20x160 square tube process, galvanized strip 30x190 square tube, 20x100 square tubeLarge diameter square tubes, also known as square cold-formed hollow sections, commonly referred to as square tubes or square steel pipes, are characterized by their equal side lengths. They are made by rolling steel strips after processing. Typically, steel strips are unboxed, leveled, curled, and welded into round pipes, which are then rolled into square shapes and cut to the required length.

There are mainly two production processes for square steel tubes: welding formation and seamless formation. The materials commonly used in these processes include Q235, Q345, and 20#. Q235 can be used in the welding process, while 20# can only be used in the seamless production process. Q345 material is suitable for both processes.

2. The allowable deviation for the wall thickness of square steel tubes: when the wall thickness is not greater than 10mm, it should not exceed ±10% of the nominal wall thickness; when the wall thickness is greater than 10mm, it is ±8% of the wall thickness, excluding the bend and weld areas.

3. The standard delivery length for square steel tubes is typically 4000mm-12000mm, with welding processes commonly in 6000mm and 12000mm lengths, while seamless processes are most frequent in 9000mm-11000mm lengths. Large-diameter square steel tubes may be delivered with short lengths of not less than 2000mm and non-standard sizes, and can also be supplied in joint pipe form, but the customer is required to cut off the joint pipe upon use. The weight of short lengths and non-standard products should not exceed 5% of the total delivery quantity, and for square steel tubes with a theoretical weight greater than 20kg/m, this should not exceed 10% of the total delivery quantity.

4. The bend radius of square tubes should not exceed 2mm per meter, and the total bend should not exceed 0.2% of the total length.

5. Square and round tube weight calculation:

The formula for converting from round to square: (Side length + Side length) ÷ 2 x 1.29 - Thickness = Outside Diameter of Round Tube

Calculating the weight per meter of round tube: (Diameter - Thickness) x Thickness x 0.02466