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.