Screw plunger valves are divided into two types: non-metallic seals and metal seals. In addition, externally threaded connecting plunger valves have two main types of shapes: Z-shaped and waist drum shaped. Their internal structure is completely the same and their uses are the same. They are mainly used in industries such as metallurgy, electricity, chemical, oil refining, and food. Used for opening and closing flow regulation on small diameter pipelines such as water, steam, oil, etc. with a pressure of 16-25kgf/cm2 and a temperature below 250 ℃.