Contents: v 1. Properties and selection--irons, steels, and high-performance alloys--v 2. Properties and selection---nonferrous alloys and special-purpose materials[etc ]v 21 Composites 1. Metals--Handbooks. manuals. etc. 2. Metal-work--Handbooks manuals. etc. L. ASM International Handbook Committee. IL Metals Handbook TA459M431990620.1690-115 SAN:204-7586 ISBN:0-87170-704 ASM International Materials Park, OH 44073-0002 www.asminternational.org Printed in the United States of America Multiple copy reprints of individual articles are available from Technical Department, ASM International Introduction to Failure Analysis and prevention James J. Scutti, Massachusetts Materials Research, Inc; William J McBrine, ALTRAN Corporation Introduction ANALYZING FAILURES is a critical process in determining the physical root causes of problems. The process is complex, draws upon many different technical disciplines, and uses a variety of observation, inspection, and laboratory techniques. One of the key factors in properly performing a failure analysis is keeping an open mind while examining and analyzing the evidence to foster a clear, unbiased perspective of the failure. Collaboration with experts in other disciplines is required in certain circumstances to integrate the analysis of the evidence with a quantitative understanding of the stressors and background information on the design, manufacture, and service history of the failed product or system Just as failure analysis is a proven discipline for identifying the physical roots of failures, root-cause analysis(RCa) techniques are effective in exploring some of the other contributors to failures, such as the human and latent root causes Properly performed, failure analysis and RCA are critical steps in the overall problem-solving process and are key ingredients for correcting and preventing failures, achieving higher levels of quality and reliability, and ultimately enhancing customer satisfaction This article briefly introduces the concepts of failure analysis, root-cause analysis, and the role of failure analysis as a general engineering tool for enhancing product quality and failure prevention. The discipline of failure analysis has evolved and matured, as it has been employed and formalized as a means for failure prevention. Consistent with the ent trend toward increased accountability and responsibility, its purpose has been extended to include determining which party may be liable for losses, be they loss of production, property damage, injury, or fatality. The discipline has also been used effectively as a teaching tool for new or less experienced engineers The importance and value of failure analysis to safety, reliability, performance, and economy are well documented. For ample, the importance of investigating failures is vividly illustrated in the pioneering efforts of the Wright Brothers in developing self-propelled flight. In fact, while Wilbur was traveling in France in 1908, Orville was conducting flight tests for the U.S. Army Signal Corps and was injured when his Wright Flyer crashed(Fig. 1). His passenger sustained fatal injuries(Ref 1). Upon receiving word of the mishap, Wilbur immediately ordered the delivery of the failed flyer to france so that he could conduct a thorough investigation. This was decades before the formal discipline called"failure analysis was introduced Thefileisdownloadedfromwww.bzfxw.com
Contents: v.1. Properties and selection—irons, steels, and high-performance alloys—v.2. Properties and selection—nonferrous alloys and special-purpose materials—[etc.]—v.21. Composites 1. Metals—Handbooks, manuals, etc. 2. Metal-work—Handbooks, manuals, etc. I. ASM International. Handbook Committee. II. Metals Handbook. TA459.M43 1990 620.1′6 90-115 SAN: 204-7586 ISBN: 0-87170-704-7 ASM International Materials Park, OH 44073-0002 www.asminternational.org Printed in the United States of America Multiple copy reprints of individual articles are available from Technical Department, ASM International. Introduction to Failure Analysis and Prevention James J. Scutti, Massachusetts Materials Research, Inc.; William J. McBrine, ALTRAN Corporation Introduction ANALYZING FAILURES is a critical process in determining the physical root causes of problems. The process is complex, draws upon many different technical disciplines, and uses a variety of observation, inspection, and laboratory techniques. One of the key factors in properly performing a failure analysis is keeping an open mind while examining and analyzing the evidence to foster a clear, unbiased perspective of the failure. Collaboration with experts in other disciplines is required in certain circumstances to integrate the analysis of the evidence with a quantitative understanding of the stressors and background information on the design, manufacture, and service history of the failed product or system. Just as failure analysis is a proven discipline for identifying the physical roots of failures, root-cause analysis (RCA) techniques are effective in exploring some of the other contributors to failures, such as the human and latent root causes. Properly performed, failure analysis and RCA are critical steps in the overall problem-solving process and are key ingredients for correcting and preventing failures, achieving higher levels of quality and reliability, and ultimately enhancing customer satisfaction. This article briefly introduces the concepts of failure analysis, root-cause analysis, and the role of failure analysis as a general engineering tool for enhancing product quality and failure prevention. The discipline of failure analysis has evolved and matured, as it has been employed and formalized as a means for failure prevention. Consistent with the recent trend toward increased accountability and responsibility, its purpose has been extended to include determining which party may be liable for losses, be they loss of production, property damage, injury, or fatality. The discipline has also been used effectively as a teaching tool for new or less experienced engineers. The importance and value of failure analysis to safety, reliability, performance, and economy are well documented. For example, the importance of investigating failures is vividly illustrated in the pioneering efforts of the Wright Brothers in developing self-propelled flight. In fact, while Wilbur was traveling in France in 1908, Orville was conducting flight tests for the U.S. Army Signal Corps and was injured when his Wright Flyer crashed (Fig. 1). His passenger sustained fatal injuries (Ref 1). Upon receiving word of the mishap, Wilbur immediately ordered the delivery of the failed flyer to France so that he could conduct a thorough investigation. This was decades before the formal discipline called “failure analysis” was introduced. The file is downloaded from www.bzfxw.com
Fig. 1 Crash of the Wright Flyer, 1908. Courtesy of the National Air and Space museum, Smithsonian Institution. Photo A-42555-A Unfortunately, there are many dramatic examples of catastrophic failures that result in injury, loss of life, and damage to property. For example, a molasses tank failed in Boston in 1919, and another molasses tank failed in Bellview, NJ,in 1973(Ref 2). Were the causes identified in 1919? Were lessons learned as a result of the accident? Were corrective actions developed and implemented to prevent recurrence Conversely, failures can also lead to improvements in engineering practices. The spectacular failures of the Liberty ships during World War II were studied extensively in subsequent decades, and the outcome of these efforts was a significantly more thorough understanding of the phenomenon of fracture, culminating in part with the development of the engineering discipline of fracture mechanics(Ref 3). Through these and other efforts, insights into the cause and prevention of failures continue to evolve References cited in this section 1. P.L. Jakab, Visions of a Flying Machine: The Wright Brothers and the Process of Invention, Smithsonian nstitution, 1990, p 226 2. R.W. Hertzberg, Deformation and Fracture Mechanics of Engineering Materials, John Wiley Sons, 1976, p 229-230 3. D.J. Ulpi, Understanding How Components Fail, 2nd ed, ASM International, 1999 Introduction to Failure Analysis and Prevention James J. Scutti, Massachusetts Materials Research, Inc. i william ]. McBrine, ALTRAN Corporation Concepts of failure analysis and Prevention Clearly, through the analysis of failures