The seal ring, code 136973, is a precision sealing element used in the MAN L21/31 engine to maintain a secure barrier between adjoining components and prevent the unwanted passage of operating fluids or gases. Depending on its location within the engine assembly, the seal ring may be required to retain lubricating oil, fuel, cooling water, compressed air, or another operating medium while simultaneously protecting sensitive internal components against contamination. The component is designed to maintain effective sealing despite vibration, changes in pressure and temperature, mechanical movement, and thermal expansion occurring during engine operation. Accurate dimensions, suitable material properties, and correct installation are therefore essential to its performance. By maintaining system tightness and reducing the risk of leakage, the seal ring contributes to reliable engine operation, reduced maintenance requirements, protection of associated components, and a longer service life of the MAN L21/31 engine.