Corrosion Damage and prevention

1. How to light up 8 extra BULBS/household in Trinidad? Corrosion Damage and prevention Raj Nath Mehrotra

2. Who am I? Why care about conserving energy? Energy and Corrosion? Types of Corrosion Ways of preventing Corrosion What this means for Trinidad? Conclusions and Recommendations Questions AGENDA

3. Who am I? • 30 years of academic, research and industrial sector experience. Greatest industry experience was with the leading energy manufacturer of India – NTPC Ltd. (makes over 30% of India’s energy needs) • Physical Metallurgist, Corrosion specialist and failure analyst for the Energy sector • Education: • MBA – The University of Delhi, India • M. Tech & B. Tech - Indian Institute of Technology – Kanpur, India • Personal: Friend to many, Confidante to a few, Husband to one, Father to one, Leader to more, Employee to one, Inspiration to some, Judge of none.

4. Who am I? Why care about conserving energy? Energy and Corrosion? Types of Corrosion and Prevention Methods Ways of preventing Corrosion What this means for Trinidad? Conclusions and Recommendations Questions AGENDA

5. Why care about conserving energy? 20.5% CAGR Per capital Energy use in Trinidad & Tobago

6. Who am I? Why care about conserving energy? Energy and Corrosion? Types of Corrosion and Prevention Methods Ways of preventing Corrosion What this means for Trinidad? Conclusions and Recommendations Questions AGENDA

7. Energy & Corrosion? Corrosion is the degeneration of materials by chemical reactions. Examples: Rusting of power plants, automobiles, buildings and bridges, Fogging of silverware, Patina formation on copper. Example of a Corroding Pipe Sector wise CprrCost Corrosion costs approx. 3 -3.5% of GDP of countries (1) across most sectors. Utility sector is most hit. Regardless, all affected sectors requireenergy directly or indirectly Direct Cost: Material, Maintenance, Over-design, use of Costly material Indirect Cost: Plant shut-down, loss of production, contaminations of products, loss of products (leakage etc.), liability in accidents Cost of Corrosion in USA Sector Breakup (1) http://www.corrosion-doctors.org/Principles/Cost.htm

8. Significance of Corrosion: Utllities San Bruno, CA, USA Sep 2010 Gas Pipeline Explosion 9 Dead Cause: Pipeline Corrosion

9. Significance of Corrosion: Infrastructure Impact Charlotte, NC, USA May 2000 Lowe’s Motor Speedway Bridge Collapse 114 injured Cause: Structural Corrosion

10. Zinc Acid solution + H Oxidation reaction flow of e- 2+ Zn Zn + H in the metal + H - + 2e H + H + H H (gas) 2 + H reduction reaction • Corrosion Process – The Concept • Corrosion occurs because of the natural tendency for most metals to return to their natural state; e.g., iron in the presence of moist air will revert to its natural state, iron oxide. • Corrosion requires 4 components in an electrochemical corrosion cell: 1) An anode; 2) A cathode; 3) A conducting environment for ionic movement (electrolyte); 4) An electrical connection between the anode and cathode for the flow of electron current. • If any of the above components is missing or disabled, the electrochemical corrosion process will be stopped. • Eg: Corrosion of Zinc by an acid solution- Two reactions are necessary: -- oxidation reaction: -- reduction reaction:

11. Who am I? Why care about conserving energy? Energy and Corrosion? Types of Corrosion Ways of preventing Corrosion What this means for Trinidad? Conclusions and Recommendations Questions AGENDA

12. Types of Corrosion Stress Corrosion

13. 1. Uniform Corrosion Formerly a ship

14. 2. Galvanic Corrosion • Dissimilar metals are physically joined in the presence of an electrolyte. • The more anodic metal corrodes. Bilge pump - Magnesium shell cast around a steel core. Galvanic Series (Mg – Cu – Ni – Ag – Au – Pt)

15. 3. Stress Corrosion • A structure that has SCC sensitivity, if subjected to stresses and then exposed to a corrosive environment, may initiate cracks and crack growth well below the yield strength of the metal. • Consequently, no corrosion products are visible, making it difficult to detect or prevent; fine cracks can penetrate deeply into the part. Fall of Silver Bridge 1967

16. 4. Crevice Corrosion Narrow and confined spaces

17. 5. Pitting Pitting is a localized form of corrosive attack.  Pitting corrosion is typified by the formation of holes or pits on the metal surface.  Pitting can cause failure, yet the total corrosion, as measured by weight loss, may be minimal. Boiler tube 304 stainless steel / acid chloride solution 5th Century sword

18. 6. Intergranular Corrosion along grain boundaries, often where precipitate particles form.

