Process Hazard Analysis (PHA) is the methodology to identify and assess potential hazards associated with the handling, processing, and storage of hazardous material. Techniques such as Hazard and Operability Studies (HAZOP), What-If Analysis, Failure Modes and Effects Analysis (FMEA), and Checklist may be employed during PHA.
Hazard and Operability (HAZOP) study
HAZOP method is used in many industries such as chemical, refinery, petrochemical, etc which are used to identify the potential hazard scenario from the process deviation or operability deviation such as “No Flow”, More Level”, etc impacts on the onsite people, environment, and asset. The process of reviewing will run along with the process deviation (process parameter + HAZOP guideword).
The procedure for conducting a HAZOP study
What-If study
The what-if method involves posing the question “What if” relating to initiating events to identify hazard scenarios for a process. “What-if” scenarios can be used to imagine the future and its implications. This helps anticipate and prepare for potential advancements.
In essence, “What-if” encourages a form of mental exploration, an open-minded approach where individuals or groups consider various possibilities and their potential outcomes. It’s a valuable tool for strategic planning, risk management, and fostering creativity.
The procedure for conducting a What-If Analysis.
Failure Mode Effect Analysis (FMEA)
FMEA is a hazard evaluation method in which failure modes of system components, typically, equipment components, are considered to determine the effects and safeguards in place. Failure Mode describes how a component fails such as “Open”, “Close”, “Over”, and, etc. The FMEA can be applied in deeper study as an FMECA (Failure Mode and Effects and Critically Analysis) or FMEDA (Failure Mode and Effects and Diagnostic Analysis).
The procedure for conducting a Failure Mode Effect Analysis (FMEA)
Checklist
A checklist used as a hazard evaluation method employs a predefined list. A predefined list will raise the list of questions, tasks, or steps relating to identifying concerns and prompt the analyst to accomplish, verify, or consider. Checklists are used in various fields and contexts to ensure that important items are not overlooked, tasks are completed, and processes are followed systematically.
Compare PHA Techniques
| HAZOP | What-If | FMEA | Checklist | |
| Methodology | Systematic and structured technique by dividing the system into Node. | More informal brainstorming and discussing hypothetical. | A systematic way to identify potential failure mode of individual components | Use a predefined checklist for analysis |
| Approach | Consider process parameters such as Flow and their deviation such as No Flow. | Open discussion on various scenarios. | Identify failure mode, their effects, likelihood, severity, and detectability. | Checks off items on the list |
| Output | Potential Cause, consequence, and recommendation. | Identify hazards, consequences, and recommendations. | Results in a risk priority number (RPN) for each failure mode | List of identification of specific hazards |
| Applicability | Analysis of complex processes such as refinery. | Often used in early stages or in Manage Of Change review | Commonly used in automotive, aerospace, and manufacturing | Commonly used in all industries |
The other PHA techniques are such as Preliminary Hazard Analysis (PrHA), Major Hazard Analysis (MHA), Fault Tree Analysis (FTA), Event Tree Analysis (ETA), Cause-Consequence Analysis (CCA), Consequence Analysis, and Bow-Tie Analysis (BTA)
PROcess Safety TASK 