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**LazyPup** · 07-06-2005, 06:15 AM

Disconecting the line should be very easy, however there are some safety issues that must be considered.

The primary concern is what to do about the residual gas that is in the line after the zone or main gas valve is turned off.

Begin by visually inspecting the line under the house. You will note a vertical drop from the valve you intend to remove which passes through the floor and drops down to a horizontal line that goes back to the main line it feeds from. At the point where the vertical drop meets the horizontal line you should find a TEE with the side opening attached to the horizontal line. There should also be a short stub of pipe extending downward from the TEE about 3" to 4" with a cap on the bottom end. That is the drip stubb, which is required at all points where a horizontal gas line turns upward or where a vertical drop makes a 90 deg change of direction to a horizontal line.

Now follow the horizontal line back to where it connects to the house main. Hopefully you will find a line stop or zone valve on that line. If you do not find a zone valve you will have to shut the gas off at the house Main Gas shutoff valve, which is located immediately adjacent to the gas meter or at the point where the gas line enters the structure.

The primary safety issue is what to do about the residual gas that is in the line after the line is shut off. Fortunately residential natural gas line pressure if very low, typically about 4 ounces or 1/4psi so there is not a large volume of gas in the pipe.

If there happens to be another gas appliance (Kitchen stove, gas log, water heater,gas laundry dryer, gas furnace, etc) connected to the line you intend to turn off, begin by turning that appliance ON before shutting the valve off. (If the appliance is a water heater you can run hot water until you hear the burner come on.) Once the gas valve is turned off, the appliance burner will continue to safely burn off the residual until the internal line pressure is negligible. It should only take 2 to 5 minutes to burn off the residual. You should be able to visually see the gas flame extinguish to confirm the residual gas in the line has burned off.

In a worst case scenario where there is no appliance on the line, you could open the valve and allow the residual to bleed off. If so, be sure to have the windows open for vnetilation and DO NOT run an electric fan to blow it out. Some small motors such as used on fans have electrical contact brushes and can produce sparks while running. The actual amount of gas present in the line if quite small so there should be no real fire hazard, of course common sense comes into play here. Smoking a cigarette while disconnecting gas lines is not advisable, although i have seen it done many times. If you house is constructed over an open crawlspace that has good cross ventilation, you may want to disregard opening the valve in the house and proceed to removing the pipe in the crawl space. That would vent the residual to the crawlspace where it can naturally dissipate to atmosphere.

In your post you stated you have Galvanized Iron Pipe. Be very careful here. While the International Residential Code and the Uniform Plumbing Code do list Galvanized Iron Pipe as suitable for Gas, in most areas Black Iron Pipe is the preferred material. (Most local codes only allow Black Iron Pipe, not galvanized.) It is very important that you positively identify which type of pipe you have and be sure to use a cap or plug of the same type of material. (You should never mix Galvanized and Black Iron Pipe or fittings.}

To remove the pipe you will need 2 pipe wrenches. One to hold the line pipe steady as you use the other wrench to unscrew the pipe you intend to remove.

You should be able to go under the house and unscrew the vertical riser that is going up through the floor to the valve you intend to remove. Once you have the riser unscrewed you should be able to push it upwards and pull it out from the floor above.

Once the pipe has been removed, you can install a plug in the top of the TEE fitting.

You will smell gas at this point. That is to be expected, but it should only be residual gas in the line, and there should be no real pressure.

Before installing the plug apply Pipe Dope or 3 wraps of YELLOW PTFE (teflon tape) to the threads of the plug. Yellow PTFE tape is a double density tape that is certified for GAS service. You can find it at most larger home supply stores. (Personally, for permanent gas connections i much prefer to use a PIPE dope that is certified for GAS service.) You can find small tubes of pipe dope in all hardware stores or home supply centers and the pipe dope is normally about 1/2 the price of a roll of Yellow teflon tape.

After you have the plug installed and tigthened thoroughly, you can then turn the gas on again and test the connection with soap bubble. A 50/50 mix of water and liquid dishwashing soap makes a good test solution. pour a bit of the solution on the fitting being tested and watch to see if any large bubbles start to form. If you see it blowing bubbles, you have a leak and need to further tighten the fitting.

I prefer to keep a bottle of childrens bubble blowing solution in my tool box for testing gas fittings. Not only does it make an excellant test solution, but it makes a great stress releiver on rough days. Nothing will get a stressed out crew laughing quicker than seeing the plumber blowing bubbles for a couple minutes.

After you have the gas turned on again, and you have tested the joint, you will then need to check all gas appliances and re-light any standing pilot burners.

**JakeOfAllTrades** · 07-06-2005, 07:58 AM

Wow, now that's a detailed answer!

Thanks for the swift reply. I crawled up under there & got it taken care of.

They're installing the carpet as I type.

Thanks for your swift reply!

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