How are square tubes classified?

There are many ways to classify square tubes, which can be divided by material, technology, caliber, shape, use and other aspects. Here is a summary of how square tubes are classified?
Production process classification of square tubes: hot-rolled seamless square tubes, cold-drawn seamless square tubes, extruded seamless square tubes, and welded square tubes. The galvanized square tubes are divided into: (a) according to the process - electric arc welding square tubes, resistance welding square tubes (high frequency, low frequency), gas welding square tubes, furnace welding square tubes (b) according to the weld seam - straight seam welding square tubes, spiral welding square tubes material classification square tubes according to the material: plain carbon steel square tubes, low alloy square tubes. Ordinary 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. Production standard classification of square tubes According to production standard, square tubes are divided into national standard square tubes, Japanese standard square tubes, English standard square tubes, American standard square tubes, European standard square tubes, and non-standard square tubes. Classification of square tube section shape: square tube is classified according to section shape: (1) square tube with simple section - square tube, rectangular square tube (2) square tube with complex section - flower-shaped square tube, open-shaped square tube, corrugated square tube, and special-shaped square tube are classified according to surface treatment: hot-dip galvanized square tube, electro-galvanized square tube, oil-coated square tube, acid-washed square tube. Square tube is classified according to use - square tube for decoration, square tube for machine tool equipment, square tube for mechanical industry Square tubes for chemical industry, steel structures, shipbuilding, automobile, steel beams and columns, square tubes for special purposes, square tubes for wall thickness classification, square tubes by wall thickness - ultra-thick square tubes, thick square tubes and thin square tubes