Corrosion in Marine Environments and Material Selection
Recently, an online news story caught our attention: A car owner drove their vehicle to the seaside for a "car wash," only to find that not only did the car remain dirty, but it also became undrivable. After multiple failed attempts to resolve the issue, the owner had no choice but to call a towing company for help, turning this incident into a cautionary tale against washing cars with seawater.
Many car enthusiasts take pride in keeping their vehicles spotless, but did you know that seawater is one of the worst choices for cleaning your car?
Seawater Car Wash – A Car’s Worst Nightmare
Seawater contains a high concentration of salt, about 3.5%, including compounds such as sodium chloride and magnesium chloride—aggressive enemies of automotive paint and metal components. When a car is washed with seawater, these salts initiate a rapid deterioration process, reacting chemically with the paint and causing it to lose its luster. Over time, the paint may begin to peel and flake, drastically diminishing the car’s appearance.
The damage is even more severe for the chassis. As the car’s undercarriage is constantly exposed, salt deposits accelerate metal corrosion, weakening its structural integrity and compromising stability. This is akin to undermining a car’s foundation, posing a significant threat to driving safety.
Furthermore, seawater is full of impurities, including microorganisms, algae, and sediment. When seawater is used to wash a car, these particles can infiltrate critical components such as the engine bay, radiator, and air conditioning system. Imagine the engine being clogged with sand, leading to overheating or even failure. The air conditioning system could become contaminated with microorganisms, reducing its cooling and heating efficiency. Brake systems may also suffer, as debris can reduce braking sensitivity, increasing stopping distances and endangering road safety.
Additionally, the mild alkalinity of seawater can degrade rubber components, making tires harder and more brittle. This not only shortens their lifespan but also affects traction and handling, making driving dangerously unpredictable.
Material Selection for Heat Exchangers in Seawater Aquaculture and Desalination
From automotive challenges to the marine industries—such as seawater aquaculture and desalination—the selection of materials for critical equipment, like plate heat exchangers, is of utmost importance.
For heat exchanger plates, titanium and titanium alloys are the top-tier choices. With outstanding corrosion resistance, titanium effectively withstands chloride ion attacks, preventing rust and pitting while ensuring long-term, efficient operation. Additionally, its high strength and lightweight properties allow it to withstand seawater pressure without adding unnecessary weight to the system. Industrial-grade pure titanium, such as TA1, is often the preferred option.
Among stainless steels, 316L is a popular choice due to its higher molybdenum content, which enhances its resistance to seawater corrosion. It is also a cost-effective alternative, making it a practical option for aquaculture operations where corrosion exposure is moderate, and cost control is a priority.
For more demanding marine environments, Hastelloy is the premium choice. It offers exceptional resistance to extreme temperatures and high-salinity conditions, maintaining excellent chemical stability. However, due to its higher cost, it is primarily used in high-end seawater aquaculture projects where superior corrosion resistance is non-negotiable.
Seal materials are just as crucial as the plates themselves—comparable to how tires are essential to a car’s performance. Nitrile rubber (NBR) is widely used for its resistance to oil, abrasion, and aging. It also demonstrates good resistance to seawater and maintains excellent sealing performance within a specific temperature range, making it a common choice for plate heat exchangers in aquaculture applications.
Ethylene Propylene Diene Monomer (EPDM) rubber stands out for its exceptional weather resistance, water resistance, and chemical stability. Even after prolonged exposure to seawater, it remains durable and maintains strong sealing performance. This makes it ideal for applications requiring both high corrosion resistance and long-term durability.
Conclusion
Whether it’s protecting vehicles from seawater damage or selecting the right heat exchanger materials for seawater aquaculture and desalination, understanding the properties of seawater and making informed material choices is essential for ensuring performance and longevity. We hope today’s insights help you navigate the challenges of seawater environments and achieve success in your respective industries!
