LOPA — Layers of Protection Analysis
Layers of Protection Analysis
IEC 61511 / IEC 61508
1

Risk Classification

Risk Type
Consequence Severity
TMEL (/yr) = 1.0E-05
2

Initiating Causes

RefDescriptionFreq (/yr)
3

Independent Protection Layers & Conditional Modifiers

RefDescriptionPFD
4

PFDavg Calculation

Results

Total IELt (/yr)
—
PFDavg for SIF
—
Risk Reduction Factor (1/PFDavg)
—
Integrity Level
No IL

Severity → TMEL

Failure Rate Reference

0.01PSV
0.1Inst BPCS / Pumps / Valve fails
0.01Operator well trained, no stress per start-up
0.001Above + independent verification
0.5Human response < 10 min
0.1Human response < 20 min
0.5Catastrophic failure of PV / Ignition probability
0.01Dual NRV with PSV, sized for reverse flow