Marine environments are particularly harsh environments for steels, due to the corrosive nature of the elements contained in seawater. In this brief article, we examine the causes of corrosion, and look at the best types of steel to use in a marine environment. 

Why is Seawater Corrosive?

Seawater contains a variety of corrosive elements. These include salt (particularly sodium chloride), dissolved oxygen, chloride ions, pH variations, impurities, temperature and water velocity. This makes the marine environment particularly harsh. The correct steel types must be used to ensure a solution with longevity. 

Is all Water Corrosive?

Metals can obviously be exposed to many other types of water beyond the sea. Not all water is as corrosive as seawater, but all water has the potential to cause corrosion. Generally, non-seawater can cause corrosion by elements such as dissolved oxygen, pH, impurities, temperature and velocity. In short, if steel is going to be exposed to water, corrosion needs to be taken into account. This is especially true with seawater.

What’s the Best Steel in a Marine Environment?

The best steel option in a marine environment is Stainless Steel 316. It’s also known as Marine Steel or Marine Stainless Steel. Stainless steel 316 is an alloy (meaning it is made up of different elements) which has a high degree of corrosion resistance. This is due to the inclusion in the alloy of molybdenum. In addition to corrosion resistance, SS316 is also strong, durable, retains integrity at elevated temperatures and its shiny finish always looks great on boats. 

Using SS304 in a Marine Environment

SS304 is another popular stainless steel that also has good corrosion resistance, although not the the same level as SS316. However, in some cases (where exposure to seawater is limited or intermittent, and proper maintenance practices are in place), SS304 may achieve a satisfactory performance. In addition to the engineering aspect, there are other factors to take into account - price, availability and longevity required may also come into play when selecting a steel product for use in a marine environment. 

Maximising Longevity of Steel in a Marine Environment

In addition to selecting an appropriate steel for marine usage, there are also a number of practices which can be used to ensure the maximum lifespan of your steel. These include regular cleaning, inspections, and application of protective coatings. These practices will help ensure your steel stays in good order and keep you aware of the status of all of your fittings.

Accessing High Quality Marine Grade Stainless Steel

If you’re in Australia, Bolt-In Co has a wide range of stainless steel fasteners available for purchase online and instore. Browse options on our website, or drop into our shop on Wises Road, Maroochydore on the Sunshine Coast. [View on Google Maps] In addition to our wide range of stainless steel products, we also have extensive experience and great customer service, so we can help you determine the best fasteners for your project.