and the implementation of preventive measures, significant improvements have been realized in the quality of products and systems. This requires not only an understanding of the role of failure analysis, but also an appreciation of quality assurance and user expectations Quality and User Expectations of Products and Systems. In an era that initially gained global prominence in the 1980s, corporations, plants, government agencies, and other organizations developed new management systems and processes aimed at improving quality and customer satisfaction. Some of these systems include Total Quality Management (TQM). Continuous Improvement(CD), and, more recently prominent, Six Sigma. Historically, these initiatives are founded on the philosophies of the quality visionaries W. Edwards Deming(Ref 4)and Joseph Juran( Ref 5) In their most basic descriptions, TQM and CI represent full organizational commitment to a system focused on"doing the right thing right the first time"and not merely meeting but exceeding customer requirements(Ref 6, 7). They are focused on process improvements, generally in a production environment. Six Sigma adopts these themes and extends the reach of the system to all levels of organizations, with a system to achieve, sustain, and maximize business success (Ref 8). Si
Fig. 1 Crash of the Wright Flyer, 1908. Courtesy of the National Air and Space Museum, Smithsonian Institution, Photo A-42555-A Unfortunately, there are many dramatic examples of catastrophic failures that result in injury, loss of life, and damage to property. For example, a molasses tank failed in Boston in 1919, and another molasses tank failed in Bellview, NJ, in 1973 (Ref 2). Were the causes identified in 1919? Were lessons learned as a result of the accident? Were corrective actions developed and implemented to prevent recurrence? Conversely, failures can also lead to improvements in engineering practices. The spectacular failures of the Liberty ships during World War II were studied extensively in subsequent decades, and the outcome of these efforts was a significantly more thorough understanding of the phenomenon of fracture, culminating in part with the development of the engineering discipline of fracture mechanics (Ref 3). Through these and other efforts, insights into the cause and prevention of failures continue to evolve. References cited in this section 1. P.L. Jakab, Visions of a Flying Machine: The Wright Brothers and the Process of Invention, Smithsonian Institution, 1990, p 226 2. R.W. Hertzberg, Deformation and Fracture Mechanics of Engineering Materials, John Wiley & Sons, 1976, p 229–230 3. D.J. Wulpi, Understanding How Components Fail, 2nd ed., ASM International, 1999 Introduction to Failure Analysis and Prevention James J. Scutti, Massachusetts Materials Research, Inc.; William J. McBrine, ALTRAN Corporation Concepts of Failure Analysis and Prevention Clearly, through the analysis of failures and the implementation of preventive measures, significant improvements have been realized in the quality of products and systems. This requires not only an understanding of the role of failure analysis, but also an appreciation of quality assurance and user expectations. Quality and User Expectations of Products and Systems. In an era that initially gained global prominence in the 1980s, corporations, plants, government agencies, and other organizations developed new management systems and processes aimed at improving quality and customer satisfaction. Some of these systems include Total Quality Management (TQM), Continuous Improvement (CI), and, more recently prominent, Six Sigma. Historically, these initiatives are founded on the philosophies of the quality visionaries W. Edwards Deming (Ref 4) and Joseph Juran (Ref 5). In their most basic descriptions, TQM and CI represent full organizational commitment to a system focused on “doing the right thing right the first time” and not merely meeting but exceeding customer requirements (Ref 6, 7). They are focused on process improvements, generally in a production environment. Six Sigma adopts these themes and extends the “reach” of the system to all levels of organizations, with a system to achieve, sustain, and maximize business success (Ref 8). Six
Sigma is founded on the use of measurements, facts, and statistics to move organizations in directions that constantly improve and reinvent business processes(Ref 8). The roots of this business system are in the statistical limits set for the maximum number of defects in a product, as a fraction of the total number of opportunities for such defects to occur. To the practitioners of this system, "six sigma" is a statistical metric referring to six times the statistical standard deviation of a normal distribution, which allows no more than 3. 4 defects per million opportunities(equivalent to 99.9997% reliability). This is indeed a lofty goal for any organization(be it a manufacturing company, a petrochemical plant, a service business, or a government agency), but companies committed to Six Sigma have reported significant gains in productivity with simultaneous improvements in organizational culture(Ref 7, 8, 9) The most positive result of these new management systems is that organizations have responded to the higher expectations of consumers and users and have provided higher-quality products and systems, with attendant increases in customer satisfaction. However, this notion of the quality of a product or system is multifaceted Juran described quality as fitness for use"'(Ref 5). tQM defines quality as the ability to satisfy the needs of a consumer(Ref 10). These characteristics of quality also apply internally to those in organizations, either in the services, or in manufacturing, operating, or administering products, processes, and systems(Ref 10). The intent is to provide not only products and systems that garner high customer satisfaction, but also that increase productivity, reduce costs, and meet delivery requirements In general, high quality refers to products and systems manufactured to higher standards, in response to higher expectations of consumers and users. These expectations include such attributes as Greater safety Improved reliability Higher performance Greater efficiency Easier maintenance Lower life-cycle cost Reduced impact on the environment ome or all of these qualities at one time appeared mutually exclusive. However, customer demands and the aforementioned new business-management systems have provided a means of measuring and quantifying these attributes creating a new paradigm for business. With the business-culture changes that have occurred through the implementation of one or more of the aforementioned improvement systems, users in recent years have experienced, in general improvement in all of these areas simultaneously. That translates to reduced product failure and greater likelihood of preventing failures. It is important to recognize that, with all the gains achieved under these management systems, the full potential for maximizing these attributes is yet to be achieved Though all of the various improvement systems are unique, they have two aspects in common. They are all customer focused and are founded on problem solving as a means for improvement When addressing customer focus, producers and other organizations have identified that the form, fit, function, and service-life requirements of a product or system are actually defined ultimately by customers. Customer-focused manufacturers strive to meet these requirements in designing, developing, and producing their products or systems. In a broad sense, form, fit, function, and service life represent the technically relevant properties of a product. The form, or physical characteristics of components or products, include the size and shape of a product, as well as the materials of construction and the manufacturing techniques used. The manner in which individual components are assembled into and integrate with the product as a whole describes the fit of components. The function of a product or system is its ability or apability to serve the need for which it was intended. Service life is the duration over which the product or system successfully serves its function. These characteristics define products in the customers eyes. Arguably the most important characteristics, from a consumer's perspective, are how well a product or system functions and how long it serves a usefu Problem Solving, Quality, and Customer Satisfaction. Achieving the levels of quality that meet and exceed customer expectations is paramount to customer satisfaction in a customer-focused management system. Since a customer's perspective of quality is strongly tied to the function and service life of a product or system, it follows that failure to provide adequate measures of function and service life presents problems. One proven technique to improving quality is problem solving. Problems can range broadly, from maintenance training issues, to marginal equipment reliability,to business systems conflicts, to policy inconsistencies, to poor working conditions on the shop floor. When a problem occurs, the responsible organization will analyze the problem to determine the cause and solve it. However, due to various business or cultural pressures, some organizations fall into the following pitfalls when problems arise(Ref 9) Do nothing and perhaps hope that the problem will go away Deny that the problem exists, minimize its importance, question the motives of those identifying the problem Troubleshoot in a haphazard fashion (i.e,"shotgun"troubleshooting) Thefileisdownloadedfromwww.bzfxw.com
