Kabushiki Kaisha Toshiba

Fumiharu Ishii

Kazuhiro Saito

Shigeru Harada

Satoshi Nagai

Mitsuyoshi Okazaki

Toshihiro Fujiwara

Seiichi Asatsu

Hirotsugu Kodama

Kazunari Fujiyama

Nagatoshi Okabe

Hitoshi Kichise

Takayuki Iwahashi

Masanori Minowa

Taiji Hirawawa

Mamoru Sudo

Data on inspection, diagnosis, repair and operation histories are entered in a plant-maintenance apparatus for equipment that constitute a plant to be maintained. Failure-event tree breakdown is performed on failures to be expected for the equipment. Unreliability is predicted of at least one starting item in the failure-event tree breakdown. Unreliability of each item in the failure-event tree is calculated based on a failure unreliability function. Unreliability and a cost of recovery from each failure event in the failure-event tree are multiplied and results of the multiplication are accumulated in accordance with the tree breakdown to obtain a recovery cost. Preventive maintenance expenses are calculated for preventing failure events. Maintenance timing and technique are decided through comparison between the recovery cost and the preventive maintenance expenses.

Plant maintenance method and apparatus

An apparatus for maintaining plant equipment incorporates an input unit to receive information on targets and ranges of plant equipment to be maintained and a failure-event tree breakdown unit to perform tree-breakdown on failures to be expected from events to be inspected. A failure-unreliability function calculation unit calculates unreliability of each item in failure-event tree breakdown and a failure-derived monetary loss calculation unit multiplies each unreliability and a cost of recovery from each event in accordance with the failure-event tree breakdown. A preventive maintenance expense calculation unit calculates preventive maintenance expenses for preventing failure events and a maintenance decision-making unit decides maintenance timing and technique through comparison between the recovery cost and the preventive maintenance expense.

For each component which is used at a high in-service temperature for a long period, its creep damage degree is approximated by a relational expression containing the Larson-Miller parameter. The creep damage degree is estimated by an approximation expression obtained by determining constants for each component. The creep damage degree is subjected to Weibull statistical analysis to estimate the creep damage degree probabilistically. Also, the thermal fatigue and damage degree obtained by an approximation expression is likewise subjected to Weibull statistical analysis to estimate the thermal fatigue and damage degree probabilistically. Therefore, the probabilistically estimated creep damage degree and the probabilistically estimated thermal fatigue and damage degree allows the life of each component subjected to a high in-service temperature to be assessed precisely and quickly.

Method and equipment for assessing the life of members put under high in-service temperature environment for long period

Growing community of inventors

Tokyo-to, Japan

Fumiharu Ishii