What is Process Hazard Analysis (PHA)?
High risk industries, like the chemical and manufacturing industries, are highly regulated to help prevent Major Accident Hazards like explosions, fires and toxic chemical releases-but it wasn’t always that way. Most process safety regulations around the world were put into place after major safety incidents occurred.
In Europe, for example, several process safety incidents in the 1970s led to the Seveso Directive-named after an incident in Seveso, Italy, where a plant released a toxic chemical that killed thousands of animals—followed by regulations like the European Union. In Bhopal, India, a chemical plant inadvertently released hazardous chemicals that killed thousands of people in 1984. In the years following the incident, India passed the Environmental Protection Act; the Manufacture, Storage and Import of Hazardous Chemical Rules; and the Chemical Accidents Rules. A similar incident took place in the United States, though no one was killed. This and a handful of other major safety incidents in the 1980s prompted the U.S. Occupational Safety and Health Administration to implement process safety management regulations (1910.119-in conjunction with a risk management program from the U.S. Environmental Protection Agency.
Today, these regulations are combined under the umbrella of process safety management. This includes Process Hazard Analysis (PHA), which is a system used to identify potential hazards before they occur and help prevent a risk pathway from developing.
What is a Process Hazard Analysis?
A PHA is a thorough, step-by-step review of chemical and manufacturing plant operating procedures. The goal is to identify potential causes and evaluate the consequences of hazardous chemical releases. The process helps organizations identify a range of risks from equipment failures to human factors to improving safety, preventing downtime and protecting the surrounding environment.
How to Conduct a Process Hazard Analysis
Because there are several ways to conduct a PHA, it’s important to first choose a team of experts to lead the process. PHA teams should include engineers, operators, maintenance, supervisors and any other staff members or workers who are well-acquainted with the operational process being reviewed. Once appointed, the team leader generally chooses the most appropriate method to assess the process. Finding all the pertinent hazards can be the weakest link in a PHA, according to Process Safety and Environmental Protection, so picking the right, most structured method/study that will allow for as many hazards as possible to be identified—not the fastest or most convenient.
Common methods for PHA include “bow tie” analysis, Fault Tree Analysis (FTA), Failure Mode and Effect Analysis (FMEA), Hazard and Operability studies (HAZOPs) and “What If” analyses. Here is a brief overview of these common methods:
- A Bow Tie Analysis helps organizations get a visual presentation of their potential risk exposure and possible scenarios for that risk along with barriers to protect against the risk.
- A Fault-Tree Analysis starts with listing potential failed outcomes and working backward to identify possible causes.
- An FMEA helps evaluate design failures by first identifying “failure modes” or how an operation would play out given potential failures. Then an effects analysis is conducted to outline outcomes for each failure mode.
- A HAZOP is the systematic assessment tool used to evaluate an industrial process for potential deviations by breaking it in small, manageable steps.
- A “What If” Analysis is a structured brainstorming session about what could go wrong within an operational process from human error to equipment failures. The goal is to identify hazard scenarios and ensure safeguards are in place to prevent these scenarios from occurring.
Depending on local, regional and national guidelines, a PHA is required when industrial processes that involve hazardous chemicals are established as well as at regular intervals thereafter or after major facility and/or equipment changes.