| EO / oxygen flammable envelope |
Incorrect gas composition, air ingress, analyzer failure or poor isolation. |
Fire, explosion, reactor trip or major loss of containment. |
Redundant oxygen analysis, SIS trips, verified purge sequences, oxygen-clean components, relief and ESD systems. |
| Reactor hot spots / selectivity loss |
Catalyst aging, maldistribution, fouled tubes, moderator imbalance or cooling degradation. |
Higher CO₂ formation, reduced yield, accelerated catalyst damage and thermal risk. |
Multi-point temperature monitoring, cooling-circuit control, feed distribution checks and catalyst performance trending. |
| Chloride / acid corrosion |
Moderator-derived chlorides, organic acids, pH drift or wet service. |
Wall loss, fouling, contamination and unplanned shutdown. |
pH control where specified, corrosion monitoring, chloride management, metallurgy review and controlled chemical purity. |
| Recycle-gas instability |
Compressor degradation, CO₂-removal upset, inert accumulation or purge error. |
Composition drift, lower throughput and reactor-operability risk. |
Compressor condition monitoring, online GC, CO₂ analysis, purge control and critical-spares strategy. |
| EO absorber / stripper upset |
Cooling loss, foaming, tray/packing damage, steam imbalance or lean-water contamination. |
EO loss, high EO in lean water, off-spec downstream feed or overpressure. |
Level/temperature control, DPT monitoring, suitable internals, antifoam only if approved, and relief verification. |
| Catalytic hydration resin damage |
Excess temperature, EO exposure, impurities or irreversible swelling. |
Lower conversion, rising pressure drop and shortened catalyst life. |
Staged temperature control, interstage cooling, feed quality and resin inspection/replacement plan. R9 |
| Evaporator fouling / carryover |
Heavies, salts, poor water chemistry or unstable level control. |
Reduced heat transfer, product contamination and steam penalty. |
Demisters, level control, cleaning strategy, bleed management and exchanger performance monitoring. |
| Vacuum / fractionation instability |
Air leakage, condenser underperformance, ejector or vacuum-pump failure. |
Thermal degradation, color increase and off-spec MEG/DEG/TEG. |
Vacuum integrity testing, condenser monitoring, pressure control and standby philosophy. |
| Product contamination |
Cross-line leakage, wet tanks, corrosion products or unsuitable seals/coatings. |
Failure of polyester/PET quality specifications and rejected cargo. |
Dedicated clean storage, nitrogen blanketing, sampling, online/offline QC and transfer-line segregation. |