1. If the surface of the steel pipe you choose is prone to cracks, it will prove that the steel pipe is of inferior quality.Because the billet of this kind of steel pipe is adopt adobe, if encountering thermal stress, it is easy to produce cracks.

2. If the outer layer of your steel tube will have flakes, it will prove to be inferior.

3. If folding often occurs, it will prove to be inferior.

4. High-quality steel tubes are very hard and should not be scraped.

5. The inner diameter of good metal threading tube will not change greatly.

6. The composition of high-quality steel pipe contains very low content of impurities, so it will have a high rigid density.

7. The sections of inferior steel tubes are generally elliptical in shape.