The CGA fittings on regulators are designed to achieve a gas-tight
metal-to-metal seal with moderate torque. Using teflon tape, or any
foreign matter between the sealing surfaces is not only unnecessary but
can lead to issues such as an improper seal or debris being blown into
the regulator. Likewise, using teflon tape on the threads of the CGA
fitting is unnecessary as is using an "enormous" wrench.

There are wrenches made specifically for tightening CGA fittings. Note
that they are relatively short. This is deliberate, to keep folks from
yanking on them.
https://www.esafetysupplies.com/products/wrench-tank-1013-pop

The sealing surface of the fitting is typically rounded, giving a good
seal with the conical surface of the tank fitting. Note that CGA
fittings are soft brass so they slightly deform elastically in use.
Overtorquing the fitting can permanently deform the fitting, rendering
it unfit for service. If you need to use excessive force to get the
fitting to seal that is a sign that the fitting is defective and should
be replaced

Replacement CGA fittings are inexpensive and your local welding supply
store will be glad to do the job, don't do it yourself.

See also

https://www.airgas.com/resources/cleanpeaks/2017/winter/cylinder-connections

On 9/20/23 12:57 PM, Benjamin Ruekberg wrote:
> Hello,
>
> This is nothing to get excited about, just a matter of curiosity.
>
> At our annual safety training we were told not to use Teflon tape when
> attaching regulators to gas cylinders. The ultimate reason given was that
> the tape would not allow the regulator's ball to fit tightly to the gas
> cylinder's socket.
>
> I find this a bit difficult to believe. This would only apply if the
> threads on the regulator and the cylinder were tapered. Because a tapered
> thread connection stops going in once the male and female diameters are the
> same, using tapered threaded parts would require highly precise machining
> so that the male would stop going in at the precise distance to firmly seat
> the ball in the socket. Such precision would be prohibitively expensive.
> (I think.)
>
> Rather I think the reason is because white Teflon tape is not 100% Teflon
> and the other component is combustible. There is a green Teflon tape for
> use with oxidizers that *is* 100% Teflon. To avoid the use of the more
> common tape on an oxygen cylinder, the easiest way is to say "No Teflon
> tape on gas cylinders."
>
> When appropriately used, the Teflon tape acts as a lubricant, so that a
> regulator can be put on (and taken off) without the use of an enormous
> wrench.
>
> I know that I may be entirely wrong about this, so I am seeking the expert
> opinion of L-CHASers.
>
> Thank you very much,
>
> Ben
>
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