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Belzona Oil Presentation

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Belzona Oil Presentation

  1. 1. <ul><ul><li>Identifying the Hidden Threats in Austenitic Stainless Steels and Practical Repair </li></ul></ul>
  2. 2. Hidden Threats in Austenitic Stainless Steel <ul><li>SS AISI 321 was extensively used in Gasco </li></ul><ul><li>Buhasa NGL Extraction Plant intended to prevent </li></ul><ul><li>internal CO 2 corrosion and brittle fracture at : </li></ul><ul><ul><li>GAS Transmission Lines. </li></ul></ul><ul><ul><li>Equipment and Piping at Compression Section. </li></ul></ul><ul><ul><li>Cold BD Piping System and KO Vessel. </li></ul></ul><ul><ul><ul><ul><li>Key Words : </li></ul></ul></ul></ul><ul><ul><ul><ul><li>1. Chloride Stress Corrosion Cracking (CSCC) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>2. Stainless Steel (SS) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>3. Blow Down (BD ) </li></ul></ul></ul></ul>
  3. 3. Hidden Threats in Austenitic Stainless Steel <ul><li>SS AISI 321 is vulnerable to Stress Corrosion </li></ul><ul><li>Cracking in the presence of Chlorides depending on : </li></ul><ul><ul><li>Stress Levels, </li></ul></ul><ul><ul><li>Oxygen Content, </li></ul></ul><ul><ul><li>Temperature. </li></ul></ul><ul><li>External CSCC phenomenon occurred at Welding </li></ul><ul><li>Regions of the Reinforcing Pads, Wear Pads and </li></ul><ul><li>Saddles resulting in Severe Cracking and Leakage. </li></ul>
  4. 4. Typical Reinforcing Pad and Wear Pad
  5. 5. Reinforcing Pad Cross Section
  6. 6. Wear Pad Cross Section & Metallographic Examination
  7. 7. Piping Reinforcing Pad – Cracks and Leaks Leak at Reinforcing Pad Weep Hole CSCC at Reinforcing Pad Weld
  8. 8. Vessel Reinforcing Pad & Saddle - Cracks Cracks at Boot Reinforcing Pad
  9. 9. Cracks and Leaks at Wear Pads
  10. 10. Cracks and Leaks at Tack Weld Region after Wear Pad Removal
  11. 11. <ul><li>To restore the Integrity of the Plant, 8 SS Vessels had to be </li></ul><ul><li>replaced and the Transmission Gas and Process Lines were </li></ul><ul><li>also replaced at locations affected by CSCC. </li></ul><ul><li>The Cold BD Piping System is fitted with 288 Wear Pads and </li></ul><ul><li>operates at just positive Pressure and ambient Temperature. </li></ul><ul><li>In spite of the Very Low Operating Pressure cracks and Leaks </li></ul><ul><li>have been detected in some cases. </li></ul><ul><li>With the Objective of restoring the Integrity of the SS Cold </li></ul><ul><li>BD Piping System , in a planned and cost effective manner a </li></ul><ul><li>minimum risk with the Plant in Operation some options and </li></ul><ul><li>non-standard repair methods were considered and evaluated. </li></ul>Action Taken
  12. 12. Strategic Options <ul><ul><li>1. Replacement of the Cold BD Piping System. </li></ul></ul><ul><ul><li>2. Do-nothing, Monitor Crack Propagation & Leaks. </li></ul></ul><ul><ul><li>3. Glass-Fiber Reinforced Protection Wrapping. </li></ul></ul><ul><ul><li>4. Replace the Original Wear Pads with Cracks and Leaks </li></ul></ul><ul><ul><li>by Larger Cold Bonded SS Wear Pads. </li></ul></ul><ul><ul><ul><li>Option-4 Was Chosen by Buhasa Plant and Endorsed by the 2003 Shareholders Integrity Review Team. </li></ul></ul></ul><ul><ul><ul><li>The Repair Work was Implemented in accordance with the Gasco Plant Change Request procedure . </li></ul></ul></ul>
  13. 13. Test Piece New Wear Pad Belzona Primer Top Coat
  14. 14. <ul><li>Replacement of the 288 original Wear Pads with Cracks and Leaks by “Larger Cold Bonded SS Wear Pads”. </li></ul><ul><ul><li>Jack the Pipe Up. </li></ul></ul><ul><ul><li>Removal of Wear Pads by Grinding. </li></ul></ul><ul><ul><li>Assessment of Cracks with Regard to Fitness-For-Purpose Criteria (Shell Study). </li></ul></ul><ul><ul><li>SS Cold BD Line and Pads Anchor Profile >50 microns. </li></ul></ul><ul><ul><li>Cold Bonding of Larger SS Wear Pads (Belzona 1121). </li></ul></ul><ul><ul><li>Painting. </li></ul></ul>Practical Repair
  15. 15. Steps to Bond Wear Pads to the Main Line 1 2 3 4
  16. 16. Cold BD Piping System Completion Painting of New Wear pad Cold BD Partial View
  17. 17. <ul><li>Thank you </li></ul>Francisco Costa, Buhasa Inspection Head, GASCO

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