Anti-corrosion measures for long-distance natural gas pipelines

Anti-corrosion measures for long-distance natural gas pipelines

In the actual pipeline transportation process, in essence, pipeline corrosion is a normal phenomenon and cannot be completely avoided. To reduce the impact of pipeline corrosion on natural gas transportation, it can only be mitigated by the application of corresponding measures, and then the pipeline corrosion rate can be reduced. The anticorrosion of long-distance natural gas pipelines can be studied from both physical and chemical aspects. From the physical aspect, the method of adding coatings is mainly adopted, and the chemical aspect is mainly electrochemical protection measures. In most cases, the actual pipeline protection will choose to adopt a combination of physical and chemical protection measures.

(1) Add coating

The main methods of adding coatings include:

First, coal tar enamel paint.

Adding coal tar enamel outside the transportation area is a relatively mature protective measure at this stage. Coal tar enamel not only has a strong anti-corrosion function but also has a certain degree of insulation. It can prevent the pipeline from being affected by stray currents, and it plays a very important role in the protection of the pipeline. Because coal tar enamel has a relatively long service life, its economic efficiency is relatively high, and most of them choose it as the main material for additional coating.

Secondly, the PE two-layer structure.

The addition of the PE two-layer structure on the outside of the transportation pipeline is also a pipeline protection measure that has been used more frequently at this stage. The PE two-layer structure not only has an efficient anti-corrosion function but also has a strong function of inhibiting bacteria. At the same time, the PE two-layer structure also has a strong water absorption capacity, which can greatly prevent the influence of the water in the soil on the operation of the pipeline. Therefore, it is very suitable for long-distance natural gas pipelines.

Finally, the PE three-layer structure.

This PE three-layer structure belongs to the pipeline protection measures produced, and it is also the most effective protection measure at this stage. Compared with the two-layer structure, the three-layer structure adds epoxy powder in the middle link, which not only realizes the improvement of corrosion resistance but also provides assistance for the close combination of the material and the pipeline, so that it can give full play to its protective performance. In addition, because the PE three-layer structure contains epoxy powder, the material will no longer be interfered with by ultraviolet rays and can be used in the sun.

(2) Electrochemical protection

In the actual electrochemical protection of long-distance natural gas pipelines, the cathodic protection method of sacrificial anodes is often used. The principle of this anti-corrosion method for chemical transmission pipelines is very simple. In this primary battery, the anode is the active metal and the cathode is the pipe. The pipe will be protected during the actual corrosion phenomenon.

(3) Cathodic protection of external power supply

In the actual application process, the power supply should be increased on the outer wall of the pipeline, so that the pipeline can be efficiently protected. The reason for the relatively small number of applications is that most natural gas is flammable and explosive. When using this method, it is also necessary to perform a simple calculation of the voltage based on the actual situation.