1. Inferior square tubes will have a lot of burrs on the surface because they are not processed properly, and these burrs will easily scratch the surface of the tube. Therefore, the first identification method came out. The quality of the surface with many scratches is quality. not good.

2. In order to achieve a large negative tolerance, inferior square tube manufacturers will increase the reduction of the product during processing, which will result in thin and low transverse ribs of the finished product. Therefore, it is best not to buy it if it is found to be the case.

3. The reason why the square tube becomes a square tube is that the cross section of the room tube is square, and the inferior square tube is not processed properly in this respect, which will make the cross section of the room tube appear oval.

4. The inferior square tube basically can not reach the standard size, so you can easily distinguish it with a professional ruler when you buy it.