April 3, Share This Post:. The purpose of Process Hazards Analysis PHA is to identify and understand the hazards associated with the process being reviewed, to understand the potential resultant hazardous events, and to prevent those events by identifying all the potential routes to those events and ensuring that adequate safeguards are in place to mitigate their risk. The application of a suitable hazards evaluation methodology e.
This paper will look at how a variation on an old theme can significantly improve the likelihood of asking all of the right questions, in a way that capitalizes on the strengths of some of the other approaches while avoiding their weaknesses, and is easier for PHA teams to apply initially and revalidate going forward. It is best suited for the analysis of highly redundant systems. FTA identifies and graphically displays the combinations of equipment failures, human failures and external events that can result in an incident.
Computer programs are used to provide graphical representations of fault trees and to calculate top event likelihoods. FTA is not a technique that lends itself to a team-based study. Typically, one or two people construct a fault tree. It requires different training and resources than other PHA techniques. Rather it is used to identify the possible outcomes following the success or failure of protective systems after the occurrence of a given starting event and, optionally, to calculate the frequencies of the outcomes.
Event trees graphically display the progression of event sequences beginning with a starting event, proceeding to control and safety system responses, and ending with the event sequence consequences. ETA helps analysts to determine where additional safety functions will be most effective in protecting against the event sequences. Typically, ETA is used to analyze complex processes that have several layers of safety systems or emergency procedures to respond to starting events.
ETA is not a technique that lends itself to a team-based study. Typically, one or two people construct an event tree. CCA is a blend of fault tree analysis and event tree analysis that produces a CCA diagram combining fault and event trees. It is used to identify causes and consequences of hazard scenarios. The CCA diagram displays the relationships between the incident outcomes consequences and their causes and it can depict and evaluate multiple scenario outcomes, including recovery paths where the operator, or system, recovers or mitigates the consequences, as well as the worst consequence path.
CCA is commonly used when the failure logic of hazard scenarios is simple. It uses a combination of high-level fault and event trees to produce a diagram resembling a bow tie. Hazards and initiating events appear on the pre-event side left side and impacts consequences appear on the post-event side right side. The focal point of the diagram is the specific loss event that ties together the initiating events and consequences.
There is a time progression from the left to the right of the diagram. Associated prevention and mitigation safeguards are shown on either side of the loss event and they are viewed as barriers, some of which may apply to more than one cause. BTA is used for screening hazards of well-understood processes and to perform an initial analysis for existing processes or in the middle stages of process design.
Primatech offers consulting services for PHA studies including facilitation, scribing, reviewing, and mentoring and coaching. Primatech offers multiple training courses that provide instruction in different aspects of performing PHA studies including:. An appropriate set of hazard assessment criteria are established for evaluation in the checklist.
Checklists don't have to be strictly process-based or behavior-based. Sometimes, a process-based checklist may incorporate behavior-based checks, and vice versa. Often, a behavior-based checklist may be conducted for a higher-level risk assessment. If activities are then identified as higher risk, a process-based checklist can be developed to mitigate those risks. Use of checklists tends to come naturally to researchers and safety professionals.
A basic checklist asks specific questions that the user confirms upon completion of a task, availability of an item inventory or applicability. Most lab managers and senior lab staff should be able to answer these questions with moderate training. Aspects of a Job Hazard Analysis , What-if Analysis , or Standard Operating Procedures can be incorporated into a more structured checklist to help guide the user in completing a risk assessment and identifying the appropriate exposure control measures.
It is recommended that a principal investigator, laboratory manager, senior laboratory staff member who is familiar with the overall operation of the lab develop the more comprehensive laboratory safety checklists that incorporate risk assessment, such as:.
A common expectation—and potential pitfall—of checklists is to limit the scope or assessment to the questions on the list, rather than a holistic hazard analysis for the process being evaluated. So, when developing a checklist, it is critical to define the scope and to understand the audience and checklist user s. Understanding the audience and checklist user supports knowledgeable collaboration and institutional support.
Additional hazard assessments e. Source: Gawande, A. Engage with other members of the chemical safety community. Membership provides networking opportunities, access to career advancement tools, meeting discounts, and more. Join the Division Renew Your Membership. Email the Safety team at safety acs. What is Safety Culture? Notify me of new posts by email. Ammonia Week in Review. Mechanical Integrity Looking for Process Safety Consultation?
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