Plug screws with code EN47R13 are essential sealing and closing elements used throughout the MAN L21/31 engine to close threaded ports in oil, fuel, or cooling circuits. Designed to withstand pressure, temperature fluctuations, and vibration, these plug screws ensure leak-free operation and protect internal systems from contamination. Their reliable sealing performance and robust material quality make them a critical part of maintaining engine safety, cleanliness, and operational integrity.