The connection methods of pipes and pipe joints in the hydraulic system are also different, and the screw-in end of the pipe adopts the connecting thread. Tapered threads rely on their own cones to tighten and use PTFE and other substances for sealing operations, and are mainly used in medium and low pressure hydraulic systems. The sealing effect of fine thread is very good, and it is often used in high-pressure systems, but it needs to use a combination washer or O-ring to seal the end face, and sometimes a copper washer is also used, which is more suitable for connecting the pipe wall. In relatively thick pipes, the main components are the joint body, the connecting pipe and the nut. In use, the joint body is embedded in the target, the end face is sealed with the gasket mentioned above, the joint body and the nozzle are sealed with rubber, and sometimes spherical sealing is used.