Integrity Detection and Evaluation of Corrosion Protection Layer of Steel Pipeline

The external anticorrosive coating and cathodic protection system of buried oil and gas steel pipeline are important means to protect the safe operation of pipeline. For example, the damage of external anticorrosive coating or the failure of cathodic protection will accelerate the corrosion of pipeline body, cause the damage and perforation of pipeline body and lead to oil and gas leakage, which will cause serious harm in many aspects. The corrosion of steel pipelines is mainly divided into internal corrosion and external corrosion. The main influencing factors of internal corrosion are the physical and chemical characteristics of the transported medium and impurities in it; The causes of external corrosion include external force damage of external corrosion coating, quality defect of external corrosion coating, quality defect of steel pipe and corrosion of soil environment where pipeline is buried. At present, the main development direction of corrosion control of foreign oil and gas pipelines in China is external corrosion protection. 　

The external corrosion protection methods of pipelines mainly include environmental treatment method and surface coating method:

Environmental treatment method: it is to change the environment of the pipeline without affecting the process, thus reducing the corrosiveness;Surface coating method: it is to coat anticorrosion layer on the surface of pipeline.

The common method for external corrosion control of buried oil and gas steel pipelines is to adopt the combined protection method of anti-corrosion coating and cathodic protection. Proper selection and use of anti-corrosion coating can provide more than 90% protection for well-laid pipelines.

Detection content: 

· Fine detection of buried pipeline position; 

· Probe into the position of the damaged point of the anti-corrosion coating of buried pipeline; 

· Quality inspection and evaluation of external anticorrosive coating of buried pipeline; 

· Repair of damaged external anticorrosive coating of buried pipeline; 

· Detection and evaluation of cathodic protection performance of buried pipelines; 

· Detection and treatment of stray current in buried pipelines; 

· Maintenance and rectification of cathodic protection for buried steel pipelines; 

· Design, installation and construction of cathodic protection for buried pipelines.