Root Cause — Design

Functionally, however, collaborative engineering calls on a very large cross section of enterprise constituencies and is not limited to engineering or manufacturing professionals. 

Chapter 28 closed with a description of process capabilities and the tolerances that must be met. An important success factor in supply chain management (SCM) is certainly the design of the products that the supply chain must source, make, and deliver. It has been observed by many that the engineering department largely determines the cost of operations. This certainly applies to the manufacturing department in the company that must fabricate and assemble the product. It is just as tme for suppliers who must meet their customers specifications. If the tolerances described in the Chapter 28 are too tight, the product cannot be made cost effectively. Thus, the quotation above is one to keep in mind when addressing supply chain costs. 

Anthony MiUs, CASA/SME Blue Book Series 

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Nuclear power has achieved an excellent safety record. Exceptions are the accidents at Three Mile Island in 1979 and at Chernobyl in 1986. In the United States, safety can be attributed in part to the strict regulation provided by the Nuclear Regulatory Commission, which reviews proposed reactor designs, processes appHcations forUcenses to constmct and operate plants, and provides surveillance of all safety-related activities of a utiUty. The utiUties seek continued improvement in capabiUty, use procedures extensively, and analy2e any plant incidents for their root causes. Similar programs intended to ensure reactor safety are in place in other countries. 

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 the shorter case studies, only the immediate causes of the errors are described. However, the more extended examples in the latter part of the appendix illustrate two important points about accident causation. First, the precondihons for errors are often created by incorrect policies in areas such as training, procedures, systems of work, communications, or design. These "root causes" underlie many of the direct causes of errors which are described in this section. Second, the more comprehensive examples illustrate the fact that incidents almost always involve more than one cause. These issues will... 

Corrosion (direct cause) due to Design error (basic or root cause) not recovered by Inspection (failure of recovery)... 

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. 

Accidents in industry occur for many reasons. A few of which can be attributed to mechanical failure, operational error (human error), and process upset, and design error. In order to understand tlie root cause of an accident, system safety appraaches have been put to use. 

Consider again a batch polymerization process where the process is characterized by the sequential execution of a number of steps that take place in the two reactors. These are steps such as initial reactor charge, titration, reaction initiation, polymerization, and transfer. Because much of the critical product quality information is available only at the end of a batch cycle, the data interpretation system has been designed for diagnosis at the end of a cycle. At the end of a particular run, the data are analyzed and the identification of any problems is translated into corrective actions that are implemented for the next cycle. The interpretations of interest include root causes having to do with process problems (e.g., contamination or transfer problems), equipment malfunctions (e.g., valve problems or instrument failures), and step execution problems (e.g., titration too fast or too much catalyst added). The output dimension of the process is large with more than 300 possible root causes. Additional detail on the diagnostic system can be found in Sravana (1994). 

March 25, 2004) I agree with you completely that the problem should be addressed at the design level. This type of thing is the reason why some of our customers perceive us as not addressing problems at the root cause. I think it is ridiculous that we are expecting customers [to somehow] accommodate a device that we are [actually] selling TO THEM. 

EPA ARIP Responses to questionnaires sent by EPA from facilities that have had significant releases purpose is to learn about causes and consequences of hazardous material incidents 1986-Present Supplements NRC reports for more significant events Additional information on causal factors, consequences, and company safety programs Data are easily analyzed for common causes Includes all states and localities Survey relies on voluntary compliance Not comprehensive limited to select cases Checklist approach limits value of information to understand root cause Not designed to be a lessons-leamed database... 

This case study was developed with an alternative hypothesis and then a second hypothesis, and the experiments were designed properly to determine quickly the root cause of the defect in the part profile. If the hypotheses and experiments had not been developed properly, the time required to troubleshoot the problem would have increased or the project would have failed. 

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