According to manufacuring process of seamless pipe,seamless pipe can be divided into hot rolled seamless tube and cold drawn seamless tube.
Hot rolled seamless steel tubes:
Round tube → heating → perforation → three skew rolling, rolling or extrusion → detached → sizing (or reducing) → cooling → straightening → hydrostatic test (or testing) → marker → storage. raw material of seamless pipe is a round tube that embryos to go through a cutting machine to cut and sent by conveyor belt furnace heating. Billet is fed into the heating furnace with temperature of 1200 degrees.
The furnace temperature control is critical to wear air round tube.generally, common puncher is tapered roller punch with high production efficiency, product quality, perforated expanding volume, wearing a variety of steels. After perforation, round tube has been three-roll cross rolling, rolling or extrusion.
After extrusion off pipe sizing. Sizing mill by the high-speed rotation of the cone drill into the Billet punch to form a steel pipe. The steel pipe inner diameter is determined by the length of the outer diameter of the sizing mill drill. After sizing, the steel pipe to enter the cooling tower by the water spray cooling, it is necessary to be straightening after cooling. In the interior of the steel pipe there is such as cracks, bubbles detected. Steel pipe quality inspection is through a rigorous manual selection. Steel pipe use spray paint on the number, size, production batch after Quality Supervision, Inspection by a cable car hanging into the warehouse.
Cold drawn seamless steel tubes:
Round tube → heating → perforation → Heading → annealing → pickling → Oiler (copper) → multi-pass cold drawn (cold) → Preform → heat treatment → straightening → hydrostatic test (testing) → marker → storage. The method of cold drawn (rolled) seamless steel pipe is more complex than hot-rolled (extrusion of seamless steel pipe). The first three steps of their production process is basically the same. The difference from the fourth step, the circular tube was empty to begin annealing. pickling need to use a special acidic liquid after annealing and oiling. Then followed by a blank tube, multi-pass cold drawn (cold) and then specialized heat treatment. it is necessary to straightening. it is sent by conveyor and straightening the metal detection machine (or hydrostatic test) to conduct an internal flaw. In the interior of the steel pipe,there is some issues such as cracks, bubbles will be detected. Steel pipe quality inspection is also through a rigorous manual selection.