Plumbing and running natural gas & propane gas lines
How to run natural gas or propane gas lines in your house without blowing anything up
We have all been taught that running a gas line is so dangerous, you should just not bother. Just pay the professionals. This sort of teaching breeds ignorance and in a time of crisis when there's no plumber around, you might be S.O.L.

One thing that I like to remind people is that most people with a normal sense of smell will be able to smell a gas leak way way way before it is going to do any harm (assuming the gas is collecting in a relatively enclosed area). Let me give you an example. When we moved into our house, all of the pilot lights on our old stove had burned out (there are 3 pilot lights). The house had been vacant for a month and there was a distinct smell of gas in the house. Natural gas sort of smells like sulfur or a rotten egg. Keep this in mind when you are working with gas. There will be a slight odor of gas when you crack open a gas line. I lit the pilot light on the stove and that was that. No explosion.

I got a quote from 3 separate local businesses ranging from $400 to $700 to break an existing gas line that ran to the kitchen in order to install a shut off valve. Neither of these exactly fit my budget, so I set out to figure out how to do it myself.

The first thing you want to do is step back and figure out what your task is. For me, because we are planning on remodeling our kitchen, I wanted to install a shut off valve to the gas line going to the kitchen, otherwise when we do the renovations in the kitchen we'd have to shut off gas to entire house! Yes we could have simply unhooked the oven and installed a plug for 99 cents, but a shut off valve is a good safety device to have and there is a good chance we'll have to rearrange the gas plumbing in there anyway.

Think about what you need to do. Where are you running the gas line? Are you going to tap into an existing line or do you already have a "T" to work with? Are you going through walls or ceilings, etc? Try to gather up all of the materials you need before hand. You don't want to be stuck without heat or an oven because you can't find some obscure part. If adding a new line, always install a shut off valve both where you split the existing line AND at the install point of the new appliance. Furthermore, I always recommend adding an additional port for future installations. So for example if you are splitting an existing line into a "T", consider splitting it into an "X" and simply putting a "plug" in the unused portion until you need it. Next time it will turn a 1+ hour job into a 5 minute job.

Gas line to kitchen, meter, "T" fitting, elbow
Pictured above is a 3/4" gas line going to the kitchen. On the far end by the meter it's split by a T, and close to the foreground there is a 90 degree elbow.

1/2" and 3/4" black iron pipes are the most common size. A 1/2" black iron pipe will be a little less than 1" on the outside diameter and a 3/4" black iron pipe will be a little more than 1" on the outside diameter. NOTHING on a 1/2" pipe measures 1/2" so don't be too confused trying to figure out which is which. You can see this page for more detailed dimensions (look under "wrought iron pipe").

One thing to mention now that we are dealing with "black iron pipe", we suggest that you stick to either using black iron or CSST (corrugated stainless steel tubing). There seems to be ongoing discussions about mixing black iron and galvanized with natural gas and the consensus is to stick to black iron. CSST is stainless steel wrapped in orange. This stuff is great. It is very easy to work with and like the name suggests, it is flexible, making it easy to snake through walls and ceilings. It comes in pre-determine lengths. Again, I do not recommend galvanized or any other materials than black pipe or orange flexible gas line.

If you are not dealing with the "end" of a pipeline, remember that because these pipes were put together sequentially, you can't just unscrew the middle pipe (that would be too easy!) because tightening one end will loosen the other end and vice versa! Instead what you will need to do is cut the pipe, then replace what you have cut with a "union" fitting, your shut off valve and correctly sized "nipples." Nipples are pre-cut and pre-threaded pieces of black pipe that come in just about every size.

Cut the gas line herePictured Above is the length of pipe as it goes into the "T". Since our pipe has a "coupling" fitting (shown at arrow), we'll cut on the "X" and save all of the pipe to the left of the coupler. What this means is that to the right of the coupler, where we cut out the pipe, we'll need to replace the exact same length, but in the form of 2 nipples and a union fitting. A union fitting is a special fitting which allows you to tighten 2 sequential pipes which cannot be rotated.

I measured the distance between the coupler and the "T" to be about 16", so I went to the hardware store and purchased a union fitting along with many different sizes of nipples to be sure that I would get it perfectly. This may take some guess work but you want to have several different nipples in half inch increments to be sure you get a very snug fit.

While you are at the hardware store, be sure to pick up Teflon TFE paste and leak detector. Do not settle for TFE paste without Teflon. This is the gooey stuff that will be coated on the threads of the nipples and eliminate any chance of a leak if properly tightened. The leak detector is essentially a solution of soapy water which will bubble up if there are any leaks.

Another thing to think about while you are taking pipes apart is whether or not you will ever need to expand. For me I considered installing a garage heater in the future, so I also installed an additional "T" which I fitted with a shut off valve, followed by a plug.

Now that we are ready to take the system apart, think about a few things. If you are like me, you are about to cut gas out to your oven, stove, water heater and furnace. Are you going to finish this today? Are you sure? Do you have a back up plan? For me, my back up plan was to stick a "plug" in the "T" which would simply plug off the gas line to the oven, allowing me to turn back on my furnace and water heater.

Shut off all appliances that use gas. Turn off the furnace at both the thermostat, and big red switch. If you have a gas clothes dryer, don't run it while you are working on anything.

