Pipe Fitting

　　In general, in the whole pipeline, all kinds of fitting can referred to the tube fittings except straight pipe. But used to say, we referred to the elbows, tees, cross, reducers, caps and various pipe unions called the fittings. At the same time, make the flanges, valves, expansion joints, pipe support and so on respectively called. Elbow applies to round the corner for the pipe. The flanges apply to the connection of the pipe and pipe. Connect on the top of the pipe, tee pipe apply to three pipes survey of local, and the cross apply to the four pipes. Reducer can connect two different pipes together.

　　The selection principle is that to ensure the oil for laminar flow in the pipe and the pipe should be short as far as possible to reduce the loss of the pressure. On the basis of the working pressure, installation to determine the position of the pipe and connection structure to ensure that the pipe and pipe joints have sufficient strength and good sealing.

　　The following make the pipe fitting subdivided. It can separate two categories according to the straight pipe and the welding way of fittings. There will be socket welding (SW) pipe fitting and threaded (THD) pipe fitting. There also have some other kinds. Use the same material in the pipe. They are carbon steel pipe fitting (CS), stainless steel pipe fitting (SS), and butt welding pipe fitting (BW), normal pipe thread (NPT), normal pipe thread male (NPTM) and female (NPTF).

　　Butt welding category contains elbow, tee, reducer, cap, all kinds of the pipe joints (union, single head wire, double wire, plug and so on.) According to if the weld on the pipe fitting surface, it can be divided into two large kinds that is the seam pipe fitting and seamless pipe fitting.

　　GB12459-90 is the seamless pipe fitting standard and the GB/T13401-92 is the seam pipe fitting standard.