Is a lower RPN automatically acceptable?

No. Acceptance thresholds, critical characteristics, special controls, and residual-risk approval remain separate decisions. The fixed secondary assumptions are listed on this page and in the downloadable workbook so the four-input result remains auditable.

Why does severity stay the same?

Prevention and detection controls change likelihood or detection. Severity changes only if the consequence of the failure mode itself changes. The fixed secondary assumptions are listed on this page and in the downloadable workbook so the four-input result remains auditable.

Can two different risks have the same RPN?

Yes, which is why the component scores and critical-severity flag remain visible. The fixed secondary assumptions are listed on this page and in the downloadable workbook so the four-input result remains auditable.

Does this replace an FMEA?

No. It calculates and documents one failure-mode line using scores selected through the approved FMEA process. The fixed secondary assumptions are listed on this page and in the downloadable workbook so the four-input result remains auditable.

Why is only mitigated occurrence editable?

The simplified screen asks the team to state the main effect expected from the proposed prevention control while using a disclosed detection baseline. That keeps the decision focused. If the action changes both prevention and detection materially, document a full FMEA-style reassessment rather than forcing a complex risk review into four fields.

Can a low RPN make a severe contamination risk acceptable?

No. Severity must be reviewed independently, especially where contamination could cause coating failure, fatigue damage, safety risk or specification breach. RPN is a prioritization aid and can mask high-severity, low-occurrence events. Apply criticality rules and mandatory controls before using the numeric ranking.

Abrasive Blasting, Shot Peening & Surface Prep calculator

Abrasive Blast Surface Contamination FMEA Calculator

Structure a surface-contamination risk discussion with four ratings: severity, occurrence, detection and the expected occurrence score after mitigation. The calculator reports current risk priority number, mitigated risk priority number and modeled reduction while preserving severity as the consequence rating. A documented post-mitigation detection score and critical-severity trigger keep the page short and make the baseline explicit. This is a prioritization aid, not a universal acceptance rule. Teams must define scoring criteria before use and must never allow a low product score to neutralize a catastrophic contamination mechanism or a mandatory specification requirement.

What this calculator does

Use an explicit FMEA-style severity × occurrence × detection model with residual risk and a critical-severity override that cannot be hidden by a lower RPN.
Use it for media contamination FMEA, compressed-air cleanliness review, pre-coating handling risk, prioritizing controls for oil, salt, moisture, dust or cross-media contamination pathways..
Use an explicit FMEA-style severity × occurrence × detection model with residual risk and a critical-severity override that cannot be hidden by a lower RPN.

Formula used

Current risk priority number = severity × occurrence × detection; mitigation changes occurrence while fixed detection improvement is documented.
Fixed secondary assumptions compiled into this release: Critical severity threshold: 8 1–10; Detection after planned controls: 3 1–10.

Inputs explained

Contamination consequence severity: Approved FMEA severity rank for coating failure, product function, safety, or compliance impact.
Current occurrence likelihood: Approved rank based on contamination history and current controls.
Current detection difficulty: Approved rank where higher means less likely to detect before release.
Occurrence after planned controls: Expected occurrence rank after defined prevention actions.

How to use the result

Best suited to media contamination FMEA, compressed-air cleanliness review, pre-coating handling risk, prioritizing controls for oil, salt, moisture, dust or cross-media contamination pathways..
The four-input result is conditional on the disclosed fixed assumptions; use a detailed engineering model when they are not representative. RPN is ordinal prioritization, not a probability or expected loss. Different severity-occurrence-detection combinations can share an RPN. Customer and quality-system escalation rules control. RPN multiplication can hide different risk patterns that produce the same number and must not override critical-hazard rules.

Common questions

Is a lower RPN automatically acceptable? No. Acceptance thresholds, critical characteristics, special controls, and residual-risk approval remain separate decisions. The fixed secondary assumptions are listed on this page and in the downloadable workbook so the four-input result remains auditable.
Why does severity stay the same? Prevention and detection controls change likelihood or detection. Severity changes only if the consequence of the failure mode itself changes. The fixed secondary assumptions are listed on this page and in the downloadable workbook so the four-input result remains auditable.
Can two different risks have the same RPN? Yes, which is why the component scores and critical-severity flag remain visible. The fixed secondary assumptions are listed on this page and in the downloadable workbook so the four-input result remains auditable.
Does this replace an FMEA? No. It calculates and documents one failure-mode line using scores selected through the approved FMEA process. The fixed secondary assumptions are listed on this page and in the downloadable workbook so the four-input result remains auditable.
Why is only mitigated occurrence editable? The simplified screen asks the team to state the main effect expected from the proposed prevention control while using a disclosed detection baseline. That keeps the decision focused. If the action changes both prevention and detection materially, document a full FMEA-style reassessment rather than forcing a complex risk review into four fields.

Last reviewed 2026-08-25.