Classification of carbon steel pipes

Posted by zora li on September 5th, 2022

Classification of carbon steel pipes

Carbon steel pipes are divided into hot rolled and cold rolled (drawn) steel pipes.

Hot rolled carbon steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipe.

Cold rolled (drawn) carbon steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, other steel pipes, but also includes carbon thin wall steel pipe, alloy thin wall steel pipe, stainless steel pipe, special-shaped steel pipe. The outer diameter of hot rolled seamless pipe is generally greater than 32mm, the wall thickness is 2.5-75mm, the outer diameter of cold rolled seamless steel pipe can be up to 6mm, the wall thickness can be up to 0.25mm, the outer diameter of thin-walled pipe can be up to 5mm, the wall thickness is less than 0.25mm, the cold rolling is higher than the hot rolling size accuracy.

General carbon steel pipe: it is made of 10, 20, 30, 35, 45 high quality carbon steel 16Mn, 5MnV and other low alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot rolled or cold rolled. 10, 20 and other low carbon steel made of seamless pipe is mainly used for fluid conveying pipeline. 45, 40Cr and other medium carbon steel made of seamless pipe to manufacture machine parts, such as cars, tractors, force parts. Generally used carbon steel pipe to ensure the strength and flattening test. Hot rolled steel pipes are delivered in hot rolled or heat treated state; Cold rolling is delivered in heat treatment condition.

The preparation methods

The raw material of carbon steel pipe is round tube billet. The blank of round tube should be cut and processed by cutting machine, and the length of the billet is about 1 meter, and sent to the furnace by conveyor belt for heating. The billet is fed into the furnace and heated to a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Temperature control in the furnace is a critical issue. After the round tube billet comes out, it should be perforated by the pressure punch. Generally more common punch is the conical roller punch, this punch has high production efficiency, good product quality, large diameter expansion perforation, can wear a variety of steel. After perforation, the circular tube billet is successively three - roll oblique rolling, continuous rolling or extrusion. After extrusion, the diameter should be taken out of the pipe. The sizing machine rotates the steel embryo through the cone bit at high speed to punch holes and form steel tubes. The inner diameter of the steel pipe is determined by the outer diameter length of the bit of the sizing machine. Steel pipe after sizing, into the cooling tower, through water cooling, steel pipe after cooling, will be straightened. After straightening, the steel pipe is sent by the conveyor belt to the metal inspection machine (or hydrostatic test) for internal inspection. If there are cracks, bubbles and other problems inside the steel pipe, it will be detected. After quality inspection of steel pipes, they should be selected by hand strictly. After quality inspection of steel pipe, spray the serial number, specification, production batch number with paint. And hoisted into the warehouse by a crane.

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