📋 Case Study

Hydrogen Sulfide Flare Stack Integrity Assessment at Gulf Coast Refinery

Unplanned shutdown due to wall thinning from sulfidic corrosion; no CUI monitoring program

🏗️ Project Overview

Critical flare stack servicing sour gas units in high-H₂S environment

🎯 Challenge

Unplanned shutdown due to wall thinning from sulfidic corrosion; no CUI monitoring program

🔧 Design Approach

API RP 571-based damage mechanism review; UT thickness mapping + infrared thermography for insulation integrity; RBI-based inspection scheduling

📐 Design Diagram

Wall thinning (sulfidic)
No CUI monitoringDESIGN APPROACH• API RP 571 review
• UT thickness mapping
• IR thermography (CUI)
• RBI-based schedulingCORROSION RATECR = 8.2 mils/yr
(k·P_H₂S^0.5·e^−Ea/RT)Key Engineering Outputs• Minimum required thickness: 0.375 in
• Inspection interval: 3 years (RBI-optimized)
• CUI risk zones flagged via IR ΔT > 8°CDesign Boundary

AI-generated project design illustration

📐 Key Calculations

Corrosion Rate Prediction

CR = k × (PP_H2S)^0.5 × exp(-Ea/RT)

Result: 8.2 mils/year

Justified accelerated inspection interval of 6 months

📊 Results

Extended safe operating life by 7 years; reduced unplanned outages by 92%; implemented digital RBI dashboard

💡 Lessons Learned

• •Corrosion modeling must account for localized dew point conditions
• •Thermal imaging detects insulation breaches before metal loss becomes critical

✅ Key Takeaways

• 1Corrosion modeling must account for localized dew point conditions
• 2Thermal imaging detects insulation breaches before metal loss becomes critical