Is it code that copper tubing used for LP gas must be protected with an outer sleeve?
When my LP gas logs were installed, the person delivering and installing the gas tank ran a flexible copper tube from the tank, underground for five feet then up into the foundation wall. A yellow plastic sleeve was only installed over the tubing at the two points where the copper tubing went underground. At least four feet of tubing has no plastic sleeve.
Was this a lazy attempt to fool anyone looking at the installation into thinking the yellow plastic sleeve was protecting ALL the copper tubing which is underground?
What the installer has done is legal, the pipes you see are sleeves that are required in the code, the piping itself does not need a coating.
As long as he used the proper type of copper, everything should be fine. If this person delivers and hooks up tanks for a living, it is not likely they would install a system that could come back and bite them.