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Rely on MOGAS valves for Purified Terephthalic Acid (PTA) process

Service of a MOGAS ball and seat from PTA slurry service
After 9 years with no repairs or maintenance, this MOGAS 6-inch ASME 600 Class valve was moved from PTA slurry service to another application, where it is still in service today.

Purified Terephthalic Acid (PTA) is a white crystalline commodity powder and an important organic compound used as a precursor to thermoplastics, like PET (polyethylene terephthalate). Products from PTA include polyurethanes, powder coating resins, polyester fabrics, films, and plastic bottles.

Corrosion, slurries and crystalization are the main valve challenges in PTA production. The raw material of acetic acid and PTA are highly corrosive even after the slurry process. During crystallization, hard polymers stick to metallic surfaces, solidify on the ball and seat and cause erosion at the end flange.

MOGAS valve designs offer:

  • sharper leaning edge on seat to scrape ball surface for repeatable tight isolation
  • metal seats that wipe sealing surface of ball clean during operation
  • greater sealing contact area
  • dual-guided stem design and live-loaded packing to prevent stem packing leaks and risk of fugitive emissions
  • application-specific coatings that provide enhanced erosion and corrosion resistance

Purified Terephthalic Acid (PTA) Process Flow Diagram
  1. Paraxylene
  2. Acetic Acid
  3. Catalyst
  4. Air
  5. Catalyst Mixing
  6. Fresh Catalyst Pump
  7. Oxidation Reactor Recirculation
  8. Oxidation Reactor Overhead Gas
  9. Oxidation Reactor
  10. Crystallizer Solids
  11. Crystallizer Overhead Gas
  12. Crystallizer Liquids
  13. Centrifuge I Liquids
  14. Centrifuge I Solids
  15. Crude Terephthalic Acid
  16. Gas Scrubber
  17. Centrifuge Liquids Pump
  18. Acetic Acid Recycle
  19. Acetic Acid Recycle
  20. Acetic Acid Recycle
  21. Process Water
  22. Process Water
  23. Process Water
  24. Process Water
  25. Process Water
  26. Process Water
  27. Crude TPA Scubber
  28. Centrifuge II Solids
  29. Crude Terephthalic Acid Secondary Scubber
  30. Selective Hydrogennation Reactor
  31. Filter
  32. Finishing Crytalizer
  33. Finishing Cetrifuge
  34. Finishing Cetrifuge Liquids
  35. Air 
  • Heat Exchanger (not shown)
  • General Ball Valves (not shown)
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