Risk Assessment: Tools, Techniques, and Their Applications

6.2 Using Process Hazard for Procedure Design

PHA is most effectively used during the initial development of a process and the procedures for performing that process. Also, it has utility when updating/changing a process and its procedure. The following example illustrates its use for analyzing a maintenance process/procedure.

6.2.1 Purpose of Process

Flushing an automobile cooling system.

6.2.2 Initial Basic Procedure Steps

1. Begin with the engine cold and ignition off. Remove the radiator pressure cap.

2. Open the petcock at the bottom of the radiator and drain the coolant into a bucket.

3. Close the petcock and fill the radiator with water.

4. Start the engine and turn the heater control to hot. Add cooling system cleaner and idle the engine for 30 min (or as per the instructions on container).

5. Stop the engine and allow it to cool for 5 min. Drain the system.

6. Close the petcock, fill the radiator with water, and let the engine idle for 5 min.

7. Repeat step No. 5. Close the petcock.

8. Install new 50 : 50 mixture of water/ethylene glycol antifreeze/coolant.

6.2.3 Analysis

Table 6.4 shows the analysis of the procedure. Note that in a PHA the idea is to list the hazards and not to analyze each step in the procedure. Failure mode and effect analysis and failure mode, effect, and criticality analysis are better suited for analyzing the steps of the procedure.

Table 6.4 Analysis of Procedure

Note that there are two primary hazards associated with flushing the cooling ...