You tape the joints with yellow Teflon tape then screw them on using two wrenches so as not to twist any fittings. - After switching as on, spray the joints with 'gas detect' or liquid soap to check for leaks.
Either shut the gas off at the meter or install a valve on the pipe. As long as you don't have an open flame somewhere close to the gas line and have everything ready, you can take the current flex line off and install the valve with little gas excaping. Use pipe dope on the threads of the pipe instead of Teflon tape. This lets you cap the pipe with your thumb while you apply the pipe dope. Then just install the valve and tighten, making sure to hold the pipe so that you don't disturb the next joint further down the line.
I assume there is not a shut off on the supply side of the line. If you are used to working with gas, you can do it with the line charged, but it is probably best to shut the gas off at the main. If there is not a shut off valve where the flex line connects, I would put one there now. Then it is just a matter of changing the line. Do not use any pipe dope or tape on a gas connection, at least on the flex line. This is a flare fitting and does not require it. The valve to pipe connection is a plumbing connection and should have dope or tape on the threads.
Install in gas line to shut off gas to building after gas meter, or to isolate an appliance off a gas line.
If you have a 1999-2000 Ford Ranger with a flex-fuel sensor it is located just under the driver side door on the inside of the frame and the fuel line coming from your fuel filter goes right to it. You unplug it then remove the fuel line on both sides of it and re-install the new one.
For the purpose of cleaning behind a stove (great hygiene) one would think a flex pipe would be the thing to have installed. There must be approved flex pipes for use with natural gas in the home. Most travel trailers equipped with propane gas have such flex lines as the rigid line would certainly break over time and rough roads.
The 2014 Ford Flex is a gas-powered vehicle.
The 2009 Ford Flex is a gas-powered vehicle.
The 2010 Ford Flex is a gas-powered vehicle.
The 2013 Ford Flex is a gas-powered vehicle.
The 2012 Ford Flex is a gas-powered vehicle.
The 2011 Ford Flex is a gas-powered vehicle.
From the supply lines to install off your main gas line. If this is not done by a qualified person, you must have it inspected by your local codes.