The code for buried lines is different, so you can't just use
above-ground products. Where I live, poly flex pipe is typically used in
a trench 24" deep with a copper tracer wire attached so it can be
located later on. An alternative (if code allows) is the coated iron
pipe, or tin lined copper tubing. These are metal, so no tracer wire is
needed, but they can have corrosion problems in certain soils.

Plumbing supply houses should have the pipe and fittings and some won't
even balk at a DIY if you don't seem too dumb. But be aware that the gas
company might cut you off if they find any hack work attaching your line
to their meter.

Since you mentioned a foundry furnace, please consider the capacity of
your existing meter before you add on any more appliances. Look at the
tag on the front of the meter and it will list the cu.ft./hour rating.
Multiply that by 1000, and that's about how many BTU you can get through
the regulator in the meter. If the meter maxes out at 175000 BTU, and
your house needs 100K BTU for the water heater and furnace, you aren't
going to have any pressure to run a million BTU foundry furnace in the
garage.

My advice is for you to dig the ditch and hire a licensed heating
contractor to size and lay the gas line. That will save you some money
and it will keep the gas company happy.


wrote:
I'm toying with the idea of running a buried natural gas line out to
the garage for a hot air furnace as well as my foundry furnace (now
propane)

I'de have to cover about 25 feet from the basement to the detached
garage.

What are my options for piping? I recall hearing about a direct burial
stainless product, but cant seem to find any info on it for a DIY
installation.

I relaize cast iron is not suitable for direct burial, but is is OK
within a counduit of some sort?

I'de prefer something flexible for easy of installation, but will
gladly make do with whatever works best.

Vin