The inside diameter of furnace tubes are measured by through gauge in order to know the wall thickness, but it is difficult to know the minimum wall thickness due to irregular corrosion.
Therefore, the author studied the corrosion tendency and tried to calculate minimum thickness.
The results obtained were as follows:
(1) Eccentric corrosion due to bubbling are found on the heating side of radiation tubes.
(2) The minimum wall thickness of tubes are calculated by following relation:
T_m=T_o-[{Δd×(12.3√Δd+50)}/100]
T_m: minimum thickness
T_o: original thickness
Δ_d: increase of inside diameter