Corrosion Under Insulation (CUI) is one of the major cause of pipeline failure in the oil industry.  When water breaches the external cladding used to protect the insulation, it starts to corrode the external surface of the pipe.  Inspection of the pipe by removal of the insulation is expensive and time consuming.  Although less invasive techniques such as radiography and magnetic flux linkage exist, they are not applicable in practice.  This project explores the possibility of detecting CUI with an indirect approach aimed at monitoring the presence of water in the insulation; a necessary precursor to CUI.  In particular, it is observed that the pipe and the cladding form a coaxial waveguide which can be used to propagate microwaves within the insulation along the length of the pipe.  Since microwaves are highly attenuated by water, the drop of microwave signal along the pipeline could be used to detect the presence of water and hence the likely occurrence of CUI. You can view a presentation here.

Pipeline subject to corrosion under insulation

References

RE Jones, F Simonetti, MJS Lowe, IP Bradley, "use of microwaves for the detection of corrosion under insulation: a sensitivity study”, Review of Progress in Quantitative NDE, eds. D.O. Thompson and D.E. Chimenti, American Institute of Physics, New York, vol. 30, pp. 1714-1721, 2011.

RE Jones, F Simonetti, MJS Lowe, IP Bradley, "Use of microwaves for the detection of corrosion under insulation", Review of Progress in Quantitative NDE, eds. D.O. Thompson and D.E. Chimenti, American Institute of Physics, New York, vol. 29, pp. 1373-1380, 2010.