I'm making not the valves, only the canals. I try to make them in one part, I have two canals that are running over into each other, only then you see the both circels in each other, so I need to delete that at some way, and then I have 1 piece with 2 3/4 circles, and that piece must go over in 1 circle. Its a little bit hard to explane what I mean, but I hope you get it!