Acetylene safety question

Teflon tape(and paste) are NOT a sealant. It is used to lubricate threads so that they can be tightened more smoothly. Joints have an interface that has to be free of burrs and divots to seal, and all the goo you can use will only make it harder to fixlater. An Acetylene leak could be disasterous.

This is only true for Dry seal pipe threads, aka NPTF because these threads have zero clerance between the root and crest of the mating thread form. For standard NPT and machine screw fits both teflon tape and paste will seal (very low pressures on non tapered threads) by filling the spiral leakage path that existing between the crest of the male thread and the root of the female thread form.

Isn't this a metal to metal conical seal?

This is a compression fitting. No sealant

Teflon tape is NOT a sealant. It is only to lubricate the threads. You can try it wherever you want but that doesn't change the facts.

At work we had a seminar where it was proved to us that the tape doesn't seal at all. If the problem is where the regulator connects to the tank valve you shouldn't take any chances. I would return the tank. You should get credit for the unused gas.

- Regards Gordie

Did you do a soap bubble test and verify that the lead is at the connection? Just smelling the gas could mean your regulator could have a small leak.