Sigma is founded on the use of measurements, facts, and statistics to move organizations in directions that constantly improve and reinvent business processes (Ref 8). The roots of this business system are in the statistical limits set for the maximum number of defects in a product, as a fraction of the total number of opportunities for such defects to occur. To the practitioners of this system, “six sigma” is a statistical metric referring to six times the statistical standard deviation of a normal distribution, which allows no more than 3.4 defects per million opportunities (equivalent to 99.9997% reliability). This is indeed a lofty goal for any organization (be it a manufacturing company, a petrochemical plant, a service business, or a government agency), but companies committed to Six Sigma have reported significant gains in productivity with simultaneous improvements in organizational culture (Ref 7, 8, 9). The most positive result of these new management systems is that organizations have responded to the higher expectations of consumers and users and have provided higher-quality products and systems, with attendant increases in customer satisfaction. However, this notion of the quality of a product or system is multifaceted. Juran described quality as “fitness for use” (Ref 5). TQM defines quality as the ability to satisfy the needs of a consumer (Ref 10). These characteristics of quality also apply internally to those in organizations, either in the services, or in manufacturing, operating, or administering products, processes, and systems (Ref 10). The intent is to provide not only products and systems that garner high customer satisfaction, but also that increase productivity, reduce costs, and meet delivery requirements. In general, high quality refers to products and systems manufactured to higher standards, in response to higher expectations of consumers and users. These expectations include such attributes as: · Greater safety · Improved reliability · Higher performance · Greater efficiency · Easier maintenance · Lower life-cycle cost · Reduced impact on the environment Some or all of these qualities at one time appeared mutually exclusive. However, customer demands and the aforementioned new business-management systems have provided a means of measuring and quantifying these attributes, creating a new paradigm for business. With the business-culture changes that have occurred through the implementation of one or more of the aforementioned improvement systems, users in recent years have experienced, in general, improvement in all of these areas simultaneously. That translates to reduced product failure and greater likelihood of preventing failures. It is important to recognize that, with all the gains achieved under these management systems, the full potential for maximizing these attributes is yet to be achieved. Though all of the various improvement systems are unique, they have two aspects in common. They are all customer focused and are founded on problem solving as a means for improvement. When addressing customer focus, producers and other organizations have identified that the form, fit, function, and service-life requirements of a product or system are actually defined ultimately by customers. Customer-focused manufacturers strive to meet these requirements in designing, developing, and producing their products or systems. In a broad sense, form, fit, function, and service life represent the technically relevant properties of a product. The form, or physical characteristics of components or products, include the size and shape of a product, as well as the materials of construction and the manufacturing techniques used. The manner in which individual components are assembled into and integrate with the product as a whole describes the fit of components. The function of a product or system is its ability or capability to serve the need for which it was intended. Service life is the duration over which the product or system successfully serves its function. These characteristics define products in the customer's eyes. Arguably the most important characteristics, from a consumer's perspective, are how well a product or system functions and how long it serves a useful life. Problem Solving, Quality, and Customer Satisfaction. Achieving the levels of quality that meet and exceed customer expectations is paramount to customer satisfaction in a customer-focused management system. Since a customer's perspective of quality is strongly tied to the function and service life of a product or system, it follows that failure to provide adequate measures of function and service life presents problems. One proven technique to improving quality is problem solving. Problems can range broadly, from maintenance training issues, to marginal equipment reliability, to business systems conflicts, to policy inconsistencies, to poor working conditions on the shop floor. When a problem occurs, the responsible organization will analyze the problem to determine the cause and solve it. However, due to various business or cultural pressures, some organizations fall into the following pitfalls when problems arise (Ref 9): · Do nothing and perhaps hope that the problem will go away. · Deny that the problem exists, minimize its importance, question the motives of those identifying the problem. · Troubleshoot in a haphazard fashion (i.e., “shotgun” troubleshooting). The file is downloaded from www.bzfxw.com
· Chase false leads(ie,“ red herrings") In an enlightened organizational culture, products or systems require a systematic approach to problem solving, based on analysis, to achieve the levels of quality and customer satisfaction defined by the new management systems. The cultural aspect is critical, as those who have identified problems must be encouraged to come forward. Furthermore, resources and ommitment are required to formulate the solutions and implement necessary changes Problem-Solving Models. a wide range of problem-solving methods and models are available in the literature(Ref 4, 5 6,8,9, 10, 11, 12), presenting various details of approaches and processes for solving any of the general types of problems defined previously. All of these methods and models are rooted in the scientific method(summarized as allows)(Ref 6) 1. Define the 2. Propose a hype 3. Gather data 4. Test the hypothesis 5. Develop conclusions A concise problem-solving model, adapted from several of the referenced authors, and that has specific applicability to this Volume, is depicted in Fig. 2. The continuous, circular format in the graphic is significant, indicating that the process activity. Note the similarity to the classical scientific method summarized previous/y.esult of the reinitiates with the identification of a new problem or problems brought to light as a result of the first problem-solving dentify Standardize Determine root Validate and verify corrective corrective actions actions Fig 2 Problem-solving model The major steps in the model define the problem-solving process Identify: Describe the current situation. Define the deficiency in terms of the symptoms(or indicators ) Determine the impact of the deficiency on the component, product, system, and customer. Set a goal. Collect data to provide a measurement of the deficiency 2. Determine root cause: Analyze the problem to identify the cause(s) 3. Develop corrective actions: List possible solutions to mitigate and prevent recurrence of the problem. Generate alternatives. Develop implementation plan 4. Validate and verify corrective actions: Test corrective actions in pilot study. Measure effectiveness of change Validate improvements. Verify that problem is corrected and improves customer satisfaction 5. Standardize: Incorporate the corrective action into the standards documentation system of the company organization, or industry to prevent recurrence in similar products or systems. Monitor changes to ensure effectiveness The second step in the problem-solving model, determine root cause, introduces a very significant process. Solutions to prevent recurrence of problems cannot be developed without identification of the root cause
