If Scotty is beamed into the boiler, wouldn't he die from the heat? I sure hope that's a cold water pipe. Of course, then he'd probably freeze. That must be the pool-temperature pipe. Maybe it'll dump him into the pool. Where lots of female crewmembers are waiting for him in non-regulation clothing.
And.... If Scotty beamed into a water pipe, however comfortable the water may be, wouldn't he drown? I mean, I hope he took a deep breath before energizing. Not to mention the thought of panic at having materialized under water. Within a pipe. That at least happend to be a perfect fit. Considering he was probably standing when energized, all in all, I'd say his luck was good that part of him didn't materialize outside of the pipe.
I'm beginning to think the beam into the Enterprise went well. Now, Kirk and Scotty have to get somewhere on the ship in a hurry without being spotted. Scotty, probably from knowing the ship from studying it afar, and of course being the comic relief, says they'll get where they want to go fastest if they just take a deep breath and jump into this water pipe. Before Kirk can say anything about how stupid that is, Scotty's on his way. The discussion over this also gives Kirk time to take his jacket off during the scene. Hey, why can't this be?