Mitigating The Risks Of Corrosion Under Insulation With Russell NDE Systems
Thursday, February 6, 2020

Mitigating The Risks Of Corrosion Under Insulation With Russell NDE Systems

Corrosion under insulation (CUI) is one of the most pervasive issues faced by pipes, boilers, storage tanks and pressure vessels that are susceptible to moisture from rain, high humidity and fog. Corrosion costs business over $2,505,000,000 each year, and places lives, the environment, and production at risk. In addition to tying up countless man-hours with repairs and clean-up, an estimated 40-60% of piping repair costs are spent in treating or addressing the aftermath of CUI failures. Learn more about the causes of CUI below, as well as a unique preventive inspection technology below.

What Is Corrosion Under Insulation (CUI)?

CUI refers to any type of corrosion that occurs due to moisture buildup on the external surface of insulated equipment, pipelines, tanks, pressure vessels and more. This build-up can, over time, breach the protective coating (if any) and lead to the deterioration of the steel. Corrosion typically comes in one of four forms: galvanic, chloride, acidic, or alkaline. When left undetected, CUI can lead to significant issues, including the shutdowns of process units or facilities, and significant safety risks.

What Causes CUI?

Corrosion Under Insulation is such a prevalent issue (roughly 60% of pipe leaks in plants are caused by CUI) because, unlike other forms of damage, it can be quite difficult to detect without the proper tools (more on that later). There are many factors that contribute to its development, including:


Corrosion thrives in certain temperature environments, with the commonly accepted data stating that carbon and low-alloy steels operating between –4ºC (25ºF) and 149ºC (300ºF) are typically most at risk from CUI. CUI has also been observed in the 149ºC+ (300ºF+) range, where the intermittent boiling and flashing that occurs above a metal temperature of 100ºC (212ºF) can lead to an aggressive CUI environment.

Environmental Factors

While CUI can develop in a wide variety of environments, there are certain conditions that are particularly favourable to its initiation. These include:

  • Marine environments
  • Hot or humid environments
  • Climates with high rainfall
  • Contaminants from the atmosphere or from the insulation (such as chlorides and sulfides) dissolved in water
  • Intermittent wet-dry conditions
  • Systems operating below typical atmospheric dew point (sweating services)
  • Insulating materials holding moisture or not allowing moisture drainage.

How To Prevent CUI

The most vital asset you have when it comes to preventing the development and spread of corrosion is keeping your pipes, tanks and vessels free of standing moisture. Second to prevention, NDT inspection can help you catch early signs, greatly reducing the chance of extensive damage in the long term.

Inspection Solutions with Russell NDE

Russell NDE Systems has created the Bracelet Probe, that is now relied upon by industry leaders like Enbridge and HSI Group to safely and efficiently identify CUI with reliability and accuracy. Our Bracelet Probe (BP) is adaptable to any insulated pipe size starting at 4” and contains sensitive detectors that cover a 10” wide scan path. The probe scans at a rate of up to 12'/min on both horizontal and vertical pipes. The BP data is fed real-time to a computer that displays and records the underlying condition of the pipe or plate. This data can then be saved as 3D color-maps, strip charts and voltage planes which are used to size the depth of the CUI.

Learn more about mitigating the risks of CUI by contacting Russell NDE Systems today.