· Chase false leads (i.e., “red herrings”). In an enlightened organizational culture, products or systems require a systematic approach to problem solving, based on analysis, to achieve the levels of quality and customer satisfaction defined by the new management systems. The cultural aspect is critical, as those who have identified problems must be encouraged to come forward. Furthermore, resources and commitment are required to formulate the solutions and implement necessary changes. Problem-Solving Models. A wide range of problem-solving methods and models are available in the literature (Ref 4, 5, 6, 8, 9, 10, 11, 12), presenting various details of approaches and processes for solving any of the general types of problems defined previously. All of these methods and models are rooted in the scientific method (summarized as follows) (Ref 6): 1. Define the issue 2. Propose a hypothesis 3. Gather data 4. Test the hypothesis 5. Develop conclusions A concise problem-solving model, adapted from several of the referenced authors, and that has specific applicability to this Volume, is depicted in Fig. 2. The continuous, circular format in the graphic is significant, indicating that the process reinitiates with the identification of a new problem or problems brought to light as a result of the first problem-solving activity. Note the similarity to the classical scientific method summarized previously. Fig. 2 Problem-solving model The major steps in the model define the problem-solving process: 1. Identify: Describe the current situation. Define the deficiency in terms of the symptoms (or indicators). Determine the impact of the deficiency on the component, product, system, and customer. Set a goal. Collect data to provide a measurement of the deficiency. 2. Determine root cause: Analyze the problem to identify the cause(s). 3. Develop corrective actions: List possible solutions to mitigate and prevent recurrence of the problem. Generate alternatives. Develop implementation plan. 4. Validate and verify corrective actions: Test corrective actions in pilot study. Measure effectiveness of change. Validate improvements. Verify that problem is corrected and improves customer satisfaction. 5. Standardize: Incorporate the corrective action into the standards documentation system of the company, organization, or industry to prevent recurrence in similar products or systems. Monitor changes to ensure effectiveness. The second step in the problem-solving model, determine root cause, introduces a very significant process. Solutions to prevent recurrence of problems cannot be developed without identification of the root cause
Failure Definitions. In the general sense of the word, a failure is defined as an undesirable event or condition. For the purposes of discussion related to failure analysis and prevention, it is a general term used to imply that a component is unable to adequately perform its intended function. The intended function of a component and therefore the definition of failure may range greatly. For instance, discoloration of an architectural feature is a failure of its intended aesthetic but does not perform its intended function(Ref 13). This is considered a loss of function. A jeteomponent that smut can Failure can be defined on several different levels. The simplest form of a failure is a system or component that operates only produce partial thrust(insufficient to enable an aircraft to take off)is an example of a loss of function The next level of failure involves a system or component that performs its function but is unreliable or unsafe(Ref 13).In this form of failure, the system or component has sustained a loss of service life. For example, a wire rope for an elevator has lost its service life when it has sustained fatigue fractures of some of the individual wires, due to irregularities in the wrapping over the sheave. Even though the wire rope continues to function, the presence of fatigue fractures of some of the wires results in an unsafe condition and is therefore considered a failure. Another example of such a failure is the inability of an integrated circuit to function reliably In the next level of severity of failure, a system or component is inoperable(Ref 13), such as a pump shaft fracture that causes the impeller to seize or a loss of load-carrying capability of a structural bolt in-service due to fracture Failure and Failure Analysis. A logical failure analysis approach first requires a clear understanding of the failure definition and the distinction between an indicator (i.e, symptom), a cause, a failure mechanism, and a consequence Although it may be considered by some to be an exercise in semantics, a clear understanding of each piece of the situation associated with a failure greatly enhances the ability to understand causes and mitigating options and to specify appropriate corrective action Consider the example of a butterfly valve that fails in service in a cooling water system at a manufacturing facility ( table 1). Recognizing the indicators, causes, mechanisms, and consequences helps to focus investigative actions Indicators(s): Monitor these as precursors and symptoms of failures Cause(s): Focus mitigating actions on these Failure mechanism(s): These describe how the material failed according to the engineering textbook definitions If the analysis is correct, the mechanism will be consistent with the cause(s). If the mechanism is not properl understood, then all true cause(s) will not be identified and corrective action will not be fully effective Consequence(): This is what we are trying to avoid Table 1 Example--Failure of a butterfly valve in a manufacturing plant cooling water system Item Description Indicators Cause Throttling of valve by the operator outside of the design Flow gages and records Low-strength copper nickel alloy construction Material specifications Flow-induced cavitation Rumbling noise in system Failure Erosion-fatigue damage Laboratory examination of disk, nInn Inability to manufacture at normal production rates Life-Cycle Management Concepts. The concept of life-cycle management refers to the idea of managing the service life of a system, structure, or component. There is a cost associated with extending the service life of a component, for example, higher research costs, design costs, material and fabrication costs, and higher maintenance costs With regard to product failures, it must be understood that failures cannot be totally avoided, but must be better understood, anticipated, and controlled. Nothing lasts and functions forever. For some products, consumers may prefer a shorter life at a more modest cost. In contrast, the useful service life of a product such as an aircraft part may be carefull planned in advance and managed accordingly with routine inspections and maintenance, which may increase in frequency over time. In many cases, avoiding failures beyond a certain predetermined desired life provides no benefit, such as is the when a surgical implant is designed to far outlive the human recipient. There is also a point of diminishing return on stments related to extending the life of a component. a life-cycle management study of a component would look at issues as well as other factors such as the issue of obsolescence. How long will it be before the product is obsolete? Thefileisdownloadedfromwww.bzfxw.com
