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The hazards you need know: Process Hazard Analysis
(PHA)
Process Hazard Analysis (PHA) is a method to evaluate and identify
credible hazardous scenarios. PHA is a The process hazard analysis methodology selected must be
appropriate to the complexity of the process and must identify, evaluate, and control the
hazards involved in the process. One or more
of the following methods is used, as appropriate, to determine and evaluate the hazards of
the process being analyzed:
The PHA must address the following:
The PHA is performed by a team with
expertise in engineering and process operations. The
PHA team should include at least one employee who has experience with and knowledge of the
process being evaluated. One member of the team must be knowledgeable in the specific
analysis methods being used. In
performing a PHA, the first step is to define the purpose, scope and objectives of the
study. The purpose defines why the PHA is
being performed, e.g. to identify hazardous scenarios, to meet a regulatory requirement,
etc. The scope defines the boundaries of the
process being studied. The objectives define
the expectations of the PHA results.
Next
step is amass all the pertinent Process Safety Information (PSI) [see The more you
know: Process Safety Information (PSI)] and appropriate Standard Operating
Procedures. To plan the PHA, the process is
divided into smaller manageable sections.
The PHA is conducted by identifying deviations from the design
intent. The design intent includes values for
operating conditions (e.g. temperature, pressure, flow, etc.), equipment (e.g. materials
of construction, etc.) or external events (e.g. general loss of electrical power, etc.). There may be one or several causes of deviations. Causes are categorized as: 1.) Human Error, 2.)
Equipment Failure or 3.) External Events. The
team brainstorms and decides the credible causes of these deviations. If one of these deviations may occur, there are
consequences that may result. The
consequences may impact operability, quality or may be hazardous. Each scenario (deviation/cause consequence
combination) is evaluated further, particularly the hazardous scenarios. In evaluating
these scenarios, existing safeguards are documented that prevent, detect or mitigate the
scenarios. The team then determines if a
recommendation is appropriate to prevent, detect or mitigate the scenarios.
By: Mike McCue, Process Safety Columnist for Cheresources.com |
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