1979 Volume 65 Issue 7 Pages 869-875
A remaining life estimation method fbr in-service boiler tubes (2.25Cr-1Mo steel) has been studied in terms of cumulative creep strains. With the life fraction rule presentation, values between 0.98 and 1.90 have been obtained by a numben of creep rupture tests under variable temperature conditions.
The materials pre-crept to a same strain level at vanious strain rates between 0.002 and 2%/h showed the remaining life within a range of±0.2 of the value of the life fraction presentation. For a nelatively conservative estimate, correlations between tangential strains on the outside diameter of tube and remaining life have been established for a number of stress levels orresponding to hoop stresses.
The present method enables to determine the remaining life nondestructively without operational histories.