Tackling sea water corrosion
Sea water is a highly corrosive environment, capable of damaging both ferrous and non-ferrous metals through chemical and electrochemical reactions. The combination of dissolved oxygen, chloride anions, and other salts in seawater creates the perfect conditions for corrosion, especially when metals of different grades are exposed to it.
At Vulcan Seals, we've been at the forefront of providing corrosion-resistant mechanical seals to the marine shipping industry for over 25 years. Our 304-grade stainless steel seals have been used in hundreds of marine applications, offering consistent reliability and superior protection against seawater corrosion. Coupled with our commitment to top-notch product design and construction, Vulcan Seals has earned the trust of some of the largest names in the marine industry.
The evolution of 304 Stainless Steel in marine applications
Back in the 1960s, 304 stainless steel had a less-than-favorable reputation for marine applications, largely due to the way components were manufactured. Parts were supplied in their machine-finished state, leaving rough surfaces exposed to the harsh marine environment. The image below shows an example from the 1980s—a seal spring with a coarse surface finish, making it more susceptible to chloride-induced corrosion, resulting in rust and a damaged reputation for 304 stainless steel.
To combat this issue, marine industries shifted toward more expensive materials like 316 stainless steel, brass, or Monel®. Over time, 304 stainless steel became less popular in seawater applications due to its perceived vulnerability.
The benefits of electropolished metal components
At Vulcan Seals, we’ve addressed this corrosion issue by ensuring that all metal components used in our mechanical seals undergo an electropolishing process. This smooth, polished surface not only enhances the appearance of the metal but also significantly reduces its susceptibility to corrosion. The improved quality of modern 304 stainless steel, combined with electropolishing, allows us to offer a cost-effective solution without the need to resort to higher-priced materials.
For example, the uncleaned Vulcan Type 1742S seal on the left (pictured below) has served reliably in a bilge pump over an extended period. Despite prolonged exposure to seawater, the electropolished 304 stainless steel remains largely uncorroded. On the right, you can see a brand new seal with the same electropolished surface finish—a standard feature of Vulcan Seals’ products.
Preventing corrosion in sea water equipment
While electropolishing provides significant corrosion resistance, certain situations can still present challenges. Corrosion may occur in seawater equipment where multiple metals are present, as differing metal grades can create anodic or electrochemical reactions.
One solution is to standardize the metal grades used in your equipment. By using 304 or 316 stainless steel for all internal pump components, you can eliminate the potential for anodic corrosion. Mixing 304 and 316 stainless steel, or similar grades, typically poses no issue and ensures longer-lasting equipment performance.
Contact Vulcan Seals for more information
At Vulcan Seals, we continually strive to enhance the performance and durability of our mechanical seals to meet the evolving needs of the marine industry. If you're interested in learning more about how our electropolished 304 stainless steel products can benefit your operations, please don't hesitate to reach out.
Contact us via the form on this page or email us directly at: contact@vulcanseals.com
