An Approach for Cost Effective Assessment in Risk-Based Maintenance as a Life-Cycle Maintenance (LCM) Model

2004 ◽  
Author(s):  
Masataka Yatomi ◽  
Akio Fuji ◽  
Noriko Saito ◽  
Toshiaki Yoshida
Keyword(s):  
Life Cycle ◽  
Power Plants ◽  
Cost Effective ◽  
Life Extension ◽  
Maintenance Cost ◽  
Maintenance Strategy ◽  
Original Design ◽  
Maintenance Strategies ◽  
Effective Assessment ◽  
Maintenance Plan

For aged power plants in Japan, the life extension with retaining the safety and cost-effective beyond the original design lifetime is proposed. Therefore it is important to minimise the risk and maintenance cost to keep operating the plants. Life-Cycle Maintenance (LCM) is proposed for optimising maintenance plan with reliability in the life of the plants. Risk Based Maintenance (RBM) is included in the LCM to assess the risk of components in the plants. LCC and the investment assessment may be also conducted to decide the most cost effective maintenance strategy, if several maintenance strategies are proposed in RBM. In this paper, concept and an application of the LCM are described to optimise maintenance plan in the lifetime of a plant. It was found that the LCM is quite useful method to plan the most cost effective maintenance strategies in the lifetime of the plant.

Calculating Thermal Gradients in a B31.1 Welding End Transition Joint by Formulae

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
David H. Creates
Keyword(s):  
Power Plant ◽  
Computer Program ◽  
Fatigue Damage ◽  
Power Plants ◽  
Life Extension ◽  
Thermal Gradients ◽  
Plant Design ◽  
Original Design ◽  
Plant Life ◽  
Fatigue Evaluation

Fatigue evaluation in B31.1 is currently done based on equations 1 and 2 of ASME B31.1-2007 Power Piping, which only considers the displacement load ranges. However, fatigue damage, in addition to displacement load ranges, is occurring in B31.1 piping due to pressure cycling and thermal gradients. To exacerbate this, power plant design pressures and temperatures are rising, new materials are being introduced, pipes and attached components are becoming increasingly thick, and owners are requiring power plants to heat-up and cool-down at faster rates. Also, power plant owners are more and more interested in extending the life of power plants beyond their original design life. This article takes the first step in addressing the pressing need to address this additional fatigue damage by quantifying thermal gradients in the prevalent B31.1 welding end transitions in Fig. 127.4.2, or tapered transition joints (TTJs) in Appendix D, of ASME B31.1-2007 Power Piping by formulae to be able to evaluate their contribution to fatigue (see PVP2009-77148 [A Procedure to Evaluate a B31.1 Welding End Transition Joint to Include the Fatigue Effects of Thermal Gradients for Design and Plant Life Extension]). The disadvantage of this approach is that the conservatisms inherent in the calculations of thermal gradients, as per ASME Section III Subsection NB3600-2007, are also inherent in these calculations and may produce unacceptable results when evaluated as per PVP2009-77148 [A Procedure to Evaluate a B31.1 Welding End Transition Joint to Include the Fatigue Effects of Thermal Gradients for Design and Plant Life Extension]. If the results are unacceptable, it is a warning that something else needs to be done. The advantage of this approach is that it eliminates the need for a computer program to quantify these thermal gradients, a computer program that is not normally accessible to the B31.1 designer anyway. Instead, the formulae use the data that are available to the B31.1 designer, namely, physical geometry, thermal conductivity, and rate of temperature change in the fluid in the pipe. This will further help to preserve the integrity of the piping pressure boundary and, consequently, the safety of personnel in today’s power plants and into the future.

scholarly journals Uncertainty estimation in railway track life-cycle cost: a case study from Swedish National Rail Administration

2008 ◽  
Vol 223 (3) ◽  
pp. 285-293 ◽  
Author(s):  
A P Patra ◽  
P Söderholm ◽  
U Kumar
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Cost Effective ◽  
Railway Track ◽  
Statistical Characteristics ◽  
Maintenance Cost ◽  
Cost Models ◽  
Effective Decision ◽  
Effective Decision Support

Life-cycle cost (LCC) is used as a cost-effective decision support for maintenance of railway track infrastructure. However, a fair degree of uncertainty associated with the estimation of LCC is due to the statistical characteristics of reliability and maintainability parameters. This paper presents a methodology for estimation of uncertainty linked with LCC, by a combination of design of experiment and Monte Carlo simulation. The proposed methodology is illustrated by a case study of Banverket (Swedish National Rail Administration). The paper also includes developed maintenance cost models for track.