If you have any shut off valves, turn them all off.
Gas shut off valves
Shut off valves to our furnace and clothes dryer. A shut off valve is "OFF" when the valve petcock (handle) is perpendicular to the valve body. Closing valve will isolate gas between valve and appliance. Some appliances, like furnaces will need the air purged from the line if you remove all the gas in the line. Keeping some gas in the line but isolating it with the shut off valve may avoid this.

Corrugated stainless steel tubing (CSST) is shown in the background. CSST is very easy to work with because it is sold in pre-cut lengths with connectors on both ends. Furthermore, you can unscrew these gas lines at junction points instead of having to cut them like we do with black pipe.

If you have a gas water heater, turn the knob to off.
Turn off gas powered water heater
Turn knob on water heater to off. This turns off the burner if it is going, and also the pilot light.

Once you are sure everything is off, shut off the MAIN SHUT OFF VALVE.

Main shut off valve in on position
Please be careful with the main valve. There is a good chance it hasn't been turned in 50 years. Grab it with locking pliers or plumbers wrench and very slowly, rototate the one hole until it matches up with the other hole. This is so that the power company can put a lock on your gas line when you don't pay your bills. There is no "stop" on this valve, it will rotate around in circles.

Main shut off valve in off position
Put a screwdriver in this hole. It's not going to move by itself but this should suggest to anyone not to mess with it. You may want to put up a sign as well.

What about the oven? Remember we don't have a shut off valve on the oven, so AFTER we turn off the main shut off valve, we will turn on the oven and run it until it dies. The idea by closing the other shut off valves we're isolating gas between the valve and appliances. Since we have no shut off valve on the oven, the idea is to clear out the line of gas.

So now, every appliance that uses gas is off, every shut off valve is off and every appliance that doesn't have a shut off valve has been "expunged"? Let's cut.

For safety's sake, I like to vent all over the house by opening windows when I am doing this. I will do it in the basement near the water heater, kitchen near stove, etc. In this case we were cutting in the garage so I opened up the garage door. If gas leaks out you want it to dissipate.

Secondly, everyone will recommend that you use a manual hacksaw (not electric) because you do not want to produce any sources of ignition when cutting a gas line, be it from the electric motor, or from sparks. To be honest , I used a 9 amp SawZall and yes there are a few sparks. There is not enough gas left in the pipes to do anything. If you are unsure, use a manual saw.

3/4" NPT gas line cut
Above is my pipe cut. I already removed the right side in this picture. Next, I removed the left side of cut pipe that screwed into the "coupler". I put some duct tape on there just to keep any trace amounts of gas where they are; not really necessary.

Here comes the importance of PLUMBERS WRENCHES. You need TWO plumbers wrenches to do this job. Do not try to do it with locking pliers or anything else. Get wrenches that are appropriate to the size of pipe and amount of room you have to move them. Please think about the amount of money you are saving and spend the $10-$15 each on the wrenches. The grasp and amount of leverage you have is very important.

I decided to put the shut off valve closer to the kitchen. It makes sense to put the valve as close to the appliance as possible. In the first picture above, I put it right before the 90 degree elbow.

Nipple and new 3/4" shut off valve

Generously coat the threads of the pipes with teflon TFE paste. Try not to get TFE paste on the inside of the pipe. Screw in the pipe very tightly using 2 plumbers wrenches. You can wipe away excess TFE paste now. The TFE paste will harden.

Union fitting
When installing the union, take the union apart and you will notice it has 3 parts. 2 female fittings and the large union nut. Without re-arranging the parts, slide the huge union nut down the pipe that will receive one of the female fittings to get it out of the way. Attach the female pipe fittings to each of the left and right nipples. Then, place them together. This may and should require very gently moving the pipes a little bit. Slide the the large union nut into place and tighten completely. You do not need TFE paste on that. If you cannot get the 2 female fittings of the union to touch each other, you need to change sizes of your nipples until they are kissing.

Union fitting
On the left is the old coupler. We put a new nipple into that. On the far right (not shown) was the existing "T". We put a short nipple into that, then we attached a new "T" fitting which has a 3rd port which faces the wall for future use.

Now that you think everything is on there well, and your new shut off valve is closed, turn the main valve back on. With your leak detector solution, spray generously everywhere A) that you just installed and B) anything you may have disturbed in the process including old existing connections and watch carefully. If you are wondering what to look for, please check's gas leak detector page.

Remember that natural gas has a pungent odor to it. Smell carefully for this odor and don't confuse the odor of TFE post or iron piping with the smell of gas. It should be very obvious. If you are sure that there is no leak, continue by opening your individual shut off valves and turning the appliances back on one by one. I would suggest opening a valve, then turning on the appliance. Not opening all valves and then turning on all appliances.

Do not forget that some appliances will need special attention. A gas powered water heater with no electrical connection will require you to light the pilot light, as will our old oven. Close all of your windows and monitor your house for smells especially the area where you have added or modified any connections. You may want to pressure test any new connections but please beware that shut off valves are only good to 0.5 PSI and CSST tubing only 5.0 PSI.
Comments script being abused, so reworking it...

On March 13, 2008, 1:44 pm test said:

On March 13, 2008, 1:44 pm Mark said:
Greetings. I found your article very informative. Who knew working with gas pipes could be so easy? ;)