Each month, Stainless Solutions from IMOA covers a different stainless steel issue with tips on design and specification, and links to technical resources. This month they provide resources to help assess the corrosiveness of coastal environments.
Assessing the Corrosiveness of Coastal Environments
It is not uncommon to apply general rules to the specification of materials, such as proximity to the coast. This type of guidance can be very helpful but there are exceptions to every rule. The ‘typical’ coastal construction site where Type 316 stainless steel is used successfully has these characteristics:
-at least 0.2 km and up to 16 km (0.12 miles to 10 miles) from a large saltwater body (ocean or harbor)
-low to moderate salt, pollution and particulate level exposure
-none of the exterior surfaces are sheltered
-surfaces are regularly subjected to heavy rain cleaning which minimizes the accumulation of corrosive substances
Severe coastal environments where precautions should be taken may meet the requirements above but there are additional site conditions which make them more corrosive:
-close proximity to salt water
-rocky shorelines
-salt combined with heavy industrial pollution
-hot, low-rain environments with high surface salt accumulations where evening humidity or salt fog dampens surfaces
-volcanic fume exposure
-sheltered areas in hot humid environments that cannot be rain washed
-regular light, misty, high-salt-content rain and/or salt fog that dampens but does not clean surfaces
Without finish specification or design changes, at least light superficial “tea staining” corrosion of Type 316 can occur in more severe locations. In such cases, a more corrosion resistant stainless steel such as 2205 duplex will be needed, particularly if there is an aesthetic expectation of a pristine appearance. The corrosiveness of the site, aesthetic requirements, and expected maintenance frequency determine effective solutions. IMOA has a website page to provide guidance on identifying and selecting materials in coastal climates. It includes links to two articles with guidelines for typical and severe locations.
IMOA’s selection system can help you determine whether the site is more severe and our case studies show how it is used. Case studies 3 (New York and Miami), 4 (Singapore), 5 (Hong Kong), 6 (Canary Islands), 7 (Barcelona), 9 (Australia), 10 (New York), 11 (Thames Barrier) and 14 (New Zealand) illustrate a variety of applications and site conditions.
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- Stainless Steel Sustainable Design
- Bioclimatic Design With Stainless Steel Weather Screens
- Stainless Steel Structural Design
- Stainless Steel Specification For Corrosive Applications
- Deicing Salt: Stainless Steel Selection to Avoid Corrosion
- Stainless Steel Finish Specification
- Advanced Stainless Steel Specification and Problem Avoidance
- Specification of Stainless Steel Finishes and Grades For Corrosive ApplicationsFor more information or to schedule a workshop contact Catherine Houska, 412-369-0377.