Nope, I think pbekkerh means the bolt on flange you use on race pipes, like these Tyga ones, you bolt the flange to the cylinder then attach the pipes to the flange with the springs (or not, it can't fall off once the frame bolt is in).

And as mentioned air tight is the aim, it's not the reality for the average sprung chamber.
_________________
Please do not PM me technical questions, if you can't find it on the Forum start a thread