Marine Engineering Services: Cathodic Protection Systems

Today, a great deal of steel’s infrastructure is seriously being threatened by a persistent and highly destructive agent. What is it? Corrosion. If you’re a marine facility owner, it’s decaying at this very moment if it’s not adequately protected. The corrosion rate for bare, clean steel is a minimum of 5 mils a year. This key loss in thickness can be potentially increased by various elements such as water velocity, water composition, and highly-oxygenated cells relative to marine growth.

Several owners of marine facilities mistakenly think that submerged steel coating doesn’t need any cathodic protection at all. But, research proves that as much as half of the coating on these submerged steel structures is either damaged, or entirely eliminated when under construction. Even perfectly intact coatings can potentially be affected by existing minute pinholes that often result in an increase of concentrated spots of corrosion. This relentless type of pitting corrosion can significantly boost the rate of corrosion as high as 80 mils a year, which can lead to 1/4″ steel plates being fully penetrated in four years or less.

It’s generally used together with coatings and is commonly thought of as a backup corrosion management practice. The main corrosion management technique on any given submerged steel structure is typically a system ranging in efficiency anywhere between 50 – 99 percent, based on the installation method, type, and age.

An adequately maintained and designed cathodic marine protection system will address what’s left leading to a 100 percent efficient and capable protection system.

Is using these kinds of systems really necessary? Consider the following information to answer that question:

• Benefits and Uses of Cathodic Marine Protection 
The main benefit of using cathodic protection instead of other kinds of anti-corrosion methods is that it’s simply applied by retaining a DC circuit in addition to continuously monitoring its overall effectiveness.

• The Philosophy of Cathodic Protection 
Metal that’s mined from its fundamental ore has a natural inclination to try and revert back to its original state through the action of water and oxygen. This particular action is what’s known as corrosion and the most typical example of it is rusting steel.

• Corrosion Costs Big Dollars 
It’s estimated between 3 – 5 percent of the GNP (Gross National Product) of all developed countries stems from damage due to corrosion. Metal corrosion can cost an average economy nearly $300 billion each year. It’s also estimated that almost one third of this expense could be avoided by choosing better preventative methods for corrosion.

Cathodic marine protection is generally applied to a certain coated steel structure in order to provide adequate corrosion management to key areas where the coating itself is more vulnerable or damaged and may be also be applied to existing steel structures in order to extend their longevity.