Cheers mate.Are you sure you have the right size pipe work?
You should not have water leaking between the outside of the pipe and the inside of the bulkhead?
But I have never used these slip type ones so could be wrong.
Don't solvent weld the screw thread as you will never get it apart again if you ever need to.
Good luck
I called the company today and apparently you are supposed to use one pipe which goes the whole way through the bulkhead, so the same pipe as the drain and then plumbing underneath. and then the screw underneath makes it water tight.
so going to have to buy a load more pieces tonight as have cut all the pipework to how I thought it should have been lol will just use some coupler's to sort it out to sonething