Does Stainless Steel Pipe Need Cathodic Protection

Due to its excellent comprehensive properties, stainless steel not only has good corrosion resistance, but also has high strength, high temperature and pressure resistance, radiation resistance and low temperature resistance. It plays an important role in the fields of petroleum, chemical industry, energy, aerospace and marine development. However, stainless steel can suffer from pitting corrosion, crevice corrosion, stress corrosion and other local corrosion under specific environment and conditions. These local damage or performance degradation can lead to sudden accidents. Cathodic protection is one of the most effective means to protect stainless steel from local corrosion damage and ensure its service life.

Cathodic protection refers to the method of applying cathodic current to the metal material to be protected so that only the reduction reaction takes place on the cathode, while the oxidation reaction takes place on the auxiliary electrode, so that the metal is protected from corrosion due to taking away electrons. Appropriate cathodic protection can protect the passive film of stainless steel and reduce the uniform corrosion of the sample surface. When the metal surface is polarized by the cathode, the adsorption of Cl - on the metal surface is blocked, which avoids the destruction of the passivation film and reduces the risk of local corrosion. For the existing cracks and pitting defects, the cathodic protection can increase the pH near the metal / solution interface and effectively inhibit the autocatalytic process.

Pipeline cathodic protection is an internationally recognized anti-corrosion technology, and the anti-corrosion effect is particularly significant. Generally speaking, cathodic protection is required for pipelines that will corrode and pipelines with high requirements for pipeline rust prevention, such as buried pipelines and pipelines used in water. Overhead pipelines generally do not need cathodic protection, because most of the air (dry, normal pH, no pollution) will not cause corrosion.

Cathodic protection is widely used in buried pipelines and metal structures in seawater environment, which can minimize the corrosion of corrosive ions such as Cl -, microorganisms and other substances in the environment, and extend the service life of pipelines.