ΕΘΝΙΚΟ ΜΕΤΣΟΒΙΟ ΠΟΛΥΤΕΧΝΕΙΟ ΣΧΟΛΗ ΝΑΥΠΗΓΩΝ ΜΗΧΑΝΟΛΟΓΩΝ ΜΗΧΑΝΙΚΩΝ ROOT CAUSE ANALYSIS ΚΩΝΣΤΑΝΤΟΥΛΑΚΗΣ ΙΩΑΝΝΗΣ - PDF

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ΕΘΝΙΚΟ ΜΕΤΣΟΒΙΟ ΠΟΛΥΤΕΧΝΕΙΟ ΣΧΟΛΗ ΝΑΥΠΗΓΩΝ ΜΗΧΑΝΟΛΟΓΩΝ ΜΗΧΑΝΙΚΩΝ ROOT CAUSE ANALYSIS ΚΩΝΣΤΑΝΤΟΥΛΑΚΗΣ ΙΩΑΝΝΗΣ Επιβλέπων καθηγητής: Βασίλειος Ι. Παπάζογλου ΑΘΗΝΑ 2010 INDEX CHAPTER 1 DEFINITIONS

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ΕΘΝΙΚΟ ΜΕΤΣΟΒΙΟ ΠΟΛΥΤΕΧΝΕΙΟ ΣΧΟΛΗ ΝΑΥΠΗΓΩΝ ΜΗΧΑΝΟΛΟΓΩΝ ΜΗΧΑΝΙΚΩΝ ROOT CAUSE ANALYSIS ΚΩΝΣΤΑΝΤΟΥΛΑΚΗΣ ΙΩΑΝΝΗΣ Επιβλέπων καθηγητής: Βασίλειος Ι. Παπάζογλου ΑΘΗΝΑ 2010 INDEX CHAPTER 1 DEFINITIONS ROOT CAUSE ANALYSIS QUALITY CONTROL Quality assurance Failure testing Statistical control Company quality Total quality control FAILURE ANALYSIS Forensic investigation SYSTEMS ANALYSIS Overview Practitioners GENERAL PRINCIPLES OF ROOT CAUSE ANALYSIS...9 CHAPTER 2 - GENERAL PROCESS FOR PERFORMING AND DOCUMENTING AN RCA BASED CORRECTIVE ACTION PHASE I DATA COLLECTION PHASE II ASSESSMENT Assessment and Reporting Guidance Analyze and determine the events and casual factor chain Summarize findings, list the casual factors, and list corrective actions PHASE III CORRECTIVE ACTIONS PHASE IV INFORM PHASE V FOLLOW-UP...18 CHAPTER 3 - ROOT CAUSE ANALYSIS METHODS BAYESIAN INFERENCE Evidence and changing beliefs CURRENT REALITY TREE Simplified explanation Contextual explanation Example FAILURE MODE AND EFFECTS ANALYSIS History Implementation 3.3.3 Using FMEA when designing Timing of FMEA Uses of FMEA Advantages Limitations Software Types of FMEA FAULT TREE ANALYSIS History Why Fault Tree Analysis? Methodology Analysis WHYS Example History Criticism ISHIKAWA DIAGRAM Overview Causes Categories KEPNER-TREGOE PROBLEM ANALYSIS Kepner-Tregoe (company) Kepner-Tregoe (technique) PARETO ANALYSIS Steps to identify the important causes using Pareto analysis RPR PROBLEM DIAGNOSIS Overview Limitations History...38 CHAPTER 4 - BASIC ELEMENTS OF ROOT CAUSE ANALYSIS...39 CHAPTER 5 - ROOT CAUSE ANALYSIS AND CASUALTY INVESTIGATION IN MARITIME INDUSTRY THE WAY INVESTIGATIONS USED TO BE DONE WHY INVESTIGATE INCIDENTS?...40 CHAPTER 6 - REPORTS AND ANALYSIS OF NON- CONFORMITIES AS DESCRIBED IN THE COMPANY S SAFETY MANAGEMENT SYSTEM MANUAL 6.1 GENERAL RESPONSIBILITIES DEFINITIONS Non-conformities Accidents Hazardous Occurrences (Near-misses) PROCEDURES REPORTING NON-CONFORMITIES (NCRs) CORRECTIVE ACTIONS Treatment Corrective actions Assessment of the cause Root Cause Analysis Methodology Training for Root Cause Analysis Recording...48 CHAPTER 7 - ANALYSIS OF REAL CASES WITH NON- CONFORMITIES AND NEAR-MISSES...49 CHAPTER 8 - SUMMARY AND RECOMMENDATIONS...94 CHAPTER 9 REFERENCES CHAPTER 1 DEFINITIONS 1.1 ROOT CAUSE ANALYSIS Root cause analysis (RCA) is a class of problem solving methods aimed at identifying the root causes of problems or events. The practice of RCA is predicated on the belief that problems are best solved by attempting to correct or eliminate root causes, as opposed to merely addressing the immediately obvious symptoms. By directing corrective measures at root causes, it is hoped that the likelihood of problem recurrence will be minimized. However, it is recognized that complete prevention of recurrence by a single intervention is not always possible. Thus, RCA is often considered to be an iterative process, and is frequently viewed as a tool of continuous improvement. RCA, initially, is a reactive method of problem detection and solving. This means that the analysis is done after an event has occurred. By gaining expertise in RCA it becomes a pro-active method. This means that RCA is able to forecast the possibility of an event even before it could occur. Root cause analysis is not a single, sharply defined methodology; there are many different tools, processes, and philosophies of RCA in existence. However, most of these can be classed into five, very-broadly defined schools that are named here by their basic fields of origin: safety-based, production-based, process-based, failure-based, and systems-based. Safety-based RCA descends from the fields of accident analysis and occupational safety and health. Production-based RCA has its origins in the field of quality control for industrial manufacturing. Process-based RCA is basically a follow-on to production-based RCA, but with a scope that has been expanded to include business processes. Failure-based RCA is rooted in the practice of failure analysis as employed in engineering and maintenance. Systems-based RCA has emerged as an amalgamation of the preceding schools, along with ideas taken from fields such as change management, risk management, and systems analysis. 