PROJECT 7TH SEM REPORT

AN INDUSTRIAL DEFINED PROJECT
Prepared By: Team Creative Minds Page 1
To Study Adverse Effect of Sea Water Corrosion in
Centrifugal Pump
A PROJECT REPORT
Submitted by
Pradip M. Vasoya(120040119008)
Utsav C. Gor(120040119031)
Yagnesh P. Parjiya(120040119053)
Under the Guidance of
Mr. Vasudev Patel (Industrial Guide)
Prof. Dhruv Patel (Institute Guide)
Undergraduate Student,
Mechanical Engineering Department
B. H. Gardi College of Engineering & Technology,
Rajkot
Gujarat Technological University, Ahmadabad
October, 2015

Certificate
This is to certify that Pradip Vasoya, Utsav Gor and Yagnesh Parjiya form B. H. Gardi
College of Engineering & Technology Rajkot, has been carried out project, under my guidance
fulfillment of the degree of Bachelor of Engineering in Mechanical 7th
Semester of Gujarat
Technological University, Ahmadabad during the academic year 2015-16.
Guide:____________ __________________________
Mr. Dhruv Patel Mr. Virang Oza,
Prof. of Mechanical Department Head of Mechanical Department

Abstract
This project involves study & discovering Types of corrosion due to sea water and
environmental effects on material. Our goal is to study the corrosion and find the possible
solution to reduce it. This has been done by studying the related topics such as Corrosion
engineering. Project shows the importance of corrosion study to prevent it by different methods.
Considering that pumping systems account for 20% of the world’s electrical demand and the cost
of energy represents 95% of the cost to run pumping equipment, it is obvious that all industry
would benefit from any solutions aimed at increasing pump performance.

Acknowledgements
It is always a pleasure to remind the fine people in the Engineering program for their sincere
guidance. I received to upload my practical as well as theoretical skill in engineering.
Firstly I would like to thank Mr. NISCHAL RAVANI (HR-Deputy Manager of Adani Power
Ltd.) for meticulously planning academic curriculum in such a way that students are not only
academically sound but also industry ready by including such industrial project.
I would also like to acknowledge and my heartfelt gratitude to MR. VASUDEV PATEL
(GM) who continuously supported us in every possible way, from initial advice to
encouragement till this date.
I express my immense pleasure and deep sense of gratitude to MR. DHRUV PATEL(Prof. of
Mechanical Department) and MR. RAHUL MUKHERJEE (Assistance Engineer, Mechanical
Maintenance Department) and solicitor to for spending his valuable time with us and also helped
me in completion of task.
I would also like to thanks MR. SIDDHARTH JADEJA (Executive Director of B. H. Gardi
College) for the positive attitude he showed for my work, always allowing us to question him
and giving prompt replies for my uncertainties in all the fields including educational, social and
managerial work.
Finally, I would also like to thanks all the members for guiding us during the course of the
project.

TABLE OF CONTENT
1. INTRODUCTION………………………………………………8-10
I. Introduction of Project…………………………………………........8
II. Objective of Industrial Project……………………………………… 9
III. Summary of Report………………………………………………… 10
2. THE INDUSTRIAL BACKGROUND………………………..11-12
3. CORROSION THEORY……………………………………….13-20
I. Definition……………………………………………………………13
II. Importance of Study…………………………………………………13
III. Condition…………………………………………………………….14
IV. Effect of Material Selection…………………………………………14
V. Classification………………………………………………………...15
VI. Factor Influence……………………………………………………...20
4. PROBLEM IDENTIFICTION…………………………………21-33
I. Real Field Project Identification……………………………………..21
II. Duplex Stainless Steel Property……………………………………...23
III. Sea water useful Property…………………………………………….26
IV. Chemical Composition of Material………………………………….27
V. Types of Corrosion Concern in that case……………………………..28
VI. E-pH Diagram………………………………………………………...31

5. CANVAS……………………………………………………….34-37
I. AEIOU…………………………………………………………….34
II. Empathy…………………………………………………………...35
III. Ideation………………………………………………………........36
IV. Product Development……………………………………………..37
6. LITERATURE SURVEY……………………………………..38-44
7. CONCLUSION………………………………………………..45
8. FUTURE WORK……………………………………………...46
9. REFERENCES………………………………………………..47

LIST OF FIGURES
Fig-1 Out-side View of Adani Power Plant
Fig-2 Sea Water Properties
Fig-3 (a) Galvanic Corrosion
(b)Galvanic Corrosion
Fig-4 Crevice Corrosion
Fig-5 Pitting Corrosion
Fig-6 (a)E-pH Diagram
(b)E-pH Diagram
Fig-7 Graph of Log I corr Vs Log Nacl
LIST OF TABLES
Table-1 Mechanical Properties of 2205 Grade Stainless Steels
Table-2 Physical Properties of 2205 Grade Stainless Steels
Table-3 Chemical Composition of Material

