https://pscfiles.tamu.edu/symposia/2005/050%20Arunraj.pdf

Risk-based maintenance—Techniques and applications

An evaluation of maintenance strategy using risk based inspection

Purpose – Maintenance, an essential element of facilities management and a fundamental requisite for increasing availability and sustaining stable processes, has been the focus of technical research for decades. However, there has not been a concrete and well‐structured classification of different maintenance types that is accepted globally. The need for such a widely acceptable classification is the main incentive to delve into and create a new maintenance taxonomy. This paper aims to address this issue.Design/methodology/approach – The paper gathers and reviews several examples of maintenance classifications and viewpoints from different geographical regions in the world. Afterwards, it integrates various maintenance‐related terms and terminologies with the authors' systematic‐thinking approach, systems thinking, based on which strategic thinking is formed. Consequently, this combination results in a globally acceptable systematic classification of maintenance.Findings – The outcome of this scientific e...

A strategic standpoint on maintenance taxonomy

A risk-based shutdown inspection and maintenance interval estimation considering human error

Petrochemical plants and refineries consist of hundreds of pieces of complex equipment and machinery that run under rigorous operating conditions and are subjected to deterioration over time due to aging, wear, corrosion, erosion, fatigue and other reasons. These devices operate under extreme operating pressures and temperatures, and any failure may result in huge financial consequences for the operating company. To minimize the risk and to maintain operational reliability and availability, companies adopt various maintenance strategies. Shutdown or turnaround maintenance is one such strategy. In general, shutdown for inspection and maintenance is based on the original equipment manufacturer's (OEM) suggested recommended periods. However, this may not be the most optimum strategy given that operating conditions may vary significantly from company to company. The framework proposed in this work estimates the risk-based shutdown interval for inspection and maintenance. It provides a tool for maintenance planning and decision making by considering the probability of the equipment or system for failure and the likely consequences that may follow. The novel risk-based approach is compared with the conventional fixed interval approach. This former approach, characterized as it is by optimized inspection, maintenance and risk management, leads to extended intervals between shutdowns. The result is the increase in production and the consequent income of millions of dollars. The proposed framework is a cost effective way to minimize the overall financial risk for asset inspection and maintenance while fulfilling safety and availability requirements.

A framework to estimate the risk-based shutdown interval for a processing plant

Risk-based inspection and maintenance systems for steam turbines

PROBLEM TO BE SOLVED: To provide the soleplate of a steam turbine which can sufficiently withstand the reaction generated by the deflective reaction by an excessive thermal expansion and a gas turbine thrust and whose enforcement is easy. SOLUTION: A soleplate 20 for installing a steam tiurbine is placed on a base concrete 12 through a grout pad 14 and fixed between the base concrete 12 and the soleplate 20 by concreting. In such soleplate, a shear plate 23 projected downward by a shorter distance than the space from this plate main body to the base concrete 12 is provided on the lower surface of the plate main body 21 of the soleplate.

Soleplate of steam turbine, installation structure of steam turbine and uniaxial combined cycle plant

PROBLEM TO BE SOLVED: To provide an examining device for the internal structure of a turbine capable of reducing procedure of disassembly of a device and quantitatively examining circumstances of a turbine nozzle in the inspection of the inside of the device, especially, the inspection of a nozzle and a moving blade in a turbine. SOLUTION: In the examining device constituted of a video probe and a carrier for carrying the video probe, and examining the internal structure of the turbine by inserting the video probe in the turbine, the carrier includes at least either a mechanism for deciding the advancing direction of the carrier and a facing angle of the tip of the video probe or a mechanism for deciding the positions of the axle of the carrier and the video probe. The circumstances of the turbine nozzle are quantitatively examined by making the carrier stably travel along a blade line in such a state that at least either the advancing direction of the carrier and the facing angle of the tip of the video probe or the positions of the axle of the carrier and the video probe is decided. COPYRIGHT: (C)2008,JPO&INPIT

Examining device for internal structure of turbine and examining method using same

PROBLEM TO BE SOLVED: To provide an apparatus capable of predicting an amount of damage of equipment members quantitatively, evaluating probability that the amount of damage needing repairing is reached and its risk, and detecting optimal repair criteria and repair time. SOLUTION: Inspection data of the equipment members, information on operation history, repair history, and member rotation history are inputted; a relation between a measured value of the damage to be a precursory phenomenon of nonconformity of the equipment members and a duration of use parameter is statistically calculated; probability distribution of the period that the amount of repair marginal damage is reached; a damage risk function is obtained by relating the damage value to costs needed for repair therefor and by using product of the probability distribution of the period that the amount of repair marginal damage is reached and the costs needed for the repair; and an amount of repair marginal damage in which the total risk costs over the members' total duration of use and the repair costs accumulation value from a cost data base storage means become lower than a prescribed sum given by the damage risk function calculating means or lower than an accumulation gain by operation, and the repair time and the number of repair corresponding to the amount are determined. COPYRIGHT: (C)2006,JPO&NCIPI

Kenichiro Furuya

Papers

Risk-based inspection and maintenance systems for steam turbines

Soleplate of steam turbine, installation structure of steam turbine and uniaxial combined cycle plant

Examining device for internal structure of turbine and examining method using same

Repair plan support method and apparatus for plant equipment member