Assessment of Remaining Life for Class 1 Piping Components Experiencing Wall Thinning

2004 ◽  
Author(s):  
Rajnish Kumar
Keyword(s):  
Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Life Extension ◽  
Remaining Life ◽  
Original Design ◽  
Accelerated Corrosion ◽  
Wall Thinning ◽  
Class 1 ◽  
Plant Components

Assessment of remaining life of power plant components is important in light of plant life management and life extension studies. This information helps in planning and minimizing plant outages for repairs and refurbishments. Such studies are specifically important for nuclear power plants. Nuclear Safety Solutions Limited (NSS) is involved in conducting such studies for plant operators and utilities. Thickness measurements of certain piping components carrying fluids at high temperature and high pressure have indicated higher than anticipated wall thinning rates. Flow accelerated corrosion (FAC) has been identified as the primary mechanism for this degradation. The effect of FAC was generally not accounted for in the original design of the plants. Carbon steel piping components such as elbows, tees and reducers are prone to FAC. In such cases, it is important to establish the remaining life of the components and assess their adequacy for continued service. Section XI of the ASME Boiler and Pressure Vessel Code is applicable for evaluation of nuclear power plant components in service. This Section of the Code does not specifically deal with wall thinning of the piping components. Code Case N-597 provides guidelines for evaluation for continued service for Class 2 and Class 3 piping components. For Class 1 piping components, this Code Case suggests that the plant owner should develop the methodology and criteria for evaluation. This paper presents methodology and procedure for establishing the remaining life and assessment of Class 1 piping components experiencing wall thinning effects. In this paper, the rules of NB-3600 and NB-3220 and Code Case N-597 have been utilized for assessment of the components for continued service. Details of various considerations, criteria and methodology for assessment of the remaining life and adequacy for continued service are provided.

A Procedure to Evaluate a B31.1 Welding End Transition Joint to Include the Fatigue Effects of Thermal Gradients for Design and Plant Life Extension

2009 ◽  
Author(s):  
David H. Creates
Keyword(s):  
Power Plant ◽  
Computer Program ◽  
Power Plants ◽  
Additional Term ◽  
Life Extension ◽  
Thermal Gradients ◽  
Plant Design ◽  
Original Design ◽  
Plant Environment ◽  
Fatigue Evaluation

Fatigue evaluation in B31.1 is currently done based on Equation 1 & 2 [B31.1-2007] which considers only displacement load ranges. Yet, fatigue damage is also occurring due to pressure cycling and thermal gradients. To exacerbate this, power plant design pressures and temperatures are rising, new materials are being introduced, pipes and attached components are become increasingly thick, and owners are requiring the power plants to heat-up and cool-down at faster rates. Also, power plant owners are more and more interested in extending the life of power plants beyond their original design life. Although the knowledge of thermal gradients has been available for many years, no attempt has been made to incorporate this into the B31.1 Code. This paper takes the first step in addressing this pressing need in today’s power plant environment. Granted there are several configurations where the effects of thermal gradients could be assessed. As the first step, this paper provides a procedure to evaluate the fatigue effects of thermal gradients in the prevalent Welding End Transition Joint (ASME B31.1 Fig 127.4.2) based on thermal gradients calculated as per [PVP2009-77147]. The disadvantage of this approach is that the conservatism in the calculation thermal gradients inherent in ASME Section III Sub-section NB-3600-2007 is inherent in these calculations as well, and may produce unacceptable results. If the results turn out to be unacceptable, it is a warning that something else needs to be done in the way of either monitoring or modifying or further evaluation. The advantage of this methodology is that it maintains the traditional B31.1 approach to fatigue by controlling SE with the same limit of SA except that there is now an additional term, f ‘, to account for the fatigue effects due to thermal gradients. In addition, it eliminates the need for a computer program to calculate this additional term, a computer program that is not normally accessible to the B31.1 designer anyway. Considering the fatigue effects of thermal gradients in this way will further help to preserve the integrity of the piping pressure boundary and consequently, the safety of personnel in today’s power plants and into the future.

