Seamless steel pipe for structure (GB/T8162-2008) is used for general structure and mechanical structure of seamless steel pipe.

Used for manufacturing seamless steel tubes for pipes, vessels, equipment, fittings and mechanical structures

Construction: hall structure, sea trestle, airport structure, dock, safety door frame, garage door, reinforced lining steel doors and Windows, indoor partition wall, cable bridge structure and highway security guards, railings, decoration, residential, decorative pipes

Auto parts: automobile and bus manufacturing, transportation tools

Agriculture: Agricultural equipment

Industry: Machinery, Solar support, offshore oil field, mining equipment, mechanical and electrical hardware, Engineering, mining, heavy and resources, process Engineering, material processing, mechanical parts

Transportation: pedestrian railings, guardrails, square structures, signage, road equipment, fences

Logistics storage: supermarket shelves, furniture, school appliances

Main grade of steel pipe

Q345, 15CrMo, 12Cr1MoV, A53A, A53B, SA53A, SA53B

Seamless steel tube size and allowable deviation

Carbon steel tube (GB/8162-2008)

This kind of structural steel pipe is generally smelted by converter or open hearth, its main raw material is molten iron and scrap steel, the content of sulfur and phosphorus in steel is higher than that of high quality carbon structural steel pipe, generally sulfur ≤0.050%, phosphorus ≤0.045%. The content of other alloying elements, such as chromium, nickel and copper, brought into the steel by raw materials is generally not more than 0.30%. According to the composition and performance requirements, the grade of this kind of structural steel pipe is indicated by steel grade Q195, Q215A, B, Q235A, B, C, D, Q255A, B, Q275 and so on.

Note: “Q” is the Chinese phonetic alphabet of yield “qu”, followed by the minimum yield point (σ S) value of the grade, followed by the symbol according to the impurity elements (sulfur, phosphorus) content from high to low with changes in carbon and manganese elements, classified into four grades A, B, C, D.

This kind of structural steel pipe output is the largest, the use is very wide, more rolled into plate, profile (round, square, flat, work, groove, Angle, etc.) and profile and manufacturing welding steel pipe. Mainly used in workshop, bridge, ship and other building structures and general fluid transport pipes. This kind of steel is generally used directly without heat treatment.

Low alloy high strength structural steel pipe (GB/T8162-2008)

In addition to a certain amount of silicon or manganese, the steel pipes contain other elements suitable for China’s resources. Such as vanadium (V), niobium (Nb), titanium (Ti), aluminum (Al), molybdenum (Mo), nitrogen (N), and rare earth (RE) trace elements. According to chemical composition and performance requirements, its grade is represented by Q295A, B, Q345A, B, C, D, E, Q390A, B, C, D, E, Q420A, B, C, D, E, Q460C, D, E and other steel grades, and its meaning is the same as carbon structural steel pipe.

In addition to grade A and B steel, grade C, GRADE D and Grade E steel should contain at least one of the refined grain trace elements such as V, Nb, Ti and Al. In order to improve the performance of steel, A, B grade steel can also be added to one of them. In addition, the residual element content of Cr, Ni and Cu is less than 0.30%. Q345A, B, C, D, E are the representative grades of this kind of steel, among which A, B grade steel is usually called 16Mn; More than one trace element should be added to grade C and above steel pipe, and one low temperature impact property should be added to its mechanical properties.

The ratio of this kind of structural steel pipe to carbon structural steel. It has the advantages of high strength, good comprehensive performance, long service life, wide application range and comparative economy. It is widely used in Bridges, ships, boilers, vehicles and important building structures.