The first mode of production: the tube billet (plate, strip) is formed directly into the pipe, and its main process is the forming, welding and sizing of plate tape. Features: low production process, simple engineering process, short production cycle, low precision of product.
The second mode of production: the tube billet welding (plate, belt) direct forming into a certain size of steel pipe, and then after cold drawn or cold rolled into a finished product steel tube, known as the DOM welded steel pipe. Its main process is forming, welding, sizing, cold rolling or cold drawing (with a mandrel or no mandrel), or continuous cold drawing (that is, the welding, cold pulling joint production line). Features: the production procedure, the technological process and production cycle is long, covers an area of big, dimension precision products, both inside and outside surface is bright and clean, good mechanical properties and microstructure of state.
The third kind of mode of production: the tube billet welding (plate, belt) direct forming into a certain size of steel pipe, into the continuous cold sinking into a finished product reducing mill for steel. Its main process is forming, welding, continuous cooling reduction. Features: the production process is compact, the process flow is concise, the production efficiency is high, the specification scope changes fast, the production small diameter and thin wall electric welding steel pipe.
Source: China Steel Pipe Manufacturer - Yaang Pipe Industry Co., Limited (www.yaang.com)