Corrosion Under Insulation
Corrosion Under Insulation is external corrosion that develops beneath thermal insulation and may remain hidden until significant damage occurs.
What this term means in maintenance
Corrosion Under Insulation is external corrosion that develops beneath thermal insulation and may remain hidden until significant damage occurs.
Why CUI occurs
Moisture can enter through damaged cladding, joints, supports, penetrations, or poor sealing.
Common risk areas
Risk may be higher around:
- Insulation damage
- Pipe supports
- Nozzles
- Cladding joints
- Cyclic temperatures
- Outdoor exposure
- Contaminated environments
Practical example
Insulation is removed from selected pipe locations and hidden external corrosion is found around supports.
Control methods
Controls may include inspection, coating, sealing, drainage, insulation design, risk-based location selection, and repair.
Common mistake
A clean external cladding surface does not prove the metal beneath is free from corrosion.
Related concepts
Related maintenance terms
Keep exploring connected CMMS, reliability, and maintenance planning terms.
Wall Thickness Measurement
Wall thickness measurement determines the remaining material thickness of piping, vessels, tanks, and other components affected by corrosion or erosion.
Risk-Based Maintenance
Risk-based maintenance prioritizes maintenance decisions according to the likelihood and consequence of equipment failure.
Static Equipment
Static equipment is process or facility equipment without a primary rotating mechanism, such as vessels, tanks, piping, structures, and heat exchangers.
Glossary FAQs
- What does CUI stand for?
CUI stands for Corrosion Under Insulation.
- Why is CUI difficult to detect?
The corrosion is hidden beneath insulation and cladding.
- Where is CUI commonly found?
Damaged cladding, supports, nozzles, joints, penetrations, and cyclic-temperature areas.