Marine corrosion is the degradation of materials at sea. With extreme moisture levels, seawater, waves, and the wind to contend with, it’s not surprising that equipment gets damaged far quicker out on the ocean than on land. As many industries depend on the sea, corrosion is a pricey problem. In fact, it takes away about 4% of the Gross National Product.
Offshore equipment manufacturers, however, are adapting their sea-equipment to these inhospitable conditions. Facilities in Houston, for example, are redesigning their products to cater to the high demand for more durable machines.
What is Marine Corrosion?
Marine corrosion in ships, structures, and other equipment is caused by the salt water that they are exposed to. The unique atmospheric conditions while near or at sea also cause this type of corrosion.
The most common problem is aqueous corrosion. This electrochemical process begins when alloys or metals come in contact with the varying pH levels of the water. The salt content, in addition, makes for an efficient electrolyte. The altering the balance of charges on a metal surface can make it more susceptible to oxidation.
The issue does not only affect materials submerged in water. Splash and sea mist can also speed up the corrosion process for metals.
While the seawater plays an important role in corrosions, there are other, more subtle factors that speed up the process. These “allies” help saltwater along with the process of corrosion. Here are some of them:
Stress areas – stress in a structure is often not equally distributed. This results in high-tension areas which are more likely to corrode.
Formation of small holes – through deposits of small amounts of water or through impact, it is possible that small holes or cavities can form on surfaces. These cavities compromise the protective layers on a surface, revealing a much more vulnerable layer underneath.
Biological factors – sea creatures, including microbiological organisms, can contribute to chipping protective layers away. This will allow corrosion to set in. Sulfate-reducing bacteria are also common enemies of steel and copper surfaces.
Manufacturing Techniques that Fight Corrosion
Manufacturing methods have evolved to minimize losses due to corrosion. These resistive applications increase the reliability of marine structures, prolonging their service lives. Some of them are more effective than others, so careful consideration of the industry’s specific requirements is still necessary.
Painting – special marine-grade paint can prevent seawater from seeping into the corrosive surface.
Cathodic protection – this method uses “sacrificial” anodes. Strategic placement of the anodes is necessary for the solutions.
Using corrosion-resistant alloys – mixes of alloys and other metals can be very resistant to corrosion. A concern with this method is its prohibitive cost, however, as corrosive metals are usually more expensive.
Prevention of Marine Corrosion
The factors that contribute to corrosion have been identified. This makes it an easier to focus efforts on how to avoid the problem. By choosing the right materials, performing regular inspections, and conducting proper maintenance activities, marine corrosion does not have to be a major concern for sea-based industries. Consulting with experienced manufacturers along with making good material choices will make it possible to have equipment that can stand this challenge.