Threaded joints refer to threaded pipe connectors, which are the most common pipe fittings in industry and life. Threaded joints make the connection of pipes simpler and easier to disassemble and replace, which greatly saves the cost of pipe connections. Threaded joints generally include threaded elbows, threaded tees, threaded unions, threaded pipe caps, threaded pipe hoops, threaded reducers, threaded plugs, threaded external wires, core fillers, etc. Threaded joints used in industry are generally made of metal, with high pressure resistance, and the materials include carbon steel, stainless steel, alloy steel, brass, etc.;threaded joints used in daily life are generally made of PC, PVC, PE, PPR, etc.