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

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 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. 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? 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 % 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)

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. 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:

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

13. 1. Uniform Corrosion
Formerly a ship

14. 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)

15. 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.

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 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).

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 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

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. 

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
Exterior Coating
Exterior Inspections
Interior Coating

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 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

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 & 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

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. Questions

34. Appendix

35. US Energy Mix

36. Est. Energy Recoverable from Corrosion – Details
Metric
Cost ($ or otherwise)
Assumptions
GDP (1)
$ B
Cost of Corrosion
$ 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 M
Approx. 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)
328000
Energy / household
27.75 kwH
Number of high-energy bulbs (150W) that this corresponds to 8