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Selecting metal for gen-sets enclosures along the coastline or on an island has been a tough job. Salt, wind, storms -- there’s always a threat out there, waiting to make your gen-sets and housings corrode on which you spent so much. However, choosing suitable materials for coastal-use gen-sets can at least slow the decay of your project’s neatness and structural integrity while reducing your maintenance needs.
Here’s how to protect against salt water and more:
Metal corrosion is most pronounced on coastal homes within 3,000 feet of the ocean. Of course, whether your structure is submerged in seawater or not in direct contact plays a big part in how it will hold up.
A lack of oxygen limits underwater corrosion; lower chloride and moisture content limits corrosion above high tide levels. Still, both situations are more corrosive than inland conditions.
Corrosion is most severe within splash and tidal zones, where a frequent wetting and drying cycle results in high chloride and oxygen content.
Do not blindly specify a product just because some company slapped “corrosion-resistant” on the label. Evaluate:
And no matter which metal you pick, follow these practices:
Steel has weak resilience in coastal environments and hence requires coating protection for endurance.
In salty environments, bare carbon steel will corrode quickly. Weathering steels will not generate the expected protective surface oxide, hence their corrosion rates will be comparable to those of unprotected carbon steel. Bare carbon steel is more than 100 times more prone to corrosion than aluminum and more than 8,000 times more prone than 316 stainless steel – more on that later.
Carbon is more anodic than stainless steel or copper, thus it must be separated carefully to avoid further ugliness.
Despite these shortcomings, steel roofs are popular on the coast due to their weather resilience and energy efficiency. (They reflect sunlight, reducing air conditioning expenditures.) However, keep in mind that these roofing items are coated with weather-resistant primer/paint coating systems that have been tested outside.
Salt can dissolve the protective oxide that forms on the defensive oxide layer of aluminum.
Surface pitting can cause fatigue failure in structural aluminum. You have the option of using more resistant high-strength alloys.
Some tempers, such as 2XXX and 7XXX, are not suitable for coastal living since they will corrode and crack.
Anodizing or painting the aluminum, along with regular cleaning, is frequently required to maintain its shining appearance.
Aluminum must be separated from other metals to prevent even faster corrosion. Galvanic corrosion will occur if standard aluminum fasteners and hardware come into direct contact with preservative-treated wood.
There are numerous copper alloys, some of which are frequently used in seawater. Roofs and other architectural projects frequently use highly pure alloys.
In coastal conditions, their corrosion rates range from aluminum-like to ten times higher. As a bonus, copper corrosion appears to be rather appealing.
Copper is a possible biocide, so use it with caution near more vulnerable coastal habitats.
Stainless steel is the most commonly used corrosion-resistant metal in coastal architecture. However, there are some differing opinions concerning its most popular grades.
316 stainless steel contains 2% to 3% molybdenum, which increases its corrosion resistance. This is the most common grade utilized in coastal applications.
Meanwhile, regardless of application type, 304 stainless steel is the most often used grade. The issue is that it is prone to corrosion in saline areas such as the seaside. If you're concerned about surface stains, don't specify it for a coastal project. Because 304 requires frequent cleaning, it can be difficult to manage. It should be noted that 304 stainless steel can nevertheless have a corrosion rate of 1/10th to 1/100th that of popular aluminum architectural alloys. So, even if surface staining occurs, don't assume your project is doomed to fail.
However, if you request a more corrosion-resistant stainless with a smooth finish, such as 317LMN, 2205, or 904L, you can probably avoid cleaning. How important are appearances to you? That will be a major consideration in your metal selection, especially with stainless steel.
Remember to avoid combining stainless with dissimilar metals, especially those with high galvanic potential, as this encourages corrosion.
Is it better to buy a cheaper metal and replace it every five years, or a more expensive alloy that will last five decades? A less expensive material may be more cost-effective if you're developing a short-term use (such as a temporary construction) in a corrosive climate.
You should also think about the level of volatility in your coastal application. For example, if you're building 2,900 feet from the beach, a painted carbon steel roof may survive 20 years and an aluminum roof may last 40 before you have to pay to repair it. 29 feet from the water's edge? Not at all.
Just keep in mind that a structural failure could result in additional charges. A leaking roof is never just a leaky roof; you may also require insulation replacement, mold removal, and other services. A huge failure of this magnitude would cost far more than choosing a stronger metal in the first place.
On the environmental front, keep in mind that corrosion-damaged materials cannot be recycled. A faster replacement is more salvageable.
Speak with an expert manufacturer during the design process, especially if you intend to use a 2XXX or 7XXX class aluminum alloy.
If you're still unsure, check with a manufacturer who specializes in corrosion prevention to guarantee your materials are marine-friendly. An on-site inspection is beneficial in the most remote places.
