①Main production process of hot-rolled seamless steel pipe (main inspection process):Tube billet preparation and inspection → tube billet heating → perforation → pipe rolling → steel pipe reheating → fixed (reduced) diameter → heat treatment △ → finished pipe straightening → finishing → inspection (

Thermal expansion is a processing method of steel pipes, which is to process small-diameter steel pipes into large-diameter steel pipes. The mechanical properties of hot-expanded steel pipes are slightly worse than those of hot-rolled steel pipes. Limited to the limited specifications of seamless st