Pipe fitting union, also known as oil coupling or free coupling, is an important component in pipe fitting connection. It is mainly composed of three parts: the nut, the

cloud head and the flat joint. It is a pipe fitting used to connect two pipes. The pipes can be disassembled and assembled by rotating the nut. Oil valves are typically used

in situations where frequent disassembly is required, such as when installing faucets and valves, for maintenance or replacement.

According to their different forms, union joints are further classified into 330 and 340. For those who are new to pipe fittings, it is often confusing to tell them apart. Today,

we will take you through the method of picture decomposition to intuitively understand and recognize what different union joints look like.

330   Union

340   Union

342   Copper Ring Tapered Seat Oil Seal

Regular Union