Hazard Inputs
Example Data Table
| Hazard | Type | Method | Inputs | Base | Controls (%) | Residual | Category |
|---|---|---|---|---|---|---|---|
| Unshielded coupling | Mechanical | Matrix | S=4, L=3, E=4 | 48 | 25 | 36 | Medium |
| Overheated bearing housing | Thermal | Matrix | S=3, L=3, E=3 | 27 | 40 | 16.2 | Low |
| Electrical panel open cover | Electrical | Matrix | S=5, L=3, E=3 | 45 | 10 | 40.5 | Medium |
| Solvent vapor near ignition | Fire/Explosion | FMEA | S=9, O=6, D=7 | 378 | 20 | 302.4 | High |
| Unlabeled chemical transfer | Chemical | FMEA | S=7, O=5, D=6 | 210 | 35 | 136.5 | Medium |
Formula Used
- Risk Matrix score: Score = Severity × Likelihood × Exposure (each 1–5, range 1–125).
- FMEA score (RPN): RPN = Severity × Occurrence × Detection (each 1–10, range 1–1000).
- Residual estimate: Residual = Base × (1 − ControlEffectiveness/100).
How to Use This Calculator
- Enter a short hazard name and select the hazard type.
- Choose the scoring method used in your workflow.
- Fill the scale inputs and estimate control effectiveness.
- Press Submit to see base and residual classifications.
- Download CSV or PDF to attach to audits and actions.
Why hazard classification matters
Engineering sites handle energy, motion, chemicals, and pressure daily. A consistent score turns observations into comparable risk signals. In this tool, matrix scores span 1–125 and RPN scores span 1–1000. Categories help route actions: Low supports routine monitoring, while Critical triggers immediate isolation. Documenting people exposed, location, and controls improves traceability during audits and incident learning. The same record can support job safety analyses, maintenance permits, and design change reviews.
Selecting the right scoring method
The matrix option suits rapid field assessments with 1–5 scales. It multiplies Severity, Likelihood, and Exposure to reflect consequence, frequency, and contact time. The RPN option fits design and process reviews using 1–10 scales for Severity, Occurrence, and Detection. Detection highlights how early a failure mode is noticed. Use one method consistently within a program for stable trending. If teams mix methods, keep separate registers and align escalation rules.
How thresholds guide prioritization
Embedded thresholds provide a practical starting point for triage. For the matrix, scores up to 20 map to Low, 21–50 to Medium, 51–90 to High, and above 90 to Critical. For RPN, the bands are up to 100, 101–300, 301–600, and above 600. These bands support queueing work orders, assigning owners, and escalating approvals. Review distributions quarterly so categories reflect real capacity and risk appetite.
Estimating residual risk with controls
Controls reduce risk when they are effective and maintained. The calculator estimates residual score as Base × (1 − effectiveness/100). For example, a matrix case with S=4, L=3, E=4 produces 48. With 25% effectiveness, residual becomes 36, potentially shifting urgency. Treat effectiveness as an evidence-based estimate tied to inspections, training records, or test results. Consider layering controls; multiple weak barriers rarely equal one verified safeguard.
Turning outputs into documented action
Use the result block as a mini risk register entry. Capture the hazard class, recommended actions, and existing controls, then export a CSV or PDF for review meetings. Re-score after changes to verify improvement. When residual remains High or Critical, consider engineering redesign, interlocks, guarding, or isolation. Consistent use supports defensible decisions and continuous risk reduction. Saved reports also support contractor onboarding, regulatory walkthroughs, and management system reviews.
FAQs
What is the difference between base and residual risk?
Base risk reflects the initial score from your selected method. Residual risk estimates the remaining score after considering control effectiveness, helping you judge whether current safeguards are sufficient or if additional actions are needed.
When should I use matrix scoring instead of RPN?
Use matrix scoring for quick on-site assessments where teams prefer 1–5 scales. Use RPN for design, maintenance, or process reviews where occurrence and detection detail matters and 1–10 scales are already standard.
How do I choose a control effectiveness percentage?
Base it on evidence, not optimism. Use inspection results, test records, incident history, and observed compliance. If controls are new or unverified, choose a conservative value and update it after validation or performance monitoring.
Can I change the category thresholds?
Yes. Thresholds are defined in the classification functions near the top. Update the numeric bands to match your corporate standard, then keep them stable so trends remain meaningful across departments and time.
Does a higher detection number mean better detection in RPN?
No. In common FMEA practice, a higher detection score means poorer detectability, so the risk priority increases. Lower detection scores indicate you can detect the issue earlier or more reliably.
Is this tool a substitute for a formal risk assessment?
It supports triage and documentation, but it does not replace formal methods. Use it alongside your procedures, permits, and multidisciplinary reviews, especially for major hazards, changes, or complex interactions.