That would be pipe dope and not putty. All the pipefitters that do gas work in the homes I have built or renovated all use pipe dope, and never Teflon tape.
I've only ever used pipe dope (except of course with flare fittings where no sealant should ever be used) but there are several kinds of yellow PTFE tape made for gas lines. Each apparently has a slightly different composition and use requirement.
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"You can't buy happiness, but you can buy an RV. And that is pretty close."
I too mostly use pipe dope at home and on jobs, but in my trailer tool kit I bring along some gas tape for convenience and storage.
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2017 Escape 5.0 TA
2015 Ford F150 Lariat 3.5L EcoBoost
2009 Escape 19 (previous)
“Most folks are about as happy as they make up their minds to be.” — Abraham Lincoln
Just checked mine, was at 12.0 with the fridge and 1 burner of the stove on. Dropped it down to 11.5 as opposed to 11 as the fridge was working just fine last time we used it, hate to screw it up. This was with a new last year regulator.
It's now 12 with nothing on, 11.8 with just the fridge, and 11.5 with both fridge and 1 burner.