My maintenance schedule gets me to replacing two damaged gas lines. I air soap tested the existing lines and about every joint was leaking so I decided to replace everything from the original 5/8" feeder back.
I wanted to test with a gas test gage but I couldn't lay my hands on one on a Sunday, so I picked up a valve stem with 1/8" threads at the auto parts store, a 1/4" brass "T", a reducer, a 60lb gage, and a 1/4" nipple. I attached the gage to the gas line and soap tested the gage set up. Now I'm pressure testing at 25 lbs.
I loaded the line with shop air reduced to 25 pounds.