A Hierarchy of Controls Analysis (HCA) is a highly structured risk-mitigation methodology. It is specifically required under CalARP Program 4, which applies to petroleum refineries operating within California.
While a standard Process Hazard Analysis (PHA) identifies risks and lists existing safeguards, an HCA forces a facility to systematically evaluate whether hazards can be eliminated or reduced using the most reliable, inherently safer design methods before relying on add-on equipment or human intervention.