Regulation & compliance
COMAH 2015
Great Britain’s major-hazard regulations for sites holding dangerous substances above Seveso III thresholds.
Control of Major Accident Hazards Regulations 2015
- Category
- Regulation & compliance
- Scope
- Great Britain
- Edition / refs
- SI 2015/483 (implements Seveso III, 2012/18/EU)
MSA output
- HAZOP worksheets & LOPA calculations
- SIF register & SIL verification
- Proof test records & IEC 61511 lifecycle
- Expert Review & Certification Support
What is COMAH 2015?
The COMAH Regulations 2015 implement the Seveso III Directive (2012/18/EU) in Great Britain. They apply to establishments where dangerous substances are present at or above the threshold quantities in Schedule 1, which are classed as lower-tier or upper-tier.
COMAH is enforced by a joint Competent Authority: HSE together with the Environment Agency in England, Natural Resources Wales in Wales and SEPA in Scotland. Every operator must take all measures necessary to prevent major accidents and to limit their consequences for people and the environment. Northern Ireland has its own equivalent regulations.
Who it applies to
- Operators of lower-tier and upper-tier establishments
- Process safety and control and instrumentation engineers
- Engineering contractors and SIS integrators working on COMAH sites
- Consultants preparing safety reports
Key requirements
- 01
General duty
Take all measures necessary to prevent major accidents and limit their consequences.
- 02
Notification
Notify the Competent Authority of the establishment, its activities and its dangerous substances.
- 03
Major accident prevention policy
Prepare a MAPP and implement it through a proportionate safety management system.
- 04
Safety report (upper tier)
Demonstrate that major accident hazards have been identified and the necessary measures taken; review it at least every five years and after significant changes.
- 05
Emergency planning
Upper-tier operators prepare and test internal emergency plans; the local authority prepares the external plan.
- 06
Information and change
Provide information to the public and keep documents current through management of change.
Summary for orientation only. Always refer to the current official text of COMAH 2015 and any applicable legislation.
MSA for COMAH 2015
What MSA generates
Evidence produced from your engineering inputs, traceable end to end and exported to Word, PDF or Excel.
HAZOP worksheets & LOPA calculations
Structured hazard identification and risk reduction analysis that can support the safety report.
SIF register & SIL verification
Evidence that instrumented protection meets its integrity targets.
Proof test records & IEC 61511 lifecycle
Records showing that protection layers are maintained over time.
Expert Review & Certification Support
CMSE-qualified engineering reviews, standards and gap verification, and competent person sign-off.
Frequently asked questions
What makes a site lower tier or upper tier?
The quantities of dangerous substances present compared with the thresholds in Schedule 1, including the aggregation rule for substances in the same hazard category.
Does COMAH require IEC 61511?
Not by name. But the Competent Authority judges measures against relevant good practice, and for safety instrumented systems that is BS EN 61511.
Does MSA offer expert support for COMAH sites?
Yes. For regulated industries and COMAH sites we offer expert review and certification support: CMSE-qualified engineering reviews, standards and gap verification, and competent person sign-off on top of the full platform.
Generate COMAH 2015 evidence from your own data
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