Taizhou Zhongfa iron and steel industry has good welded pipes. His family adopts high-efficiency and high value-added pipe-making technology with automatic production line equipment, such as online leveling of weld, online bright annealing and online eddy current detection. The welded steel pipe has high precision, uniform wall thickness and high brightness of the inner and outer surfaces of the pipe (the brightness of the steel pipe surface is determined by the surface grade of the steel plate), and can be cut at any length. Therefore, it is economical and beautiful in the application of high-precision, medium and low-pressure fluids.