Corrosion under insulation (CUI) is a major challenge for equipment operators in the process industries. In the US alone, repair and downtime caused by CUI is estimated to cost the industry around USD 300 billion per year.

CUI occurs when insulated pipework and other equipment is exposed to high temperatures and temperature fluctuations. As the corrosion is hidden beneath insulation, it is difficult to detect and can cause extensive damage before it is spotted. As a result, repair work can be expensive, requiring long periods of plant shutdown. This is a significant problem in downstream oil & gas refineries, where CUI accounts for approximately 10 per cent of the maintenance budget.

A leading supplier to the process industries for over 50 years, Hempel offers a broad range of proven coatings for high heat and insulated environments. Hempaprime CUI 275 is the latest addition to its portfolio – and offers a number of benefits to asset owners and applicators.

During tests, Hempaprime CUI 275 has shown significantly higher crack resistance at high temperatures than traditional epoxy phenolic coatings, which reduces the risk of cracking and premature failure during service. It is also extremely fast-drying, which increases applicator productivity.

Zechariah Lim, Product Manager (CUI, high heat and insulation) at Hempel, comments: “Insulated pipework and equipment can be exposed to temperature fluctuations and harsh wet/dry cycling, which makes specifying for CUI service challenging. Hempaprime CUI 275 is suitable for use in a wide range of temperatures from cryogenic up to 275°C and has excellent crack resistance under cycling. This makes specification simpler and ensures a more reliable performance in service.”

He continues: “Importantly, Hempaprime CUI 275 also has a very short overcoating interval – just 90 minutes at 20°C. As a result, applicators can coat more sections in one shift, increasing productivity in fabrication situations and reducing the time needed to re-insulate equipment during maintenance work. This can lead to significant cost savings for customers.”

Hempaprime CUI 275 meets the ISO 19277: 2018 standard for categories CUI-1, CUI-2, CUI-3 and all cryogenic equivalents.

Hempaprime CUI 275 was launched in June. It is available globally as a standard part of Hempel’s coating portfolio for the process industries, including oil & gas and power generation.

Hempaprime CUI 275 at a glance

A fast-drying, alkylamine-cured epoxy paint, Hempaprime CUI 275 provides long-lasting barrier protection in severe corrosive environments, high temperatures and wet conditions beneath thermal insulation.

• Short overcoating interval (90 minutes at 20°C (68°F) increases productivity during application
• Wide temperature resistance from cryogenic up to 275°C (527°F) simplifies specification
• Pre-qualified to ISO 19277: 2018 for categories CUI-1, CUI-2, CUI-3 and all cryogenic equivalents
• Excellent crack resistance compared to traditional epoxy phenolic coatings
• Wide application temperature range, down to -10°C (14°F), reduces heating costs during in-shop application and extends the maintenance season in cold climates
• Can be applied on hot surfaces up to 204°C (399°F) to minimise disruption and shutdown during maintenance