Galvanized pipe for natural gas?

[Bill Jobe]

There's also a different thread sealer. It's yellow (I think. I'm colorblind).

[Tom M King]

The teflon tape for gas is yellow. There are a number of brush on sealers, but I can't think of a single yellow one. It runs at pretty low pressure, so is not hard to seal. Most tests call for 35 psi around here. I test close to as high as my gauge goes. The inspector here wants to see the gauge that's been holding over a weekend.

For exterior pipe, as in the old OP's question, I've always just used black pipe, sanded the outside of it, acetoned it until clean, and painted with a more durable paint. I've seen it outside for decades with nothing better than the original paint, which of course was long gone, but was still in operation-not saying I'd go with that.

I've never had to redo a joint using Rectorseal no. 5, but it's still easy to get apart years later for modifications. It's also fine for use with regular plumbing. I had an air compressor that the only way I could keep the joints leak-free was with no. 5 on both sides of teflon tape. That compressor hasn't leaked down for probably 20 years now.

[Bill Dufour]

The thing is that galvanized pipe and fittings have no zinc on the inside were the fluids are. I suppose there may be a tiny amount on the end of nipples but probably not enough to make any difference. I rally do not understand why they ever worried about the outside coating. Copper I do understand the issue since it has copper on the inside not just the outside.
Bil lD