Statistical data for the oil and gas industry shows that 40-60% of pipe maintenance budgets are related to corrosion under insulation (CUI). Millions of dollars are spent annually, yet many facilities still lack maintenance programs focused on insulated process equipment and piping.

The good news is that combating CUI does not have to consume a large percentage of maintenance budgets anymore. Implementing a CUI-focused Inspection and Maintenance Program can significantly reduce costs and downtime.  



Corrosion under insulation (CUI) is a damage mechanism common within the offshore installation, refineries, and petrochemical industries. The exterior corrosion is usually caused by water ingress into the insulation, worsened by moisture holdup, elevated temperatures (between 32 - 250 F / 0 - 120 C), absence or breakdown of coating, salts, and poor or broken insulation/cladding. Some insulation types have been known to accelerate corrosion when water is introduced, due to reduced pH and dissolved salts.

Because the corrosion is hidden beneath the insulation, CUI tends to remain undetected, leading to critical failure of components and potential major safety incidents.


Traditional CUI inspection requires insulation removal, scaffolding, coating, and reinstating the insulation on the component again after visual inspection. This is an expensive and time-consuming process, and much of the work is done to confirm that the surface under the insulation is in good condition.

Adopting a CUI-focused inspection and maintenance program is the best approach to address this problem. The components of a sound and comprehensive program will assist facility managers in making informed decisions to fight CUI whilst maintaining safe operations.



Axess Group has developed a focused inspection strategy to reduce the costs for evaluating the condition of insulated process equipment and piping. It entails visual inspection (VT) of insulated carbon and ferromagnetic steel piping and vessels, combined with the use of an advanced pulsed eddy current (PEC) screening tool, the Eddyfi’s Lyftᵀᴹ. This qualitative technique easily detects damaged areas, but to verify the corrosion severity, further Digital Radiographic Test (RT) is deployed to ensure accuracy, prior to making the decision to remove insulation.

Lyftᵀᴹ PEC, with its real-time C-scan imaging, fast data acquisition (up to 15 readings per second), and dynamic scanning modes, can measure the wall thickness of pipes and vessels without removing the insulation. After the turnaround at Statoil Tjeldbergodden industrial facility in 2016, Axess took the opportunity to test the capabilities of Lyft ᵀᴹ, and the results was within the range of previous Ultrasonic Thickness Measurements done while the insulation was removed. This gave Axess the confidence in LyftTM as a screening tool.

Due to Axess’ systematic CUI detection and assessment, the amount of external insulation removal and scaffolding can be kept at a minimum. This will reduce the overall maintenance cost, and based on typical costs related to insulation removal and refurbishment, show a potential for savings of more than 90%. This CUI inspection strategy will reduce the overall cost of inspection and maintenance of CUI related problems, and allow for optimized use of budgets.



A comprehensive report with detailed findings and optimal solutions is vital to systematic decision making. Additionally, adopting a digitalized reporting process such as the inspection software Axess Bridge could provide easy access to the technical and organizational recommendations and the captured data. When implemented, such a software solution reduces the time from inspection to decision.


The extensive expertise of Axess inspectors’ and the application of various NDE techniques, deliver key success measures to fight and monitor CUI. Implementing a CUI-focused inspection and maintenance program, which eliminates the need for extensive insulation removal and scaffolding erection, promotes savings, operational and personnel safety and technical asset integrity.

Axess Group’s team of engineers and technicians have an extensive filed experience and various levels of certification such as API 570, 510, NACE, CSWIP, NS 415, NS476, etc.

Discuss your CUI inspection and maintenance needs today. Contact us at