Какви са различните модели безшевни квадратни тръби? Как да класифицираме квадратните тръби?

What are the various models of seamless square tubes?
The specification marking method of square pipe is mainly expressed as side width * side width * tube wall thickness.  For example, 16 x 16 x 0.4-1.5 indicates that the edge width is 16mm and the wall thickness is 0.4-1.5mm.  
Square tube commonly used specifications and models are 30x50, 50x50, 40x60, 40x80, 80x80, 50x100, 100x100, 120x120 commonly used size, all kinds of thickness, see your own needs.

How to classify square tubes?  
According to the production process: hot rolled seamless square tube, cold drawn seamless square tube, welded square tube, extrusion seamless square tube.  
According to the surface treatment: hot dip galvanized square tube, electric galvanized square tube, oil coated square tube, pickling square tube  
According to the material: plain carbon steel square tube, low alloy square tube.  General carbon steel is divided into: Q195, Q215, Q235, SS400, 20# steel, 45# steel;  Low alloy steel is divided into Q345, 16Mn, Q390, ST52-3, etc.  
Classification by section shape :(1) simple section square tube -- square tube, rectangular tube (2) complex section square tube -- flower shape square tube, open shape square tube, corrugated square tube, special-shaped square tube
Classified by use - square pipe for decoration, machine tool equipment, machine industry, chemical industry, steel structure, shipbuilding, automobile, steel beam and column, special purpose square pipe  
Classification by wall thickness - ultra thick wall square tube, thick wall square tube and thin wall square tube

How to store square pipe?  
The storage site or warehouse of steel pipes should be in a clean place with unobstructed drainage and away from factories and mines that produce harmful gas or dust.  Remove weeds and all debris from the site and keep the steel pipe clean.  The warehouse requires attention to ventilation in sunny days, attention to moistureproof in rainy days, and often maintain a suitable storage environment  
When the square tube is put into the warehouse, it is necessary to check whether the warehouse is absolutely dry and whether there is moisture.  If the warehouse is too wet, square pipes are not suitable.  The warehouse should be cleaned out.  If the warehouse leaks, fix the leak before continuing to use it.  Check the square pipe for rust before entering the warehouse.  Nowadays, seamless processes are commonly used to prevent rusting of square tubes.  Where rust is found, all rust should be removed before continuing use.  
If the rust is too severe, such square tubing is not suitable for storage and should be used at short notice.  If necessary, you can also apply some anti-rust oil to prevent rust.  Nodular cast iron pipes should also be noted.  They are, after all, square tubes that rust easily.  Rust not only affects the appearance, but also affects the use of square tube.