Structured determination, root cause

Chapter 9—Determining Root Causes—Structured Approaches... 

For a major incident investigation using a comprehensive root cause analysis system, teams will be formed to acquire information relevant to determine the structure and analyze the causes in depth. In addition to evaluations of the immediate causes, imderlying causes are likely to be evaluated by investigations in areas such as safety and quality management. Both paper- and computer-based systems will be used to acquire and record information for subsequent detailed analyses. 

This chapter addresses methods and tools used successfully to identify multiple root causes. Process safety incidents are usually the result of more than one root cause. This chapter provides a structured approach for determining root causes. It details some powerful, widely used tools and techniques available to incident investigation teams including timelines, logic trees, predefined trees, checklists, and fact/hypothesis. Examples are included to demonstrate how they apply to the types of incidents readers are likely to encounter. 

Progressive companies use a more structured and comprehensive team approach to identify root causes. Scientific principles and concepts are applied to determine root causes and make recommendations to prevent recurrence. Effective investigations should use tested data analysis tools and methodologies to seek the identification of multiple causes. To be repeatable, the investigation should use a systematic approach, which may also be prescriptive. As a rule, the benefits of this systematic approach result from two actions ... 

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. 

Determining the causes is a necessary precursor to detailing findings, formulating recommendations, and implementing actions. This chapter presents two overall approaches to structured root cause investigation and develops a set of tools to identify root causes. 

HC-ToxIn. Early attempts to Isolate and characterize this toxin from a corn pathogen, Helmlnthosoorlum carbonum race 1 were performed In 1967-71 (Hfi, 1791. Nany other reports of structure determinations have been summarized (1801. Purified HC-toxIn [44], a host-specific toxin, causes substantial root growth Inhibition at ca 0.5 /tg/m1 (1811. A very similar compound, chlamydocin [45], has been Isolated from Dlheterosoora chlamvdosDora (IS2, I l). 

The photochemical properties of titania surfaces are of interest for several reasons. They determine the stability of pigmented paint systems [76], the rate at which pollutants can be degraded in systems designed to purify air and water [77], and are the root cause of poorly understood phenomena such as water photolysis [78] and super hydrophilicity [79]. Using thin rutile epilayers with five low index orientations, it has been shown that the relative rates of photochemical reactions catalyzed by titania depend on the surface orientation [80]. In this chapter, experiments used to map the complete orientation dependence of the relative photochemical reactivity of TiO are described [81-83]. In this case, the relevant reactions are carried out at room temperature and this gives us the opportunity to fix both the surface morphological structure and stoichiometry. For the reactions described here, all of the surfaces were... 

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