In the modern industrial system, hexagonal bolts, as one of the most fundamental fasteners, may seem ordinary but shoulder the crucial mission of maintaining the stable operation of large equipment and heavy structures. Especially under heavy-load working conditions, such as the vigorous operation of mining machinery, the long-term load-bearing of bridge engineering, and the frequent lifting of port cranes, the performance of bolts is directly related to the safety and reliability of the entire system. A improperly selected bolt may quietly fail under long-term heavy load stress, causing equipment shutdown, structural damage and even safety accidents. Therefore, mastering the selection logic of hexagonal bolts under heavy load conditions is a core skill that industrial practitioners must possess.