Propane is heavier than air. You need venting at the top and bottom.Maxcamp8 said:Plenty of venting in the lid gaps and around the (open to air) gas regulator. No gasket on lid.
5.2.6.1 Ventilation of Compartments Containing LP-Gas
Containers. Compartments shall be
ventilated at or near the
top and at the extreme bottom to facilitate diffusion of vapors.
The compartment shall be ventilated with at least two vents
having an aggregate free area equal to at least 1 sq/in for each 7 lb
(1 cm 2 per 500 grams) of the total LP-Gas fuel capacity ....
So, for a 20lb tank, two 1-1/2" diameter holes (one top / one bottom) should work.
This is only true for tapered gas fittings. As @Basil48@Basil48192 said, fittings using o-rings or flare fittings do not depend on machined threads to seal. The threads only secure the connection. Any dope or tape can interfere with the intended seal.Maxcamp8 said:For sealing brass gas fittings (not the tank) see IBC Section 403.8.3 (Threaded Joint Sealing) of the 2021 International Fuel Gas Code. Yellow Teflon tape on gas joints, white on plumbing. Dope plus tape is common on todays' poorly machined thread tolerances.