- Place a holofirelock on the pipe that you plan to unwrench.
- Alt-Click the tile that the pipe is on, you now have a new tab in the chat-half of the game where you can interact with the stuff on the tile.
- Unwrench the pipe, all of the contents of the pipe will be trapped on the tile because of the holofirelock.
- Get a portable scrubber, activate it, and shove it under the holofirelock.
This will not work with fire.