## 4 Corrosion Protection Measures
### Anticrovise Coating
#### 4.1.1 Organic Anti-Corrosion Coating  
Organic corrosion-resistant coatings are the most widely used type of corrosion-resistant coatings. Organic coatings typically possess excellent electrochemical, chemical, and mechanical properties, allowing them to effectively perform their physical barrier function. In environments where corrosive media penetration is more severe, coatings containing corrosion inhibitors can be used to provide additional protection. Some organic coatings can also achieve electrochemical protection through sacrificial anodes by incorporating metal anode materials. (1) Good electrochemical properties  
Theoretically, in a complex corrosive environment, it is inevitable that the corrosive medium permeates the organic anticorrosive coating to contact the protected metal, so the coating is often used in conjunction with cathodic protection. However, in the cathodic protection operation, ions combine to generate alkali, which affects the anticorrosive coating and accelerates the peeling of anticorrosive coating [86]. Some coatings are too insulating, thus isolating the protection current. Therefore, according to [PERSON] [87], it is better to carry out a cathodic stripping test before the organic coating is used as a pipeline anticorrosive coating for the project; the radial stripping distance of the anticorrosive coating around the defect should not exceed 12.5 mm after the test. Figure 3: Anti-corrosion measures commonly used in pipelines (**a**,**b**). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Type of Coating** & **Classification** & **Characteristics** & **Advantages** & **Disadvantages** & **Applications** \\ \hline \multirow{6}{*}{ \begin{tabular}{c} Asphalt-based coating \\ \end{tabular}  } & Petroleum & \multirow{4}{*}{Rust removal requirements are not high; Poor resistance to mechanical damage; Resistance to soil surplus stress differences; improved, and it will not be damaged by microorganisms} & Low cohesive force, easily eroded by soil bacteria and penetrated by plant roots and relatively short service life. & Non-cohesive soil with low humidity \\ \cline{2-6}  & Petroleum & & Good electrical insulation, water resistance, and chemical resistance. & & \\  & & & & \begin{table}
\begin{tabular}{c c c c c c} \hline
**Type of Coating** & **Classification** & **Characteristics** & **Advantages** & **Disadvantages** & **Applications** \\ \hline  & & & & & Bonding ability with steel is not strong, especially at \\  & & & & & high temperatures. The \\  & & & & & \\  & & & & & coordination with the \\  & (Z-Layer & Bottom layer binder, top & permeability, good anti-corrosion & cathode protection is poor, and under the action of & Commonly used in \\  & Polyethylene) & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\  & & & & & \\ \end{tabular}
\end{table} 
Table 2: Cont. (2) Good chemical properties  
In modern engineering, metallic pipelines are often used as permanent underground facilities, with long design service life and large investments in manpower and material resources for maintenance and repair. Moreover, pipelines are mostly located in sparsely populated areas (except urban underground pipelines) [88] and sometimes pass through acid and alkali, swamps, and industrial pollution areas. Therefore, the coating must be able to resist acid, alkali, and some mixed solutions. Researchers such as [PERSON] [89] studied the chemical properties of organic anticorrosive coatings using simulation methods and then used SEM to observe coating performance, for example, coating cracking, dissolution, peeling, etc. They also carried out adhesion detection. (3) Good mechanical properties  
Usually, the operating environment of buried pipelines is complicated. Landslide disasters along the pipeline can threaten the safety of construction personnel during the pipeline construction and can also cause deformation and damage to the pipeline during the operation period, including serious pipeline rupture and oil and gas leakage, leading to explosions.