1) INTRODUCTION
I. Introduction of Project
 Corrosion can be viewed as a universal phenomenon, everywhere, air, water, soil and in
every environment, we encounter.
 There is no single figure for loss to the nation due to corrosion. It can be a minimum of
3.5% of the nation’s GDP. Losses due to corrosion could be around Rs. 2.0 lakh crores
per annum in India. Corrosion costs manifest in the form of premature deterioration or
failure necessitating maintenance, repairs and replacement of damaged parts.
 Corrosion has a huge economic and environmental impact on all facets of national
infrastructure; from highways, bridges, buildings, oil and gas, chemical processing, water
and waste water treatment and virtually on all metallic objects in use. Other than material
loss, corrosion interferes with human safety, disrupts industrial operations and poses
danger to environment.
 Awareness to corrosion and adaptation of timely and appropriate control measures hold
the key in the abatement of corrosion failures.

 India is a rapidly developing country. In any country’s development energy plays Very
important role. Mostly in India 70% of energy produced by thermal power plant. Primary
requirement of thermal power plant is water. So most of thermal power plant situated
near sea to suck that water pump is used. In that pump corrosion is occur due to sea water
saltiness and impurities.
 Tens of billions of dollars are lost annually in the World because of corrosion damage to
metals. Adani Power Ltd., Mundra is also face same kind of problem. They face the
problem of changing the pump which is damaging due to corrosion in short time.
 So our project is related to corrosion in Sea water suck pump at Adani Thermal Power
Plant.
II. Objectives of Industrial Project
 To determine the which types of corrosion occur in centrifugal pump used to suck the sea water.
 To find the rate of Corrosion in Material of Pump.
 Try to reduce that corrosion with possible set of Solutions.
 To Increase pump performance and plant performance.
 To be the part of Nation’s Development.

III. Summary for Report
 Our project is related to corrosion occur on to the material which is duplex stainless steel
in Single stage centrifugal pump at Adani Power Limited Mundra sea intake pump
house. Our main goal is to reduce corrosion in to sea intake pump starting with find the
which types of corrosion occur due to sea water, sea water properties, material properties,
effect of sea water on that particular material.

2) THE INDUSTRIAL BACKGROUND[1]
 The company is India's largest private power producer, with capacity of 10,440 MW.
 The company operates five supercritical boilers of 660 MW each (as per March 2012)
at Mundra Gujarat.
 It is India's first company to achieve the supercritical technology. The plant is the only
thermal power plant in India to be certified by UN under CDM.
 The company is implementing 16500 MW at different stages of construction. Its mission
is to achieve 20000 MW by 2020. The company produces electricity using only coal.
Fig-1

 Adani power was started as a power trading company 1996. It started generation in July
2009 by implementation of its first 330 MW of 4620 MW at Mundra. The Mundra super
mega project is the largest coal-based power project of India and fifth largest in the
world.
 A 4620 MW (4x330, 5x660 MW) coal-based thermal power plant at Mundra, Kutch
district, Gujarat. This plant is fully functional. It operates first power transmission project
of 400 kV Double Circuit Transmission System from the Mundra plant to Dehgam
(430 km).

3) Corrosion Theory[2]
I. Definition of Corrosion
 Corrosion may be defined as a destructive phenomena, chemical or electrochemical,
which can attack any metal or alloy through reaction by the surrounding environment and
in extreme cases may cause structural failure. Corrosion can be also defined as the
deterioration of material by reaction to its environment. The 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. Metals can be corroded by
the direct reaction of the metal to a chemical; e.g., zinc will react with dilute sulfuric acid,
and magnesium will react with alcohols.
II. Importance of Corrosion Studies
 The importance of corrosion studies is two folds. The first is economic, including the
reduction of material losses resulting from the wasting away or sudden failure of piping,
tanks, metal components of machines, ships, hulls, marine, structures…etc. The second is
conservation, applied primarily to metal resources, the world’s supply of which is
limited, and the wastage of which includes corresponding losses of energy and water
resources accompanying the production and fabrication of metal structures.