Management of Component Fatigue in CANDU Stations for Life Extension

2008 ◽  
Author(s):  
M. Yetisir ◽  
G. L. Stevens ◽  
S. Robertson
Keyword(s):  
Pilot Study ◽  
Nuclear Power ◽  
Power Plants ◽  
Life Extension ◽  
Pressurized Water Reactor ◽  
Original Design ◽  
Pressurized Water ◽  
Warm Up ◽  
Water Reactor ◽  
Secondary Systems

CANDU® nuclear generating stations and their components were designed for 30 effective full power years (EFPY) of operation. Many CANDU plants are now approaching their design end-of-life and are being considered for extended operation beyond their design life. The Canadian regulator, the Canadian Nuclear Safety Commission (CNSC), has asked utilities to consider component fatigue issues in plant life extension (PLEX) applications. In particular, environmental effects on fatigue is identified as an issue that needs to be addressed, similar to that being addressed for license renewal for U.S. nuclear power plants. To address CNSC concerns, CANDU stations have initiated a program to develop component fatigue management programs for PLEX operation. A pilot study conducted in a typical CANDU plant showed that: • Only 10 to 15% of the numbers of design transients have been used after 25 EFPY of operation. Hence, a significant amount of original design fatigue usage margin remains available for PLEX operation. • Environmental fatigue considerations in heavy water (D2O) were included in the assessment. Only warm-up transients are assessed to have dissolved oxygen concentrations that can result in a significant environmental effect for the ferritic steels used in the CANDU primary and secondary systems. • Due to the low accumulation of transients, and the relative absence of thermal stratification mechanisms, thermal fatigue is not as significant an issue in CANDU plants as in pressurized water reactor (PWR) and boiling water reactor (BWR) plants. This paper summarizes the results of the pilot study conducted for the Canadian CANDU plants.

Calculating Thermal Gradients in a B31.1 Welding End Transition Joint by Formulae

2009 ◽  
Author(s):  
David H. Creates
Keyword(s):  
Power Plant ◽  
Computer Program ◽  
Fatigue Damage ◽  
Power Plants ◽  
Life Extension ◽  
Thermal Gradients ◽  
Plant Design ◽  
Original Design ◽  
Bending Loads ◽  
Fatigue Evaluation

Fatigue evaluation in B31.1 is currently done based on Equation 1 & 2 [B31.1-2007] which considers only displacement load ranges. However, fatigue damage, in addition to displacement load ranges, is occurring in B31.1 piping due to pressure cycling and thermal gradients. To exacerbate this, power plant design pressures and temperatures are rising, new materials are being introduced, pipes and attached components are becoming increasingly thick, and owners are requiring power plants to heat-up and cool-down at faster rates. Also, power plant owners are more and more interested in extending the life of power plants beyond their original design life. This paper takes the first step in addressing the pressing need to address this additional fatigue damage by considering thermal gradients. Granted there are several configurations where thermal gradients could be calculated. As the first step, this paper provides formulae to quantify the thermal gradients in the prevalent B31.1 Welding End Transitions Fig. 127.4.2, or Tapered Transition Joints (TTJ) Appendix D [B31.1-2007] which produce bending loads in the pipe around the full circumference and add to the fatigue damage of these welded joints. The disadvantage of this approach is that the conservatisms inherent in the calculations of thermal gradients as per ASME Section III Subsection NB3600-2007 are also inherent in these calculations and may produce unacceptable results when evaluated as per [PVP2009-77148]. If results are unacceptable, it is warning that something else needs to be done. The advantage of this approach is that it eliminates the need for a computer program to quantify these thermal gradients, a computer program that is not normally accessible to the B31.1 designer anyway. Instead, the formulae use data that is available to the B31.1 designer, namely physical geometry, Thermal Conductivity and the Rate of temperature change of the fluid in the pipe. Calculating the magnitude of thermal gradients in a B31.1 TTJ is an essential step in evaluating their fatigue effects for design and in plant life extension considerations (see PVP2009-77148). This will further help to preserve the integrity of the piping pressure boundary and consequently, the safety of personnel in today’s power plants and into the future.

Study on in-Service Bridge LCC Decision Model Based on Maintenance Management System

2011 ◽  
Vol 255-260 ◽  
pp. 3933-3937
Author(s):  
Yu Meng Wu ◽  
Jun Chang
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Decision Model ◽  
Management Strategies ◽  
Maintenance Management ◽  
Management Decision ◽  
Maintenance Strategy ◽  
Maintenance Strategies ◽  
Bridge Maintenance ◽  
Optimal Maintenance

In this paper, decision-making tree and Markov process are used to select maintenance strategies of in-service bridges with the minimum LCC (life-cycle cost). Other costs in life cycle are considered comprehensively when establish the model to find the optimal maintenance strategy. Finally, an example is given to verify the efficiency of the model. The research methodology can provide effective support to bridge maintenance management decision-maker for making management strategies.

