Understanding CUI: The Hidden Enemy of Industrial Facilities

Corrosion Under Insulation (CUI) is a pervasive, hidden threat in asset-intensive industries. It happens when water or moisture seeps into thermal insulation and attacks the metal beneath – causing corrosion to progress up to 20 times faster than on uninsulated steel . In GCC industrial plants (oil & gas, petrochemical, power, desalination), CUI silently eats away at pipes, vessels and tanks, often without detection. Over time this leads to leaks, equipment failures and safety hazards. In fact, CUI can account for 40–60% of piping maintenance costs in many facilities , and in severe cases oil and gas plants have faced tens of millions in downtime losses from CUI failures

A corroded industrial pipe with damaged insulation, highlighting maintenance needs in a processing facility.

What Causes Corrosion Under Insulation?

CUI is caused by trapped moisture and contaminants. Common culprits include rainwater infiltration, condensation and process leaks that saturate insulation . For example, a minor insulation crack or gap can allow water vapor to enter and condense on a cold pipe. When the pipe heats up again, that moisture is “baked” but chlorides/sulfates are left behind – accelerating pitting and stress-corrosion, especially in stainless steels . Insulation materials themselves can wick or hold water, and high humidity environments (like the Gulf coast) only add to the moisture load. In short, moisture + poor sealing + temperature cycling creates a perfect storm for corrosion under insulation

• Moisture ingress: Water enters through cracks, tears or poor seals in the jacketing.

• Condensation: Temperature swings (hot day to cool night) cause water to condense inside insulation .

• Contaminants: Chloride salts from seawater or acid vapors attack metal when trapped under insulation .

• Damage to insulation: Any physical damage or penetration lets moisture reach the metal core

Why CUI is a Major Problem

CUI is especially insidious because it stays hidden until major damage has already occurred. Operators often only discover it during shutdowns or inspections. When uncovered, the consequences are severe: equipment rupture, hazardous leaks and forced outages. Industry studies show that corrosion costs oil & gas and petrochemical plants billions each year. For example, in one analysis corrosion (including CUI) imposed a $17.6 billion direct cost on industry . In a single refinery, CUI-related damage can eat up 40– 60% of the maintenance budget

Typical damage from CUI includes metal thinning and hole-through corrosion on pipes, tanks and boilers. Carbon steel under wet insulation generally shows non-uniform general corrosion or deep pitting. Austenitic stainless steels can suffer sudden chloride-induced cracks (even in just months) if moisture and chlorides concentrate . Over time, corroded flanges and valves may fail, causing spills or gas releases – putting personnel and facilities at risk.

• High maintenance costs: Fixing or replacing CUI-damaged assets is expensive and time-consuming .

• Production loss: Emergency shutdowns to repair CUI pits lead to lost throughput and revenue (often millions per day).

• Safety hazards: Undetected CUI can lead to fires, explosions or toxic leaks if a line ruptures. Regulatory exposure: Leaks or accidents from corroded equipment can incur fines and reputational damage.

  
  

A line of industrial valves with red wheels is positioned against a worn brick wall, reflecting signs of age and use in a classic mechanical environment.

GCC Climate: A Recipe for Corrosion

GCC facilities face extreme environmental stressors that exacerbate CUI risks. Hot, arid deserts give way to humid, saline coastal air – both problematic for insulated equipment. Summer temperatures routinely exceed 50 °C, and even at night pipes can swing above and below the dew point. Each day’s heating and cooling cycle wrings moisture into insulation . Gulf coast winds carry salt spray onto plant exteriors. When that salt-laden water accumulates under insulation, it forms highly conductive electrolyte films that accelerate corrosion rates

Facilities in the UAE, Saudi Arabia and other Gulf states must therefore contend with:

• High humidity and dew: Morning condense forms on pipes and is trapped by insulation .

• Salt exposure: Coastal fog and aerosol leave chlorides that breach stainless steel passivity

• Thermal cycling: Extreme temperature swings dry out metals, leaving acidic salts behind .

• Dust and sand: Wind-blown particles can damage insulation jackets and hold moisture.

Simply put, when metal meets sea spray, heat and humidity, “the ideal conditions are formed for CUI” . In Gulf refineries and power plants, even brief rainfall or firewater tests can initiate CUI under tank and pipe insulation if not fully sealed.

A rusted and corroded industrial pipe joint on a metal grating platform, showing signs of wear and exposure, with a gray protective cover partially attached.

Where CUI Strikes Most

CUI tends to hit assets that operate in the moderate temperature range (roughly 50–150 °C) – warm enough for condensation but not so hot to boil off water . Common trouble spots include:

Insulated mid-temperature piping: Steam or process lines around 60–150 °C. When shut down or cooled, they condense moisture under their lagging.

Flanges, valves and fittings: Non-uniform insulation over clamped joints often lets water accumulate. These points may corrode first (flange faces and gaskets).

Vertical vessels and tanks: The bottoms and lower shells of insulated towers and storage tanks collect condensate and corrosive runoff.

Idle equipment: Turned-off boilers, heaters or pipes lying idle in humid ambient will drip condensation inside insulation.

