A double-ended stud, without a head, is a type of fastener in which only two sections are externally threaded. When connecting, one end of it must be screwed into the part with the internal threaded hole, the other end must pass through the part with the through hole, and then screw the nut, even if the two parts are tightly connected as a whole. This form of connection is called a stud connection, which is also a detachable connection. It is mainly used for occasions where one of the connected parts is thick, requires a compact structure, or is not suitable for bolt connection due to frequent disassembly. When the main body is large equipment, accessories need to be installed, such as sight glass, mechanical seal seat, deceleration frame, etc. At this time, a stud bolt is used, one end is screwed into the main body, and the other end is equipped with a nut after the accessory is installed. Since the accessory is frequently disassembled, the thread will be worn or damaged, and it is very convenient to use the stud bolt to replace. When the thickness of the connecting body is very large and the bolt length is very long, stud bolts are used. It is used to connect thick plates and places where it is inconvenient to use hexagonal bolts, such as concrete roof trusses, roof beam suspension monorail beam suspension parts, etc.