Asset Intelligence Report

A Primer on Corrosion Under Insulation (CUI)

Corrosion Under Insulation (CUI) is one of the most well-known damage mechanisms in the O&G and chemical processing industries, yet CUI still makes up a very large percentage of plant maintenance expenditures. In the simplest terms, CUI is any type of corrosion that occurs due to moisture buildup on the external surface of insulated equipment. The damage/attack can be caused by one of multiple factors and can occur in equipment operating at ambient, low, and heated services, depending upon conditions. Moreover, CUI can occur in equipment that is in service, out of service, or in cyclic service. The corrosion itself is most commonly galvanic, chloride, acidic, or alkaline corrosion. If undetected, the results of CUI can lead to the shutdown of a process unit or an entire facility, and in rare cases it may lead to a process safety incident.

This Asset Intelligence Report contains the following sections:

  • Overview of Corrosion Under Insulation
  • History of Corrosion Under Insulation
  • Causes of Corrosion Under Insulation
  • Effective Inspection Techniques
  • Methods of Prevention/Mitigation
  • Codes, Standards, and Best Practices
  • Further Reading

As with other Asset Intelligence Reports, this document is not intended to serve as a comprehensive guide, but rather an introductory primer on corrosion under insulation. Since the information is provided in a condensed format, we recommend printing and laminating copies that can be referenced by you and your co-workers at your convenience.

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A Primer on Corrosion Under Insulation (CUI)

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