Home Forums Hunting & Shooting Hunter's Campfire Question for the Propane people

A few days ago I hit the pipe with the lawn mower, that leads from my tank to the house, where it comes out of the ground. Just bent it a little, and no leak there. Copper pipe, and want to check that there is not a leak under the house from the movement of the hit. There is a tee where I can install a gauge and a place to pump air, and hold pressure. Question is, how much pressure, and how long do you leave in place to be sure that there is no leak? Assuming that pressure is OK and it does not need a vacuum. miles

I’m no propane expert, but propane is already under pressure. Get a spray bottle with soapy water and spray it on any questionable areas. It will tell you if you have a leak… oh, and no smoking.

The propane guys disconnect the line at the tank, then use the gauge there to see if it holds pressure to, and throughout your house.

I'd ask the propane company to check it.

I am wanting to check the parts of the line, under the house without crawling around under there. Outside is fine, but I will have the damaged part replaced, although it is not leaking there now. miles

I live a long way from the propane company, and would rather have it fixed before calling them out. I have a neighbor (air conditioning man) that will repair the line, I just want to check for any leaks under the house, before and after the repair. Repair is outside the house. Where the line comes out of the ground, and before it goes under the house, there is a tee, with one side plugged. Easy to take out the plug, and put in a gauge and a place to put in air. Leave for a period, to see if it holds. Just need to know pressure and how long to leave it. miles

With a new installation minimal pressure is required for leak test, I normally let it go overnight, 10 to 15 PSI.

The pipe can withstand substantial PSI but your regulator and propane devices most often can not.

If you can isolate both ends of the pipe, blast away, the pipe can take it.

Remember, there will be a small amount of pressure drop, if you leave the test pressure on overnight, due to the temp. drop.

For instance, we use to test pipelines at 300 psi for 24 hrs. They allowed somewhere around 5% pressure drop for the change in temp.

I'd put 10-15 psi on it and let it stand for an hour or so. If it hasn't dropped by then, it's ok. When I replaced the gas pipes in my house, the gas company only tested for 15 min.

^^^This. The regulator on the tank is either a single stage set at 5# and another one on the house set at 11"WC or there is a two stage on the tank with a larger line that is at 11". Either way it won't take much air to damage the regulator.

Thanks Randy. miles

I know a guy, now retired, who did HVAC all his life. He always checked for leaks with a lighter. He never had a problem until he did. Explosion knocked him out, burns…. When he came to his first words were, “I’ve been doing this schitt too long.” This was the same guy who assured me there’d be no problem plugging my tig welder into 3 phase when his sister needed some stainless equipment welded in her restaurant kitchen. It looked a little spooky with the automotive jumper cables running from the service box, but it worked.

As stated the propane company have the proper gauge to tell if you have a leak anywhere in your system from the tank. If their instrument indicates a leak then (and only then) you will have to find it. That will keep you from looking for a leak that may not be there. They can detect a very minor leak.

All the propane I've gotten has been odorized. If it's leaking, particularly in an enclosed space, you should be able to smell it.

Cal-blue is a very good brand of leak detector spray for very small leaks that you can encounter on low pressure systems such as natural gas or propane

I am old, have a bad back, one knee replaced which makes it hell to try to crawl around looking or smelling for a leak under the house, when a simple (to me) pressure check should eliminate all of that. miles

I can't remember the psi but when I built the addition on my house I know that it held within ONE pound for over 48 hours before the inspector looked at it.... I think it was only 15-20 psi. I was concerned because I did all of the work from the tank to the house (about 100' of 1" pipe). The inspector said a pound or 2 was normal with temp swings???

This is true but the odor (mercaptan) is only perceptible to the human nose in small quantities (parts per million). In a case where there is a high amount of gas present, the smell may not be detected by a nose. This is why an open flame is no good for leak detection. Also, a small enough leak will not ignite with an open flame, but it sure enough will give a detectable odor. An electronic gas sniffer (detector) is safe and invaluable tool for this work, but it will detect leaks that are nearly impossible to fix such as from gaskets or porous castings on gas valves. But if there is a leak that needs fixing, it will go there like a Bloodhound on the trail of a subversive.
When using air to test, all appliances must be valved off and preferably disconnected, because some will sustain damage when subjected to abnormally high pressure. The working pressure for propane appliances is a mouse fart compared to 5-10 lbs psi. Also remember LP is heavier than air and will accumulate in low places presenting an explosion hazard.

Disconnect from your tank. Purge your lines with air. So you don't cause an explosion. cap your lines at your appliances and air up your line and trap the pressure with a gauge in line so you can monitor for leaks. If you have a leak it will bleed off of course. While it is pressurized you can spray the connections you can easily access with a spray bottle with water and dishwashing liquid. Leaks will form easy to recognize bubbles.
If it leaks and you can't find the leak put a little of your soapy water in the.line and air it up again the leak will be where the bubble bath foam is.
You can blow the soap and water out of the lines with air.

This.

OK, I will try to make this as simple as possible. There are two different types of propane systems feeding a house from a propane tank. In early use of propane the regulator on the propane tank would take the tank pressure lbs to 9" to 11" water column on the outlet of the regulator.
In the mid 90's we started converting to a 2 stage system, That means a high pressure regulator (10 lbs outlet pressure) on the tank and a low pressure regulator (11" wc) mounted on the gas line right before it enters the home.

From your description it sounds like you have a single regulator at your tank because of your copper line description. Most of the newer 2 stage systems use poly pipe systems. If you have access to a water column gauge its a piece of cake to pressure test at the tee you described. Close the valve on your propane tank, close the gas cock valves to each appliance in your home. open the tank valve and pressure up your gas line, then close the propane tank valve. If you have any leaks in your line it will show real quick. If you have a 2 stage system then you can use a lbs gauge.