Production process of hot rolled steel pipe: 

1. Main production process (main inspection process) of hot rolled seamless steel pipe: pipe blank preparation and inspection → pipe blank heating → perforation → pipe rolling → steel pipe reheating → sizing (reduction) → heat treatment → finished pipe straightening → finishing → inspection (nondestructive, physical and chemical, bench inspection) → warehousing 

2. The main production process of cold rolled (drawn) seamless steel pipe: blank preparation → pickling lubrication → cold rolled (drawn) → heat treatment → straightening → finishing → inspection. 

The production process of general seamless steel pipe can be divided into cold drawing and hot rolling.

The production process of cold rolled seamless steel pipe is generally more complex than that of hot rolling. The pipe blank shall be subject to three roll continuous rolling first, and the sizing test shall be carried out after extrusion. If the surface does not respond to the crack, the round pipe shall be cut by the cutting machine, and the blank with a growth of about one meter shall be cut. Then enter the annealing process. The annealing shall be pickled with acid liquid. During pickling, pay attention to whether there are a large number of bubbles on the surface. If there are a large number of bubbles, it indicates that the quality of steel pipe can not meet the corresponding standards. The appearance of cold-rolled seamless steel pipe is shorter than that of hot-rolled seamless steel pipe. The wall thickness of cold-rolled seamless steel pipe is generally smaller than that of hot-rolled seamless steel pipe, but the surface looks brighter than that of thick wall seamless steel pipe. The surface is not too rough and the diameter is not too many burrs.