OpenRBI — API 581 Level 2 Consequence Module

0. Application boundary

This module is an engineering calculation and workflow tool for API 581 Level 2 consequence-of-failure analysis. It does not replace a process simulator, validated thermodynamic package, validated atmospheric-dispersion software, a full QRA, or competent engineering review.

Study title Equipment / component tag API 581 component type Component inside diameter D

Engineer Calculation date

Internal engine controls

Stored fluid phase for release Heat capacity ratio k = Cp/Cv Discharge coefficient Cd Viscosity factor Kv Default liquid density if missing (kg/m³) Latent heat for flash estimate (kJ/kg) Normal boiling point (°C) for flash estimate Cp liquid for flash estimate (kJ/kg-K) Assumed pool depth (m) Entrained liquid fraction (assumed) Auto-fill screening outcome areas Engine mode

Use thermo engine Use release-rate solver Use flash/pool engine Use dispersion screening

Engine log: idle

1. Fluid definition

Enter the actual fluid composition. Totals must equal 100%. The app will not silently normalise.

Composition basis Fluid name / stream ID Composition data source

Name	Formula / ID	MW (kg/kmol)	%	Flammable	Toxic	Source

I confirm I want to continue even though the composition total is not 100% (required if total ≠ 100%).

2. Operating conditions

SI units are used internally. Gauge and absolute pressure are distinguished explicitly.

Operating pressure value Pressure unit Pressure type Operating temperature Temperature unit Atmospheric pressure (absolute)

Equipment inventory (kg) Connected inventory (kg) Liquid level (m) Vapour-space volume (m³) Release elevation (m) Release orientation Isolation time (s) Detection-system rating (Table 4.5) Isolation-system rating (Table 4.5)

SI operating pressure (absolute): —

3. Thermodynamic-property inputs

Import/manual verified values preferred. Internal thermo engine can calculate mixture MW, ideal-gas vapour density, and a simple flash-fraction estimate. Calculated cells are tagged. Override anytime.

Thermo engine: not run

Property package Equation of state Software name + version Calculation date Source file Engineer approval (thermo)

Property	Value	Unit	Status	Source / note

4. Flammability and toxicity properties

Enter or import published or calculated values. Each value needs a source. Distinguish published / calculated / assumed.

Property	Value	Unit	Kind	Source

5. Release cases

Hole sizes follow API 581 component type (Part 3 Table 4.4 / Annex 3.A). Diameters are capped by component D. Internal release-rate solver uses SI orifice equations consistent with Part 3 §4.3 (Crowl & Louvar / Eq. 3.3, 3.5–3.7), plus factdi and leak duration from Tables 4.6–4.7.

Hole	dn (m)	Area (m²)	Phase	Liq rate (kg/s)	Vap rate (kg/s)	2φ rate (kg/s)	Mass (kg)	Duration (s)	Cont/Inst	GFF (1/yr)

6. Flashing, rainout and pool behaviour

Import verified results, or use the internal flash/pool screening engine (isenthalpic flash estimate + assumed entrainment + cylindrical pool).

Flash/pool engine: not run

7. Atmospheric dispersion

Import validated dispersion results when available. Internal engine is a Pasquill–Gifford Gaussian screening model only — not a validated Level 2 dispersion package.

Dispersion engine: not run

Dispersion software Model Source file Wind speed (m/s) Stability class Ambient temperature (°C) Relative humidity (%) Surface roughness (m) Assumptions

8. Event outcomes

For each release-hole size, enter applicable outcomes with probability and consequence results (verified / imported).

9. Event-tree weighting

Weighted outcome consequence = outcome probability × outcome consequence. Sum for each hole. Probabilities for applicable outcomes must total 1.0.

10. GFF hole-size weighting

Overall COF = Σ[(gff_n × COF_n) / gff_total]. Do not multiply hole consequences together.

Hole	gff_n	Weight	Unweighted COF	Weighted contribution

11. Consequence category

Example API 581 area category boundaries. Owner-operator must establish its own risk-acceptance criteria.

Overall COF area basis Manual overall area (m²) if used

12. Engineering controls

Assumptions register Limitations Missing data log (auto + manual) Engineer comments Reviewer name Authorisation status Authorisation date Source references

I confirm that all numerical consequence and property inputs used in this study are verified engineering inputs or imported model results, and that no unsupported automatic values were accepted.

13 / 14. Report

Clear report for engineering review. Recalculate before export.