Optical system reveals power station defects
15 Jan 2000
PowerGen is employing an optical inspection technique, infrared thermography, to monitor the condition of the organic, anti-corrosion coatings on the steel walls of desulphurisation units. The harsh environment can cause thinning and holing in the steel.
Traditional visual inspection and spark testing of the units only reveal serious problems that are several millimetres thick, but such methods cannot spot separation between the coating and the wall.
PowerGen's novel approach, called transient thermography, employs a portable thermal camera to map variations in heat flows on the surface to reveal the defects.
A trial at Ratcliffe-on-Soar's 2000MW power station detected a 1mm diameter gas pore in the coating on a gas-to-gas reheater. In a later inspection, it found an area of coating that was becoming detached.
`Transient thermography enables rapid inspection, critical when a company wants to minimise plant downtime.,' said PowerGen researcher Colin Brett.
`The technique could find plenty of applications elsewhere - the chemical, water and sewage industries all need to monitor anti-corrosion coatings too.'
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