Welded pipe, also known as welded steel pipe, basically made of steel plate or strip steel after coil forming and then welded into a steel pipe. The use of welded pipe is mainly used for boilers, automobiles, ships, Hong wu rented building with light structure of the doors and windows of the steel shelter megabytes, furniture, all kinds of agricultural machinery, scaffolding, wire threading pipe, high-rise shelves, containers and so on. Welded pipe classification by use of square hail sail method: according to the use of general welded pipe, galvanized welded pipe, oxygen blowing welded pipe, wire casing, metric welded pipe, roller pipe, deep well pump pipe, automotive pipe, transformer pipe, electric welded thin-walled pipe, electric welded shaped pipe and spiral welded pipe.