316L stainless steel pipes have excellent seawater corrosion resistance, intergranular corrosion resistance, good high temperature mechanical properties and impact resistance, and are widely used in high-tech fields such as petroleum, chemical industry, nuclear submarines and nuclear reactors. However, inferior finished products not only have unsatisfactory performance but also have a short service life. However, many customers do not know what kind of pipes are inferior products when purchasing. Today, we have compiled some content for you. As long as the 316L stainless steel pipe has one of the following five problems, it is an inferior product.
1. Folding
Fake and inferior welded stainless steel pipes are prone to folding. Folds are various fold lines formed on the surface of the steel pipe. This defect often runs through the entire longitudinal direction of the product. The reason for the folding is that the counterfeit manufacturers excessively pursue high efficiency and the amount of pressing is too large, which causes ears to form in the tube. Folds are formed during the next rolling process. The folded product will crack after bending, and the strength of the tube will be significantly reduced. The surface of fake and inferior 316L stainless steel pipes will have pockmarks. The rough surface is caused by severe wear of the rolling groove, resulting in irregular and uneven surface defects.
2. Scarring
The surface of fake and inferior stainless steel welded pipes is prone to scarring. There are two main reasons for this. One is that the material is uneven and contains many impurities. Another problem is that the manufacturer's equipment is simple, which makes it easy for steel to stick. These impurities bite into the rollers and easily form scars.
3. Crack
The surface of inferior products is also prone to cracks because the blanks are poor quality blanks with many pores. During the cooling process, they are subjected to thermal stress, which forms cracks, and then they will appear after rolling.
4. Large dimensional tolerance
The negative tolerance of inferior 316L stainless steel pipes usually exceeds the regulations. They contain many impurities, have low density, and have serious dimensional deviations. Therefore, if there is no vernier caliper, you can weigh and check them.
5. Others
The surface of inferior stainless steel pipes has no metallic luster and will appear light red or similar to pig iron. There are two reasons for this. One is that the blank is adobe. Another is that the rolling temperature of counterfeit and inferior pipes is not standard. The steel temperature is measured visually, so it cannot be rolled according to the prescribed austenite area, and the performance of the product naturally cannot meet the standards. Inferior welded pipes are also easily scratched because the manufacturer's production equipment is simple, which can easily form burrs and scratch the surface of the steel. Deep scratches will also weaken the strength of the 316L stainless steel pipe.
The above is how to identify inferior 316L stainless steel pipes. If the steel pipe has folds, scars, cracks, large dimensional tolerances, a color similar to pig iron, excessive ovality, etc., it is an inferior product.
Read more: How to Weld 316 Stainless Steel Pipes?
