Energy flow targets

The eventual target s) of unwanted or uncontrolled energy flow targets may be either people or objects)... 

Actual Energy (A) = Target (T) + Cross-Pinch Energy flow (XP)... 

If controlling the hazards through improved design or engineering is impossible or impractical, the next course of action should be to use physical guards or barriers to separate potential unwanted energy flows or other hazards from potential targets. 

The HazOp study is also similar to the ETBA in that it traces energy flows through a facility, studies barriers to control energy flows, and identifies the targets of unwanted energy flows. 

Provide barriers to energy flows on the energy source, between the source and the target, and/or on the target... 

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. 

Identify and evaluate the barriers that are in place to control the energy and the potential targets of any unwanted energy flow that could occur if the barriers fail. 

Column 3—Targets. List the persons or objects at this particular location that could be in the path of an unwanted energy flow. Quantify if possible (number of people, value of property). Include other systems and subsystems that could be adversely affected by the unwanted energy flow. 

Column 4—RAC. Enter the risk assessment code associated with this particular unwanted energy flow. List a separate RAC for each potential target. 

Figure 18-9 Unwanted energy flow. Many accidents are the result of a series of unwanted energy flows, barrier failures, and vulnerable targets.

For analysis purposes, the changes under the accident block make little difference. The three main branches on the specific control factors side continue to be the contributory events that allowed the unwanted energy flow (or hazardous environment), the LTA barriers, and the targets in the energy path (or vulnerable to the hazardous environment). 

Barrier analysis includes determining whether or not the barrier failed, if a barrier was provided and used. If a barrier was provided but not used, the analysis then seeks to identify the task performance errors which caused the barrier not to be used (Fig. 18-12). This process is used to evaluate barriers on the energy source, between the energy source and the persons and/or objects to be protected, or on the target person or object. The same process is also used if the barrier evaluated consists of separating the potential targets from potentially harmful energy flows or environments by time or space. 

Figure 18-13 Targets. This branch addresses the persons and/or objects which are the targets of the unwanted energy flow (or harmful environmental condition).

Energy control provisions Were the safest forms of energy used, consistent with operational requirements Were adequate barriers provided Was the safety precedence sequence properly applied Were energy flows carefully considered and routed away from vulnerable targets where possible ... 

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