What are specs for pipe to install between two concrete slabs connecting a generator to a propane tank

Question

I live in the desert outside Palm Desert in a rural flat area (everything is sand). I am adding a generator and a propane tank behind my house (15' from back of house). I am doing my own concrete for both slabs that will hold the generator and the propane tank. I want to prepare and terminate the pipe connecting the slabs (like I show in the picture below).

I know from my generator doc that for a 20' run I need a 3/4' pipe so at least I have that. Can someone help me with anything else I need to so? That is, are their specific corner pipe specs I need? I live in earthquake country so am wondering if the pipe should be something besides copper, or is copper good enough because it bends a little. I was planning on mounting it right through the concrete so the connection is clean.

Any tips are appreciated. I do plan on having a plumber come later when I get the tank and generator (along with the electrician), but I want to have the pad and the pipe ready now.

Answer 1

There are building code rules applicable to gas piping under a slab below or feeding a building, but I suppose if these slabs are just out in the open those wouldn't apply.

It'll be a good idea to run a sleeve (a larger pipe) through the concrete. That'll prevent concrete bonding to the gas line. The ability for the gas line to move is important because the ground and the slab may move over time: subsidence of the backfill around the pipe, heaving or settling of the soil moving the slab due to changes in moisture level or freezing (I know, you said Palm Desert, but just for completeness sake!), etc.

The distance is short enough I'd probably apply a bit of overkill and just run a 2 inch PVC conduit/pipe the whole way. Then fish copper or CSST tube through it. Use long-radius elbows (24 or even 36 inch) to make a nice gentle bend coming out of the ground. You won't find these elbows in a home center; you'll have to go to a supply house like Platt or Graybar or whatever is near you. It's also possible to custom bend the pipe yourself by heating it with a heat gun or torch.

The International Fuel Gas Code (section 404.12 in the 2018 edition) stipulates that outdoor underground piping systems should be a minimum depth of 12 inches, except that a line serving an individual appliance may be at a depth of just 8 inches.

My own personal editorial on that is I'd definitely want to use a casing of some sort if I were burying a gas pipe at such shallow depths!