Energy trace and barrier analysis

The sides of the accident triangle that are discussed in the MORT program are the unwanted energy flow, barriers that are less than adequate to prevent or control the energy flow, and targets (persons or objects) in the energy path (Fig. 13-1). This approach is the basis for ETBA, which systematically analyzes these three factors and their interrelations. 

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A typical system safety task for hazard identification would be the preparation of a preliminary hazard list (PHL). Hazard identification or discovery is accomplished by reviewing lessons learned, accident reports, and other historical data. A PHL may be prepared through an informal conference, the use of checklists, and occasionally other techniques such as energy trace and barrier analysis (ETBA). 

Laundry lists of analyses frequently mix types of analyses (preliminary hazard analysis, system hazard analysis, and operating hazard analysis) with the methods or techniques for performing analyses (fault tree analysis, energy trace and barrier analysis, failure modes and effects analysis, common cause analysis, change analysis, and so on). Whether fault hazard analysis is a type or a method depends upon the reference in use. For all practical purposes, fault hazard analysis and system (or subsystem) hazard analysis seem to be the same thing, which is apparently called gross hazard analysis occasionally. 

The methods used for preparation of a PHL include informal conferencing and the use of checklists and/or energy trace and barrier analysis (ETBA). 

The recommended techniques for preliminary hazard analysis are energy trace and barrier analysis (ETBA) and failure modes and effects analysis (FMEA). Recommended techniques for system and subsystem hazard analyses are FMEA, fault tree analysis (FTA), common cause analysis, sneak circuit analysis (for electrical, electronic, and some hydraulic or pneumatic circuits) and, of course, software hazard analysis for software. 

Failure tpodes and effects analysis (FMEA) and energy trace and barrier analysis are the techniques recommended to aid in conducting PHAs. 

Analytical trees are also very useful as feeder documents for several hazard analysis techniques, for example, failure mode and effects analysis (Chapter 14), fault tree analysis (Chapter 15), energy trace and barrier analysis (Chapter 13), and project evaluation tree analysis (Chapter 16), the primary hazard analysis tools for many projects. Virtually any analytical technique or any type of analysis can be simplified by starting with the analytical tree as a base document. 

Figure 13-2 Energy trace and barrier analysis worksheet.

Figure 18-8 Accident triangle. The incident , LTA barriers , and vulnerable target concept is the basis for Energy Trace and Barrier Analysis (ETBA) described in Chapter 13.

Figure 9.1 Sample energy trace and barrier analysis (ETBA) worksheet.

Fault (or Functional) Hazard Analysis (FHA) Management Oversight and Risk Tree (MORT) Energy Trace and Barrier Analysis (ETBA) Sneak Circuit Analysis (SCA)... 

Energy Trace and Barrier Analysis -0 Subsystem Hazard Analysis -0 Subsystem Hazard Analysis Accident/Incident Analysis - Change Analysis... 

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