Studs are welded to the collar/cover plate that is in side the tank, and the nuts are on the outside.* My point was if oval then would not have to be split.* A solid collar would make a better*seal.* The other point was if the cover plate was on the inside, instead of the collar then the pressure of the fuel would push the cover plate against the tanks rather than away from it which would make a better seal, which requires an oval.**The last point was make the hole big enough to clean, inspect and repair the entire tank, rather than multi little holes.
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Been there, done that and hope not to do it again.* ****