Details of common 3PE anti-corrosion steel pipes

First, why can 3PE anti-corrosion steel pipes be anti-corrosive?

3PE anti-corrosion steel pipes mean three layers of anti-corrosion PE steel pipes. 3PE anti-corrosion steel pipes are widely used today and are a type of steel pipe with good corrosion resistance. What anti-corrosion materials are the structure of 3PE anti-corrosion steel pipes made of? What are the principles of 3PE anti-corrosion steel pipes to prevent corrosion?

1. Pipeline anti-corrosion usually adopts two common main means: external coating and cathodic protection.

2. Although most of the surface of the pipeline is covered with a coating, a slight leak will produce an unimaginable corrosion rate, even perforation or cracking. Therefore, in pipeline anti-corrosion, the coating system and cathodic protection are usually used together to achieve 100% coverage to avoid unimaginable consequences in the future.

3. The cathodic protection used for pipeline anti-corrosion is divided into sacrificial cathodic protection and impressed current cathodic protection.

4. The purpose of using coating for a 3PE anti-corrosion steel pipeline is to form a continuous covering layer of insulating material, which directly insulates the electrolyte in direct contact with the metal so that the correct electrolytic reaction cannot occur.

5. The discontinuous points in the coating laying process are called leak points. The main reason for their occurrence is the coating, transportation, or installation process. It may also be caused by coating aging, soil stress, or pipeline movement in the soil. The damage caused by the third party is not discovered in time.

6. Principle of impressed current cathodic protection: by applying amplitude current to the protected metal, through cathodic polarization, the potential of all cathode points reaches the open circuit potential of the most active anode point, and the corrosion on the structure stops.

7. Composition of impressed current cathodic protection: rectifier and constant potentiostat

8. Rectifier: converts AC into DC.

Second, the difference between reinforced 3PE anti-corrosion steel pipe and ordinary 3PE anti-corrosion steel pipe

At present, there are two standards for 3PE anti-corrosion steel pipe, namely GB/T 23257-2009 and GB/T 23257-2017. GB/T 23257-2017 is a new standard and was implemented in December 2017. The two standards differ mainly in the following aspects:

1. The design temperature of the anti-corrosion layer is different. The old standard (GB/T 23257-2009) is 50 degrees at room temperature, 70 degrees at high temperature, 60 degrees at room temperature, and 80 degrees at high temperature.

2. The thickness of the anti-corrosion layer of the 3PE anti-corrosion steel pipe weld is not less than 70% of the old standard and 80% of the new standard.

3. The thickness of the epoxy powder in the old standard is greater than or equal to 120 microns, and the new standard is greater than or equal to 120 microns for steel pipes with a diameter less than 500, and greater than or equal to 150 microns for steel pipes with a diameter greater than or equal to 500.

4. The total thickness of the anti-corrosion layer is the same for the old and new standards for less than 1200. The old standard for diameters greater than 1200 is 3.0 mm, and the reinforcement level is 3.7 mm, while the new standard is 3.3 mm, and the reinforcement level is 4.2 mm.

5. Other aspects are better than the old standard.