Challenging ISO 12944: Assessing the Real-World Validity of Cyclic Ageing Tests via Non-Destructive Evaluation of Rust Creep and Coating Degradation

The ISO 12944 standard is widely adopted as a benchmark for prequalifying coatings, ensuring durability and effectiveness in safeguarding offshore steel structures against corrosion. However, its cyclic ageing test, designed to simulate the harsh conditions faced in real-world environments, has come under scrutiny for its accuracy in predicting actual field performance. This study critically evaluates the real-world validity of the ISO 12944 cyclic ageing tests by comparing their outcomes with long-term field data to identify discrepancies and areas for improvement. Advanced non-destructive testing (NDT) methods, including the Scanning Acoustic Microscopy (SAM) and optical 3D Profilometry, are developed to assess rust creep and coating degradation. The results unveil that optical 3D Profilometry and SAM can serve as non-destructive test methods, providing more efficient and accurate evaluations of rust creep as well as offering valuable insights into the underlying coating breakdown mechanism. This stands in stark comparison to the predominantly used destructive rust creep testing method outlined in ISO 12944-9.