Threaded coupling is an accessory used to connect two pipes, also known as pipe clamp or external joint. It realizes the connection of pipelines conveniently and quickly through threaded connection, and is widely used in civil construction, industry, agriculture and other fields. According to its manufacturing process, it can be divided into two types: forging and casting. Forging refers to heating and forging steel ingots or round bars into shape, and then processing threads on a lathe. Casting refers to melting the steel ingot and pouring it into a fixed pipe hoop mold, and then waiting for it to cool.