III. Conditions for corrosion
 For the purpose of this manual, electrochemical corrosion is the most important
classification of corrosion. Four conditions must exist before electrochemical
corrosion can proceed:
1. There must be something that corrodes (the metal anode).
2. There must be a cathode.
3. There must be continuous conductive liquid path (electrolyte, usually condensate and salt
or other contaminations).
4. There must be a conductor to carry the flow of electrons from the anode to the cathode.
This conductor is usually in the form of metal-to-metal contact such as in bolted or
riveted joints. The elimination of any one of the four conditions will stop corrosion.
IV. Effect of material selection
 One of the fundamental factors in corrosion is the nature of the material. Materials are
usually selected primarily for structural efficiency, and corrosion resistance is often a
secondary consideration in design.
i. Water intrusion
 Water intrusion is the principal cause of corrosion problems encountered in the field use
of equipment. Water can enter an enclosure by free entry, capillary action, or
condensation. With these three modes of water entry acting and with the subsequent
confinement of water, it is almost certain that any enclosure will be susceptible to water
intrusion.

ii. Environmental factors
 At normal atmospheric temperatures the moisture in the air is enough to start corrosive
action. Oxygen is essential for corrosion to occur in water at ambient temperatures.
Other factors that affect the tendency of a metal to corrode are:
1. Acidity or alkalinity of the conductive medium (pH factor).
2. Stability of the corrosion products.
3. Biological organisms (particularly anaerobic bacteria).
4. Variation in composition of the corrosive medium.
5. Temperature.
 The corrosion problem at KSC is complex. The presence of salts and acids on metal
surfaces greatly increases the electrical conductivity of any moisture present and
accelerates corrosion. Moisture tends to collect on dirt particles.
V. Classification
 All metallic materials consist of atoms having valiancy electrons which can be donated or
shared. In a corrosive environment the components of the metallic material get ionized
and the movement of the electrons sets up a galvanic or electrochemical cell which
causes oxidation, reduction, dissolution or simple diffusion of elements.
 The metallurgical approach of corrosion of metals is in terms of the nature of the alloying
characteristics, the phases existing and their inter-diffusion under different environmental
conditions. In fact, the process of corrosion is a complex phenomenon and it is difficult to
predict the exclusive effect or the individual role involved by any one of the above
mentioned processes. Based on the above processes, corrosion can be classified in many
ways as low temperature and high temperature corrosion, direct oxidation and
electrochemical corrosion, etc. The preferred classification is:

1. Chemical corrosion: In which the metal is converted into its oxide when the metal is
exposed to a reactive gas or non-conducting liquids.
2. Electrochemical corrosion: The formation of hydrous oxide film occurs when the metal
is immersed in a conducting liquid containing dissolved reactive substance. The reaction
is considered to take place at the metal- solution interface, due to the heterogeneity on
the metal surface, which creates local anodic and cathodic sites on the metal.
 Electrochemical nature of corrosion can be understood by examining zinc dissolution in
dilute hydrochloric acid.
 Zn + 2HCl = ZnCl2 + H2
 Anodic reaction is Zn = Zn++ + 2e with the reduction of 2H+ + 2e = H2 at cathodic areas
on the surface of zinc metal. There are two half reactions constituting the net cell
reaction.
 Environmental effects such as those of presence of oxygen and other oxidizers, changes
in flow rates (velocity), temperature, reactant concentrations and pH would influence
rates of anodic and cathodic reactions.
 Even though the fundamental mechanism of corrosion involves creation or existence of
corrosion cells, there are several types or forms of corrosion that can occur. It should
however be borne in mind that for corrosion to occur, there is no need for discrete
(physically independent) anodes and cathodes. Innumerable micro level anodic and
cathodic areas can be generated at the same (single) surface on which anodic (corrosion)
and cathodic (reduction) reactions occur. Each form of corrosion has a specific
arrangement of anodes and cathodes and specific patterns and locations depending on the
type can exist

 The most important types are
1. Uniform Corrosion
 It leads to relatively uniform thinning. For round bars and wires, corrosion proceeds
radically at an essentially uniform rate around the entire circumference. Castings suffer
corrosion starting at the wall exposed to the fluid (for example, the impeller face of the
casting) and proceeding gradually and uniformly to the outer wall. In many instances it is
complicated by the velocity, pressure, and nature of the pumped fluid.
 Methods of reducing or eliminating general corrosion are the use of coatings, the
selection of a more corrosion- resistant material (a general rule is to select an alloy with a
higher chrome and/or nickel content), the use of inhibitors, or cathodic protection.
 In pumps, the recognition of general corrosion is compounded by velocity and pressure
variations. The surface casing may show whorls and pockets where velocity variations
have influenced the rate of corrosion. These variations may appear to be caused by solids
or erosive products in the fluid. However, close examination will always reveal the fact
that corrosion has left an etched appearance on the surface.
2. Galvanic Corrosion
 A potential difference exists between two dissimilar metals when they are immersed in a
corrosive and conductive solution. If these metals are now connected electrically and
conductive on the outside, an electron flow is produced. One of the two metals will
corrode faster than the other metal.
 The metal, which is corroding at a faster rate, becomes anodic, while the other metal is
cathodic. There are several ways in which to combat galvanic corrosion: A. Material
selection is extremely important. Substitution of impellers of different alloys in an
existing system must be done carefully. Care should be taken to avoid wide separation in
the relevant galvanic series.