4 Despite the seeming disparity in purpose and definition among the various schools of root cause analysis, there are some general principles that could be considered as universal. Similarly, it is possible to define a general process for performing RCA. 1.2 QUALITY CONTROL In engineering and manufacturing, quality control and quality engineering are used in developing systems to ensure products or services are designed and produced to meet or exceed customer requirements. Quality control is the branch of engineering and manufacturing which deals with assurance and failure testing in design and production of products or services, to meet or exceed customer requirements Quality assurance One of the most widely used paradigms for quality assurance management is the PDCA (Plan-Do-Check-Act). This problem solving process was made popular by Dr. W. Edwards Deming, who is considered by many to be the father of modern quality control Failure testing A valuable process to perform on a whole consumer product is failure testing (also known as stress testing), the operation of a product until it fails, often under stresses such as increasing vibration, temperature and humidity. This exposes many unanticipated weaknesses in a product, and the data is used to drive engineering and manufacturing process improvements Statistical control Many organizations use statistical process control to bring the organization to Six Sigma levels of quality, in other words, so that the likelihood of an unexpected failure is confined to six standard deviations on the normal distribution. This probability is 3.4 one-millionths. Items 5 controlled often include clerical tasks such as order-entry as well as conventional manufacturing tasks. Traditional statistical process controls in manufacturing operations usually proceed by randomly sampling and testing a fraction of the output. Variances of critical tolerances are continuously tracked, and manufacturing processes are corrected before bad parts can be produced Company quality During the 1980s, the concept of company quality with the focus on management and people came to the fore. It was realized that, if all departments approached quality with an open mind, success was possible if the management led the quality improvement process. The company-wide quality approach places an emphasis on three aspects: 1. Elements such as controls, job management, defined and well managed processes, performance and integrity criteria and identification of records. 2. Competence such as knowledge, skills, experience, qualifications. 3. Soft elements, such as personnel integrity, confidence, organizational culture, motivation, team spirit and quality relationships. The quality of the outputs is at risk if any of these three aspects is deficient in any way Total quality control Total Quality Control is the most necessary inspection control of all in cases where, despite statistical quality control techniques or quality improvements implemented, sales decrease. If the original specification does not reflect the correct quality requirements, quality cannot be inspected or manufactured into the product. For instance, all parameters for a pressure vessel should include not only the material and dimensions but operating, environmental, safety, reliability and maintainability requirements. 6 1.3 FAILURE ANALYSIS Failure analysis is the process of collecting and analyzing data to determine the cause of a failure and how to prevent it from recurring. It is an important discipline in many branches of manufacturing industry, such as the electronics industry, where it is a vital tool used in the development of new products and for the improvement of existing ones. It relies on collecting failed components for subsequent examination of the cause or causes of failure using a wide array of methods, especially microscopy and spectroscopy. The NDT or nondestructive testing methods are valuable because the failed products are unaffected by analysis, so inspection always starts using these methods Forensic investigation Forensic inquiry into the failed process or product is the starting point of failure analysis. Such inquiry is conducted using scientific analytical methods such as electrical and mechanical measurements, or by analysing failure data such as product reject reports or examples of previous failures of the same kind. The methods of forensic engineering are especially valuable in tracing product defects and flaws. They may include fatigue cracks, brittle cracks produced by stress corrosion cracking or environmental stress cracking, for example. Witness statements can be valuable for reconstructing the likely sequence of events and hence the chain of cause and effect. Human factors can also be assessed when the cause of the failure is determined. There are several useful methods to prevent product failures occurring in the first place, including Failure Mode and Effects Analysis(FMEA) and Fault Tree Analysis (FTA), methods which can be used during prototyping to analyse failures before a product is marketed. Failure theories can only be constructed on such data, but when corrective action is needed quickly, the precautionary principle demands that measures be put in place. In aircraft accidents, for example, all planes of the type involved can be grounded immediately pending the outcome of the inquiry. Another interesting aspect of failure analysis is associated with No Fault Found (NFF) which is a term used in the field of failure analysis to describe a situation where an originally reported mode of failure can not 7 be duplicated by the evaluating technician and therefore the potential defect can not be fixed. NFF can be attributed to oxidation, defective connections of electrical components, temporary shorts or opens in the circuits, software bugs, temporary environmental factors, but also to the operator error. Large number of devices that are reported as NFF during the first troubleshooting session often return to the failure analysis lab with the same NFF symptoms or a permanent mode of failure. The term Failure analysis also applies to other fields such as business management and military strategy. 