Classification by connection 
Pipe by pipe end connection can be divided into: light pipe (pipe end without thread) and threading pipe (pipe with threaded ends). 
Car wire tube is divided into: general threading pipe and pipe threading pipe end upsetting. 
Thick threading pipe can be divided into: EUE (with external thread), the thickening (with female thread) and internal and external thickening (with external threads), etc. threading pipe. 
If you press threading pipe thread type can be divided into: general cylindrical or conical screw thread and other places of special threading pipe. 
In addition, according to user needs, threading pipe fittings generally come with the delivery.