Can anyone recommend a plumber who works on natural gas lines?
 

I've been told that there is a device that can be installed on the incoming natural gas line that will interrupt the flow of gas should there be a sudden demand for gas, as when the gas line in the attic, the thickness of a soda can, ruptures, no matter what the cause (say, a lightning strike). Thank you.

I am a plumbing contractor we do natural gas. I have never heard of this HOWEVER nobody knows it all call your local gas company..

OR, has anyone actually replaced the gas lines the thickness of a soda can in the attic and through the walls to the appliances with "real" black pipe to carry the gas from source to point of use within the house. Thank you.

If soda cans were made of stainless steel.I did a lot of commercial gas piping.They make a solenoid that is activated by smoke alarms.Shuts off gas totaly when detector is activated.Detector in attic solenoid on gas main at meter.

Such a device does exist for fuel oil (OSV) but I've never heard of such a device for natural gas although a solenoid could be used triggered by any number of alarm devices.

A Google search using the phrase "emergency gas shut off valve" gives lots of results. This might be a place to start getting information. I would also suspect there would be a permit requirement, so a call to the county building department might be in order. The local gas company probably also has this information, and may have some specific requirements also.
Hope this helps.

And you will want to use a licensed gas fitter as opposed to a "plumber that works on gas lines".

In Florida any licensed plumber can install.The valves are from Maxon and I have installed them on commercial waters heaters in schools. You would need a electrician to wire them.