Scupper Plugs - available in nylon, aluminium and steel
Most ships have toilet, firewater, wash water systems and pipework, which all have to be leak tested.
Available in nylon (resistant to salt water) steel and aluminium.
Plugs can be used for a variety of other applications on board as well.
Pipestopperâ„¢ Marine Hole & Pipe Stopping Mechanical Test Plugs