Failure Definitions. In the general sense of the word, a failure is defined as an undesirable event or condition. For the purposes of discussion related to failure analysis and prevention, it is a general term used to imply that a component is unable to adequately perform its intended function. The intended function of a component and therefore the definition of failure may range greatly. For instance, discoloration of an architectural feature is a failure of its intended aesthetic function. Failure can be defined on several different levels. The simplest form of a failure is a system or component that operates, but does not perform its intended function (Ref 13). This is considered a loss of function. A jet engine that runs but can only produce partial thrust (insufficient to enable an aircraft to take off) is an example of a loss of function. The next level of failure involves a system or component that performs its function but is unreliable or unsafe (Ref 13). In this form of failure, the system or component has sustained a loss of service life. For example, a wire rope for an elevator has lost its service life when it has sustained fatigue fractures of some of the individual wires, due to irregularities in the wrapping over the sheave. Even though the wire rope continues to function, the presence of fatigue fractures of some of the wires results in an unsafe condition and is therefore considered a failure. Another example of such a failure is the inability of an integrated circuit to function reliably. In the next level of severity of failure, a system or component is inoperable (Ref 13), such as a pump shaft fracture that causes the impeller to seize or a loss of load-carrying capability of a structural bolt in-service due to fracture. Failure and Failure Analysis. A logical failure analysis approach first requires a clear understanding of the failure definition and the distinction between an indicator (i.e., symptom), a cause, a failure mechanism, and a consequence. Although it may be considered by some to be an exercise in semantics, a clear understanding of each piece of the situation associated with a failure greatly enhances the ability to understand causes and mitigating options and to specify appropriate corrective action. Consider the example of a butterfly valve that fails in service in a cooling water system at a manufacturing facility (Table 1). Recognizing the indicators, causes, mechanisms, and consequences helps to focus investigative actions: · Indicators(s): Monitor these as precursors and symptoms of failures. · Cause(s): Focus mitigating actions on these. · Failure mechanism(s): These describe how the material failed according to the engineering textbook definitions. If the analysis is correct, the mechanism will be consistent with the cause(s). If the mechanism is not properly understood, then all true cause(s) will not be identified and corrective action will not be fully effective. · Consequence(s): This is what we are trying to avoid. Table 1 Example—Failure of a butterfly valve in a manufacturing plant cooling water system Item Description Indicators Throttling of valve by the operator outside of the design parameters Flow gages and records Operator logs Low-strength copper nickel alloy construction Material specifications Laboratory analysis Cause Flow-induced cavitation Rumbling noise in system Vibration of system Failure mechanism Erosion-fatigue damage Laboratory examination of disk, thinning Consequences Inability to manufacture at normal production rates Life-Cycle Management Concepts. The concept of life-cycle management refers to the idea of managing the service life of a system, structure, or component. There is a cost associated with extending the service life of a component, for example, higher research costs, design costs, material and fabrication costs, and higher maintenance costs. With regard to product failures, it must be understood that failures cannot be totally avoided, but must be better understood, anticipated, and controlled. Nothing lasts and functions forever. For some products, consumers may prefer a shorter life at a more modest cost. In contrast, the useful service life of a product such as an aircraft part may be carefully planned in advance and managed accordingly with routine inspections and maintenance, which may increase in frequency over time. In many cases, avoiding failures beyond a certain predetermined desired life provides no benefit, such as is the case when a surgical implant is designed to far outlive the human recipient. There is also a point of diminishing return on investments related to extending the life of a component. A life-cycle management study of a component would look at these issues as well as other factors such as the issue of obsolescence. How long will it be before the product is obsolete? The file is downloaded from www.bzfxw.com
Understanding how the typical distribution of failure for a given product must be factored with time is also important when looking at failure patterns(Fig. 3). Early life failures are often associated with fabrication issues, quality-control issues. or initial"shakedown"stresses. while age-related failure rates would increase with time. This is discussed in more detail in the article "Reliability-Centered Maintenance"in this volume failure Wearout failure period Intrinsic failure period Time Fig3 Typical time distribution of failures("bathtub curve Once the concept of a managed life is prudently adopted over a simple failure prevention concept, design and fabrication costs can be reduced and maintenance and other life-prolonging activities can be optimized Diligence in Use of Terminology. Communicating technical information is of paramount importance in all engineering areas, including failure analysis. The choice of technical descriptors, nomenclature, and even what might be considered technical jargon is critical to conveying technical ideas to other engineers, managers, plant personnel, shop personnel maintenance personnel, attorneys, a jury, and so forth. It is instructive in this introductory article to emphasize that a descriptor can mean something very specific to a technical person and mean something very different to a business manager or an attorne For example, the term"flaw is synonymous with defect"in general usage. However, to a fracture mechanics specialist, flaw is a discontinuity such as a crack. Under some circumstances, when the crack is smaller than the critical size (i.e subcritical), the crack is benign and therefore may not be considered a defect. To the quality-control engineer, flaws are characteristics that are managed continuously on the production line, as every engineered product has flaws, or deviations from perfection"(Ref 14). On the manufacturing floor, these flaws are measured, compared with the preestablished limits of acceptability, and dispositioned as acceptable or rejectable. A rejectable characteristic is defined as a defect(Ref 14). To the Six Sigma practioner, a defect is considered anything that inhibits a process or, in a broad sense, any condition that fails to meet a customer expectation(Ref 9). To the attorney, a defect refers to many different types of deficiencies, including improper design, inadequate instructions for use, insufficient warnings, and even inappropriate advertising or marketing(Ref 15) Similar nuances may occur in the basic definitions and interpretations of technical terms used in materials failure analysis Terms such as ductile and brittle, crack and fracture, and stable and unstable crack growth are pervasive in failure analysis. Even these seemingly basic terms are subject to misuse and misinterpretations, as suggested in Ref 16--for example"brittle cleavage, which is a pleonasm that does not explain anything. Another example noted in Ref 16 is the term " overload fracture, which may be misinterpreted by nonanalysts as a failure caused by a load higher anticipated by the materials or mechanical engineers. This limited interpretation of overload failure is incomplete described in the article"Overload Failures"in this volume Judgmental terminology should be used with prudence when communicating analytical protocols, procedures, findings, and conclusions. Communications during the preliminary stages of an investigation should be factual rather than judgmental. It is important to recognize that some of the terminology used in a failure analysis can be judgmental, and onsideration must be given to the implications associated with the use of such terminology. For example, when examining both a failed and an unfailed component returned from service, references to the unfailed sample as"good and the failed sample as"bad"should be avoided. This is because the investigation may reveal both samples to contain the same defect, and therefore both could be considered"bad. Similarly, neither may be bad" if the analysis actually indicates the failed component met all requirements but was subjected to abuse in service. On completion of the failure analysis, judgmental terminology is often appropriate to use if the evidence supports it, such as in the example of asting defect that has been confirmed in the example bolt failure analysis While discussions of the semantics of terminology may seem pedantic, communicating the intended information gleaned from a failure analysis relies heavily on precision in the use of language References cited in this section 4. W.E. Deming, Out of the Crisis, MIT Center for Advanced Engineering Study, 1986