1.4 SYSTEMS ANALYSIS Systems analysis is the interdisciplinary part of science, dealing with analysis of sets of interacting entities, the systems, often prior to their automation as computer systems, and the interactions within those systems. This field is closely related to operations research. It is also an explicit formal inquiry carried out to help someone, referred to as the decision maker, identify a better course of action and make a better decision than he might have otherwise made Overview The terms analysis and synthesis come from classical Greek where they mean respectively to take apart and to put together . These terms are used in scientific disciplines from mathematics and logic to economy and psychology to denote similar investigative procedures. In general, analysis is defined as the procedure by which we break down an intellectual or substantial whole into parts or components. Synthesis is defined as the opposite procedure: to combine separate elements or components in order to form a coherent whole. The systems discussed within systems analysis can be within any field such as: industrial processes, management, decision making processes, environmental protection processes, etc. The brothers Howard T. Odum and Eugene Odum began applying a systems view to ecology in 1953, building on the work of Raymond Lindeman (1942) and Arthur Tansley (1935). 8 Systems analysis researchers apply mathematical methodology to the analysis of the systems involved trying to form a detailed overall picture Practitioners Practitioners of systems analysis are often called upon to dissect systems that have grown haphazardly to determine the current components of the system. This was shown during the year 2000 reengineering effort as business and manufacturing processes were examined and simplified, as part of the Year 2000 Problem (also known as the Y2K problem or the millennium bug) automation upgrades. Current employment titles utilizing systems analysis include, but are not limited to, Systems Analyst, Business Analyst, Manufacturing Engineer, Enterprise Architect, etc. While practitioners of systems analysis can be called upon to create entirely new systems, their skills are more often used to modify, expand or document existing systems (processes, procedures and methods). 1.5 GENERAL PRINCIPLES OF ROOT CAUSE ANALYSIS 1. Aiming performance improvement measures at root causes is more effective than merely treating the symptoms of a problem. 2. To be effective, RCA must be performed systematically, with conclusions and causes backed up by documented evidence. 3. There is usually more than one root cause for any given problem. 4. To be effective the analysis must establish all known causal relationships between the root cause(s) and the defined problem. 5. Root cause analysis transforms an old culture that reacts to problems to a new culture that solves problems before they escalate, creating a variability reduction and risk avoidance mindset. 9 CHAPTER 2 GENERAL PROCESS FOR PERFORMING AND DOCUMENTING AN RCA BASED CORRECTIVE ACTION Every root cause investigation and reporting process should include five phases. While there may be some overlap between phases, every effort should be made to keep them separate and distinct. [1] Phase I. Data Collection. It is important to begin the data collection phase of root cause analysis immediately following the occurrence identification to ensure that data are not lost. (Without compromising safety or recovery, data should be collected even during an occurrence). The information that should be collected consists of conditions before, during, and after the occurrence; personnel involvement (including actions taken); environmental factors; and other information having relevance to the occurrence. Phase II. Assessment. Any root cause analysis method may be used that includes the following steps: 1. Identify the problem. 2. Determine the significance of the problem. 3. Identify the causes (conditions or actions) immediately preceding and surrounding the problem. 