Square and rectangular steel tubes, also known as equal-sided steel pipes. They are formed by rolling steel strips through a process. Typically, steel strips are unpacked, leveled, curled, and welded into round tubes, which are then rolled into square tubes and cut to the desired length. Generally, there are 50 tubes per package.

Also known as square and rectangular cold-formed hollow section steel, commonly referred to as square tube and rectangular tube, with codes F and J respectively.

1. Allowable deviation for square tube wall thickness: when the wall thickness is not greater than 10mm, it should not exceed ±10% of the nominal wall thickness; for wall thickness greater than 10mm, it is ±8% of the wall thickness, excluding the bend and weld areas.

2. The standard delivery length for square tubes is typically 4000mm to 12000mm, with 6000mm and 12000mm being the most common. Square tubes may be delivered in short lengths of not less than 2000mm or in non-standard lengths, and can also be supplied as joint tubes, but the customer should remove the joint tubes upon use. The weight of short lengths and non-standard products should not exceed 5% of the total delivery quantity, and for square tubes with a theoretical weight greater than 20kg/m, it should not exceed 10% of the total delivery quantity.

3. The bend of the square tube shall not exceed 2mm per meter, and the total bend shall not exceed 0.2% of the total length.