3. Erosion-Corrosion
 Erosion is the removal of metal by the movement of fluids against the surface. The
combination of erosion and corrosion can provide a severe rate of corrosion.
4. Pitting Corrosion
 Pitting corrosion is a complex but important problem that is at the root of many corrosion
failures. It has been studied in detail for many years, yet crucial phenomena remain
unclear. In pitting corrosion the surface of the metal is attacked in small-localized areas.
Organisms in water or breaks in a passive film can initiate corrosion. In pitting corrosion
very little metal is removed from the surface but the effect is marked. In passivated
metals or alloys that are exposed to solutions containing aggressive anions, primarily
chloride, pitting corrosion results in local dissolution leading to the formation of cavities
or (holes). The anodic and cathodic electrochemical reactions that comprise corrosion
separate spatially during pitting.. The pH in the pit is lower owing to cation hydrolysis
and the absence of a local cathodic reaction. The acidic chloride environment thus
generated in pits is aggressive to most metals and tends to propagate the pit growth.
5. Crevice Corrosion
 Crevice corrosion occurs when there is a difference in ion, or oxygen, concentration
between the metal and its surroundings. Oxygen starvation in an electrolyte at the bottom
of a sharp V-section will set up an anodic site in the metal that then corrodes rapidly.
6. Intergranular Corrosion
 Corrosion occurs at the grain boundaries due to a difference in potential between the
anodic grain boundaries and the cathodic grains. "Sensitized" stainless steels, where
carbides have been precipitated in the grain boundaries during improper heat treatment or
in the heat-affected zone of a weld, are particularly susceptible to intergranular corrosion.

7. Localized Corrosion
 This form is used very loosely to describe corrosive attack in a specific small area. It is
not to be confused with pitting and crevice corrosion. In castings, this form of attack is
usually caused by mechanical faults such as inclusion, gas holes, segregation, or cold
shuts. The corrosive liquid will eat out the foreign material, or set up local cells between
the metal and the inclusion or segregation. This form is very difficult to identify without
complete knowledge of the foundry practices employed in making the casting. These bad
spots in the casting will occur in certain, very localized areas and without regard to, or in
connection with, any other type of corrosion. This form of corrosion in the pump industry
may be referred to as defective casting corrosion.
8. Cavitation
 Cavitation damage is located anywhere between the inlet eye of the impeller and the tip
of the blades. The closely spaced pits are usually seen on the lagging side of the blades.
In certain violent instances, damage is noticed on the leading side of the blades. The
extent and location of the damage is dependent on the fluid being handled, the
temperature, partial pressures and the degree of re- circulation flow inherent in the
design.
9. Stress Corrosion Cracking
 Failure is due to the simultaneous influence of static tensile stresses and a corrosive
environment and this is specific to a particular metal. The stresses may be internal such as
those caused by cold work, welding, heat treatment or external forces caused by
mechanical stresses set up by assembly practices. A good example of this form of
corrosion is 316 stainless steel in marine environments. 316 stainless steel was developed
to withstand attacks in chloride environments, but if stressed the steel will fail by stress
corrosion cracking.

VI. Factors Influence Corrosion
 The nature and extent of corrosion depend on the metal and the environment. The
important factors which may influence the corrosion process are:
a. Nature of the metal, nature of the environment and the corrosion products.
b. Temperature.
c. Concentration of electrolyte.
d. Electrode potential.
e. Aeration & Agitation.
h. Hydrogen over voltage and pH of the electrolyte.

