Corrosion Under Insulation (CUI): A Full Life-cycle Approach
Corrosion under insulation (CUI), is a major operational and safety hazard across all manner of industries that require industrial insulation systems. A large proportion of maintenance budgets are spent on CUI every year. Implementing appropriate inspections and maintenance procedures is key to helping prevent CUI taking hold but, this is just one method in what should be a complete life-cycle approach of the insulation system.
Plant (Mechanical) Design
An insulation system and measures to prevent CUI are often an afterthought, when considerations should be made at the mechanical design stage of a project.
Plant layout should allow sufficient clearance from structural steels, walkways, equipment, and assets for the specified insulation thickness to be installed. Cladding best practice should also be adhered to; provide effective cladding protection and maintaining the mechanical fix of the cladding throughout the system. Learn more >>
Insulation System Design
When designing a fit for purpose insulation system, the designer needs to understand several key factors about what is being insulated, the environment & operating conditions it is subject to, and the performance requirements.
Broadly this includes:
- What is being insulated & where it will be situated
- Operating / ambient temperatures
- Installation / functionality / performance requirements
- Insulation material specification
- Cladding & support substructure specification
Having this understanding at the design stage will prevent major issues like CUI further along the life-cycle of the insulation system: Learn more>>
Installing a substructure as part of an insulation system will improve the performance of the insulation system for several reasons:
- Prevent the insulation material moving or slipping; maintain the integrity of the insulation material.
- Increase the mechanical strength of the insulation system, protecting it from damage, keeping the system watertight, and in turn the risk of water intrusion.
Thermally Sprayed Aluminium (TSA) and other metallic coatings are incredibly durable specialist coatings which act as sacrificial anodes, acting as a barrier to corrosion providing cathodic protection to the underlying asset.
Insulation Material Specification
Although research shows that corrosion can occur under any insulation material regardless of its properties and abilities to prevent it. However, the rate at which the corrosion takes hold can be slowed by selecting the correct insulation material specification to meet the requirements of the insulation system.
When on-site measuring, during manufacturing, in transit to site, and during installation, measures need to be taken to ensure and protect the integrity of high-quality fabrications. Using highly trained and experienced fabricators, state of the art machinery and advance manufacturing techniques will increase the quality of fabrications. Learn more >>
During installation use qualified insulation operatives to achieve a high-quality installation. Following cladding best practice and ensuring watertight cladding seams will help prevent water ingress. Learn more >>
Inspections & Maintenance
Regular inspections need to be performed by certified inspectors that are trained to spot signs of CUI – which occurs out-of-sight. Inspections should cover the whole insulation system, insulation material, cladding, substructure, ancillary materials, and any coatings system.
For areas which are at an increased risk of CUI like bends and vertical rows, and where cyclic conditions are present, inspection procedures should be carried out at more frequent intervals.
Proactive maintenance should be implemented to enable the best chance of protecting assets from CUI. Any signs of damage to the cladding surface should be rectified immediately to prevent water ingress into the insulation system. Any signs of degradation of the insulated asset should be reported and acted upon as a priority to stop the spread of CUI. Learn more >>
The insulation system is more often an afterthought which is part of the reason problems, like CUI, arise. Considering and implementing preventative strategies right from the mechanical design of a plant through the specification, fabrication, installation, and maintenance of the insulation system will significantly help prevent, track, and mitigate corrosion under insulation.