The material for nuts, code 300100, refers to the specified engineering material requirements for fastening nuts used within the MAN L21/31 engine. These nuts are typically manufactured from high-strength alloy steels selected for their ability to withstand high preload forces, cyclic mechanical stresses, vibration, and elevated operating temperatures. Material specifications ensure that the nuts maintain their mechanical properties and clamping performance throughout prolonged engine operation, especially in demanding marine and industrial environments. Proper material selection is critical for maintaining fastening integrity, preventing premature failure, and supporting the structural stability of major engine assemblies. High-quality fastening materials contribute directly to operational safety, maintenance efficiency, and the long service life of the engine.