4) Problem Identification
1. Real Field Project Identification
 We have visited Adani Thermal Power Plant, Mundra During our Summer Internship and
we have noticed a crucial problems of corrosion in sea water suck pump.
 The same thing was giving to us for doing project on it by Mr. Vasudev Patel, GM O&M
APL-Mundra that Corrosion is the major problem for us. Not only Adani but all thermal
power plants and who so ever extract the direct sea water through pump. Because of Sea
water pH and High Salinity Up to 3.5%. Due to this problem in successfully and
effectively running of plant.
 So Mechanical Department has to do great amount of maintenance work related to the
same.
 So we group of student decided to carry out this problem in our project work and try to
study & minimize it during entire project work.
 After that Industrial visit we finalize that our project is related to corrosion in Sea water
suck pump but we don’t know how we will go further.
 At our institute one of faculty Mr. Dhruv M Patel completed their B.E. as well as M.E in
Metallurgy Field so we meet them and discuss our industrial problem to them. As he is a
man of field metallurgy gives suggestion to study the particular location where corrosion
occur atmosphere, sea water pH ,sea water salinity ,which types of corrosion occur due to
sea water, in our case there is which type of material used, effect of sea water on that
particular material, property of material, possible solutions for reduction of corrosion.

 So for above questions from institute guide we again reached at Adani Power Limited for
getting answers and more detail about project problem. We visited sea intake house
where direct sea water suck. There is mainly 2 sea intake pump house at adani each house
has 6 Single stage Vertical type centrifugal Pump.
 There is 9 units so each unit has separate pump within that 3 stand by pump is placed our
there for any emergency. Operator give brief idea how water comes from sea there is one
separator dug has the cleaner mechanism having grid or net so large particle cannot enter
in to that separator from that separator pipes was extract the water.
 After Entering in to pump sea Water has the sand particles, impurities, insects and most
effective salt.
 So it is all leads to successive corrosion in pump parts. Also sea water itself has the pH
value and electrolytic property so water itself major reason for corrosion.
 Then we met the Mechanical Maintenance Department(MMD) person Er.Rahul
Mukherjee who gave us all the answers which in our mind as well project problem
related.
 Mainly four measure question from ourside is following:
1. Which Type of Pump used in Adani Power Limited Mundra in to sea intake house?
2. Which material used in that Pump?
3. How many salt percentage (Salinity) present in to sea water?
4. How they measure rate of corrosion?

We get answers from MMD:-
1. Single Stage Vertical Centrifugal Pump
2. Duplex Stainless Steel 2205
3. Salinity 3.5%
4. Weight Measurement, Visual Inspection, Ultrasonic testing
Now our project is related to corrosion so we concerned with the material used.
i.e. Duplex Stainless Steel 2205
2. Duplex Stainless Steel Property[3]
 Introduction
 Duplex 2205 stainless steel (both ferrite and austenitic) is used extensively in applications
that require good corrosion resistance and strength. The S31803 grade stainless steel has
undergone a number of modifications resulting in UNS S32205, and was endorsed in the
year 1996. This grade offers higher resistance to corrosion.
 At temperatures above 300°C, the brittle micro-constituents of this grade undergo
precipitation, and at temperatures below -50°C the micro-constituents undergo ductile-to-
brittle transition; hence this grade of stainless steel is not suitable for use at these
temperatures.

 Mechanical Properties
 The typical mechanical properties of grade 2205 stainless steels are listed in the table
below. Grade S31803 has similar mechanical properties to that of S32205.
Table 1 - Mechanical properties of 2205 grade stainless steels
Grade
Tensile Str
(MPa) min
Yield Strength
0.2% Proof
(MPa) min
Elongation
(% in 50mm) min
Hardness
Rockwell C (HR C) Brinell (HB)
2205 621 448 25 31 max 293 max
 Physical Properties
 The physical properties of grade 2205 stainless steels are tabulated below. Grade S31803
has similar physical properties to that of S32205.
Table 2 – Physical properties of 2205 grade stainless steels
Grade
Density
(kg/m3
)
Elastic
Modulus
(GPa)
Mean Co-eff of
Thermal
Expansion
(μm/m/°C)
Thermal
Conductivity
(W/m.K)
Specific
Heat
0-100°
C
(
J/kg.K)
Electrical
Resistivity
(nΩ.m)
0-
100°C
0-
315°C
0-
538°C
at 100°C at 500°C
2205 782 190 13.7 14.2 - 19 - 418 850
 Heat Resistance
 The high oxidation resistance property of Grade 2205 is marred by its embrittlement
above 300°C. This embrittlement can be modified by a full solution annealing treatment.
This grade performs well at temperatures below 300°C.

 Heat Treatment
 The best suited heat treatment for this grade is solution treatment (annealing), between
1020 - 1100°C, followed by rapid cooling. Grade 2205 can be work hardened but cannot
be hardened by thermal methods.
 Applications
 Some of the typical applications of duplex steel grade 2205 are listed below:
 Oil and gas exploration
 Processing equipment
 Transport, storage and chemical processing
 High chloride and marine environments
 Paper machines, liquor tanks, pulp and paper digesters

3. Sea water useful Property
 At Mundra Adani Power plant use water of adani port Mundra On average, seawater in
the world's oceans has a salinity of about 3.5% (35 g/L). This means that every kilogram
of seawater has approximately 35 grams of dissolved salts.
 Seawater pH is between the range of 7.5 to 8.4.
Fig-2
Salinity
in Sea
Water
3.5%
Sea Water
pH
8(Avg.)

