Production technology of large diameter thick wall seamless steel pipe

The invention relates to a manufacturing process of a large-diameter thick-walled seamless steel pipe, belonging to the field of production methods of large-diameter thick-walled seamless steel pipes. The production method is as follows: the steel smelted by electric furnace is refined by ladle, the ingot after bet is annealed under argon protection, hot-cut at the bottom of the riser, heated and punched by a vertical hydraulic press, then drawn by a horizontal hydraulic press, then heated and drawn, heated to about 900℃, sprayed with water, quenched and tempered, and processed by internal boring and external scraping, internal and external grinding technology, nondestructive testing, shape detection, etc. The method of the invention can produce large-caliber thick-walled seamless steel pipes with an outer diameter of 325-325- 1066.8 mm, a wall thickness of 25- 162 mm and a length less than or equal to 8500 mm.. The seamless steel pipe conforms to the national standards, and can be used as large-diameter thick-walled seamless steel pipes for power stations and high-pressure boilers, as well as pressure vessel cylinders, oil cylinders, chemical steel pipes and centrifugal pipe casting molds.