another tank query

["Brian A.Tink" <batink@domain.elided>]

Gents

The fuel pipe exiting from the fuel tank has a bulb on it.  The purpose of which would be to stop the pipe from falling into the tank and the second reason to form a point on which the securing nut has something on which to press.

Question:  is the suppose to be an "O" ring in the opening to form a seal??

forever staggering onwards.

brian