The Truth Behind the 82% Failure Rate of Robot Chassis in Coastal Projects

Why do chassis in coastal projects always fail within 2-3 years?

In coastal engineering projects, sudden corrosion and perforation of chassis equipment, brackets, and fasteners have become the most common failures. Latest industry data reveals that chassis components predominantly made of 304 stainless steel exhibit failure rates as high as 82% in salt spray environments—far exceeding inland project averages. This phenomenon exposes a critical misconception in material selection: 304 stainless steel is not a universal “corrosion-resistant” material, particularly in marine settings where its performance falls significantly short of expectations.

How Does Salt Spray “Assassinate” the Chassis?

The air in coastal regions is rich in chloride ions. When these microscopic particles adhere to metal surfaces, they penetrate the protective layer of 304 stainless steel, triggering pitting and crevice corrosion. As the critical component supporting and connecting equipment, the chassis will cause the entire system to fail if rust perforation occurs.

Actual cases show that some 304 stainless steel chassis used in coastal wind power, bridge, and port facilities developed honeycomb pitting corrosion and weld fractures within 30 months of service. The costs of repair or replacement often exceeded the original value of the equipment.

Why does 304 stainless steel fail?

304 stainless steel (containing 18% chromium and 8% nickel) performs well in ordinary environments, but its composition lacks molybdenum, rendering it unable to resist corrosion from high concentrations of chloride ions. In coastal areas with annual salt spray deposition exceeding 600mg/m², chloride ion concentrations can easily surpass the 200ppm threshold, accelerating the corrosion process. Many projects rely solely on the conventional assumption that “304 = food-grade corrosion resistance” during design phases without conducting on-site environmental assessments, leading to severe mismatches between materials and application scenarios. Historical project statistics indicate that over 60% of coastal engineering projects neglected regional corrosion characteristics during material selection, ultimately incurring significant costs.

Solutions

To address high failure rates, our new specifications mandate that projects within 50 kilometers of the coastline must conduct chloride ion environment classification testing on metal materials:

Critical structural components such as chassis and fasteners must utilize 316L stainless steel (containing 2-3% molybdenum), 2205 duplex steel, or a composite solution combining hot-dip galvanizing with anti-corrosion coatings.

For instance, in the new LNG receiving terminal project in Zhoushan, Zhejiang, all steel materials must pass a 72-hour accelerated salt spray test before site acceptance. Although 316L stainless steel procurement costs are 30% higher, its lifecycle maintenance expenses are reduced by 40%, significantly enhancing project economics and safety.

304 stainless steel is not a reliable choice in marine environments. Only through environmental assessments, material upgrades, and standard optimization can the persistent threat of “invisible corrosion” to infrastructure be avoided.