BATTLING CORROSION ABOARD SHIPS - Part 3

Strategies for Prevention

Preventive measures will decrease maintenance costs, early system failures, and an overall improve service life of ships granted they are detected in enough time.

a. Modifying the Corrosive Environment

Hence, Inhibitors are salt water or electrolyte solutions which are controlled. Anodic inhibitors migrate to the anode creating a protective barrier which as a result, stops corrosion in its tracks. Therefore, Cathodic Inhibitors migrate to the cathode which prevents the absorption of oxygen or hydrogen.

In addition, Cathodic protection uses sacrificial metal to act as the anode which creates a protective barrier. This metal deteriorates first instead of the ships protected layers.

For example on the hull of a ship, zinc plates prevent corrosion of any sub-surfaces.

b. Protecting the Corrosive Environment

As a result, in the hope of protecting the vessel coat it with three different paint solutions.

Binders – Therefore, the binder is a film forming component of paint.

Pigments/Extenders – these powders mix with the binder at various particle sizes and enhance the overall effectiveness of the binders.

Solvents -Eventually evaporate from the surface and help for easy application.

In conclusion, it is important to have the proper plating before the equipment is put to work. As a result the equipment will last longer and will become resistant to the elements.

Importance of Corrosion Protection During Storage and Transportation

Products that are transported for a longer period of time or stored for an extended period are often in need of corrosion protection. Corrosion protection packaging prevents corrosion without having to treat the metal with oil, grease or paint.

Corrosion is a significant problem in the handling, storage and shipping of products. Bare metal parts corrode easily. Temperature changes, contaminated air, sea salt and moisture, all create corrosion. 

Due to temporary corrosion, time is diverted to handling complaints and customer loyalty is potentially lost. Delayed deliveries due to reworking of corroded components translate to avoidable losses. Therefore, planning for corrosion protection during temporary storage and transportation is a logical strategy to minimize these losses.

There are several different solutions for protecting the product from corrosion depending on parameters such as: product type, means of transportation, and the length of the transit time.

The Importance of Temporary Corrosion Protection

There are many industrial applications where temporary corrosion protection during transit and storage is critical for the final processing and end use of parts and components. If semi-finished or machined components are left unprotected, or roller bearings are not coated with a rust inhibitor during storage, or internal combustion engines are transported and stored without corrosion prevention, then they may deteriorate or become damaged due to corrosion. Any subsequent rust removal will not restore a component to its original quality and geometrical accuracy. 

Permanent corrosion protection cannot be used for temporary applications because it must be removed before further processing or assembly. Because corrosion can appear within hours or days a temporary corrosion prevention method must be implemented.

During transportation and storage, fasteners (e.g., wedges, springs, bolts, nuts, washers, screws) and associated tools require protection from corrosive chemical reactions on their surfaces. 

General Care for Preventing Corrosive Deterioration

Desiccants to control air humidity are used to prevent corrosive deterioration during storage and transport. Silica gels and molecular sieves are occasionally used as desiccants to absorb excess air moisture. Sealed films of high pressure polyethylene and special waterproof and airproof packaging systems are used for critical applications.

Cost, Safety and Health

Allowing temporary corrosion and rust on materials during interstage processes and transportation is costly due to the direct and indirect costs involved in rework and warranty damages. When carefully chosen, preventive solutions are cost effective for both application and subsequent removal.

For confined spaces, authorized specialists must be consulted. Ensure compliance with personal protective equipment (PPE) and firefighting regulations.

The combustion products of coatings can be highly toxic. Hence exposure control must be planned for in advance. Precautions should be taken to avoid eye contact and skin exposure with proper PPE suitable for the application method used. Respiratory protection might be needed in a few cases.