Curtain wall square and rectangular tubes are also known as square and rectangular cold-formed hollow sections, referred to as square tubes and rectangular tubes, codenamed F and J respectively.
1. The allowable deviation of the wall thickness of square and rectangular pipes shall not exceed plus or minus 10% of the nominal wall thickness when the wall thickness is not greater than 10mm. When the wall thickness is greater than 10mm, it shall be plus or minus 8% of the wall thickness. Corner and weld areas Except wall thickness.
2. The usual delivery length of square and rectangular tubes is 4000mm-12000mm, with the majority being 6000mm and 12000mm. Square and rectangular pipes are allowed to be delivered in short length and non-fixed length products of not less than 2000mm, and can also be delivered in the form of interface pipes, but the purchaser should cut off the interface pipes when using them. The weight of short-length and non-fixed-length products shall not exceed 5% of the total delivery quantity, and the weight of square and rectangular pipes with a theoretical weight greater than 20kg/m shall not exceed 10% of the total delivery quantity.
3. The curvature of square and rectangular tubes shall not be greater than 2mm per meter, and the total curvature shall not be greater than 0.2% of the total length.
Process classification
Square and rectangular tubes are divided according to the production process: hot-rolled seamless square tubes, cold-drawn seamless square tubes, extruded seamless square tubes, and welded square tubes.
Section shape classification
Square tubes are classified according to cross-sectional shape:
1. Simple cross-section square tube: square square tube, rectangular square tube.
2. Complex cross-section square tubes: flower-shaped square tubes, open-shaped square tubes, corrugated square tubes, and special-shaped square tubes.