end above ground where it comes out to your equipment. Hope this helps.

 

[Qapla]

Around here the plastic line they use for GAS is yellow. Make sure however you do it, you check your local code. It is always best to follow the code if it is done by you our a company (yes, some companies don't follow code).

One thing to keep in mind ... if you do use plastic, bury a wire along the run of the pipe. This is done as a way to locate the pipe in the future. The locator signal is sent down the wire. This is required here when gas line is buried. The wire does not have to be connected to anything on either end when you burry it, just make it's long enough that you don't have to dig it up to find it.

 

[rjkobbeman]

Please remember that pulling a copper pipe through a conduit will create a nice spot for propane to accumulate if there is a leak.

Yup. I ran big conduit through a BIG creek at my place for the power. Saved me lots of coin. While I was trenching (with a big track hoe), I asked if I could put a second conduit in the trench for the gas line. Their answer was 'no', for the very reason you state.

Gas was a lot cheaper to run... so it probably wouldn't have saved me much anyway.

 

[MacLawn]

Yup. I ran big conduit through a BIG creek at my place for the power. Saved me lots of coin. While I was trenching (with a big track hoe), I asked if I could put a second conduit in the trench for the gas line. Their answer was 'no', for the very reason you state.

That is very interesting! I like using conduit, but would probably not have thought of the potential gas accumulation issue - man, that could be dangerous! Now, I know to avoid conduit when I run a gas line...

 

[LBrown59]

You used plastic for a gas line? Never heard of that...

I've had plastic since 66.
Never had a line rust out since.