Major Accident Hazard (MAH) Analysis

What makes a site an MAH installation

A site becomes a Major Accident Hazard installation when the hazardous chemicals it stores or handles exceed the threshold quantities set out in the Manufacture, Storage and Import of Hazardous Chemical Rules, 1989. Related duties sit in the Factories Act, 1948.

The determination is done chemical by chemical against listed thresholds, and it is worth confirming rather than assuming - sites sometimes cross a threshold through an inventory change nobody flagged.

What MAH status brings with it

• Identification and documented assessment of major accident scenarios
• A safety report covering hazards, controls and consequences
• An on-site emergency plan, tested and kept current
• Information supplied for off-site emergency planning by the authorities
• Notification duties, and reporting of major accidents
• Periodic review as the plant changes

Exact obligations depend on the chemicals, the quantities and the state, so applicability should be confirmed against the current rules and with the concerned authority.

How MAH analysis is built

MAH analysis is not a standalone technique so much as an assembly of the studies underneath it:

• HAZID and HAZOP identify the scenarios
• Consequence and dispersion analysis quantifies what each one does
• FERA handles fire and explosion effects and escalation
• QRA combines consequence with frequency to give individual and societal risk
• SIL studies set how reliable the protective functions must be