Views: 0 Author: Site Editor Publish Time: 2023-04-19 Origin: Site
The mechanical equipment was exported by sea and upon arrival at the shore, it was found that there were rust issues on the surface of some equipment and some parts. The customer raised doubts about the quality. Why did it still rust even though transportation protection was in place? What are the reasons for equipment corrosion during sea transportation? How to carry out rust prevention protection? This article aims to explore the reasons for equipment corrosion during sea transportation and how to prevent it.
Electrochemical Corrosion as the Main Cause of Rust on Maritime Equipment
There is a large amount of electrolyte in seawater, and steel contains iron and carbon, forming a primary battery. Iron is the negative electrode, which loses electrons and is oxidized, resulting in corrosion. Mainly due to the micro defects in the surface coating of the equipment and the unevenness of the surface of the component substrate, corrosive media or water can penetrate the surface paint film and enter the surface of the steel component substrate, leading to corrosion and rusting.
Corrosion Risk to Ordinary Carbon Steel During Shipping by Sea
When shipping by sea, seawater has a strong corrosiveness. Even without direct contact with seawater, air containing seawater can easily cause corrosion of ordinary carbon steel.
Surface treatment issues with fasteners
Fasteners treated with electroplating have relatively mild corrosion, while fasteners treated with blackening have more severe corrosion.
Electroplating and blackening are commonly used surface treatment methods for connectors, but their ability to prevent rust varies and their usage scenarios also vary. Although the electroplating layer has good protective properties on the surface of steel, if the pre-treatment before electroplating is poor, the coating is uneven, or the thickness does not meet the rust prevention requirements, the protective ability will be greatly reduced. In addition, if the protection during transportation is not in place, the coating may be damaged due to collision or other external factors, which not only fails to prevent rust, but also accelerates the corrosion of the steel substrate.
Quality defects in spraying primer
The painting of the entire equipment has two main functions: decorative and surface protection (waterproofing, insulation, rust prevention, etc.)
Defects in the quality of the primer, as well as collisions during transportation and assembly, may cause localized corrosion. Once the paint layer is damaged, it can expose the steel surface and come into direct contact with damp sea air, making it prone to corrosion.
Due to the need to achieve rust prevention under long-term, high moisture, and salt spray conditions during sea transportation, unconventional corrosion inhibitors are not suitable. Moreover, traditional rust preventive oils are not suitable for rust prevention of mechanical and electrical equipment:
Firstly, the equipment has a large volume and cannot be immersed in oil, while the brushing method is very time-consuming.
Secondly, electrical components such as circuit boards, contactors, and air switches cannot be oiled.
Finally, the oil has a strong odor, pollutes the environment, and requires additional cleaning costs, which affects the user experience.
For equipment export transportation, vapor phase anti rust materials can be used for rust protection. Vapor phase anti rust materials continuously volatilize VCI vapor phase corrosion inhibitor gas, adsorb on the metal surface to form a gas protective layer, blocking water and oxygen in the air from corroding the metal. Compared with rust preventive oil, vapor phase rust prevention has advantages such as cleanliness, environmental protection, safety, and comprehensive rust prevention. This is based on the characteristics of gases, which penetrate into the interior of mechanical and electrical equipment without any holes, achieving the protective effect on all metal surfaces
