What to do if 316L thick-walled stainless steel pipes corrode

Because 316L thick-walled stainless steel pipes are corrosion-resistant, impact-resistant, and high-temperature resistant, they are commonly used in pharmaceuticals, chemicals, food, light industry, chemical machinery, industrial pipelines, and mechanical parts. Of course, thick-walled stainless steel pipes are also suitable for the production and manufacturing of exhaust pipes and various basic pipelines. However, corrosion can occur in thick-walled stainless steel pipes after a period of use. So, what should be done if 316L thick-walled stainless steel pipes corrode?

We know that when 316L thick-walled stainless steel pipes are corroded by thermocouples, the anodic oxidation is destroyed, and the negative electrode is protected. If we try to keep the thick-walled stainless steel pipe as a negative electrode from beginning to end, then the thick-walled stainless steel pipe will not easily corrode. This anti-corrosion method is called pipeline cathodic protection. This is also a method in pipeline protection. It not only uses movable metal material as a protective film, but also destroys movable metal material, protecting the metal material components. Further scientific research on thick-walled stainless steel pipes can also perform anodizing without destroying the anodic oxidation. Therefore, cathodic protection methods can be divided into protective film methods and electrical equipment protection methods.

Using a relatively active alloy as a protective film, it is inserted into the surface of the 316L stainless steel welded pipe, or connected to the protective metal material with a transmission line, making the protective film and the protective metal material the two sides of a galvanic cell reaction. Since the protective film is an active metal material, it has an anodic oxidation effect in the cell, and is damaged by corrosion from air oxidation. The protective alloy acts as the negative electrode, and the original small rechargeable battery terminates or weakens at the negative electrode, then the protective metal material component is damaged. When the protective film is about to rust, it can be replaced with another protective film.

Therefore, this anti-corrosion method is a protection method for thick-walled stainless steel pipes, also known as cathodic protection. For example, there are zinc blocks in gas-fired steam boilers, and zinc is often embedded around ship propellers. Zinc is more reactive than iron, so zinc slowly corrodes and protects the heating furnace and aircraft propellers. During electrolysis, the electrode connected to the negative terminal of the switching power supply is not easily damaged. In this electrode, electronic devices are unnecessary, so the negative-walled 316L thick-walled stainless steel pipe itself cannot lose electronic devices and becomes a positive ion.

In other words, the negative electrode is not easily damaged. Based on this fundamental principle, we can use an external current to connect the thick-walled stainless steel pipe to the negative terminal of the switching power supply as the negative connection, and set the auxiliary power supply and the positive terminal of the switching power supply as the anodizing connection, then maintain the negative mechanical equipment. Anodizing can be applied to some wastewater pipes, old train tracks, etc., where corrosion occurs slowly under low conditions. This method is similar to the protective film method.