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1. Classification by production method
(1) Seamless pipe — hot rolled pipe, cold rolled pipe, cold drawn pipe, extrusion pipe, pipe jacking (2) Welded pipe (a) According to the process — arc welding pipe, resistance welding pipe (high frequency, low frequency), gas welding pipe, furnace welding pipe (b) according to the welding line — straight welded pipe, spiral welded pipe.

A. Hot rolled seamless steel pipe: hot rolled is as opposed to cold rolled, which is rolled below the recrystallization temperature.Hot rolling is rolling above the recrystallization temperature.
Adavantage: can destroy the ingot casting organization, refining steel grain  and remove the defects of the microstructure, which makes steel group is close-grained, mechanical performance is improved.This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic to a certain extent, bubbles, cracks and looseness formed during pouring can also be welded under high temperature and pressure.

B. cold rolled steel pipe:Cold-rolled seamless pipe (GB3639-2000) is used for mechanical structure and hydraulic equipment with high dimensional accuracy and table
Cold drawn or cold rolled precision seamless steel tubes with good surface finish.
Advantages: it can destroy the casting structure of steel ingot, refine the grain of steel, and eliminate the defects of microstructure, so that the microstructure of steel can be compactness and mechanical properties can be improved.This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic to some extent;Bubbles, cracks and looseness formed during pouring can also be welded under high temperature and pressure.

C. extrusion pipe:The heated tube blank is placed in a closed extrusion cylinder, and the perforated rod moves with the extrusion rod to make the extrusion part extrude from the smaller die hole.This method can produce steel pipe with small diameter.

Adavantage: With good metal compactness and uniform structure, it is suitable for the production of almost all kinds of steel tubes, especially for the production of high-alloy, non-deformable steel and all kinds of special-shaped cross-section tubes. Because of its performance advantages, hot extruded steel pipe products have irreplaceable application prospects in high-end and key fields of national economy such as military industry, nuclear power, thermal power, aviation, mining, oil well and petrochemical industry. Efforts to research and develop high performance, high technology content and high added value of hot extruded steel pipe products, to promote the development of national high-end steel pipe technology and strengthen the comprehensive economic strength has far-reaching significance

3. Classification by section shape
(1) Simple section steel tubes — round steel tubes, square steel tubes, elliptic steel tubes, triangular steel tubes, hexagonal steel tubes, diamond steel tubes, octagonal steel tubes, semicircular steel tubes, and other (2) complex section steel tubes — unequal hexagonal steel tubes, five-lobe quinted-shaped steel tubes.
Pipe, double convex steel tube, double concave steel tube, melon seed steel tube, conical steel tube, corrugated steel tube, watchcase steel tube, others.
4. Classification by wall thickness — thin-wall steel tube, thick-wall steel tube.
5. Classification by use — pipe, thermal equipment, mechanical industry, petroleum, geological drilling, container, chemical industry, special purpose, others.


Post time: Nov-17-2020