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

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

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.

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

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

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

Energy & Corrosion? Sector wise CprrCost 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. Corroding Pipe Example of a 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 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 Cost of Corrosion in USA Sector Breakup (1) http://www.corrosion-doctors.org/Principles/Cost.htm

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

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

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 - Acid solution reduction reaction H + 2 (gas) flow of e- in the metal Two reactions are necessary: -- oxidation reaction: -- reduction reaction:

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

Types of Corrosion Corrosion Uniform Corrosion Erosion Control Galvanic Crevice Pitting Intergranular Selective Leaching Erosion Control Stress Corrosion

1. Uniform Corrosion Formerly a ship

Galvanic Series (Mg – Cu – Ni – Ag – Au – Pt) 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)

3. Stress Corrosion Fall of Silver Bridge 1967 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.

4. Crevice Corrosion Narrow and confined spaces

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

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

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

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

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

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

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

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

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

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

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

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

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) = = Proximity to Sea Wet Corrosion = = 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

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

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 Trinidad should set up a teaching discipline with in Engineering in the field of Metallurgy & Material Science to prepare future experts in: Metallurgy & Material Sciences Review Status Establish Corrosion awareness cell under leadership of UTT & CARIRI Create in conjunction with UTT, Gov. & Industry to establish Corrosion Research lab Encourage all to adopt Corrosion & Corrosion mitigation program Prepare directory of world wide corrosion best practices Emphasize the development of corrosion management practices for protection of environment Adopt existing corrosion standards Material selection Experts Failure Analysis / Damage Assessment and mitigation Remaining life estimation experts Normalize education and certification requirements

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

Questions Email: rajmehr@gmail.com

Appendix

US Energy Mix

Est. Energy Recoverable from Corrosion – Details Metric Cost ($ or otherwise) Assumptions GDP (1) $28.096 B Cost of Corrosion $842.88 M Conservative 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 Terms INR 9482.4 M Approx. conversion rate 1 USD = 45 INR Equivalent energy equipment that this cost saving can buy 474.12 MW Cost of energy installation: Est. INR 20M / MW (NTPC estimates) Power produced by this energy equipment 9103.10 MwH No of households in Trinidad (2) 328000 Energy / household 27.75 kwH Number of high-energy bulbs (150W) that this corresponds to 8 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