This issue gives the distribution of stress and displacement of the dangerous field on the tube-plate and the edges of man-hole and the tube-plate through the finit element method analysis of the boiler structure.

The author of this paper thoroughly analyzed the leakage lead to by the manhole flange failure of T 303 spherical tank and made some calculations as well As a result,she found out the causes of the failure of the flange and put forward a series of corresponding measures for revampin

Result of analysis shows that the main cause resulting in tube-burst of low-temperature reheater is as follows: the thermal insulation of manhole gate is not perfect, making the tube-row near the manhole gate to suffer locally serious fly ash wornout.