4. Chemical Composition of Material[4]
Chemical %
Carbon (C) 0.03
Manganese (Mn) 2.0
Silicon(Si) 1.0
Chromium(Cr) 22.0
Nickel (Ni) 6.0
Molybdenum(Mb) 3.1
Iron (Fe) Balanced

5. Types of Corrosion Concern with our case[5]
Galvanic Corrosion
 Galvanic corrosion is an electrochemical process in which one metal corrodes
preferentially to another when both metals are in electrical contact, in the presence of
an electrolyte.
 Like crevice corrosion, the low resistivity of seawater also promotes strongly galvanic
corrosion.
Fig-3(a)
Impurities %
Phosphorus (P) 0.03%(max)
Sulphur (S) 0.02%(max)

 Galvanic corrosion is seen as a major concern for materials performance in marine
environment.
 A well known example is corrosion due to the sea water in centrifugal pump for galvanic
corrosion. Also stainless steel can suffer galvanic corrosion.
 Galvanic Corrosion occur in Centrifugal Pump Blades there is electrolytic Medium is Sea
water two metals is act as anode AND cathode and this corrosion can takes place.
Fig-3(b)
Crevice Corrosion:
 This type of corrosion attack is usually associate with holes, extended surface, lap joints,
crevice under bolt and rivet heads.
 Crevice corrosion is a major problem in marine environment because of the low
resistivity of the water .

Fig-4
 Extended Area or Joints Connected by nut and Bolts There Crevice Corrosion Takes
place.
Pitting Corrosion
 Pitting corrosion, or pitting, is a form of extremely localized corrosion that leads to the
creation of small holes in the metal.
 Pit may be described as a cavity or hole with the surface diameter the same as or less than
the depth of that component.
 Inside casing of the Centrifugal Pump there is a Pit occurs due to this type of corrosion.
Fig-5

6. E-pH Diagram[6]
 Eh–pH diagram, any of a class of diagrams that illustrate the fields of stability of mineral
or chemical species in terms of the activity of hydrogen ions (pH) and the activity of
electrons (Eh). Consequently, the reactions illustrated on Eh–pH diagrams involve either
proton transfer (e.g., hydrolysis) or electron transfer (oxidation or reduction) or both. In
natural environments, pH values extend from 1 to 9.5, and Eh values from -500 to +800
millivolts. Rarely are temperatures and pressures other than those normally encountered
on the Earth’s surface considered.
 The area on an Eh–pH diagram that represents the range of these variables within which a
particular mineral is stable is called the stability field of that mineral. Such a
representation enables a geochemist to determine whether a mineral is in equilibrium
with its surroundings or subject to chemical transformation.
 Pourbaix diagrams are also known as EH-pH diagrams due to the labeling of the two axes.
The vertical axis is labeled EH for the voltage potential with respect to the standard
hydrogen electrode (SHE) as calculated by theNernst equation. The "H" stands for
hydrogen, although other standards may be used, and they are for room temperature only.
 The horizontal axis is labeled pH for the -log function of the H+
ion activity.

 The lines in the Pourbaix diagram show the equilibrium conditions, that is, where the activities are
equal, for the species on each side of that line. On either side of the line, one form of the species will
instead be said to be predominant.
 In order to draw the position of the lines with the Nernst equation, the activity of the chemical species
at equilibrium must be defined.
The stability region of water
 In many cases, the possible conditions in a system are limited by the stability region of
water. In the Pourbaix diagram for uranium, the limits of stability of water are marked by
the two dashed green lines, and the stability region for water falls between these lines.
 Under highly reducing conditions (low EH/pE) water will be reduced to hydrogen
according to
or
 Using the Nernst equation, setting E0
= 0 V and the hydrogen gas fugacity (corresponding
to activity) at 1, the equation for the lower stability line of water in the Pourbaix diagram
will be
 at standard temperature and pressure. Below this line, water will be reduced to hydrogen,
and it will usually not be possible to pass beyond this line as long as there is still water
present to be reduced.
 Correspondingly, under highly oxidizing conditions (high EH/pE) water will be oxidized
to oxygen gas according to[3]

 Using the Nernst equation as above, but with an E0
of 1.229 V, gives an upper stability
limit of water at
 At standard temperature and pressure. Above this line, water will be oxidized to form
oxygen gas, and it will usually not be possible to pass beyond this line as long as there is
still water present to be oxidized.
Fig-6(a) Fig-6(b)

