1. The allowable deviation of the wall thickness of the square tube shall not exceed plus or minus 10% of the nominal wall thickness when the wall thickness is not more than 10mm, and plus or minus 8% of the wall thickness when the wall thickness is more than 10mm, excluding the wall thickness of the corners and weld areas.

2. The usual delivery length of the square tube is 4000mm-12000mm, with 6000mm and 12000mm being the most common. Square tubes are allowed to deliver short-length and non-fixed-length products of not less than 2000mm, and can also be delivered in the form of interface tubes, but the demander should cut off the interface tube when using it. The weight of short-length 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

2. The usual delivery length of the square tube is 4000mm-12000mm, with 6000mm and 12000mm being the most common. Square and rectangular tubes are allowed to be delivered in short lengths and non-fixed lengths of not less than 2000mm. They 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 length and non-fixed length products shall not exceed 5% of the total delivery quantity. For square and rectangular tubes with a theoretical weight greater than 20kg/m, it shall not exceed 10% of the total delivery quantity.