JPS57157138A - Foretelling method and device for device life - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a trouble due to fatigue, creep, and corrosion, by a method wherein data is collected at an evaluation position of a device to compute and decide a life remaining in terms of a strength. CONSTITUTION:A metal temperature by a thermocouple 21 and each steam temperature by a steam temperature detector 22 are inputted to a thermal stress computer 30a to compute a thermal stress, each steam pressure measured by a steam pressure detector 23 is inputted to an inner pressure stress computer 30b to compute an inner pressure stress which is inputted to an adder to compute a resultant stress. A comparator 41 compares absolute values of an allowable stress 41a and the resultant stress, and a deciding device 42 decides safety. Meanwhile, the resultant stress is inputted to an analyzer whereto an operation output data 24 is previously introduced, a stress wave form analysis takes place by means of a time-to-stress cuver 50a to decide a stress component. The stress component is inputted to computers 51 and 52 to compute a growing amount of crack, an adder 55 adds each growing amount, a comparator 61 compares it with an allowable crack size 61a, and a decider 62 decides a remaining life of a device.