The PHA Study is a systematic and comprehensive review of a process or change to:
The purpose of a PHA Study is to evaluate the potential risks to human health and safety, the environment and certain asset risks, based upon the information available. The PHA Study is used to:
All processes that require a qualitative risk assessment (PHA) as identified through Procedures should be periodically revalidated on an established frequency in accordance with applicable regulations and procedures.Methodology:
The what-if technique is a systematic method for examining the response of a process system to equipment failures, operator errors and off-normal process conditions. The team uses the what-if analysis technique to brainstorm the various types of accidents and deviations from normal operation that can occur within the process.For example: What if the pump stops?
During brainstorming of what-if questions, the team focuses on initiating causes/events rather than consequences.
The specific steps of the What If / Checklist Study methodology used in the assessment are:
The HAZOP methodology uses deviation guidewords to systematically focus the team on the identification of process deviations that can lead to undesirable consequences. The guidewords, (i.e., No, More, Less) in conjunction with key process parameters, (i.e., Flow, Level, Pressure) are used to prompt the study team to brainstorm possible causes of deviations (i.e., No Flow, More Level, Less Pressure) from design operation.
The specific steps of the HAZOP Study methodology used in the assessment are:
An IPL is a device, system, or action that is capable of preventing a scenario from proceeding to its undesired consequence independent of the initiating event or the action of any other layer of protection associated with the scenario.
To determine whether or not a safeguard qualifies as an IPL, consider the "3 D's" and the independence as follows:
After identifying the cause, consequences, and safeguards for a hazardous scenario determine which safeguards qualify as IPLs. The identified safeguards must pass all four characteristics in order to qualify as IPLs: Specificity, Independence, Dependability and Auditability. These characteristics are defined as: