On metal materials resistant to seawater corrosion

In addition to the materials mentioned above, for pipelines or tubular heat exchangers, low-alloy steels such as 10CrMoAl can also be used. Of course, cathodic protection is required to meet the corrosion resistance requirements. Pipelines or heat exchangers used for transporting seawater can also employ super stainless steel 254SMO; however, it is best to use this material at room temperature, and the flow rate should be increased as much as possible. In the case of plate heat exchangers, titanium or Hastelloy must be used, as copper-nickel alloys and super stainless steels are not suitable for use in plate heat exchangers exposed to seawater.

Why must materials be limited to metallic materials? In fact, PVC pipes can be used to transport seawater at temperatures below 50 degrees, while PP pipes can be used for seawater at temperatures below 100 degrees ； If it is a heat exchanger, graphite heat exchangers can be used entirely; these materials can remain intact in seawater over long periods without corroding. Moreover, the heat transfer coefficient of graphite is much higher than that of carbon steel and stainless steel, which makes graphite heat exchangers particularly suitable for use in seawater environments. For example, the graphite heat exchangers supplied by our company for a seawater desalination project have been in use for three years now, and everything is working properly. :call: 13962096400 B13962096400@126.COM

Currently, the AL2003--2205--Zeron100(2507) type of triple-phase steel is widely used for seawater corrosion protection.

Two-way stainless steel, inexpensive, and offers excellent resistance to seawater

There are also many different types of titanium materials, and composite materials can be used as well; their price isn’t very high either, so it’s actually quite cost-effective if you do the math

Features and Applications of CORTEN-A Weathering Steel ----Steel Encyclopedia ----China Building Materials Network 【Features of weathering steel】 refer to low-alloy structural steels that possess a protective rust layer that resists atmospheric corrosion; they can be used to manufacture steel structures such as vehicles, bridges, towers, and containers. Compared to ordinary carbon steel, weathering steel exhibits superior corrosion resistance in the atmosphere. Compared to stainless steel, weathering steel contains trace amounts of alloying elements such as phosphorus, copper, chromium, nickel, molybdenum, niobium, vanadium, titanium, etc.; the total amount of these alloying elements accounts for only a few percent, which enhances its resistance to atmospheric corrosion and seawater corrosion. 【Principle of weathering steel】By adding trace elements such as phosphorus, copper, chromium, and nickel to steel, a dense and highly adhesive protective film is formed on the surface of the steel. This film prevents rust from spreading and progressing inward, protecting the base material beneath the rust layer and thereby slowing down its rate of corrosion. The amorphous spinel-type oxide layer formed between the rust layer and the base metal, with a thickness of approximately 50μm to 100μm, is dense and has good adhesion to the base metal. Due to the presence of this dense oxide film, oxygen and water from the atmosphere are prevented from penetrating into the steel base metal, which slows down the progression of rusting within the steel material and **improves its resistance to atmospheric corrosion. When weathering steel is used in contact with the atmosphere, a dense and highly adhesive amorphous oxide layer forms on the surface of the metal matrix. Its color changes from rust red to dark green, and eventually to dark purple; at this point, further rusting stops, and the structure becomes stable. This protective layer effectively prevents corrosion from occurring, thereby extending the service life of the components. An independent research institution abroad compared the corrosion resistance of weathering steel and ordinary carbon steel in different environments, showing the excellent weather resistance of the corrosion-resistant steel. After 16 years in a coastal environment, the average corrosion depth of high-quality weathering steel is about 0.1–0.2 mm, while in industrial areas and rural regions it is approximately 0.02–0.04 mm. Tests conducted by Wuhan Iron and Steel Company in our country on the weathering steel it produces have shown that even in coastal cities, the average corrosion rate of this steel is approximately 0.02 mm per year. Even taking other abnormal factors into account, it is generally believed that the resistance of weathering steel to atmospheric corrosion is 5 to 8 times that of ordinary structural steel; even when used without any protective coating, its corrosion-resistant lifespan can exceed 30 years. The use of CORTEN-A weathering steel allows for thinner applications, use in exposed conditions, or simplified painting processes. This steel grade is resistant to rust, which helps components resist corrosion and thus extends their lifespan; it also enables thinner designs that reduce material usage, saving labor and energy – bringing benefits to both component manufacturers and users. The product is used for manufacturing structural components such as containers for use in environments with hydrogen sulfide-corrosive media, including those in container construction, railway vehicles, oil derricks, port facilities, oil drilling platforms, and chemical and petroleum equipment. The technology of using weathering steel in bridges and buildings without painting for corrosion protection, which emerged in the 1960s, has already been widely applied in Europe and Japan. 　　

Ultimately, it still depends on the working environment – it’s not just a matter of corrosion resistance; factors such as erosion and pipeline cleaning also come into play. Overall, titanium is still the best material