5) Canvas
a. AEIOU

b. Empathy

c. Ideation

d. Product Development

6) Literature survey
1. Effect of temperature and Cl-
concentration on pitting of 2205 duplex
stainless steel[7]
Dong Chaofang, Luo Hong, Xiao Kui, Liu Qian, Sun Ting,Li Xiaogang
Corrosion and Protection Center, University of Science and Technology Beijing,
Beijing 100083
 The effects of temperature and chloride concentration on 2205 Duplex Stainless Steel
were investigated using gravimetric measurements, potentiodynamic polarization,
electrochemical impedance spectroscopy and scanning electron microscopy. Temperature
and chloride concentration can highly affect the pitting corrosion resistance of 2205.
 The critical pitting temperature plays an important role in 2205 corrosion. The corrosion
rate in FeCl3 increased with the solution temperature increasing. When the temperature is
above, critical pitting temperature the corrosion rate is even faster.
 Increasing either NaCl concentration or the solution temperature shifts Ep of 2205 DSS
towards more active direction, representing a decrease of corrosion resistance, and a
greater possibility of pitting corrosion tendency.
 Generally for 2205 DSS, Icorr increased with the temperature rise. Icorr is foundto increase
linearly with the raise of the concentration of NaCl, accordance with the formula: log
Icorr= a+ b logC.

0.01 0.1 1 10
0.3
0.6
0.9
1.2
1.5 30℃
40℃
50℃
60℃
70℃
LogIcorr
(μAcm
2
)
Log[NaCl] (M)
Fig-7
 Temperature and chloride concentration not only change the thickness of the passive
film, but also change the shape of pits. When the NaCl concentration and the temperature
are low, pits are all small, scattered and with hemisphere-like shape. However, higher
temperature and NaCl concentration lead pits to the appearance of lacy cover. Moreover,
with the temperature and concentration increasing, the exterior lacy cover of the pits will
be dissolved, leaving a large hole with arough interior surface and dish-shaped profiles.

2. CORROSION OF STEELS INDUCED BY MICROORGANISMS[8]
Biljana S. Maluckov*
Technical Faculty in Bor, University of Belgrade, VojskeJugoslavije 12, 19210
Bor, Serbia
Received 28.02.2012
Accepted 03.04.2012
 Diverse types of steels have found application in industry owing to their ability to form
passive films resistant to the electrochemical corrosion. However, the presence of
microorganisms in the production environment can cause undesired corrosion of metals.
Therefore, any information on the chemical structure of corrosion products and
microbiological deposits, as well as the estimation of the biocorrosion level can be
extremely useful in applications.
 The deterioration of steel structures in fresh water and marine environments is crucially
dependent on the bio corrosion processes. In industrial practice, due to their importance
and effects these processes attract special attention . Studies have shown the complexity
of the microbiologically induced corrosion in different environments. Related to this,
each particular case of bio corrosion requires development of the unique approach . Here
is a brief review of the techniques developed for investigation of the bio corrosion
processes on steel components in different environments.

 The ability of steel to form a passive layer in the oxidative conditions is highlyexploited
in industrial applications. However, in the living environment the growth of
microorganisms on the surfaces is inevitable. They form biofilms that corrode the
surfaces. Microscopically obtained data on the type of microorganisms, combined with
the data from the chemical analysis of surfaces, and electrochemical measurements
provide information about the chemical composition of the corrosion products and
microbiological deposits, can be used to estimate the level of corrosion. In order to
prevent or reduce biocorrosion selection of materials and design of technological
equipment, as well as the proper and regular cleaning of the equipment are of theextreme
significance.

3. Corrosion of Duplex Stainless Steels in Seawater[9]
by
BengtWallén,
Avesta Sheffield AB, Research & Development, SE-774 80 Avesta, Sweden
Seawater as a corrosive medium
 The noble corrosion potentials, normally in the 300 to 350 mV range, mean that the risk
for initiation of localized corrosion such as crevice and pitting corrosion is greater in
natural, living seawater than in solutions like artificial seawater or sodium chloride
solutions, where the potentials are at least a couple of hundred mV lower. This means
that also the propagation rate of any localized corrosion is higher in the natural water.
Seawater tests
 When stainless steels are used for handling seawater the main corrosion risks are crevice
corrosion and sometimes pitting corrosion in weld areas. Stress corrosion cracking
seldom occurs at the water temperatures normally encountered.
 In this section just crevice and pitting corrosion tests will be treated. The most frequent
way of testing the crevice corrosion resistance is to apply some kind of crevice formers
on the surface of the specimens and then immerse them in the water. Pitting corrosion
may occur on the creviced specimens but, since crevice corrosion is normally the major
type, pitting is often studied on welded specimens without using intentional crevices.
Tests of this kind are valuable for the screening of stainless steels in that they indicate the
probability of localized corrosion initiation. However, the most reliable (and most
expensive) way of evaluating the crevice and pitting corrosion resistance of a material is
to perform tests with prototype systems composed of real components.