For instance, industrial surveys have found that over 80% of CUI failures occur on carbon steel surfaces in the 25–150 °C range . Stainless steel chillers and heat exchangers in GCC desalination plants have also developed chloride stress-cracks within a few years when exposed to saline wash and humidity .

Preventing CUI: Technical and Practical Measures

Dealing with CUI requires multiple strategies, from design to maintenance. Key practices include:

• Quality insulation design: Use closed-cell or hydrophobic insulation materials, ensure robust vapor barriers, and tightly seal joints. Prevent any water ingress at the start .

• Protective coatings: Apply corrosion-resistant primers and coatings under insulation on carbon steel and stainless parts . This barrier guards the bare metal even if moisture seeps through the jacket.

• Regular inspection: Integrate advanced NDT methods (pulsed eddy current, thermography, etc.) to “see” under insulation without ripping it off. Predictive maintenance tools can flag problem areas early.

• Humidity monitoring: In critical plants, moisture sensors or wireless CUI monitors can alert staff to trapped water before corrosion advances .

• Component encapsulation: Apply specialized encapsulation coatings on flanges and valves to eliminate wet recesses (see Izoteck’s Enviropeel below).

Combining these steps limits water residence time and removes contaminants, significantly cutting CUI rates . However, retrofitting legacy plants is especially challenging in GCC conditions. This is where advanced solutions like Izoteck’s products come in

Illustration demonstrating strategies to prevent CUI (Corrosion Under Insulation) using both technical and practical approaches, showcasing icons of sealed pipes, personnel, and technology interfaces.

Izoteck Solutions for CUI Protection

Izoteck offers state-of-the-art materials specifically engineered to tackle CUI in harsh environments. Its portfolio includes nano-ceramic insulations and permanent protective coatings that address moisture intrusion at the source. Key products for CUI control are:

• ISOLLAT Liquid Ceramic Insulation: A spray-on nanoceramic insulation that bonds directly to metal, eliminating gaps and cladding. In “ISOLLAT EFFECT” form it creates a seamless, elastic coating that prevents water and steam from reaching the pipe . Even if a leak occurs, ISOLLAT swells to channel fluid outward and maintain a dry barrier. Unlike wet fibrous lagging, it never absorbs moisture, so it sustains its R-value and kills off CUI pathways

• EonCoat Permanent Corrosion Coating: A two-part, ceramic-based spray coating that chemically alloys with steel to form an ultra-durable barrier . It can be applied over rusty steel (no need for perfect blasting), curing quickly into an iron-phosphate layer and a ceramic topcoat. Applied at about 500 microns, EonCoat is specifically formulated for insulated service: it stops ongoing corrosion under insulation and dramatically extends repaint intervals . Its superior adhesion and hard ceramic film mean fewer maintenance cycles and virtually no flash rusting after blasts

By combining these technologies, Izoteck provides a comprehensive CUI protection system: liquid ceramic insulations to keep moisture out, and ceramic/plastic coatings to shield the metal itself. Each product contributes to long-term savings and safety. For example, EonCoat’s ceramic barrier can halve corrosion maintenance costs by arresting rust permanently. Meanwhile, ISOLLAT’s high-R insulation saves energy (less heat loss) and avoids the collapse of insulation performance after a rain or leak.

Benefits: Cost Savings and Safety

Implementing Izoteck’s CUI solutions pays off quickly. Facilities that switch to these systems report drastically lower maintenance budgets and extended asset life. Corrosion “creep” is halted, so pipelines and vessels stay fit far longer. In practical terms, that means fewer unexpected shutdowns and repairs, directly boosting operational efficiency. As one industry study notes, each hour of downtime can cost ~$220,000 , so preventing CUI-related outages can save millions per year.

The enhanced safety is equally important: by eliminating hidden corrosion, Izoteck products reduce leak risks and the threat of bursts. Worksite safety improves too, because many Izoteck coatings are applied cold (no hot works or flames) and contain no volatile solvents. Moreover, keeping systems at proper insulation values means more stable process conditions, another layer of operational reliability.

• Lower maintenance and downtime: Durable coatings like EonCoat and Enviropeel mean inspections and repainting happen far less frequently .

• Greater safety: Fewer corroded leaks means a safer plant and compliance with safety regulations. Dry, stable insulation also reduces fire risk.

• Energy efficiency: ISOLLAT’s superior insulation lowers heat loss, saving fuel and emissions.

• Extended asset life: By effectively eliminating CUI, equipment can run longer or reach retirement without replacement

Industrial efficiency visualized: a pipeline system symbolizing cost savings and improved performance with key benefits highlighted, as a worker oversees operations.

Take Action: Explore Izoteck’s CUI Protection

Don’t let hidden corrosion eat away your facility’s profitability. For industries across the GCC, CUI protection is not optional – it’s essential. Izoteck’s specialized corrosion insulation solutions (from Abu Dhabi to Riyadh) are engineered for these harsh climates. Their advanced insulations and coatings provide reliable industrial insulation and corrosion shields tailored to Gulf conditions.

Take the next step: Learn how Izoteck’s CUI protection offerings can safeguard your plant. Visit our website or contact our technical team to discuss a corrosion control strategy customized for your operations. Protect your assets, cut costs, and ensure safety with Izoteck’s proven solutions for corrosion under insulation.