Bulkhead rubber washer

[Joe DeSantis]

Hello!
I have a question about the rubber gasket that seals bulkheads. One side is completely smooth while the other side is ribbed. Should the ribbed side contact the tank surface or should it contact the inner lip of the bulkhead??? I am pretty sure that the ribbed side should contact the tank surface..am I right??

 

[WannaBeReefer]

Thats how I have mine, It came installed that way.

 

[taikonaut]

It won't make any difference if both the tank and the contact surface of the bulkhead are both smooth. The only wrong way to install it is to have the gasket on the nut side.

 

[Joe DeSantis]

Thanks guys