Understanding how the typical distribution of failure for a given product must be factored with time is also important when looking at failure patterns (Fig. 3). Early life failures are often associated with fabrication issues, quality-control issues, or initial “shakedown” stresses, while age-related failure rates would increase with time. This is discussed in more detail in the article “Reliability-Centered Maintenance” in this Volume. Fig. 3 Typical time distribution of failures (“bathtub curve”) Once the concept of a managed life is prudently adopted over a simple failure prevention concept, design and fabrication costs can be reduced and maintenance and other life-prolonging activities can be optimized. Diligence in Use of Terminology. Communicating technical information is of paramount importance in all engineering areas, including failure analysis. The choice of technical descriptors, nomenclature, and even what might be considered technical jargon is critical to conveying technical ideas to other engineers, managers, plant personnel, shop personnel, maintenance personnel, attorneys, a jury, and so forth. It is instructive in this introductory article to emphasize that a descriptor can mean something very specific to a technical person and mean something very different to a business manager or an attorney. For example, the term “flaw” is synonymous with “defect” in general usage. However, to a fracture mechanics specialist, a flaw is a discontinuity such as a crack. Under some circumstances, when the crack is smaller than the critical size (i.e., subcritical), the crack is benign and therefore may not be considered a defect. To the quality-control engineer, flaws are characteristics that are managed continuously on the production line, as every engineered product has flaws, or “deviations from perfection” (Ref 14). On the manufacturing floor, these flaws are measured, compared with the preestablished limits of acceptability, and dispositioned as acceptable or rejectable. A rejectable characteristic is defined as a defect (Ref 14). To the Six Sigma practioner, a defect is considered anything that inhibits a process or, in a broad sense, any condition that fails to meet a customer expectation (Ref 9). To the attorney, a defect refers to many different types of deficiencies, including improper design, inadequate instructions for use, insufficient warnings, and even inappropriate advertising or marketing (Ref 15). Similar nuances may occur in the basic definitions and interpretations of technical terms used in materials failure analysis. Terms such as ductile and brittle, crack and fracture, and stable and unstable crack growth are pervasive in failure analysis. Even these seemingly basic terms are subject to misuse and misinterpretations, as suggested in Ref 16—for example “brittle cleavage,” which is a pleonasm that does not explain anything. Another example noted in Ref 16 is the term “overload fracture,” which may be misinterpreted by nonanalysts as a failure caused by a load higher than anticipated by the materials or mechanical engineers. This limited interpretation of overload failure is incomplete, as described in the article “Overload Failures” in this Volume. Judgmental terminology should be used with prudence when communicating analytical protocols, procedures, findings, and conclusions. Communications during the preliminary stages of an investigation should be factual rather than judgmental. It is important to recognize that some of the terminology used in a failure analysis can be judgmental, and consideration must be given to the implications associated with the use of such terminology. For example, when examining both a failed and an unfailed component returned from service, references to the unfailed sample as “good” and the failed sample as “bad” should be avoided. This is because the investigation may reveal both samples to contain the same defect, and therefore both could be considered “bad.” Similarly, neither may be “bad” if the analysis actually indicates the failed component met all requirements but was subjected to abuse in service. On completion of the failure analysis, judgmental terminology is often appropriate to use if the evidence supports it, such as in the example of a casting defect that has been confirmed in the example bolt failure analysis. While discussions of the semantics of terminology may seem pedantic, communicating the intended information gleaned from a failure analysis relies heavily on precision in the use of language. References cited in this section 4. W.E. Deming, Out of the Crisis, MIT Center for Advanced Engineering Study, 1986
5. J M. Juran and F, M. Gryna, Ed. Juran's Quality Control Handbook, 4th ed, McGraw-Hill, 1988 6. P.F. Wilson, L D. Dell, and G F. Anderson, Root Cause Analysis: A Tool for Total Quality Management, ASQ Quality Press, 1993, p 7 7. F.w. Breyfogle Ill, Implementing Six Sigma: Smarter Solutions Using Statistical Methods, John Wiley Sons 1999, p xxvii 8. P.S. Pande, R. P. Neuman, and R.R. Cavanaugh, The Six Sigma Way, McGraw-Hill, 2000, P xi 9. M. Harry and R. Schroeder, Six Sigma: The Breakthrough Management Strategy Revolutionizing the World's Top Corporations, Doubleday Co, Inc, 1999 10. G.F. Smith, Quality Problem Solving, AsQ Quality Press, 1998, p7 11. B. Anderson and T. Fagerhaug, Root Cause Analysis: Simplified Tools and Techniques, ASQ Quality Press, 2000 p7,125 Reporting Workplace Errors, Max Ammerman/Quality Resources, 1998 oach to Identifying, Correcting, and 12. M. Ammerman, The Root Cause Analysis Handbook: A Simplified Appr 13. Engineering Aspects of Failure and Failure Analysis, Failure Analysis and Prevention, Vol 10, &th ed. Metals Handbook, American Society for Metals, 1975, p 1-9 14. R.K. McLeod, T Heaslip, and M. Vermij, Defect or Flaw-Legal Implications, Failure Analysis: Techniques and Applications, Conf. Proc. International Conference and Exhibits on Failure Analysis, 8-11 July 1991(Montreal Quebec, Canada), ASM International, 1992, p 253-261 15. J.J. Asperger, Legal Definition of a Product Failure: What the Law Requires of the Designer and the Manufacturer, Proc. Failure Prevention through Education: Getting to the Root Cause, 23-25 May 2000 ( Cleveland, OH), ASM International, 2000, p 25-29 6. D. Broek, Fracture Mechanics as an Important Tool in Failure Analysis, Failure Analysis: Techniques Applications, Conf. Proc. International Conference and Exhibits on Failure Analysis, 8-11 July 1991(Mont Quebec, Canada), ASM International, 1992, p 33-44 Introduction to Failure Analysis and Prevention James ]. Scutti, Massachusetts Materials Research, Inc. William ]. McBrine, ALTRAN Corporation Root-Cause analysi Failure analysis is considered to be the examination of the characteristics and causes of equipment or component failure In most cases this involves the consideration of physical evidence and the use of engineering and scientific principles and analytical tools. Often, the reason why one performs a failure analysis is to characterize the causes of failure with the erall objective to avoid repeat of similar failures. However, analysis of the physical evidence alone may not be adequate to reach this goal. The scope of a failure analysis can, but does not necessarily, lead to a correctable root cause of failure. Many times, a failure analysis incorrectly ends at the identification of the failure mechanism and perhaps cau influences. The principles of root-cause analysis(RCA)may be applied to ensure that the root cause is understood and appropriate corrective actions may be identified. An RCa exercise may simply be a momentary mental exercise or an extensive logistical charting analysis Many volumes have been written on the process and methods of RCA. The concept of rca does not apply to failures alone, but is applied in response to an undesirable event or condition(Fig. 4). Root-cause analysis is intended to identify the fundamental cause(s) that if corrected will prevent recurrence Thefileisdownloadedfromwww.bzfxw.com
