With such downsides to Cathodic protection, it would only be natural to ask: Are better options available?
The higher durability requires less maintenance and extends the lifespan of screens and filters, ultimately saving the industry precious stakeholders’ time and money in the long-term.
If better corrosion resistance can be obtained by upgrading the steel, the traditional choice of 316L steel for ballast water screens, which necessitates Cathodic protection, needs to be re-evaluated.
BOTTOM LINE
ALTERNATIVES TO CATHODIC PROTECTION
One of the best alternatives to Cathodic protection is using a higher grade stainless steel for ballast water filtration. For example, 904L steel eliminates the need for Cathodic protection altogether. Traditionally used in the high- technology, aerospace, and chemical industries, 904L is also famously utilized in Rolex’s luxury watches. It has been chosen by luxury watch manufacturers thanks to its higher polish and water-corrosion resistance, enabling wearers to go about their daily business wearing the high-ticket accessory worry-free.
Austenitic stainless steel 904L has a higher percentage of nickel and chromium than 316L steel, in addition to copper. Its composition provides it with superior corrosion resistance capabilities, rendering Cathodic protection unnecessary.
Indeed, 316L steel is the traditional staple coating historically relied on by the ballast water market, and as such, it is regularly produced and widely available. But while 904L is less common, it is still relatively available, and can be supplied with excellent lead time.
Though the initial cost of 904L steel is higher than that of 316L steel, due diligence processes have found that the benefits of applying 904L steel for ship ballast filters in seawater applications far outweigh the costs.
94 | The Report • June 2021 • Issue 96
Using Cathodic protection to prevent corrosion of ballast water filter screens made of 316L steel requires more frequent maintenance and part replacements, leading to increasing costs over time. The sacrificial anodes used in Cathodic protection stimulate the formation of scale, which clogs the screens. Installation of Cathodic protection is complicated, and the anodes need to be immersed in an electrolyte for a significant portion of the voyage. Overall, Cathodic protection is complicated to install and is a less durable corrosion prevention approach than other existing solutions available in the market today, such as using a higher grade stainless steel.
Several parameters have been used to evaluate corrosion prevention approaches for ballast water filtration systems, including Pitting Resistance Equivalent Number (PREN), Pitting Resistance Accelerated Test, corrosion rates in acidic conditions, and natural seawater tests. A new comparative analysis of corrosion resistance approaches is now available for download in a special free white paper.
Filtersafe® products filter 25% of the world’s ballast water. It is a world leader in automatic water filtration, specializing in self-cleaning, high-capacity fine-mesh filters. Using patented and leading-edge technologies, Filtersafe’s seawater filters for ballast water bring unrivalled value and environmental responsibility to numerous industries. The company’s filters’ tailored designs and simple modularity enable supplies from 10 microns upwards, with flow rates from 50-6840m³/hr in a single unit and limitless capacity in a modular configuration. To optimize ballast water filters’ protection, Filtersafe has shifted its focus to 904L steel due to its exceptional durability.
Source: Filtersafe
For more information, visit
https://filtersafe.net/
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