When burying an LP gas line, go I have to take into account the frost line for the depth, or is that just for water pipes?

-- I got gas (large@propane.cylinder), June 24, 1999

Answers

Our frost line (Northern snow belt) several feet, but pipes installed by our propane company at 6 inches, traveling about 10 feet to house. No problems, assuming you use standard stuff.

-- BigDog (BigDog@duffer.com), June 24, 1999.

You should use a COPPER line, buried 12" deep. If you use anything else, you'll have to put it in conduit.

-- Dennis (djolson@pressenter.com), June 24, 1999.

There should never be water (from condensate or as impuritites in the supplied gas) in a LP gas tank.

However, "should never" be can always become "might be" if soemthing goes wrong. Call the LP supply company, get their recommendation, otherwise as mentioned in the other responses. If good (clean) supplies are provided, once the tank is "blown down" the first time to clear the lines, you should be okay.

-- Robert A. Cook, PE (Kennesaw, GA) (cook.r@csaatl.com), June 24, 1999.

Once ground is frozen it does not fall below the 30-32 degree temperature that was required to freeze it. Ergo ice caves, igloos, etc. The temperature of LP gas is substantially lower than this as you may have seen when it comes into contact with an outside surface or skin.

Another curiosity of frost is that is does not travel laterally. We install copper water service lives within inches of the foundation wall in areas that reach -60 degree F without fear of freezing pipes, as long as there are no drafts. The frost line within inches of the outside of the foundation may well reach 15 feet deep with extended exposure to these temperatures.

-- Michael (mikeymac@uswest.net), June 24, 1999.

I'm having a 1000 gallon propane tank installed soon - the supplier told me that the gas line will be installed 6-8 inches below ground. I'm in southern Minnesota where it can get to -25 below zero so apparently the depth of the gas line is not extremely important. YMMV.

Sincerely,

-- Jim Morris (prism@bevcomm.net), June 24, 1999.

Well, don't forget that burying the line that far underground is a simple way to prevent (minimize) physical damage too.

-- Robert A. Cook, PE (Kennesaw, GA) (cook.r@csaatl.com), June 24, 1999.

Oops. Dennis is correct and we did put our line a foot deep, not 6 inches.

-- BigDog (BigDog@duffer.com), June 24, 1999.

Just replaced our 500 gallon tank with a 1,000 gallon tank. Had to move the lines due to construction of a garage. The new line was buried about 6 inches deep. We did place it in pvc pipe where it will run under the driveway. The only other thing was that the company said the propane line needed to be 30 inches away from the electric lines if they cross.

-- lparks (lparks@eurekanet.com), June 24, 1999.

Here in Cascadia, we usually follow these general rules of thumbs(sic)

1. Electric lines 36" deep

2. Natural gas 24" deep

3. Water service 18" deep

4. Phone Service 12" deep

This is done to attempt to standardize the ground cover over various lines, so the next person either repairing the line, or installing a new line can find it without damaging the buried lines. Usually these will intersect at various locations on the property.

Locating devices can oonly give approximate location of an existing line, which is very susceptible to the *hoh-man* factor (:^}

-- Michael (mikeymac@uswest.net), June 24, 1999.

Related (?) question: I need to know how deep to bury certain freezing-sensitive items, such as mayonaisse (which separates and turns ugly if frozen). I am in S Michigan. Any suggestions?

-- alan (foo@bar.com), June 24, 1999.

"Once ground is frozen it does not fall below the 30-32 degree temperature that was required to freeze it."

Not quite. There is a temperature gradient falling from near the ambient air temperature at the surface to the freezing point at the frost line. The frost line may go as deep as 7 feet. Snow cover if present insulates the surface of the soil and can reduce frost penetration.

That's the way it works in Minnesota, anyway.

-- Tom Carey (tomcarey@mindspring.com), June 24, 1999.