The game doesn't need PHYSICAL pipes
I think the current pipe system is overcomplicated for what it's supposed to accomplish. The whole point of water tanks, sprinklers and automated farming is to reduce repetitive work. But right now setting it up can be more annoying than just watering plants manually.
And gardening isn't really important enough to the main gameplay loop to justify that effort. You rarely need to grow plants in quantities where spending so much time on plumbing feels worth it.
You have to place pipes, fight with snapping and orientation, route them around walls and floors, and somehow make them not look terrible inside the airship. So don't think better snapping alone fixes the core issue.
My suggestion: make pipes virtual.
Assume they're routed inside the hull, walls and floors.
You enter a Pipe Construction Mode, click the source, then click the destination. They're connected.
For more complex setups, you could add virtual splitter/junction nodes.
While in Pipe Mode, the game could show an overlay with connection lines, flow direction and which pipes are currently active. Outside that mode, the network is hidden.
This would keep the useful part of the system - deciding what connects to what - without making players manually wrestle with pipe geometry.
The main goal of this system should be to make the player's life easier, and I think virtual pipes would do that much better than the current implementation.
(here’s a really quick sketch of how this could be visualized in-game)