Pipeliners Dictionary

Corrosion Under Insulation (CUI)

Corrosion under insulation (CUI) is a type of corrosion that occurs on the surface of pipelines, tanks, and other equipment that are covered by insulation. This type of corrosion can result from moisture that is trapped between the insulation and the surface of the equipment, which can create a corrosive environment.

CUI is a significant concern for pipelines and other equipment because it can go undetected for long periods of time, allowing corrosion to progress and cause significant damage. The damage can result in leaks, reduced equipment life, and increased risk of safety hazards.

CUI can occur as a result of a variety of factors, including:

  1. Moisture infiltration: Moisture can penetrate through gaps or defects in the insulation or cladding, or through the vapor barrier, resulting in moisture buildup and corrosion under the insulation.

  2. Ambient temperature: High ambient temperatures can cause moisture to condense on the surface of the equipment, increasing the risk of CUI.

  3. Environmental factors: Environmental factors such as high humidity, exposure to rain or other precipitation, and proximity to saltwater can increase the risk of CUI.

To prevent CUI, pipelines and other equipment must be properly designed and constructed, with adequate insulation and vapor barriers, to reduce the risk of moisture infiltration. Additionally, regular inspections and maintenance must be performed to detect and address any signs of CUI as soon as they occur.

In some cases, CUI can be prevented or mitigated by applying a protective coating to the surface of the equipment, or by using a corrosion-resistant material. In addition, cathodic protection can be used to reduce the risk of CUI by controlling the electrical potential of the equipment and reducing the risk of corrosion.

In conclusion, CUI is a type of corrosion that can occur on the surface of pipelines and other equipment that is covered by insulation. It is a significant concern because it can go undetected for long periods of time and cause significant damage if left unaddressed. It is important to take measures to prevent CUI, including proper design and construction, regular inspections and maintenance, and the use of corrosion-resistant materials and protective coatings, in order to maintain the integrity and reliability of the equipment over time.

Go back to list



We are here to help you

Any questions?


Get in touch

Top 100 innovators of germany

It’s for a reason that we are amongst Germany’s Top 100 innovators. Because our mission is to overcome these inspection challenges and, together with our clients, continuously improve the safety and reliability of all pipelines.