Maintenance and Inspection of Chimney




Due to age deterioration, lining or bricks inside the chimney may separate and fall damaging the chimney itself, joints or clog openings, all of which can result in accidents. Therefore, chimneys must be inspected periodically to maintain their healthy condition.

By utilizing the heat conduction caused by the difference between the temperature inside the chimney and the temperature outside, NEC Avio’s TS9230 & TS9260 Thermal Imaging Cameras can detect defective sections based on the surface temperature distribution of a chimney.  Fig.1 is an outline drawing of a steel chimney. When the lining, which protects the steel plate from exhaust smoke, is separated from the steel plate causing an air layer between the two, surface temperature of the separated section will become low because it is difficult for the inside temperature to be conducted to the surface. On the other hand, when the lining has separated and fallen off, the surface temperature will become high because the inside temperature is conducted directly to the steel plate.

Fig.2 is an outline drawing of a RC (reinforced concrete) chimney. The section where the brick thickness is thin or the brick has fallen off, inside temperature is directly conducted to RC, resulting in high surface temperature.Photo 1 is a thermal image of a steel chimney. Photo 2 is a visible image of the same chimney. The structure of the chimney is such that the external steel plate is 5cm thick, lining is 10cm thick, and the height is 100m. When observation was made, internal temperature was 30℃ and external temperature was 2℃. Separated section was observed as a low temperature section.

Photo 1 and 2
(Photo 1 using TVS-2100)



      Fig.1: Steel chimney                 Fig.2: RC chimney