Material Selection for Corrosive Service
Carbon steel, stainless steels, duplex, nickel alloys — how to select the right material for aggressive process environments.
Why Material Selection is the Highest-Value Intervention
Correct material selection at design stage is far more cost-effective than managing corrosion in the field. Upgrading from carbon steel to a corrosion-resistant alloy might add 20-50% to equipment cost but can reduce inspection, maintenance, and failure risk by an order of magnitude over asset life. Many aging asset integrity problems originate in material selections made decades ago.
Carbon Steel vs. Corrosion-Resistant Alloys
Carbon steel is appropriate when pH > 7, CO2 partial pressure < 0.5 bar, no H2S, temperature < 400 C.
Austenitic SS (304/316) is susceptible to chloride SCC above 60C — NEVER use in wet chloride service above this temperature.
Duplex SS (2205/2507) has much higher chloride SCC resistance — preferred for seawater and high-chloride service.
Nickel alloys (625, 825, C-276) for severe service: high temperatures, concentrated acids, complex corrosion environments.
Key Takeaways
Correct material selection at design is the most cost-effective corrosion mitigation
Carbon steel is suitable for most service conditions — but fails when process chemistry assumptions are wrong
Austenitic SS (304/316) is susceptible to chloride SCC above 60C — a common dangerous misapplication
Duplex stainless (2205/2507) is the preferred material for seawater and chloride service
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