A connection method in pipeline installation, that is, screw connection, also known as threaded connection, which connects pipes to pipes, pipes and valves through internal and external threads. This kind of connection is mainly used for the connection between steel pipes, copper pipes and high-pressure pipes, pipe fittings and valves. At present, most of the threads of welded steel pipes are operated by threading machines, while for high-pressure pipes that require high thread processing accuracy and surface roughness All must be machined.

Screwed ball valve and flange gate valve are the same type of valve, the difference is that its closing part is a sphere, and the sphere rotates around the center line of the valve body to achieve opening and closing. Ball valves are mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. 2PC ball valve and 3PC ball valve are a new type of valve that has been widely used in recent years.