Square and rectangular tubes, a term for steel tubes with equal sides, are made by rolling steel strips through a process. Typically, steel strips are unpacked, leveled, curled, and welded into round tubes, which are then rolled into squares and cut to the required length. They usually come in packages of 50.

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

1. The allowable deviation for square rectangular tube wall thickness is as follows: 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.

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

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