4. Identify the reasons why the causes in the preceding step existed, working back to the root cause (the fundamental reason which, if corrected, will prevent recurrence of these and similar occurrences throughout the facility). Phase III. Corrective Actions. Implementing effective corrective actions for each cause reduces the probability that a problem will recur and improves reliability and safety. Phase IV. Inform. Entering the report on the Occurrence Reporting and Processing System (ORPS) is part of the inform process. Also included is discussing and explaining the results of the analysis, including corrective actions, with management and personnel involved in the occurrence. In addition, consideration should be given to providing information of interest to other facilities. 10 Phase V. Follow-up. Follow-up includes determining if corrective action has been effective in resolving problems. An effectiveness review is essential to ensure that corrective actions have been implemented and are preventing recurrence. Management involvement and adequate allocation of resources are essential to successful execution of the five root cause investigation and reporting phases. 2.1 PHASE I DATA COLLECTION As mentioned before, is important to begin the data collection phase of the root cause process immediately following occurrence identification to ensure that data are not lost. (Without compromising safety or recovery, data should be collected even during an occurrence). The information that should be collected consists of conditions before, during, and after the occurrence; personnel involvement (including actions taken); environmental factors; and other information having relevance to the condition or problem. For serious cases, photographing the area of the occurrence from several views may be useful in analyzing information developed during the investigation. Every effort should be made to preserve physical evidence such as failed components, ruptured gaskets, burned leads, blown fuses, spilled fluids, partially completed work orders and procedures. This should be done despite operational pressures to restore equipment to service. Occurrence participants and other knowledgeable individuals should be identified. Once all the data associated with this occurrence have been collected, the data should be verified to ensure accuracy. The investigation may be enhanced if some physical evidence is retained. Establishing a quarantine area, or the tagging and segregation of pieces and material, should be performed for failed equipment or components. The basic need is to determine the direct, contributing and root causes so that effective corrective actions can be taken that will prevent recurrence. Some areas to be considered when determining what information is needed include: Activities related to the occurrence Initial or recurring problems Hardware (equipment) or software (programmatic-type issues) associated with the occurrence Recent administrative program or equipment changes 11 Physical environment or circumstances. Some methods of gathering information include: Conducting interviews/collecting statements - Interviews must be fact finding and not fault finding. Preparing questions before the interview is essential to ensure that all necessary information is obtained. Interviews should be conducted, preferably in person, with those people who are most familiar with the problem. Individual statements could be obtained if time or the number of personnel involved make interviewing impractical. Interviews can be documented using any format desired by the interviewer. Consider conducting a walk-through as part of this interview if time permits. Although preparing for the interview is important, it should not delay prompt contact with participants and witnesses. The first interview may consist solely of hearing their narrative. A second, more-detailed interview can be arranged, if needed. The interviewer should always consider the interviewee s objectivity and frame of reference. Interviewing others - Consider interviewing other personnel who have performed the job in the past. Consider using a walkthrough as part of the interview. Reviewing records - Review relevant documents or portions of documents as necessary and reference their use in support of the root cause analysis. Record appropriate dates and times associated with the occurrence on the documents reviewed. Examples of documents include the following: Operating logs Correspondence Inspection/surveillance records Maintenance records Meeting minutes Computer process data Procedures and instructions Vendor Manuals Drawings and specifications Functional retest specification and results Equipment history records 12 Design basis information Safety Analysis Report (SAR)/Technical Specifications Related quality control evaluation reports Operational Safety Requirements Safety Performance Measurement System/Occurrence Reporting and Processing System (SPMS/ORPS) Reports Radiological surveys Trend charts and graphs Facility parameter readings Sample analysis and results (chemistry, radiological, air, etc.) Work orders Acquiring related information - Some additional information that an evaluator should consider when analyzing the causes includes the following: Evaluating the need for la
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