Use of microwaves for the detection of Corrosion Under Insulation (CUI)
BP, Imperial College
Corrosion Under Insulation (CUI) is a significant cause of pipeline failure in the oil and gas industry. When water breaches the external cladding used to protect the insulation, it allows corrosion of the external pipe surface to initiate.
Inspection of the pipe by removal of the insulation is expensive and time consuming, and the majority of techniques capable of non-invasively inspecting for CUI can only inspect small areas at a time which renders them impractical for the inspection of the miles of pipeline typically found at a facility.
This project explored the possibility of detecting the presence of water within the insulation, a necessary precursor to CUI. In particular, the pipe and the cladding can form a coaxial waveguide which can be used to propagate microwaves within the insulation along the length of the pipe. Since water has a relative permittivity much higher than that of the surrounding insulation, any patches of water along the pipeline will give rise to a strong reflection of the incident microwave signal, providing a method to detect and locate the water patches.