scholarly journals Identification of key challenges associated with the implementation of renovation & modernization (r & m) projects in India using factor analysis

2018 ◽  
Vol 7 (4.5) ◽  
pp. 767
Author(s):  
Purnima Bajpai ◽  
Prof. K. Chandrashekhar Iyer ◽  
Shubham Bansal
Keyword(s):  
Factor Analysis ◽  
Exploratory Study ◽  
Power Plants ◽  
Thermal Power ◽  
Maintenance Cost ◽  
Thermal Power Plants ◽  
Original Design ◽  
Design Values ◽  
Overall Performance ◽  
Survey Approach

The Renovation & modernization (R&M) of coal fired thermal power plants deals with making the power plants units well equipped with the latest technology and systems with an aim of improving their overall performance in terms of output and availability as compared to the original design values, reduce the maintenance cost and enhanced efficiency. The aim of this study was to identify the key challenges associated with implementation of R & M Projects in India. An exploratory study of 42 variables was conducted through factor analysis using the data obtained through a questionnaire survey approach The results obtained 6 key challenges , namely Contractual risks, funding risks, planning risks, regulatory risks, market related risks and management risks which hamper the rate of implementation of R & M Projects in India.  

Unbonded flexible pipe integrity management, reuse and life extension

2008 ◽  
Vol 48 (1) ◽  
pp. 319
Author(s):  
Adriana Botto ◽  
Céline Banti ◽  
Enda O'Sullivan
Keyword(s):  
Asset Management ◽  
Production Systems ◽  
Cost Effective ◽  
Later Life ◽  
Life Extension ◽  
Original Design ◽  
Flexible Pipe ◽  
Effective Manner ◽  
Manufacturing Testing ◽  
Integrity Management

Australia has a long tradition of innovation in the use of floating production systems in the past 20 years. The classical solution adopts unbonded flexible pipe, a key technology, to enable floating facilities to produce in relatively shallow waters. While unbonded flexible pipe is a reliable technology that has been in use for approximately 30 years, damage, and ultimately failure can occur during its early (i.e. during manufacturing/testing, installation and early operation) and later life. Accurate assessments of the historical records of flexible pipe usage have led to an increased understanding of the potential failure mechanisms. This enables mitigation of incidents by developing operating strategies and procedures to manage the flexible pipe in a knowledgeable and cost effective manner. This paper discusses the available techniques for the inspecting and monitoring requirements of flexible pipe, including consideration of the value offered by conventional general visual inspection (GVI) techniques. Examples of developed alternative technologies are discussed, as well as how these alternatives can reduce the requirement for GVI when supplemented with an integrated integrity management strategy. Furthermore, given the advances in understanding of complex flexible pipe inter-layer behaviour, this paper demonstrates that through proper asset management, flexible pipe technology service life can be extended beyond the original design value. Similarly, flexible pipe that had previously been considered damaged and requiring early replacement can be justified for extension to beyond the original design life. Consideration has also been given to the potential for the re-use of flexible pipes and the hazards which can arise from this activity including recovery, storage, testing and installation. The key stages required to safely manage this process have been outlined.

Modelling Total Life Cycle Cost

1986 ◽  
Vol 200 (1) ◽  
pp. 31-40 ◽  
Author(s):  
B Bhadury ◽  
S K Basu
Keyword(s):  
Life Cycle ◽  
Preventive Maintenance ◽  
Life Cycle Cost ◽  
Power Plants ◽  
Thermal Power ◽  
Weibull Model ◽  
Point Of View ◽  
Maintenance Cost ◽  
Design Development ◽  
Total Life

In this paper, the concept of terotechnology and the formulation of life cycle cost has been taken from the point of view of the user as against that of the manufacturer, and the stages of design, development of prototypes, manufacture and testing of the machine have not been considered. This is felt appropriate since terotechnology has to date found greater application (and will continue to do so, except for military systems and installations wherein it has possibly found the greatest application) in the case of large capital equipment and machines, for example for process plants, integrated iron and steelworks, power plants etc. The hazard curve provides the basis for the estimation of the time-dependent maintenance cost incurred over the life cycle of an equipment. Accordingly a system study of the hazard rate of power units of a thermal power plant was undertaken and has been presented. Using the modified ‘bath-tub’ curve obtained from the case study and the Weibull model, an equation of the total life cycle cost has been developed. Thus the model takes into account deterioration of components and system performance over time. The model brings out the efficacy of preventive maintenance action in the form of condition monitoring and shows that the total life cycle can be increased if appropriate preventive-maintenance actions are taken in the random failure and wear-out failure regions.

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