However, there are many classifications of square tubes, including differentiation based on material, production process, and production standards, as well as differentiation based on shape. In short, there are a plethora of thousands of species, classified as follows:

方管按材质分类

Classification of square tubes by material

普碳钢方管、低合金方管。普碳钢分为：Q195、Q215、Q235、SS400、20#钢、45#钢等；低合金钢分为Q345、16Mn、Q390、ST52-3等。

Plain carbon steel square tubes, low alloy square tubes. Plain carbon steel is divided into Q195, Q215, Q235, SS400, 20 # steel, 45 # steel, etc; Low alloy steel is divided into Q345, 16Mn, Q390, ST52-3, etc.

方管按生产标准分类

Square tubes are classified according to production standards

国标方管，日标方管，英制方管，美标方管，欧标方管，非标方管。

National standard square tube, Japanese standard square tube, English standard square tube, American standard square tube, European standard square tube, non-standard square tube.

方管按断面形状分类

Classification of square tubes based on cross-sectional shape

简单断面方管——方形方管、矩形方管

Simple cross-section square tubes - square tubes, rectangular tubes

复杂断面方管——花形方管、开口形方管、波纹形方管、异型方管

Complex cross-section square tubes - flower shaped square tubes, open shaped square tubes, corrugated square tubes, and irregular square tubes

方形方管、矩形方管

Square square tube, rectangular square tube

方管按表面处理分类

Classification of square tubes according to surface treatment

方管按表面处理分： 热镀锌方管、 电镀锌方管、涂油方管、酸洗方管

Square pipes are classified according to surface treatment: hot-dip galvanized square pipes, electrogalvanized square pipes, oiled square pipes, and pickled square pipes

方管按生产工艺分类

Classification of square tubes by production process

热轧无缝方管、冷拔无缝方管、挤压无缝方管、焊接方管。

Hot rolled seamless square tubes, cold drawn seamless square tubes, extruded seamless square tubes, and welded square tubes.

其中焊接方管又分为：

The welded square tube is further divided into:

(1)按工艺分——电弧焊方管、电阻焊方管(高频、低频)、气焊方管、炉焊方管

(1) According to the process - Arc welding square tube, Electric resistance welding square tube (high-frequency, low-frequency), gas welding square tube, furnace welding square tube

(2)按焊缝分——直缝焊方管、螺旋焊方管

(2) Classified by weld seam - straight seam welded square pipe, spiral welded square pipe

方管按用途分类

Classification of square tubes by purpose

方管按用途分类——装饰用方管、机床设备用方管、机械工业用方管、化工用方管、钢结构用方管、造船用方管、汽车用方管、钢梁柱用方管、特殊用途方管、光伏用方管等。

Square tubes are classified according to their purpose - decorative square tubes, machine tool equipment square tubes, mechanical industry square tubes, chemical square tubes, steel structure square tubes, shipbuilding square tubes, automotive square tubes, steel beam column square tubes, special purpose square tubes, photovoltaic square tubes, etc.