When you right-click with a pipe to attach it to a universal pipe, you lose the pipe in your inventory even if you're in creative mode. Also, breaking any kind of pipe causes it to drop as an item even in creative mode. Both of these things should only happen in survival. Tested on version 1.0.1.

This is mostly fixed, with one exception: when breaking an advanced universal pipe, any pipes attached to it still drop, even though they're not consumed when you attach them.

That would require much bigger changes (especially in template classes that are also used in my other mod) to implement than the part that has been fixed so far and also compared to the relevance of the improvement it would bring.
So I will leave this remaining "impurity" there for now.

The thing with also consuming items when attached as pipe connection in creative could be changed.
But I think, it makes sense to still let Filters be consumed when inserted in creative because the same Filter is usually only attached to one pipe.

Dropping items in creative is related to the fact that all blocks in all of my mods also drop items in creative if they have special drops (drop different/additional items, attach NBT data, have inventories, etc.) because these are all handled the same for simplicity.
Maybe I can find a way to improve this without making the implementation of block drops unnecessary complicated for me. I mean this is just creative, items getting lost in survival would be far more problematic.