1. The allowable deviation of the wall thickness of rectangular pipes shall not exceed ± 10% of the nominal wall thickness when the wall thickness is not greater than 10mm, and ± 8% of the wall thickness when the wall thickness is greater than 10mm, except for the wall thickness in the bending and welding areas.
2. The typical delivery length of square rectangular tubes is 4000mm-12000mm, with a majority of 6000mm and 12000mm. Square rectangular tubes allow delivery of short and non fixed length products not less than 2000mm, and can also be delivered in the form of interface tubes, but the purchaser should cut off the interface tubes when using them. The weight of short and non fixed length products shall not exceed 5% of the total delivery quantity, and for square tubes with a theoretical weight greater than 20kg/m, it shall not exceed 10% of the total delivery quantity.
3. The curvature of the square tube shall not exceed 2mm per meter, and the total curvature shall not exceed 0.2% of the total length.