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:

方管按材質分類

Classification of square tubes by material

普碳鋼方管、低合金方管。普碳鋼分為：Q195、Q215、Q235、SS400、20#鋼、45#鋼等；低合金鋼分為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.

方管按生產標準分類

Square tubes are classified according to production standards

國標方管，日標方管，英制方管，美標方管，歐標方管，非標方管。

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

方管按斷面形狀分類

Classification of square tubes based on cross-sectional shape

簡單斷面方管——方形方管、矩形方管

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

復雜斷面方管——花形方管、開口形方管、波紋形方管、異型方管

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

方管按表面處理分類

Classification of square tubes according to surface treatment

方管按表面處理分： 熱鍍鋅方管、 電鍍鋅方管、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

方管按生產工藝分類

Classification of square tubes by production process

熱軋無縫方管、冷拔無縫方管、擠壓無縫方管、焊接方管。

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

其中焊接方管又分為：

The welded square tube is further divided into:

(1)按工藝分——電弧焊方管、電阻焊方管(高頻、低頻)、氣焊方管、爐焊方管

(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)按焊縫分——直縫焊方管、螺旋焊方管

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

方管按用途分類

Classification of square tubes by purpose

方管按用途分類——裝飾用方管、機床設備用方管、機械工業用方管、化工用方管、鋼結構用方管、造船用方管、汽車用方管、鋼梁柱用方管、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.