Find and axis of a STEP PIPE

Hi i need to find the flow of the water into different Pipe.

I was able to find all the point that i need exept those show in the picture.

i Tried to create line from the point that i allready have to find the intersection with "Multiple curve intersection" but it don't work.

I need to find the clean curve because i want to use "shortest walk"

Esploso%20per%20tubolari.gh