PEC inspection is possible at high temperatures.
By placing a ceramic block in between probe and hot wall, the probe can be shielded from the heat and readings can be taken as normal. In this way, PEC is able to produce accurate measurement at temperatures up to 550°C.
An example of a high-temperature inspection involved a refinery where two heat exchanger shells had been mistakenly exposed to hydrogen chloride attack, resulting in suspected wall loss at the top of the shells. Insulation material was removed from the heat exchangers to take ultra sound wall thickness readings.
The high temperature of the heat exchangers hampered the ultrasound measurements and reliable data could only be obtained at a limited number of points. PEC performed more successfully. PEC data, collected along the circumference of the heat exchanger at several points, proved consistent with the ultrasound data at those points producing reliable ultrasound readings.The worst case of wall loss detected by PEC at the refinery is displayed in the figure opposite, showing about 3 mm wall loss. As this was acceptable from the integrity point of view, the asset owner decided not to replace the shells.