What is a Process Hazard Analysis?

A Process Hazard Analysis (PHA) is a structured evaluation of a process to identify hazards that could lead to fires, explosions, toxic releases, or other major incidents, and to assess the adequacy of existing safeguards. In the US, OSHA's Process Safety Management (PSM) standard requires a PHA for covered processes.

Process Hazard Analysis vs. Preliminary Hazard Analysis

The same acronym is used for two related but distinct activities:

  • Process Hazard Analysis — a detailed hazard study performed on an existing or fully designed process, often using techniques like HAZOP, What-If, or Fault Tree Analysis
  • Preliminary Hazard Analysis — an early-stage, high-level hazard review conducted during the initial design of a system, before detailed engineering is complete

Common PHA methodologies

  1. What-If analysis — brainstorming potential deviations and their consequences
  2. HAZOP — a structured guide-word-based review of process deviations
  3. Fault Tree Analysis (FTA) — working backward from an undesired event to its possible causes
  4. Failure Mode and Effects Analysis (FMEA) — evaluating how individual components could fail and the resulting effects

References