4. The Corrosion of Centrifugal Pumps in Aqueous Environments[10]
Frank Gall
Industry Technical Consultant, Nalco-Ecolab
 The official NACE International definition of corrosion is that “Corrosion is a naturally
occurring phenomenon commonly defined as the deterioration of a substance (usually a
metal) or its properties because of a reaction with its environment. Although the NACE
definition of corrosion is designed to capture non-metallic and exotic environmental systems,
it applies equally to common metals in aqueous environments such as those encountered in
centrifugal pump construction and application. Some degradation processes such as particle
impingement erosion, cavitations, fatigue and adhesive we are considered purely physical in
mechanism and are not generally considered as corrosion. Degradation processes such as
general corrosion, pitting corrosion, galvanic corrosion, crevice corrosion, selective corrosion
and inter-granular corrosion are considered to be purely chemical in mechanism. Other
degradation processes such as erosion corrosion and stress-cracking corrosion involve
mechanisms containing both mechanical and chemical aspects. Corrosion within centrifugal
pumps can be general in nature, affecting all wetted surfaces or highly localized affecting
only a small portion of a single component. It is often these highly localized forms of
corrosion that are the cause of corrosion related pump failure. Localized corrosion is not
easily identified during visual inspection and may be confined to a very small area making
the probability of discovery very low unless the examiner is highly experienced.
 Centrifugal pumps constitute some of the hardest working and most critical plant components
within industry. There are many physical and chemical mechanisms activity working to
damage pump components. Many of the damaging mechanisms are occurring simultaneously
and have the potential to accelerate each other.

 As the direct result of existing damaging producing chemical and hydrodynamic by-
products, new damaging mechanisms can be initiated. Although significant corrosion
mechanisms have been discussed through the discourse of this paper, there are many others
too specific to review within the cope. A significant conclusion drawn from the many
damaging mechanisms discussed is that knowledge of the service water chemistry plays (and
how it may change) is paramount for selecting the most durable pump materials package. It
therefore stands to reason that to achieve the best possible leverage of OEM pump supplier
knowledge and experience, spending resources to quantify water chemistries and potential
changes to these chemistries is a wise investment.

7) Conclusion
 This project is about to study the adverse effect of sea water corrosion in centrifugal
pump to justify our topic we was done the first study of all types of corrosion second sea
water properties third type of material used i.e. Duplex Stainless steel 2205and in
addition types of Corrosion occur due to sea water in particular coastal area.
 Similarly refer research papers related to sea water salinity effect on material,
temperature effect, corrosion due to microorganism, effect corrosion on stainless steel in
aqueous environment, Corrosion solution worldwide.
 To reduce that corrosion the possible solutions are Coating, Material Change, Painting, as
well as Anodic Cathodic Protection.
 These Project gives the study about world’s most concentrated topic Corrosion in
Thermal Power Plant which reduce 2-3% nation‘s GDP.

8) Future Work
 Immersion Test
 Rate Of Corrosion Measurement
 Cathodic/Anodic Protection
 Coating
 Changing Material
 Study the Microstructure of Material

9) References
[1] Adani power Ltd., Mundra, www.adanipower.com
[2] Corrosion Introduction – Definitions and Types www.nptel.com
[3]Duplex Stainless steel-research.stainless@outokumpu.com
[4]British stainless steel association- www.bssa.org.uk
[5]corrosion in pumps by Ronald S. Miller
[6] Effect of microstructure on impact toughness of duplex and super duplex stainless steels by
S. Topolska a,*, J. Łabanowski b- journal of material and manufacturing achievement
[7] Effect of temperature and Cl-
concentration on pitting of 2205 duplex stainless steel by Dong
Chaofang, Luo Hong, Xiao Kui, Liu Qian, Sun Ting,Li Xiaogang
[8] corrosion of steels induced by microorganisms by Biljana S. Maluckov
[9] Corrosion of duplex stainless steel in sea water-Bengt Wallen Sweden 1998
[10] The Corrosion of Centrifugal Pumps in Aqueous Environments by Frank Gall

PROJECT 7TH SEM REPORT

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