The development of the steel industry has provided great convenience for our travel. The railway, high-speed railway and automobile industries are inseparable from the development of the steel industry. Similarly, the development of the steel industry also depends on the development of other industries and machine technology.

The operating torque of butterfly valve has different values due to different openings and valve opening and closing directions. For horizontal butterfly valves, especially large diameter valves, the torque caused by the difference between the upper and lower head of the valve shaft due to the water depth cannot be ignored. In addition, when the elbow is installed at the inlet side of the valve, bias flow will be formed and the torque will increase. When the valve is in the middle opening, the operating mechanism needs self-locking due to the action of hydrodynamic moment