📋 Case Study
Ammonia Refrigeration System HAZOP & LOPA Integration at Midwest Food Processing Plant
Unplanned releases during maintenance due to undocumented isolation points and missing P&IDs
🏗️ Project Overview
Retrofit of legacy ammonia chiller system serving 300k sq ft food processing facility
🎯 Challenge
Unplanned releases during maintenance due to undocumented isolation points and missing P&IDs
🔧 Design Approach
Integrated HAZOP-LOPA workshop with operations team; added dual-block-and-bleed valves, automated lockout logic, and real-time NH₃ monitoring with 50 ppm alarm threshold
📐 Design Diagram
AI-generated project design illustration
📐 Key Calculations
SIL Target
LOPA-derived frequency × consequence multiplier
Result: SIL 2
Defined SIS architecture requirements
Dispersion Radius (ERPG-2)
PHAST Gaussian model with 99th percentile wind data
Result: 320 m
Informed emergency response zone planning
📊 Results
Zero unplanned releases over 3 years; 47% reduction in PHA rework cycles; OSHA VPP Star certification achieved💡 Lessons Learned
- •Cross-functional PHA participation improves detection of procedural hazards
- •Real-time gas monitoring validates dispersion models
- •SIL assignment must reflect actual proof test discipline
✅ Key Takeaways
- 1Cross-functional PHA participation improves detection of procedural hazards
- 2Real-time gas monitoring validates dispersion models
- 3SIL assignment must reflect actual proof test discipline