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Plenty of sites handle hazardous chemicals. A smaller number cross the thresholds that make them a Major Accident Hazard installation - and some of those crossed the line through an inventory change nobody flagged at the time.
What triggers MAH status
The Manufacture, Storage and Import of Hazardous Chemical Rules, 1989 set out lists of hazardous chemicals with threshold quantities. A site becomes an MAH installation when what it stores or handles exceeds those thresholds. Related duties sit in the Factories Act, 1948.
The determination is chemical by chemical against listed quantities, and it is worth actually doing rather than assuming - particularly after a capacity increase, a new product, or a change in how much intermediate is held on site.
The quiet way sites cross the line: nobody adds a new hazardous chemical. Storage of an existing one simply grows - a larger tank, a second bullet, more drums held for a campaign - and the total passes a threshold without any single decision looking significant.
What MAH status brings
- Identification and assessment of major accident scenarios - documented, not assumed
- A safety report covering hazards, controls and consequences
- An on-site emergency plan, tested and kept current
- Information for off-site emergency planning by the authorities, who need it to plan for the surrounding area
- Notification duties, and reporting of major accidents
- Periodic review as the plant changes
Exact requirements depend on the chemicals, quantities and state, so applicability should be confirmed against the current rules and with the concerned authority rather than from general guidance.
The studies that sit underneath
MAH analysis is less a single technique than an assembly of studies:
| Study | Contribution |
|---|---|
| HAZID and HAZOP | Identify the credible scenarios |
| Consequence and dispersion analysis | Quantify what each scenario does and how far it reaches |
| FERA | Fire and explosion effects, and escalation |
| QRA | Consequence combined with frequency - individual and societal risk |
| SIL studies | How reliable the protective functions must be |
| Bow-Tie | Barrier ownership and performance standards |
The gap most sites have
Not the absence of documentation - most MAH sites have a safety report and an emergency plan. The gap is that both describe a plant that has since changed.
- Inventories increased after the report was written
- A new unit was added and never assessed against the major accident scenarios
- The emergency plan references a road, a gate or an assembly point that has moved
- Contact lists name people who left years ago
- The plan has never been tested under realistic conditions
An emergency plan that has not been exercised is a document, not a capability - and that distinction becomes obvious at exactly the wrong moment.
What good looks like
- Threshold determination rechecked whenever inventory changes materially
- Safety report revised when the plant is, not on a fixed cycle alone
- Emergency plan exercised, with findings fed back into it
- Scenarios traceable back to the studies that identified them
- Barriers with named owners, which is where Bow-Tie analysis earns its place
Frequently Asked Questions
What makes a site a Major Accident Hazard installation in India?
A site becomes an MAH installation when the hazardous chemicals it stores or handles exceed the threshold quantities listed in the Manufacture, Storage and Import of Hazardous Chemical Rules, 1989. The assessment is made chemical by chemical against those listed quantities, and related duties also arise under the Factories Act, 1948.
What documentation does an MAH installation need?
Typically documented identification and assessment of major accident scenarios, a safety report covering hazards and controls, an on-site emergency plan, and information provided to authorities for off-site emergency planning, along with notification duties. Specific requirements vary with the chemicals, quantities and state, and should be confirmed with the concerned authority.
How often should a safety report be updated?
It should reflect the plant as it currently is. Periodic review is expected, but the more important trigger is change - increased inventory, a new unit, a modified process or an altered layout. A report that describes a plant that has since changed provides little protection.
Can a site stop being an MAH installation?
If inventories fall below the threshold quantities, the classification can change. Because the determination depends on quantities actually held, it should be reassessed after significant inventory reductions as well as increases, and confirmed with the concerned authority.
What is the difference between an on-site and an off-site emergency plan?
The on-site emergency plan is prepared by the occupier and covers response within the facility boundary. The off-site plan is prepared by the district authorities and covers the surrounding area, using information the facility supplies about credible major accident scenarios and their likely impact distances.
Need expert help with this?
We support MAH installations with hazard analysis, safety reports, on-site emergency plans and the studies underneath them.
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