it seems that pipes are not completely optimised for their function.
It took me whole a lot of time just to find out that i have to disable crossfeed restrictions to make them work.
I am playing on higher difficulties and i dont want to be forced to change difficulty settings to use pipe the way it should be.
Without "resource transfers obeys crossfeed rules" disabled there is no buttons to operate resource transfer after pipe link is made.
Or at least there could be small hint about it, as it took me whole afternnon to figure this one out.