A neighbor put rubber foam insulation on the exposed length of steel pipe from the meter into the house . Is this a good idea ?
HECK NO ! I just came from the subject neighbors house where I held a flashlight while the gas company man removed the meter and associated pipe because the owners pipe going from the meter into the house was corroded through and leaking (blowing bubbles with soap water) the whole 16" inch exposed length. Apparently it was ordinary 1.5 " diameter steel pipe, approximately 15 years old ( age of the house) and is now covered in thick loose rust. I did not touch the rust as it is not my house. The neighbor is out of town is why I was there. As soon as I got home I looked at my 20 year old uninsulated pipe ; it looks excellent. The gas man was there because the gas had been shut off and a gas company notice tag left on the front door. Contractors working next door noticed gas smell and shut off the meter. After removal of the pipe part of it could be crushed by hand.
No, but it just have to have inside junction made by soldering (and not made with "tightening-type" fittings) or be contained into another pipe closed on the "inside". So an eventual gas leak is routed trough the outer pipe to the ouside, this at under UNI regulations.
So steel pipe is usually not adopted for indoor usage because it needs "outer pipe", copper is used instead for the inside.