Sw2k9 Cutting Pipes Perpendicular

I'm making pipes knot with 3 pipes from movie below. Wall thickness of these pipes is 10mm. Green pipes touch themselves together and red tube act as pipe added onto green pipes. I used Combine tool to get red tube. As you see at movie finish red tube has big chamfer area. I dont want this chamfer because these pipes will be welded and where this chamfer is now there must be weld.I want cut on these blue lines which I selected at movie finish - perpendicular to external pipe surface. Project Curve tool doesnt work - because cant project onto nonplanal surface. Convert entities cant help too due to impossibility to draw on pipe. Have tries some other tools without results too.

In other words: how convert / project two selected edges (blue lines) from finish movie on pipe's external surface ? and later I need cut perpendicular on this projected lines to avoid / delete these chamfers.

why dont you draw one tube, array, then create a weldment of the 3 together.

Or take your green piece and mirror it with a plane that bisects one of the tubes since each tube is 120degrees apart.

If you have your tube cross section at the end(non intersection) part of the red tube, you can extrude it up to your surface.

How do you plan to cut these in reality?

As far as projecting 3d curves onto surfaces you should be fine doing this in a 3dsketch.

sorry i dont have SW in front of me, those are the first things that came to mind.