CUI Detection-When to Use Profile Radiography

Corrosion under insulation (CUI) is a common and challenging issue in insulated piping systems. Choosing the right inspection technique is critical to effectively assess and manage CUI-related damage. Among the available non-destructive testing (NDT) methods, Profile Radiography is a proven option for identifying and quantifying corrosion in localized areas. Here's a guide to understanding when profile radiography is the best choice for CUI detection.

Versatility of Profile Radiography for CUI Detection

Profile radiography is an excellent method for inspecting insulated piping systems without the need to remove insulation, enabling the assessment of pipe conditions while saving both time and costs. It is particularly effective for evaluating localized corrosion or pitting damage, providing accurate wall thickness measurements with the use of a comparator ball. This technique is also highly beneficial for in-service pipelines, allowing inspections to be conducted without halting operations, thereby minimizing production disruptions. Additionally, profile radiography performs well on piping systems starting from 1 NPS, offering reliable localized evaluations, although limitations may arise for larger pipe diameters depending on the radiation energy and source strength. Furthermore, it is a fast and dependable option for detecting significant corrosion, enhancing the overall efficiency of CUI detection during preliminary inspections.

Making the Decision

Profile radiography is best suited for applications where quick, localized inspection of insulated piping is required without disrupting operations. Its ability to detect uniform corrosion and pitting damage through insulation makes it a valuable tool in many industries dealing with CUI. However, the method's limitations, such as size constraints and safety considerations, must be evaluated to ensure it aligns with inspection goals and site requirements.

By understanding these factors, you can select profile radiography confidently when tackling CUI challenges in your piping systems.

The accompanying (above) image provides an excellent visual example of how this technique can identify corrosion damage and measure wall thickness accurately.

Limitations

While profile radiography is highly effective for certain applications, it does have some limitations:

• Pipe Size and Thickness: It becomes less effective for pipes over 8 inches in diameter or with very thick walls, depending on the radiation energy used.
• Radiation Safety Requirements: Strict safety protocols, including large exclusion zones, can complicate inspections in busy facilities.
• Image Distortion: Vibrations in in-service piping can affect image clarity, making analysis more challenging.
• Pitting Orientation: Damage not perpendicular to the radiographic beam may require geometric correction to determine the true pit depth.