Corrosion under insulation (CUI) is a severe form of localised external corrosion that occurs in carbon and low alloy steel equipment that has been insulated. CUI occurs when water is absorbed by or collected in the insulation. The equipment begins to corrode as it is exposed to water and oxygen. CUI is one of the costliest corrosion issues for the oil and gas, petrochemical and general processing industries. Our team at Wagon Paints outlines the preventative methods to minimise the risk of catastrophic shutdowns, maintenance repairs and even explosions on live plants.
Potential contaminants are acid or high salt content, rain and chemicals (chlorides/sulfides) leaching from insulation systems. These can form acidic compounds which accelerate the rate of corrosion.
The predominant steel materials used in industrial processing are carbon (CS) and stainless steel (SS, austenitic or duplex) types. Both are susceptible to CUI via multiple corrosion mechanisms. Corrosion Under Insulation (CUI) is common in refineries and process plants that typically operate equipment at high temperatures. The temperatures at which extensive CUI (either in cyclical or constant operation) occurs in CS range from -4 to 175 °C. The corresponding temperatures for SS are 50 to 175 °C. The rate of corrosion is directly related to the CUI system, the suitability of the CUI coating, the type of insulation and the quality of the cladding installation.
Corrosion is at its worst where thermal cycling occurs. In this instance, the moisture condenses back on to the core material until it is flashed off when the plant is brought back into operation.
Wagon Paints is the exclusive Australian distributor for Performance Polymers, the developers of Thermaguard high temperature resistant coatings.
Thermaguard TIC 400 acts as a thermal barrier which can improve energy efficiency, prevent Corrosion Under Insulation (CUI) occurring, reduce condensation build up and provide personal protection in accordance with ISO 13732-1 (SafeTouch™ properties). Properties include water based, single component, ambient curing, ultra-high-build inorganic polymeric siloxane matrix and Thermal Insulation Coating (TIC) for elevated temperatures. Construction Thermaguard TIC 400 provides a seamless, hydrophobic, water-resistant insulation film which operating temperatures from 60 to 400ºC.
Thermaguard CUI 300 is a unique inorganic single component, ambient curing polysiloxane coating formulated specifically to provide corrosion protection to under insulation environments where wet and dry cycling can occur. It offers solvent free (100% solids), ultra-low VOC for demanding environmental regulations and safety aspects during hot application.
Thermaguard CUI 180 is a high performance, water based, single component, ceramic filled acrylic, Thermal Insulation Coating (TIC). It provides seamless water-resistant insulation film which can improve energy efficiency, prevent Corrosion Under Insulation (CUI), reduce condensation build up and provide personal protection according to ISO 13732-1 (SafeTouch™ properties). It acts as a thermal barrier, protecting interior temperatures against cold, warm and humid weather conditions.
Offering exceptional temperature resistance, this third generation, pure inorganic single component, ambient curing polysiloxane coating is formulated specifically to provide corrosion protection to under insulation environments where wet and dry cycling can occur. Available in light and dark grey, Thermaguard CUI 650 conforms to the NACE SP0198-2010 classification, inert multi polymeric matrix coatings for Corrosion Under Insulation (CUI) in both cryogenic and elevated temperature applications. It can withstand temperatures from -196 to 650ºC, exceptional resistance to thermal cycling, hot saline water immersion and chemical exposure throughout its operating temperature range. Additionally, the product can be applied in service to hot equipment operating up to 260ºC, removing the need for plant shut down periods.
Do you need help choosing suitable Corrosion Under Insulation (CUI) products for your requirements? Use our System Selector or contact the Wagon Paints technical support team to ensure you find a long-lasting solution for your project. For more information, contact Wagon Paints today on +61 3 9729 1344 or complete an online enquiry form.