ALARP Demonstration Studies
A defensible reasonably practicable argument that we engineer to withstand HSE, COMAH and CSB style scrutiny
ALARP Demonstration
Studies
ALARP, the principle of reducing risk as low as is reasonably practicable, comes from the UK case Edwards versus National Coal Board in 1949 and is set out in the HSE guidance Reducing Risks Protecting People, and it has become the dominant Western risk acceptance test. The principle is asymmetric, so as risk climbs toward the intolerable region, around one in a thousand per year for a worker and one in ten thousand for the public, the disproportion factor needed to reject further mitigation rises sharply, and the HSE applies a gross disproportion factor of three to ten for high hazard cases. ALARP is not a single calculation but a documented argument that combines adherence to codes and standards, good practice benchmarking, cost benefit analysis for genuinely novel decisions and design that builds ALARP in at FEED. The regulatory environment after Buncefield, Macondo and Texas City has tightened scrutiny, so an argument must now address Bow Tie barrier escalation, low frequency and high consequence cases and the cliff edge where modest investment crosses from intolerable to tolerable, and we engineer it to do exactly that. ALARP increasingly applies in Indian process safety contexts through PESO Schedule 7 and MoEFCC environmental impact assessment and across the Australian, Canadian and Brazilian safety case regimes.
How the study is executed
A structured, facilitated process that runs from scope definition through close out and produces defensible, actionable outputs.
Establish applicable tolerability criteria (HSE R2P2 / CCPS / NORSOK / MoEFCC framework), overlay QRA risk contours (LSIR / IRPA / F N) against broadly acceptable, tolerable if ALARP, and intolerable bands, identify scenarios in the ALARP region requiring structured justification.
Compile all technically feasible risk reduction measures from engineering, operational, and administrative domains, categorise as codes and standards, good practice benchmarking, ISD (FEED stage Substitute / Minimise / Moderate / Simplify), or novel engineering measures, document status (implemented / under consideration / rejected).
Demonstrate ALARP by compliance where well established codes (OSHA PSM, IEC 61511, API RP 752, NFPA) are fully met, document gap analysis against current code editions, identify code exceedance Good Engineering Practices (GEP) adopted voluntarily as ALARP credit.
Perform CBA for genuinely novel or disproportionately costly risk reduction options using HSE VPF (£2.36m / fatality, 2024) or national equivalent, calculate Net Present Value of risk reduction (ΔPLL × VPF × NPV factor) versus implementation cost, document CBA inputs and uncertainty ±50% sensitivity.
Select Gross Disproportion Factor (GDF) from HSE 1× to 10× sliding scale based on risk tolerability proximity and hazard nature, reject measures where cost > GDF × benefit, document disproportion narrative per option with engineer of record attribution, map against Bow Tie barrier upgrade options.
Issue ALARP demonstration report with risk tolerability framework, option register, CBA worksheets, GDF selection rationale, BAT benchmarking dossier, and residual risk acceptance statement signed at appropriate corporate authority, build ALARP archive reusable for MOC, 5 year safety case, and post incident review.
What the study covers in full
Outcomes of ALARP Demonstration Studies
- We test every credible barrier upgrade option against a quantitative cost benefit analysis
- We anchor residual risk acceptance with engineer of record traceability
- We drive inherent safer design upstream where building ALARP in is cheaper
- Your argument holds up under post incident litigation and CSB style scrutiny
- Your demonstration holds up under UK COMAH, HSE R2P2 and the Inspection Manual
- It withstands an ALARP challenge from the HSE, the Environment Agency, the OSHA national emphasis programme or MoEFCC
- It provides decision record evidence for a post incident litigation defence
- It supports director and corporate officer due diligence
- We capture the collective engineering judgement at the right moment
- We prevent the re litigation of risk decisions through documented disproportion
- We give your management of change reviewers a defensible ALARP baseline
- We build organisational ALARP literacy for your future safety cases
- We defend not implementing grossly disproportionate measures that the cost benefit analysis rejects at three to ten times
- We sequence risk reduction capital against a quantified benefit
- We avoid the gold plating that a compliance only approach drives
- We sharpen your dialogue with insurers on residual loss expectancy
Codes & standards we work to
Triggers that signal the need
Where ALARP Demonstration Studies applies
Wellheads, separators, gas compression, FPSO topsides, produced water systems.
Distillation columns, reactors, heat exchangers, storage spheres, LPG handling.
Cryogenic exchangers, liquefaction trains, BOG compressors, storage and sendout.
Reactive systems, batch reactors, solvent handling, runaway reaction scenarios.
Boilers, HRSGs, steam headers, hydrogen systems, ammonia SCR units.
Sterile vessels, CIP/SIP, pressure fermenters, solvent recovery, spray dryers.
Tangible deliverables
- A demonstration report with the risk tolerability framework
- A risk reduction option register that records each option as implemented, rejected or deferred
- Cost benefit worksheets for each option with the value of preventing a fatality, net present value and sensitivity
- The rationale for the gross disproportion factor we selected
- A best available technique and good practice benchmarking dossier
- Bow Tie barrier upgrade integration
- A decision record and engineer of record audit trail
- A residual risk acceptance statement signed at the appropriate authority
Ready to start your project?
Speak with our team to scope an engagement tailored to your facility, regulatory context, and lifecycle stage.