Root cause failure analysis

Improved Root Cause Failure Analysis (RCFA)... 

Root cause failure analysis (RCFA) is conducted by different teams and departments to identify the main causes of a failure. Different tools are in use by the industry to conduct these analyses. A robust RCFA system provides critical information to the operators and advice on the sequence of corrective actions. The industry has gained several benefits including the integration of several information sources resulting in more automated and proactive conditions with possible diagnosis and advice (Weidl 2004). The purpose of such analyses could be to resolve problems related... 

Mobley, R. K. 1999. Root cause failure analysis. Plant engineering maintenance series. USA Newnes Publishers. 

Bowers (at Life Cycle Engineering, cbowerse LCE.com) mentions the following risk assessment tools that can be employed to help preserve asset resources Simplified Failure Mode Effects Analysis, Root Cause Failure Analysis, and Reliability-Centered Maintenance. Should safety and health professionals step forward to train maintenance managers in risk assessment concepts ... 

Special attention should be given to the valve actuator when conducting a root cause failure analysis. Many of the problems associated with both process and fluid-power control valves are really actuator problems. 

As in any proactive maintenance organiTation you must perform Root Cause Failure Analysis in order to eliminate liiture component failures. Most maintenance problems or failures will repeat themselves without someone identilying what caused the failure and proactively eliminating it. A preferred method is to inspect and analyze all component failures. Identify the following ... 

As indicated in Table 13, vent valve 100PV experienced frequent problems. After the third failure, a root cause failure analysis determined that the valve was defective. The valve was replaced, and has not exhibited any failures since. 

After the hazard analysis is finished, a question based on the hazard root cause failure mechanism is created and added to the hazard checkhst. The Independent Verification and Validation Group (IV V) generates a respective test case. These test cases are collected in a Hazard Test Procedure Book. 

The causes of low pressure, for example, could be cither hydraulic or mechanical. In many cases of failure analysis, asking Wliy. and Wliat and answering those questions, until you can no longer ask why , will almost always get you to the answer. If all evidence leads to a mechanical reason for the failure, the problem is probably maintenance induced. If the evidence leads to a hydraulic reason for the failure, the problem is eitJier operations or design induced. In cases where the reason for failure was not determined, a more extensive analysis is necessary. The additional analysis is recommended to take advantage of the pump supplier experience in identifying the root cause. 

In general, the value of a psychological perspective in incident analysis is that it directs the analyst to search for causes that would not otherwise have been considered. This means that the development of preventative strategies will be better informed. In addition, an evaluation of causes from a psychological perspective can be useful when the "root cause" appears to be an otherwise incomprehensible failure on the part of an individual. A psychological analysis can break the "causal log jam" by providing an explanation. 

The change management process should also ensure that a root cause analysis has been conducted to make sure the real problem has been identified and corrected. For example, if a pump seal fails it could simply be replaced with an identical seal. However, it may have failed because it was left in service beyond its natural life and the real failure was in the preventative maintenance program that should have replaced it earlier. 

The report presents the findings from the analysis of the RCP failures. Estimates of the annual frequency for the spectrum of leak rates induced by RCP seal failures and their impact on plant safety (contribution to coremelt frequency) are made. The safety impact of smaller RCP seal leaks was assessed qualitatively, whereas for leaks above the normal makeup capacity, formal PRA methodologies were applied. Also included are the life distribution of RCP seals and the conditional leak rate distributions, given a RCP seal failure the contribution of various root causes and estimates for the dependency factors and the failure intensity for the different combinations of pump designers and plant vendors. 

Predictive maintenance utilizing vibration signature analysis is based on the following facts, which form the basis for the methods used to identify and quantify the root causes of failure ... 

Although failure-mode analysis identifies the number and symptoms of machine-train problems, it does not always identify the tme root cause of problems. Root cause must be verified by visual inspection, additional testing, or other techniques such as operating dynamics analysis. 

All machines have a finite number of failure modes. If you have a thorough understanding of these failure modes and the dynamics of the specific machine, you can learn the vibration analysis techniques that will isolate the specific failure mode or root-cause of each machine-train problem. 

Probably the most interesting and enlightening analysis you could ever perform is to analyze why failure analysis fails. By its pure definition, it is impossible for failure analysis to fail—so how come it does The answers (root causes) often lie with the problem solvers themselves, as well as their management support groups. 

Another type of logic tree, the event tree, is an inductive technique. Event Tree Analysis (ETA) also provides a structured method to aid in understanding and determining the causes of an incident.(i) While the fault tree starts at the undesired event and works backward to identify root causes, the event tree looks forward to display the progression of various combinations of equipment failures and human errors that result in the incident graphically. 

This step is always performed. Using analysis tools and methods such as fault trees, causal factor charting, checklists, predeveloped trees, or alternative methodologies will help to identify the root causes of the failures. 

The immediate cause was failure of the ring joint seal on the solid rocket booster. Yet, a root-cause analysis revealed a much more complex scenario. According to information published after the investigation, post flight evidence from as far back as early 1984 showed that the joint seals were failing to meet design specifications. 

Causal factor identification is relatively easy to learn and apply to simple incidents. For more complex incidents with complicated timelines, one or more causal factors can easily be overlooked, however, which inevitably will result in failure to identify their root causes. There are a number of tools, such as Barrier Analysis, Change Analysis, and Fault Tree Analysis, that can assist with bridging gaps in data and the identification of causal factors. Each of these tools has merits that can assist the investigator in understanding what happened and how it happened. 

Analysis of Esso Longford as well as analysis in the UK Health and Safety Executive (HSE) investigation report into petrochemical complex major incidents all show that common underlying causes are often repeated. The Longford incident clearly illustrates the multiple root cause concept. A number of PSM system failures occurred either in... 

Alternatively, processes such as failure mode and effects analysis or root cause analysis can be used to identify systems ripe for quality improvement activities. Failure mode and effects analysis is a prospective procedure used to identify areas for quality improvement before they become a problem (Cohen et al., 1994 DeRosier et al., 2002 NCPS, 2001). Once pos-... 

Traditional accident models were devised to explain losses caused by failures of physical devices (chain or tree of failure events) in relatively simple systems. They are less useful for explaining accidents in software-intensive systems and for non-technical aspects of safety such as organizational culture and human decision-making. Creation of an infrastructure based on which safety analysis can function efficiently and effectively is needed. A so called safety culture for a development company and processes associated with routine tasks there, in general, is now identified as an area of root cause of accidents and that there is the greatest... 

M. Zamanzadeh, E. Larkin and D.Gibbon, A Re-Examination of Failure Analysis and Root Cause Determination, Mateo Associates, Pittsburgh, Pennsylvania, December 2004. 

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