Yes, Trac Pipe is available for UG installations. It's called Trac
Pipe PS, for "pre-sleeved." Comes in 100 foot lengths, and has
venting capacity so you can use it under a slab, etc. This stuff is
new, I guess. The HVAC supplier I got my Trac cert at doesn't carry
it yet, and there was no mention of it in the training, that was 3-4
years ago. I also don't know if it's approved locally yet, L.A. isn't
always the fastest to okay new stuff.
By the way, Trac Pipe uses a self-flaring connection, not compression.
Comprfession fittings are pretty much universally banned for fuel gas
of any kind.
I wanted to explore the PE option cost-wise. I already knew about the
sweep risers, and that I wouldn't have to do fuse joints. If it costs
signifcantly more than coated steel, then I'll go with the steel, and
save 6 inches of digging. I don't have access to a ditch witch, and
my back yard is REALLY tough to dig in.