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CORROSION DAMAGE AND PREVENTION Raj Nath Mehrotra HOW TO LIGHT UP 8 EXTRA BULBS/HOUSEHOLD IN TRINIDAD?

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Presentation on theme: "CORROSION DAMAGE AND PREVENTION Raj Nath Mehrotra HOW TO LIGHT UP 8 EXTRA BULBS/HOUSEHOLD IN TRINIDAD?"— Presentation transcript:

1 CORROSION DAMAGE AND PREVENTION Raj Nath Mehrotra HOW TO LIGHT UP 8 EXTRA BULBS/HOUSEHOLD IN TRINIDAD?

2 AGENDA 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

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 Indias 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 AGENDA 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

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

6 AGENDA 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

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. Corrosion costs approx % of GDP of countries (1) across most sectors. Utility sector is most hit. Regardless, all affected sectors require energy 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 (1) Sector wise CprrCost Example of a Corroding Pipe Cost of Corrosion in USA Sector Breakup

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 Lowes Motor Speedway Bridge Collapse 114 injured Cause: Structural Corrosion

10 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- Zinc Oxidation reaction Zn 2+ 2e - Acidsolution reduction reaction H + H + H 2 (gas) H + H + H + H + H + flow of e - in the metal Two reactions are necessary: -- oxidation reaction: -- reduction reaction:

11 AGENDA 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

12 Corrosion Uniform Corrosion GalvanicCrevicePittingIntergranular Selective Leaching Erosion Control 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 Boiler tube 304 stainless steel / acid chloride solution 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. 5th Century sword

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

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

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

21 AGENDA 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

22 Corrosion Prevention 22 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 O 2 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. steel zinc Zn 2+ 2e2e - 2e2e - e.g., zinc-coated nail Galvanized Steel Metal (examples: Al, stainless steel) Metal oxide

23 Transpassive Active Passive Noble Active Potential, E Log i i crit - E p Uses: Storage & handling of H 2 SO 4 H 2 SO 4 cooling heat exchangers Various other misc. uses Anodic Protection (1)

24 V Working electrode Reference electrode Auxiliary electrode 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 Apparatus used for anodic polarization studies Anodic protection is used in metals that behaves passively after certain anodic potential is applied as shown in figure below: Anodic Protection (2)

25 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. Sacrificial Anode

26 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 Barrier Protection

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

28 AGENDA 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

29 Corrosion is & will continue being chief problem hurting Trindads growth = = = = Proximity to Sea Dependence on Natural Gas Wet Corrosion Dry/Gaseous Corrosion (High Temperature Corrosion) Est. conservatively 3% of GDP (2) Energy equivalent to EIGHT 150W bulbs per household running 24 hours (1) (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 AGENDA 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

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 & Tobagos 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 AGENDA 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

33

34 Appendix

35 US Energy Mix

36 Est. Energy Recoverable from Corrosion – Details MetricCost ($ or otherwise)Assumptions GDP (1)$ B Cost of Corrosion$ MConservative estimate 3% of GDP Cost which can be recovered$210.72M 25% of total costs lost to corrosion. Ref: NACE International. Converting this costs in INR TermsINR MApprox. conversion rate 1 USD = 45 INR Equivalent energy equipment that this cost saving can buy MW Cost of energy installation: Est. INR 20M / MW (NTPC estimates) Power produced by this energy equipment MwH No of households in Trinidad (2) Energy / household27.75 kwH Number of high-energy bulbs (150W) that this corresponds to8 (1)http://www.blx.com/paginasInfoLatam.aspx?PAG_ID=38&CAT_ID=5http://www.blx.com/paginasInfoLatam.aspx?PAG_ID=38&CAT_ID=5 (2)http://eprints.lse.ac.uk/29938/1/Home_improvement_grants_in_Trinidad_and_England(LSERO).pdfhttp://eprints.lse.ac.uk/29938/1/Home_improvement_grants_in_Trinidad_and_England(LSERO).pdf


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