Method for assessing remaining lifespan of bolt used at high temperatures

Abstract of the Disclosure The present invention is intended to provide a method for assessing remaining lifespan of a bolt with higher precision than conventional methods, which can be applied to a bolt comprising a high alloy with fewer tissue changes caused by creep damage. The present invention provides a method for assessing the remaining lifespan of a bolt used at high temperatures, including: carrying out a creep test for a bolt material that constitutes a bolt to be assessed and determining a life-time and a life-elongation rate; determining a time-temperature parameter based on the life-time and the creep test temperature; creating a lifespan-assessment diagram by plotting the time-temperature parameter with respect to the life-elongation rate; measuring a elongation rate between before and after the use of the bolt to be assessed; and assessing the remaining lifespan of the bolt with the use of the elongation rate between before and after the use of the bolt to be assessed and the lifespan-assessment diagram. 0- 0 0 0 * 0 0 * * 0 I~~~. .-CJ -. .. ... .. IncoC~c t I o . .. ... ..& 4 2 22. 4 4 ... Lo) ... ~ ~ j * *~ .:.. ... ... 4 4. . _ .. ... ... ... ... C4. CL., 0 2 E4! .4~ a... cur Go (0 22 2 2 i 0 .. $...S...6...4... 44... a ... 4 4-4 E5 T?: E ... E r Lo r0 04 c) C C))