Is it safe or in code to use the yellow flex gas line for underground gas routing. I am running the gas line about 50 feet to a firepit from my pool heater. Thx.

CSST can be used but requires special fitting for under ground. Flexible Corrugated Gas Piping from Gastite: Underground Gas Piping Products and Accessories

Thanks Ballengerb1. I am having this work done by liensed plumber and checking because when the pool was installed 10 yrs ago, they used gas gavalzied pipeing. Do you think I should be concerned?

So the pipe to the pool is 10 years old, ask the plumber to evaluate it. Galvanized isn't forever, especially under ground but don't lose any sleep.

My area does not allow csst underground. Are you talking about csst, or yellow plastic gas pipe? If the plastic is what they are using, then its fine,, I would suggest checking local codes before allowing them to use corrogated flex underground.

Galvenized should have never been used for gas piping(although some codes still accept it.) Black iron was the standard up until the csst came out. But neither galv or black iron should be buried, unless sleeved or wrapped, as it will rot out.