The first mode of production: the tube (plate, belt) molded directly welded into the pipe, the main steps of the strip forming, welding, sizing. Features: less production processes, engineering process is simple, short production cycle, product accuracy is slightly lower.

The second mode of production: the tube (plate, belt) first formed directly welded into a certain size pipe, then through the cold-drawn or cold-rolled into a finished tube, known as DOM welded steel pipe. The main processes are forming, welding, sizing, cold-rolled or cold-drawn (with mandrel or without mandrel), or continuous cold drawn (ie, cold drawn welded joint production line). Features: decentralized production processes, long process and production cycle, large area, good dimensional accuracy, smooth inner and outer surfaces, mechanical properties and microstructure good state.

The third mode of production: the tube (plate, belt) first formed directly welded into the pipe after a certain size, enter the continuous cold reducing mill reducer into finished tubes. The main processes are forming, welding, continuous cold reducing. Features: compact production processes, process simplicity, high efficiency units, fast conversion specifications for the production of small diameter and thin-walled welded steel pipe.