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How to Connect Gas Pipe Lines

Use the correct fittings for a safe hook-up

FH09OCT_CONGAS_01-2 gas pipe, flexible gas line, gas line, gas dryer hookupFamily Handyman
Make gas line connections from steel or copper pipes to ranges and clothes dryers safe and secure by using the proper fittings and connections. We show you how.

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How to Connect Gas Pipe Lines: Overview and materials

Gas connections for your oven or dryer are really pretty simple—it’s mostly a matter of screwing stuff together. But knowing which fittings to use where can be tricky, and using the wrong ones can lead to a dangerous leak. This article will show you how to safely connect a gas dryer hookup or gas range.

Kits containing a flexible stainless steel gas line and fittings are available at home centers and hardware stores. The kits usually have everything you’ll need, but in some cases, you may have to buy a few more fittings. But before you start, check with your local building inspections department to see if you’re allowed to do your own gas dryer hookup.

We’ll show you three common gas piping scenarios. We’ll show you one way to make each connection, but there are other equally legitimate ways using common plumbing parts. Don’t be confused by the labels FIP and MIP; they simply stand for female pipe threads and male pipe threads, respectively. And when you buy the parts, don’t hesitate to ask for help. Then screw all the gas line parts together to make sure they fit.

Situation 1: Make connections to steel gas pipe

Older houses often have threaded steel gas pipe. If your old appliance is connected with a steel gas pipe and you’re installing a new appliance, buy a gas appliance connecting kit and replace the steel gas pipe with the flexible gas supply lines stainless steel tube. But remember, you can’t connect the flare fitting on the flexible gas line supply directly to a steel pipe thread. You have to install the flare fitting that’s included with the kit.

Also replace old-style gas valves (photo below) with modern ball valves that are labeled for use with gas. Before you replace an old valve, you’ll have to find and turn off the main gas valve to the house. It’s usually located near where the gas line enters the house. When you turn the gas back on, remember to check all your gas appliances to see if they have pilot lights that need relighting.

The photo shows how to use common plumbing parts to join a new ball valve and a flexible stainless steel connector to steel pipe. Coat all threaded pipe connections with pipe thread compound before assembly. The valve shown has 1/2-in. female gas pipe threads on both sides. If necessary, use a bushing to reduce the existing 3/4-in. female pipe thread to 1/2 in. Use a 90-degree elbow at the stove to avoid kinking the gas tubing when you push the stove against the wall.

Proper Connections to Steel Pipe

Use the fittings shown for safe connections.

Old-Style Gas Valve

Old-style gas valves can leak. Replace them with approved ball valves.

Situation 2: Connections to soft copper

Connections for flexible “soft” copper are made by flaring the end of the soft copper tubing with a special flaring tool and installing flare fittings that have a matching cone-shaped meeting surface. Common sizes of flare fittings are 3/8 in., 1/2 in., and 5/8 in. Match flare fittings to the outside diameter of the soft copper you’re connecting to.

The photo below shows a soft copper line that’s kinked and should be replaced. There are two options. You could cut a new length of coiled soft copper, flare the ends and connect it with flare fitting. Or you could replace the damaged tubing with a flexible stainless connector as shown here. If the flare fitting on the flexible stainless gas line matches the size of the flare fitting on the existing gas valve, you can simply screw it on. If the fittings don’t match, one solution is to replace the valve with one that has a flare fitting on one side and a 1/2-in. female pipe thread on the other side. Then use the adapter included with your hookup kit to connect the flexible gas line. On the stove end, use another flare-to-pipe-thread fitting.

Remember to apply pipe thread compound or gas-rated Teflon tape to the threads on threaded connections before assembling them. Flare joints rely on a tight fit to seal and don’t require additional sealant.

Proper Connections to Soft Copper

Use the fittings shown for safe connections.

Kinked Copper Gas Line

Don’t try to straighten kinked copper. Replace it instead.

Reuse a soft copper coil

Pipe thread compound

Coat fittings threads with compound to help prevent leaks.

It’s common for appliances to be connected with a coil of soft copper like the one shown here. The ends of the copper tubing will be flared like the end of a trumpet. A leak-proof joint is formed by the perfect fit between the flared end of the tube and the cone-shaped fitting. If the soft copper tubing isn’t kinked or damaged, you can reuse it to connect your new appliance. For this dryer connection we purchased a brass elbow with a 1/2-in. flare fitting on one side to match the 1/2-in. flare on the copper tubing, and a 3/8-in. female iron thread fitting on the other to match the 3/8-in. pipe exiting the back of the dryer. Your tubing may be a different size and your appliance may have different threads. Buy fittings to match. Coat threads with pipe thread compound or gas-rated Teflon tape before assembling. Align the copper tubing so the flare fits perfectly before threading on the flare nut. Tighten the nut with an adjustable or open-end wrench.

Fittings for Reusing a Soft Copper Coil

Use the fittings shown to reconnect a coil of soft copper.

Test for Leaks

Turn the gas back on and swab each joint with a solution of 2 tsp. dishwashing liquid to 1 cup water or with a commercially prepared leak testing solution. Coat each connection and watch for bubbles to form. If you see a bubble, turn off the gas. First try tightening the leaky connection. If this doesn’t work, take it apart. Inspect flare connections for debris or damage. Fix leaky threaded connections by reapplying pipe joint compound or gas-rated Teflon tape and reassembling the fitting.

Required Tools for this Gas Pipe Project

Have the necessary tools for this DIY gas line project lined up before you start—you’ll save time and frustration.

  • Adjustable wrench
  • Pipe wrench
You may also need a flaring tool.

Required Materials for this Gas Pipe Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Fittings
  • Pipe joint compound