5. J.M. Juran and F.M. Gryna, Ed., Juran's Quality Control Handbook, 4th ed., McGraw-Hill, 1988 6. P.F. Wilson, L.D. Dell, and G.F. Anderson, Root Cause Analysis: A Tool for Total Quality Management, ASQ Quality Press, 1993, p 7 7. F.W. Breyfogle III, Implementing Six Sigma: Smarter Solutions Using Statistical Methods, John Wiley & Sons, 1999, p xxvii 8. P.S. Pande, R.P. Neuman, and R.R. Cavanaugh, The Six Sigma Way, McGraw-Hill, 2000, p xi 9. M. Harry and R. Schroeder, Six Sigma: The Breakthrough Management Strategy Revolutionizing the World's Top Corporations, Doubleday & Co., Inc., 1999 10. G.F. Smith, Quality Problem Solving, ASQ Quality Press, 1998, p 7 11. B. Anderson and T. Fagerhaug, Root Cause Analysis: Simplified Tools and Techniques, ASQ Quality Press, 2000, p 7, 125 12. M. Ammerman, The Root Cause Analysis Handbook: A Simplified Approach to Identifying, Correcting, and Reporting Workplace Errors, Max Ammerman/Quality Resources, 1998 13. Engineering Aspects of Failure and Failure Analysis, Failure Analysis and Prevention, Vol 10, 8th ed., Metals Handbook, American Society for Metals, 1975, p 1–9 14. R.K. McLeod, T. Heaslip, and M. Vermij, Defect or Flaw—Legal Implications, Failure Analysis: Techniques and Applications, Conf. Proc. International Conference and Exhibits on Failure Analysis, 8–11 July 1991 (Montreal, Quebec, Canada), ASM International, 1992, p 253–261 15. J.J. Asperger, Legal Definition of a Product Failure: What the Law Requires of the Designer and the Manufacturer, Proc. Failure Prevention through Education: Getting to the Root Cause, 23–25 May 2000 (Cleveland, OH), ASM International, 2000, p 25–29 16. D. Broek, Fracture Mechanics as an Important Tool in Failure Analysis, Failure Analysis: Techniques and Applications, Conf. Proc. International Conference and Exhibits on Failure Analysis, 8–11 July 1991 (Montreal, Quebec, Canada), ASM International, 1992, p 33–44 Introduction to Failure Analysis and Prevention James J. Scutti, Massachusetts Materials Research, Inc.; William J. McBrine, ALTRAN Corporation Root-Cause Analysis Failure analysis is considered to be the examination of the characteristics and causes of equipment or component failure. In most cases this involves the consideration of physical evidence and the use of engineering and scientific principles and analytical tools. Often, the reason why one performs a failure analysis is to characterize the causes of failure with the overall objective to avoid repeat of similar failures. However, analysis of the physical evidence alone may not be adequate to reach this goal. The scope of a failure analysis can, but does not necessarily, lead to a correctable root cause of failure. Many times, a failure analysis incorrectly ends at the identification of the failure mechanism and perhaps causal influences. The principles of root-cause analysis (RCA) may be applied to ensure that the root cause is understood and appropriate corrective actions may be identified. An RCA exercise may simply be a momentary mental exercise or an extensive logistical charting analysis. Many volumes have been written on the process and methods of RCA. The concept of RCA does not apply to failures alone, but is applied in response to an undesirable event or condition (Fig. 4). Root-cause analysis is intended to identify the fundamental cause(s) that if corrected will prevent recurrence. The file is downloaded from www.bzfxw.com
Systems and indicators Evident cause(s) Hidden root Fig 4 Root-cause analogy Levels. The three levels of root-cause analysis are physical roots, human roots, and latent roots(Ref 17, 18, 19, 20, 21) Physical roots, or the roots of equipment problems, are where many failure analyses stop These roots may be what comes out of a laboratory investigation or engineering analysis and are often component-level or materials-level findings Human roots (i.e, people issues) involve human factors that caused the failure, an example being an error in human judgment. Latent roots lead us to the causes of the human error and include roots that are organizational or procedural in nature. as well as environmental or other roots that are outside the realm of control These levels or root cause are best defined by the two examples Table 2 Examples of root causes of failure of pressure vessel and bolt root type Pressure vessel fail Bolt failure Physical roots Corrosion damage, wall thinning Fatigue crack; equipment vibration. lack of vibration;isolation Human roots Inadequate inspection performed Improper equipment installed Latent roots nadequate inspector training Inadequate specification verification process How deeply one goes into the root causes depends on the objectives of the RCA. These objectives are typically based on the complexity of the situation and the risk associated with additional failures. In most cases, one desires to identify root causes that are reasonably correctable. An example of the variety of possible root causes of an electric motor driven compressor assembly is provided in Table 3(Ref 22) Table 3 Possible causes of electric motor driven pump or compressor failures System design Component Shipping and Installation Operations and Distress damage or and specification manufacturer's storage responsibility maintenance failed components responsibility responsibility esponsibility responsibilit Application Material of Preparation Foundations Shock Distress damages construction for shipment Undercapacity Settling Thermal Vibration Overcapacity Improper materia//clsystem not Flaw or defect Improper or Mechanical Short/open circuit sufficient Inadequ tartup Failed components
Fig. 4 Root-cause analogy Levels. The three levels of root-cause analysis are physical roots, human roots, and latent roots (Ref 17, 18, 19, 20, 21). Physical roots, or the roots of equipment problems, are where many failure analyses stop. These roots may be what comes out of a laboratory investigation or engineering analysis and are often component-level or materials-level findings. Human roots (i.e., people issues) involve human factors that caused the failure, an example being an error in human judgment. Latent roots lead us to the causes of the human error and include roots that are organizational or procedural in nature, as well as environmental or other roots that are outside the realm of control. These levels or root cause are best defined by the two examples in Table 2. Table 2 Examples of root causes of failure of pressure vessel and bolt Root type Pressure vessel failure Bolt failure Physical roots Corrosion damage, wall thinning Fatigue crack; equipment vibration; lack of vibration; isolation Human roots Inadequate inspection performed Improper equipment installed Latent roots Inadequate inspector training Inadequate specification verification process How deeply one goes into the root causes depends on the objectives of the RCA. These objectives are typically based on the complexity of the situation and the risk associated with additional failures. In most cases, one desires to identify root causes that are reasonably correctable. An example of the variety of possible root causes of an electric motor driven compressor assembly is provided in Table 3 (Ref 22). Table 3 Possible causes of electric motor driven pump or compressor failures System design and specification responsibility Component manufacturer's responsibility Shipping and storage responsibility Installation responsibility Operations and maintenance responsibility Distress damage or failed components Application Undercapacity Overcapacity Incorrect physical Material of construction Flaw or defect Improper material Preparation for shipment Oil system not clean Inadequate Foundations Settling Improper or insufficient grouting Shock Thermal Mechanical Improper startup Distress damages Vibration Short/open circuit Failed components
