As the demand for spiral steel pipes in the market increases, the requirements for spiral steel pipes are also getting higher and higher. However, due to different industries and use environments, the quality of spiral steel pipes is also different. What should be paid attention to when purchasing spiral steel pipes?
1. The trademark and printing of high-quality tubes are relatively standard.
2. The composition of high-quality steel is uniform, the tonnage of the cold shear is high, and the end surface of the cutting head is smooth and regular. However, due to poor raw materials, the end surface of the cutting head often has the appearance of falling flesh, that is, it is uneven and has no metallic luster. Moreover, because the products of residual material manufacturers have fewer heads, big ears will appear at the head and tail.
3. Inferior spiral steel pipes often have pockmarks on the surface. The pockmarked surface is due to the serious wear and tear of the rolling groove, which causes the irregular and uneven surface of the steel. Because manufacturers of inferior spiral steel pipes want to pursue profits, there are often overruns in grooving and rolling.
4. The surface of defective spiral steel pipe is prone to scarring.
5. Cracks are easy to occur on the surface of the residual material, because its billet is adobe, and the adobe has many pores, and the adobe is subjected to thermal stress during the cooling process, causing cracks, and there are cracks after rolling.
6. Inferior thick-walled spiral steel pipes are easy to scratch. The reason is that the inferior spiral steel pipe manufacturers have poor equipment, which is prone to burrs and scratches on the surface of the steel. Deeply scratches the strength of falling steel.
7. Inferior spiral steel pipes have no metallic luster and are light red or similar to pig iron
8. For large threads with a diameter of more than 16 for three-helix steel pipes, the distance between the two trademarks is more than IM.
9. The longitudinal bars of defective steel rebar is often wavy.
10. Because there is no driving, the inferior spiral steel pipe manufacturer packs loosely. side oval
11. The transverse ribs of inferior spiral steel pipes are thin and low, and often appear to be full and dissatisfied. The reason is that to achieve a large negative tolerance, the reduction in the first few passes of the finished product is too large, the iron shape is too small, and the pass is not full.
12. The cross-section of the defective spiral steel pipe is elliptical. The reason is that to save materials, the reduction amount of the first two passes of the finished roll is too large. standard.
13. The material of the defective spiral steel pipe contains many impurities, the density of the steel is relatively small, and the scale is seriously out of tolerance, so it can be weighed and checked without a vernier caliper.
14. The inner diameter of the inferior spiral steel pipe fluctuates greatly.
15. Inferior spiral steel pipes are prone to folding. Folding is a variety of fold lines formed on the surface of the spiral steel pipe, and this defect often runs through the longitudinal direction of the entire product. The reason for the folding is that the defective manufacturers pursue high efficiency, and the reduction is too large, resulting in ears. Folding occurs during the next rolling process. The folded product will crack after bending, and the strength of the steel will drop greatly.
Post time: Dec-16-2022