LOPC Threshold Checker

LOPC = Loss of Primary Containment. Checks an incident's consequences against API RP 754 criteria to determine whether it classifies as a Tier 1 or Tier 2 Process Safety Event (PSE).

Scope note: API RP 754 Tables 1 and 2 (Annex E/F) specify substance-specific release threshold quantities by hazard category — these vary by material and are not reproduced here. Enter your own Table 1/Table 2 threshold quantity for the specific substance released (from your company's API RP 754 reference tables) to complete the quantity-based check. This tool applies the consequence-based criteria directly from API RP 754 and simply compares your entered release quantity against the threshold you provide.

Tier 1 Criteria — any one triggers Tier 1 TIER 1

Fatality — employee, contractor, subcontractor, or third party

Days-away-from-work injury — employee, contractor, or subcontractor

Hospital admission of a third party

Officially declared community evacuation or shelter-in-place (including precautionary)

On-site shelter-in-place or evacuation (excluding precautionary on-site actions)

Tier 2 Criteria — any one triggers Tier 2 (if Tier 1 not already met) TIER 2

Recordable injury — employee, contractor, or subcontractor (not days-away-from-work)

Fire / Explosion Direct Cost

Direct Cost of Fire/Explosion Damage ($) ≥ $100,000 triggers Tier 1. ≥ $2,500 (and < $100,000) triggers Tier 2. Leave at 0 if no fire/explosion occurred.

Release Quantity vs. Threshold (1-Hour Period)

Actual Release Quantity (1-hr period) Same units as your threshold values below.

Unit (for display only)

API RP 754 Table 1 Threshold (Tier 1) From your company's substance-specific API RP 754 Table 1 reference.

API RP 754 Table 2 Threshold (Tier 2) From your company's substance-specific API RP 754 Table 2 reference.

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PSE CLASSIFICATION

API RP 754 Cost Thresholds (2016 Update, Still Current)

Tier 1 fire/explosion cost	≥ $100,000 direct cost (raised from $25,000 in the 2nd Edition update)
Tier 2 fire/explosion cost	≥ $2,500 direct cost (unchanged)
Between $25,000-$99,999.99	Falls to Tier 2 (post-2016 criteria)

Reference

This checklist reflects the consequence-based Tier 1/Tier 2 criteria in API RP 754 (Process Safety Performance Indicators for the Refining and Petrochemical Industries) and the API Guide to Reporting Process Safety Events. Annex E/F Tables E.1-E.16 provide detailed worked examples, and Annex H's decision logic tree (Figure H.1) provides the official flowchart for edge cases.

Methodology, interpretation & sources

Purpose. LOPC = Loss of Primary Containment. Checks an incident's consequences against API RP 754 criteria to determine whether it classifies as a Tier 1 or Tier 2 Process Safety Event (PSE).

How to use the result. Start with source data you can verify, enter values on a consistent unit and time basis, and record the assumptions used. The main inputs on this page include Fatality — employee, contractor, subcontractor, or third party, Days-away-from-work injury — employee, contractor, or subcontractor, Hospital admission of a third party, Officially declared community evacuation or shelter-in-place (including precautionary), On-site shelter-in-place or evacuation (excluding precautionary on-site actions), Recordable injury — employee, contractor, or subcontractor (not days-away-from-work). Re-run the calculation when those assumptions change rather than carrying an old result forward.

Decision use. Use this calculator as a structured process-safety screening aid. It does not replace a formal PHA, QRA, LOPA or competent engineering review when those methods are required.

Limitations. Event definitions, consequence assumptions, exposure frequencies, safeguards and uncertainty should be documented so that the result can be independently reviewed.

Primary references. Use the current edition/version that applies to your jurisdiction and organization:

Editorial note. Prepared and maintained by Impact Tech Solutions. Editorially updated 28 September 2026. No individual professional credential is claimed on this page; high-consequence, statutory, tax, engineering or health decisions should be independently verified against the current primary source and, where required, a qualified professional.

LOPC Threshold Checker

API RP 754 Cost Thresholds (2016 Update, Still Current)

Reference

Methodology, interpretation & sources

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