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What is a steel pipe?

Nov. 01, 2019

A steel tube is a steel material having a hollow section that is much longer than the diameter or circumference. According to the cross-sectional shape, it is divided into round, square, rectangular and special-shaped steel pipes; it is divided into carbon welded steel pipe, low-alloy structural steel pipe, alloy steel pipe and composite steel pipe according to the material; it is divided into conveying pipeline and engineering structure according to the purpose. For thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, steel pipes for high-pressure equipment, etc.; according to the production process, it is divided into seamless steel pipes and welded steel pipes, of which seamless steel pipes are divided into hot rolling and cold rolling (pulling). Two kinds of welded steel pipes are divided into straight seam welded steel pipes and spiral seam welded steel pipes.

Steel pipes are not only used to transport fluids and powdered solids, exchange heat, make mechanical parts and containers, but are also an economical steel. The use of steel pipes to manufacture building structure grids, pillars and mechanical supports can reduce weight, save 20-40% of metal, and achieve mechanized construction. The use of steel pipes to manufacture highway bridges not only saves steel and simplifies construction, but also greatly reduces the area of the protective coating and saves investment and maintenance costs.

Steel pipes are divided into seamless steel pipes and welded steel pipes.

The seamless steel pipe is a long strip of steel with a hollow section and no joints around it. It can be used as a pipeline for conveying fluids, such as pipes for transporting oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, seamless steel pipe has light weight when it has the same bending and torsional strength. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes and automobile transmission shafts. , bicycle racks and steel scaffolding used in construction. The use of seamless steel tubes to manufacture ring-shaped parts improves material utilization, simplifies manufacturing processes, and saves materials and processing man-hours.

Square Tube

Square Tube

Welded steel pipe, also called welded pipe, is a welded steel pipe made of steel or steel strip after being crimped and welded. The welded steel pipe has simple production process, high production efficiency, many varieties and specifications, and low equipment investment, but the general strength is lower than that of seamless steel pipe. Since the 1930s, with the rapid development of high-quality strip continuous rolling production and the advancement of welding and inspection technology, the quality of welded joints has been continuously improved, the variety specifications of welded steel pipes have been increasing, and more and more fields have replaced Seam steel pipe.

The seamless steel pipe production process is to pass a solid tube or steel ingot into a hollow capillary tube and then roll it into a steel pipe of the required size. The different methods of perforation and rolling are used to form different methods for producing seamless steel pipes. The production process of welded steel pipe is to bend the tube blank (steel plate or strip) into a tubular shape, and then weld the gap into a steel pipe. Different methods of producing welded steel pipes are formed due to the different molding and welding methods used.

Seamless steel tubes are mainly produced by hot rolling. The extrusion method is mainly used to produce low-plastic high-alloy steel pipes or special-shaped steel pipes and composite metal pipes which are difficult to perforate. Cold rolling and cold drawing processes continue to process hot rolled tubes into small diameter and thin walled steel tubes.