I'm building an outdoor BBQ island with a natural gas grill and side burners. My building inspector and I came up with a plan. I'm going to rough in the gas line and pressure test it and then I'll have a plumber tie it into the gas meter. But, part of the conversation didn't sit right with me. I asked him if I should just run the yellow HDPE gas line underground with a collar around it where it comes out of the concrete or if I should sleeve the whole run in PVC with the end by the house sealed so any leaking gas would escape at the BBQ island (I live in earthquake country and this is what was done when we remodeled our indoor kitchen).
He told me that both are acceptable and that it's up to me. I pushed him to give me his take on pain-in-the-butt vs. safety, but he wouldn't budge. He just told me that I could do this job either way.
Now, this is my house and I want it to be safe, but I don't like overdoing things for no real reason or that make a job more difficult (running the poly pipe through the PVC). I read that you can't smell a gas leak that comes up through the ground since the smell is absorbed by soil so the PVC sleeve system would run the gas away from my house, but is this worth the extra money and effort?
Best Answer
HDPE plastic gas tube is direct buried in soil all the time. If it emerges from the ground through concrete, a sleeve is required so that the concrete and the tube can move independently. I think that rather than having the HDPE emerge from the ground, though, you'd want to transition from HDPE to a steel riser in-ground so that the part emerging through the concrete is steel rather than HDPE tube. Still, put a sleeve around it.
If I remember correctly, gas piping of any kind that runs underground below a building is required to be sleeved end-to-end (and I think both ends of the sleeve are required to vent to an above-ground location?). This is so that if a leak occurs in the portion under the building the gas would be carried to a safe location for venting, rather than accumulating inside the building.
It's true that there have been incidents in which an underground leak went undetected because the soil filtered out the mercaptan odorant. (Surely there are also cases of underground leaks that were detected by the smell, though.) Apparently it happens infrequently enough that gas utilities and building codes have not seen fit to require sleeving of everything.
By the way: IPS is not a type of tubing. It's a dimensional standard for tubing (iron pipe size). The alternative to IPS is CTS (copper tube size). HDPE tube is often offered in both flavors, especially for the 1/2" to 1" sizes.