Tank o-ring "grooves"

[fppf]

Again the reason the tank is shaped like that is for ease of machining. Its very easy to add the tapper after the theard cutting operation.

Your still thinking the oring is a solid, there is NO point of contact between the OD of the valve and the oring. Pressure will force the oring up against the top of the valve and out against the tapper of the ID of the tank.

 

[DepthCharge]

Your still thinking the oring is a solid, there is NO point of contact between the OD of the valve and the oring. Pressure will force the oring up against the top of the valve and out against the tapper of the ID of the tank.

I understand that, but there is still just 3 regions (if that's a better way to look at it) that the o-ring is in contact with, not 4. The taper of the tank, the side and the top of the valve. On a square cross section, it comes in contact with 4 regions.

 

[fppf]

It does not matter how many "regions" there are, the oring will be forced into 2 of them, at the gap. And the angle of the flats leading into the gap does not matter. The oring will flow into it.

Some oring grooves are "dove tailed" to retain the oring when the parts are taken apart.