...Although we never learned exactly what could be accessed there. Would there have been moving parts, or would the platforms merely have allowed repairmen to slap patches over possible punctures?
If seems that the "nodes" of these tube things have at least one "functional" capacity, that of shuttering the flow and allowing a firewall to slide down to cut the tube. (Perhaps the shutters are then opened again and the flow burns its way through the seemingly orifice-less firewall?)
From what we see, it's clear that the tube thing can make turns, including relatively tight ones (we see three 90-degree angles); it being "vertical" or "horizontal" may be a gross oversimplification, really. Perhaps on Kirk's ship, it becomes more like diagonal within the neck, and does a loop around the dilithium chamber for greater effect, whereas on Khan's, it really looks like a spaghetti monster?