The PHA is a pro-active attempt by chemical process operations to understand what can go wrong, how likely it is to go wrong and what steps are necessary to prevent or mitigate undesired consequences. Without a pro-active approach, without “searching out” process hazards, we are condemned to await each consequence of human error, and equipment or system failure. Prevention is our best defense, but we can’t defend against that which we don’t recognize.
To properly conduct a PHA a great deal of information is required about the materials handled, the chemical process and conditions, the control methods employed, and the equipment and systems used. This information resides in the design manuals, operating procedures and equipment files of the process of interest. Accumulation of this Process Safety Information is the first step in the PHA process.
The next step in the PHA process is to assemble a PHA team of diverse experience and expertise to examine the process in search of inherent hazards and operating risks. A hazard is a physical situation, condition or physical property with the potential to cause harm to people, the environment or facilities. Hazards are inherent in materials, equipment and activities. A qualified team leader is necessary to guide the team in a choice of hazard review methodology and to provide expertise on that methodology. A good leader is knowledgeable in the types of hazards of concern, fire, explosion and the release of materials or energy. Methods most commonly used for PHA include Checklists; What-If Checklists and Hazard and Operability Studies (HAZOP). Additional techniques may supplement the basic hazard recognition method such as Failure Mode and Effect Analysis (FMEA), Fault Tree Analysis (FTA) and Layers of Protection Analysis (LOPA).
During the PHA exercise the team is lead through the method chosen and identifies process hazards and upsets caused by human, equipment and system failures that could lead to fires, explosions, or the release of materials or energies and cause injury to personnel, the public, the environment or facilities. Each method has its strengths and weaknesses and no one method is perfect. The success of the PHA is strongly influenced by the experience and expertise of the team members and the PHA leader. For each hazard identified the team examines the existing safeguards that prevent or mitigate the undesired consequences. Safeguards are those procedures and devices used to control hazards and manage risk. Safeguards are of two types: Preventions and Mitigations. If the team can identify new or modified safeguards to reduce risk then recommendations are made and included in the PHA documentation.
The final critical aspect of the PHA effort is to provide adequate documentation of the PHA, it’s findings and recommendations. A risk management plan must follow the PHA in order to ensure that follow-up and closure occurs.
Are you expending limited resources chasing hazards or, are you managing risk? If you’re unsure of the difference let Chilworth help. Chilworth’s Process Safety Engineers have the experience and knowledge to lead and manage your PHA efforts. Chilworth’s in-house courses can teach your people to manage risk and be effective PHA leaders.