A threaded pipe includes a screw thread at a single or equally ends for assembly. Steel pipe is usually joined with threaded connections; tapered threads are cut to the end in the pipe, sealant is applied in the form of thread-sealing compound or thread seal tape (often called PTFE or http://valvesandfittings20639.blogdon.net/tubing-fitting-things-to-know-before-you-buy-11988492