To accurately judge the residual life of a heat transfer tube suffering composite damages, by calculating the degree of a fatigue damage being developed and the degree of a thickness reduction damage being developed, and calculating the residual life from the resultant values of the above calculation and a limit thickness for avoiding destruction of the heat transfer tube, thereby judging the life of the heat transfer tube.
A crack depth caused by corrosion fatigue is measured by measuring at the step 10 a corrosion fatigue crack at an inner side surface of a water wall tube. The quantity of an outer surface thickness reduction is measured by measuring at the step 12 the quantity of the outer surface thickness reduction of an outer side surface of the water wall tube. Subsequently, when adding a fatigue crack damage in hot water and a thickness reduction damage caused by pitting every year, for instance, a stress amplitude is corrected at the step 15 by a development analysis of the corrosion fatigue crack, in accordance with the crack depth and the degree of the residual thickness reduction caused by outer surface corrosion before the previous year. Crack development analysis and residual life judgement are conducted by a crack development analysis and a residual life judgement at the step 16, and a destruction limit crack depth is corrected based on the thickness by correcting at the step 17 the destruction limit crack depth over the whole thickness reduction. In comparing at the step 18, the residual thickness with the destruction limit, in the case where the residual thickness in larger than the destruction limit, the operation of a boiler is continued at the step 19, and when becoming smaller, the life is regarded as terminated, followed by change and renewal at the step 20.
KOYAMA TERUO
MORI SHUJI
MATSUMOTO TERUAKI
| JPH09119603A | 1997-05-06 | |||
| JPH06331622A | 1994-12-02 | |||
| JPH04282455A | 1992-10-07 |