Industry collaboration brings new insights on CUI

“Despite continuous improvements in materials, inspection and maintenance practices, CUI continues to be a leading cause of asset degradation and integrity loss. Industry experience shows that maintaining steel integrity under insulation requires closer collaboration and shared understanding across disciplines, linking material performance, exposure conditions and inspection insights. That is why it is important to bring together asset owners, coating experts and research partners with the shared ambition of reducing both CUI risk and lifecycle costs, which is being done in this JIP,” said Jeroen Tacq from SIRRIS.

The project aims to improve how the industry manages CUI, by developing new test methods to better understand coating degradation and by assessing what actionable data CUI moisture sensors can provide.

While several industry initiatives are ongoing globally, this collaboration has focused on simultaneous testing of CUI sensor technologies and on developing realistic test conditions for preventive coatings. Accelerated testing of coatings was combined with longer-term “slow ageing” testing.

“Continuous monitoring of moisture in insulation is an important goal for controlling corrosion under insulation. If the measurements indicated that no moisture or water is present, corrosion can effectively be ruled out,” said Peter Janssen, Expert Lead Corrosion & Materials at EbertHera and consultant for SABIC. “The SIRRIS project, including the practical test rack, has given us valuable insight into how continuous moisture monitoring methods depend on system design and insulation type. Every moisture monitoring system has its pros and cons.”

Coating testing included both accelerated laboratory methods and longer-term “slow ageing” exposure, designed to better reflect coating performance in realistic operating conditions. Comparing the degradation mechanisms in both tests helps to show how well accelerated testing reflects field performance. Tests were performed under cyclic CUI conditions, using repeated wet–dry cycles between 80 °C (wet) and 140 °C (dry), a relevant operating window for many assets.

“We believe in collaboration, and creating a structured forum where coatings experts, asset owners and researchers can meet regularly, exchange experiences and discuss CUI challenges openly, as this leads to deeper technical understanding and trust,” said Jenny Manvik, R&D Manager Speciality in Jotun.

“It has enabled customers to share real‑world learnings, helped clarify assumptions, and get a better understanding of the scope of this issue. We are proud to be one of the contributors to the project, sharing our experience from decades with corrosion challenges and coatings.”

The project has also generated valuable discussion around test interpretation, including the use of electrochemical impedance spectroscopy (EIS) to assess coating degradation under insulation. Its potential as a field inspection tool has also been explored.  Although the data from EIS measurements adds significant value, additional work is needed to further optimise the measurement approach and data handling to account for the often-localised failures.

Building on the outcomes from the first phase, a second project phase is starting this summer. This phase will further study coating degradation mechanisms, refine testing, and improve both EIS and visual analysis methods. Together with the industrial partners the potential for integration into future test standards will be assessed. The work will also expand beyond epoxy technologies to include multi‑polymeric coating systems and examine how different exposure conditions influence long‑term and accelerated-test performance.  

“For us, the participation in the SIRRIS JIP aligns closely with the company’s strategic ambition to be a trusted partner and technology leader within prevention of corrosion under insulation – and our overall ambition to help the industry maintain steel integrity,” said Ingrid Vee, Global Category Manager in Jotun.

By building shared insight through this project, the industry can improve CUI management, extend asset life and help asset owners manage asset integrity more efficiently. With CUI accounting for approximately half of all hydrocarbon leaks in the oil and gas sector, as highlighted by DNV, tackling this issue is essential for steel integrity, safety and sustainability.

“The long-term goal and vision we’ve set out is to allow estimation of remaining coating life in the field based on a combination of laboratory testing and the integration of CUI moisture monitoring data. To achieve this goal, a better understanding of the impact of exposure conditions in laboratory testing on the observed failure mechanisms is required, as well as a method to quantify coating degradation in the lab and in the field. By continuing the JIP, we want to foster further collaboration in the industry and help tackle this safety critical and costly damage mechanism,” concludes Jeroen Tacq in SIRRIS.

The first phase of the JIP brought together several operators and coating suppliers, including Shell, Equinor, BP, Chevron, SABIC, Dow and Gassco, and coating manufacturers AkzoNobel, Carboline and Jotun.