19. 7. Erosion Corrosion Brass water pump Promoted by - High flow - Turbulent conditions - Particulates in fluid Combined chemical attack and mechanical wear (e.g., pipe elbows).

20. 8. Selective Leaching Preferred corrosion of one element/constituent [e.g., Zn from brass (Cu-Zn)]. Dezincification.

21. Who am I? Why care about conserving energy? Energy and Corrosion? Types of Corrosion Ways of preventing Corrosion What this means for Trinidad? Conclusions and Recommendations Questions AGENDA

22. Metal oxide Metal (examples: Al, stainless steel) Galvanized Steel 2+ Zn zinc zinc - - 2e 2e steel e.g., zinc-coated nail • Corrosion Prevention • Use metals that passivate, form a thin, adhering oxide layer that slows corrosion. • Use metals that are relatively unreactive in the corrosion environment. • Use inhibitors (substances added to solution that decrease reactivity); slow oxidation/reduction reactions by removing reactants like O2 gas by reacting it w/an inhibitor). • Slow oxidation reaction by attaching species to the surface. Apply physical barriers: films and coatings, paint • Reduce T (slows kinetics of oxidation and reduction) • Cathodic (or sacrificial) protection; attach a more anodic material to the one to be protected.

23. Anodic Protection (1) • Uses: • Storage & handling of H2SO4 • H2SO4 cooling heat exchangers • Various other misc. uses Transpassive Noble Potential, E Passive - Ep Active Active Log i icrit

24. Anodic Protection (2) Anodic protection is used in metals that behaves passively after certain anodic potential is applied as shown in figure below: V Materials which have shown active passive behavior: Solution Metal Sulfuric acid Steels Phosphoric acid S. Steels Nitric acid Nickel Nitric Solution Nickel alloys Aqueous Ammonia Chromium Reference electrode Working electrode Auxiliary electrode Apparatus used for anodic polarization studies

25. Sacrificial Anode This field is located in Viosca Knoll, block 786, southeast of New Orleans.  It lies in water depths of approximately 1754 feet (535 meters).  Petronius is the largest free-standing structure in the world.  Texaco's choice was Galvotec-CW-III Aluminum Sacrificial Anodes for their Petronius cathodic protection system.  http://www.galvotec.com/img/texaco.jpg

26. Barrier Protection • Here the metal is protected from atmosphere by creating barrier (coatings) that resist penetration. These are three types: • Inorganic Coatings • Ceramic • Phosphate • Anodic Oxides • Organic Coatings • Inhibitors

27. Pipeline Protection Smart & Flexible Pigs Threat Monitors Pipeline Protection Exterior Coating Exterior Inspections Interior Coating

28. Who am I? Why care about conserving energy? Energy and Corrosion? Types of Corrosion and Prevention Methods Ways of preventing Corrosion What this means for Trinidad? Conclusions and Recommendations Questions AGENDA

29. Corrosion is & will continue being chief problem hurting Trindad’s growth Energy equivalent to EIGHT 150W bulbs per household running 24 hours (1) Est. conservatively 3% of GDP (2) = = Wet Corrosion Proximity to Sea = = Dry/Gaseous Corrosion (High Temperature Corrosion) Dependence on Natural Gas (1) Assumes that only 25% of the cost of losses due to corrosion can be recovered. (2) Actual might be higher, esp. closer to 5% of GDP for Trinidad

30. Who am I? Why care about conserving energy? Energy and Corrosion? Types of Corrosion and Prevention Methods Ways of preventing Corrosion What this means for Trinidad? Conclusions and Recommendations Questions AGENDA

31. Conclusion & Recommendations • Conclusion: Corrosion is a natural degenerative process affecting metals. It would continue to have paramount effect on any economy, more so on Trinidad & Tobago’s economy as it tries to grow. • Recommendations: • Educate & adopt Best practices for: • Students • Partners • Industry • Research & Collaborate: • Setup joint corrosion research lab • Gather greater government attention and resources • Partner with: • Leading industries • Top worldwide universities

32. Who am I? Why care about conserving energy? Energy and Corrosion? Types of Corrosion and Prevention Methods Ways of preventing Corrosion What this means for Trinidad? Conclusions and Recommendations Questions AGENDA

33. Questions Email: rajmehr@gmail.com

34. Appendix

35. US Energy Mix

36. Est. Energy Recoverable from Corrosion – Details • http://www.blx.com/paginasInfoLatam.aspx?PAG_ID=38&CAT_ID=5 • http://eprints.lse.ac.uk/29938/1/Home_improvement_grants_in_Trinidad_and_England(LSERO).pdf