System design Component Operations and Distress damage or and specification manufacturer's storage responsibility maintenance failed components responsibility responsibility responsibility responsibility condition assumed Improper drainage (temperature Cracking or Operating Sleeve bearing pressure, etc.) Design Incorrect physical applie Piping property assumedImproper Process surging Coupling (molecular weight, specification Wrong coating Misalignment Control error Shaft Wrong selection Inadequate Specifications Equipment not cleaning Controls Pinion/ball/turning Design error deactivated/not Inadequate installed lubrication system Inadequate or Protection support Casir wrong lubrication Operating error Insufficient control Insufficient Assembly Rotor instrumentation Inadequate liquid protection Auxiliaries drain Misalignment Impeller Improper coupling Corrosion by Utility failure Critical speed salt Assembly Shroud Improper bearing amage Insufficient Corrosion by instrumentation Piston Improper seal rain or humidityDefective material Electronic control Diaphragm Insufficient Poor packaging failure shutdown devices controls and Inadequate Wheel protective devices Desiccant bolting Pneumatic control Material of omitted failure lades foil. root construction Fabrication Connected shroud Contamination wron Lubrication Corrosion and/or Welding error with dirt. etc Labyrinth erosion Foreign Improper heat Physical material left Thrust bearing Rapid wear treatment Insufficient oil General poor Pivoted pad bearing Fatigue Improper hardness Loading workmanship dam Roller/ball bearing Strength exceeded Wrong surface Water in oil finish T Cross-head piston Galling d Oil pump failure Imbalance Cylinder Wrong hardening Insufficient Low oil pressure method Lube passages not support Crankshaft PI Design for installation Assembly Improper filtration Unsatisfactory Improper fit piping support Contaminated oil proper Improper piping tolerances Craftsmanship flexibili after Parts omitted maintenance Undersized piping Parts in wrong Improper Inadequate tolerances Thefileisdownloadedfromwww.bzfxw.com
System design and specification responsibility Component manufacturer's responsibility Shipping and storage responsibility Installation responsibility Operations and maintenance responsibility Distress damage or failed components condition assumed (temperature, pressure, etc.) Incorrect physical property assumed (molecular weight, etc.) Specifications Inadequate lubrication system Insufficient control instrumentation Improper coupling Improper bearing Improper seal Insufficient shutdown devices Material of construction Corrosion and/or erosion Rapid wear Fatigue Strength exceeded Galling Wrong hardening method Design for installation Unsatisfactory piping support Improper piping flexibility Undersized piping Inadequate foundation Improper treatment Design Improper specification Wrong selection Design error Inadequate or wrong lubrication Inadequate liquid drain Critical speed Inadequate strength Inadequate controls and protective devices Fabrication Welding error Improper heat treatment Improper hardness Wrong surface finish Imbalance Lube passages not open Assembly Improper fit Improper tolerances Parts omitted Parts in wrong Parts/bolts not drainage Protective coating not applied Wrong coating used Equipment not cleaned Protection Insufficient protection Corrosion by salt Corrosion by rain or humidity Poor packaging Desiccant omitted Contamination with dirt, etc. Physical damage Loading damage Transport damage Insufficient support Unloading damage Cracking or separating Piping Misalignment Inadequate cleaning Inadequate support Assembly Misalignment Assembly damage Defective material Inadequate bolting Connected wrong Foreign material left in General poor workmanship Operating Slugs of liquid Process surging Control error Controls deactivated/not installed Operating error Auxiliaries Utility failure Insufficient instrumentation Electronic control failure Pneumatic control failure Lubrication Dirt in oil Insufficient oil Wrong lubricant Water in oil Oil pump failure Low oil pressure Plugged lines Improper filtration Contaminated oil Craftsmanship after maintenance Improper tolerances Sleeve bearing Seal Coupling Shaft Pinion/ball/turning gear Casing Rotor Impeller Shroud Piston Diaphragm Wheel Blades; foil, root, shroud Labyrinth Thrust bearing Pivoted pad bearing Roller/ball bearing Cross-head piston Cylinder Crankshaft The file is downloaded from www.bzfxw.com
System design Component Operations and Distress damage or and specification manufacturer's storage responsibility maintenance failed components responsibility responsibility responsibility responsibility Welding error Unsatisfactory soil data Poor alignment Improper surface Liquid ingestion Imbalance Improper fit Inadequate liquid Inadequat drain bearing contact General poor Design error Inadequate testing Assembly after Parts in wrong Parts omitted Misalignment r bolt ping stress Foreign material left in ng material of construction maintenance Schedule too long Requirements for Effective RCA. Performing an effective RCa requires an interdisciplinary approach in order to ensure that the results are correct and proper corrective actions are identified. In fact, most failures involve factors that spread across many disciplines such as metallurgy, mechanical engineering, hydraulics, electrical engineering, quality control operations, maintenance, human factors, and others. The analysis team on a complex failure will ideally represent a spectrum of expertise to ensure a very broad perspective The best analysis team leader must be a good communicator, have a broad background, be able to integrate factors, and be able to select the best expertise for the project. On less complex failures it is often beneficial to have an individual with a diverse background participate in addition to the specialists, once again to ensure a broader perspective. For example, a metallurgist may be more likely to report a metallurgical deficiency in a product that contributed to the failure,a fabricator is more likely to point to fabrication-related contributors, and a designer is more likely to identify design deficiencies. All of these may be important considerations, but one, all, or none may be a primary root cause. Problems related to people, procedures, environmental concerns, and other issues can also be treated effectively by conducting problem-solving processes and RCAs(although the main focus of this article and this volume is on materials failure analysIs)
System design and specification responsibility Component manufacturer's responsibility Shipping and storage responsibility Installation responsibility Operations and maintenance responsibility Distress damage or failed components Unsatisfactory soil data Liquid ingestion Inadequate liquid drain Design error tight Poor alignment Imbalance Inadequate bearing contact Inadequate testing Welding error Improper surface finish Improper fit General poor workmanship Assembly after maintenance Mechanical damage Parts in wrong Parts omitted Misalignment Improper bolting Imbalance Piping stress Foreign material left in Wrong material of construction Preventive maintenance Postponed Schedule too long Requirements for Effective RCA. Performing an effective RCA requires an interdisciplinary approach in order to ensure that the results are correct and proper corrective actions are identified. In fact, most failures involve factors that spread across many disciplines such as metallurgy, mechanical engineering, hydraulics, electrical engineering, quality control, operations, maintenance, human factors, and others. The analysis team on a complex failure will ideally represent a spectrum of expertise to ensure a very broad perspective. The best analysis team leader must be a good communicator, have a broad background, be able to integrate factors, and be able to select the best expertise for the project. On less complex failures it is often beneficial to have an individual with a diverse background participate in addition to the specialists, once again to ensure a broader perspective. For example, a metallurgist may be more likely to report a metallurgical deficiency in a product that contributed to the failure, a fabricator is more likely to point to fabrication-related contributors, and a designer is more likely to identify design deficiencies. All of these may be important considerations, but one, all, or none may be a primary root cause. Problems related to people, procedures, environmental concerns, and other issues can also be treated effectively by conducting problem-solving processes and RCAs (although the main focus of this article and this Volume is on materials failure analysis)
