Study execution
How the study is executed
A structured, facilitated process — from scope definition through close-out — producing defensible, actionable outputs.
Scenario Scoping & IE Frequency Calibration
Select LOPA-eligible scenarios from HAZOP action register; calibrate Initiating Event (IE) frequency from CCPS LOPA Cookbook, OREDA, and site history; define consequence severity tiers and site-specific Tolerable Frequency (TF) per consequence category.
IPL Eligibility Testing
Apply CCPS strict four-part IPL test — independence, dependability, audit, and validation — to each safeguard identified in HAZOP; disqualify non-eligible controls (BPCS-dependent alarms, inadequate test frequency, shared initiator); document eligibility decisions.
LOPA Worksheets & Risk Gap Calculation
Build per-scenario LOPA worksheets applying eligible IPL credits (BPCS 10⁻¹, operator-action IPL per CCPS rules, mechanical SIF per architecture); calculate mitigated event likelihood and risk gap = TF / mitigated frequency.
Conditional Modifiers & Enabling Conditions
Apply ignition probability, presence / occupancy factor, atmospheric conditions, and escape factor as conditional modifiers; handle enabling conditions (equipment in maintenance mode, abnormal configuration) separately from IPL credit.
SIL Target Derivation & Option Register
Derive Required Risk Reduction Factor and SIL target per SIF; identify scenarios requiring additional non-instrumented IPLs; register passive, active-hardware, and administrative options with ALARP implication and SIL-inflation avoidance rationale.
Integration Package & SIL Handover
Issue LOPA worksheets, IPL eligibility log, IE frequency basis, conditional-modifier basis document, risk-gap summary, SIL allocation per SIF, and cross-reference map to HAZOP findings and Bow-Tie barrier register for downstream workflow.
