What is corrosion under insulation (CUI)?

Understanding Corrosion Under Insulation:
Causes and Prevention Techniques

What is Corrosion Under Insulation (CUI)?

Corrosion under insulation (CUI) is a pervasive issue in industries where piping, vessels, and equipment are insulated to prevent heat loss or gain. It occurs when moisture infiltrates the insulation system and comes into contact with metal surfaces, leading to corrosion, damage, and potential loss of containment. It is the presence of the water absorbing insulation itself that makes the issue so critical, accelerating corrosion rates up to 20 times faster than an uninsulated system. This phenomenon poses significant risks to the integrity and reliability of industrial infrastructure, potentially resulting in safety hazards, operational disruptions, and costly repairs. Understanding the causes of CUI and implementing effective prevention measures are crucial for maintaining asset integrity and ensuring operational efficiency.

Causes of Corrosion Under Insulation:

1. Moisture Ingress: Moisture can penetrate insulation materials through various means, such as leaks, condensation, or inadequate sealing. Once inside, it creates a corrosive environment conducive to metal degradation.

2. Temperature Variations: Fluctuations in temperature can cause moisture to condense within the insulation, creating an ideal environment for corrosion. The cyclic nature of thermal expansion and contraction can exacerbate the problem by compromising the integrity of protective coatings.

3. Insulation Damage: Physical damage to insulation and weather protecting jacketing, such as cracks, gaps, or punctures, provides pathways for moisture ingress. Exposure to harsh weather conditions, mechanical impact, or improper installation can compromise system integrity.

4. Chemical Exposure: Corrosive substances present in the operating environment, such as acids and salts, can accelerate corrosion processes when in contact with metal surfaces. Insulation may trap these corrosive agents, exacerbating the problem.

Prevention Techniques:

1. Proper Material Selection: Choose insulation materials that are resistant to moisture absorption and degradation.

2. Insulation Design and Installation: Ensure proper design and installation of insulation systems to minimize the risk of moisture ingress. This includes proper installation and sealing of joints, seams, and penetrations in the jacketing system to prevent water infiltration.

3. Protective Coatings: Metal surfaces operating in the CUI temperature range should be protected with the appropriate immersion grade coating.

4. Inspection and Maintenance: Implement regular inspection programs to detect early signs of CUI. Promptly repair damaged insulation and address underlying corrosion issues to prevent further deterioration.

5. Thermal Imaging: Employ advanced technologies like thermal imaging and other sensing technologies to identify areas of moisture infiltration and insulation damage before corrosion occurs.

6. Education and Training: Educate personnel involved in insulation maintenance and operations about the importance of CUI prevention and the proper procedures for handling insulation materials.

Conclusion:

Corrosion under insulation is a complex and potentially costly problem that can compromise the integrity of industrial assets. By understanding the underlying causes of CUI and implementing effective prevention techniques, industries can mitigate the risks associated with corrosion, prolong asset lifespan, and ensure safe and reliable operations. Vigilant inspection, proactive maintenance, and the use of advanced technologies, such as our aerogel insulation, are essential components of a comprehensive CUI prevention strategy. Investing in CUI prevention not only protects assets but also safeguards personnel and the environment from the potential consequences of corrosion-related failures.

About Aspen Aerogels

Built on over two decades of R&D investment, our Aerogel Technology Platform^® holds the potential to solve emerging global challenges and help contribute to a more sustainable future. Global organizations have utilized Aspen’s engineering expertise and advanced aerogel technology to help solve challenges in resource efficiency, electrification, and sustainability.

Our advanced aerogel industrial insulation provides superior insulation properties while reducing space and weight. By keeping process assets drier for longer, our Pyrogel^® flexible aerogel blanket insulation delivers superior defense against CUI to protect your assets, process performance, and bottom line. We have also developed Cryogel^® Z cryogenic insulation to help LNG facilities and offshore platforms mitigate CUI.