Corrosion control

1. Mahatma Jyotiba Phule Rohilkhand University,
Bareilly.
Assignment Topic: Corrosion Control
Group name:
Satyam Gupta(19CH25)
Rakib Ali Khan(19CH24)
Azhar Uddin(19CH11)
To: Dr. Harish Sir

2. Corrosion Control
Corrosion can lead to countless environmental issues. For example, ships, tankers and pipelines are often
subject to the dangerous effects of corrosion. Corroded water systems can contaminate drinking water.
These serve as threats to the environment and mankind, so effective corrosion control methods should be
implemented to prevent the damaging effects of corrosion.
Methods of Corrosion Control Corrosion can be controlled in several ways:
• Cathodic protection (CP) - This technology uses direct current to counteract corrosion in structures
such as gas pipelines and storage tanks. This helps prevent the onset of corrosion and even stop it from
worsening.
• Linings and coatings - These serve as the main tools for fighting corrosion. They are usually applied in
combination with CP to achieve the highest level and most cost-effective corrosion protection. Coating
repair and additional coatings may also be applied as part of a corrosion control plan.

3.  Corrosion inhibitors - These are substances that, when placed in a certain environment, reduce the
corrosion rate of that environment for certain materials such as metal. These can extend the lifespan of
equipment and prevent failures and system shutdowns.
 Selection of materials - This refers to choosing materials that are corrosion resistant, such as special
alloys, plastic and stainless steel.

4. Corrosion Control - Material Selection
 Metallic Metals:
 Use proper metal for particular environment
 For reducing conditions, use nickel and copper alloys
 For oxidizing conditions, use chromium based alloys
 Non metallic Metals:
 Limit use of polymers in presence of strong inorganic acids
 Ceramics have better corrosion resistance but are brittle

5. Coating
Coatings protect and beautify the surfaces to which they are applied, enhance the value of everything
— from homes and manufactured products, to bridges and other structures. Coatings are varied, but
primarily fall into three categories: Architectural, Industrial, and Special Purpose.
Architectural Coatings
Architectural coatings, as both the largest sector and segment of the paint industry, comprises more
than half of the total volume of coatings produced annually in the United States.
Industrial OEM Coatings
Coatings applied in factory settings — providing functional properties that are crucial to the
performance and durability of a wide assortment of industrial, transportation, and durable consumer
products — are known as industrial original equipment manufacturer (OEM) coatings.

6. Special Purpose Coatings
This industry segment includes a wide array of divergent coatings. The one unifying
characteristic is that these coatings tend to be “field-applied,” as opposed to being
applied in a factory setting.

7. CORROSION CONTROL BY DESIGN
As an old adage says ‘corrosion prevention must start at the blackboard, at design stage, A good design is
no more costly than a bad design. A bad design is always more expensive than a good design in reality
1 - METALLIC CONTACTS
Bimetallic corrosion is serious and it occurs when two materials differing in electrochemical potential are joints
together, Corrosion of coupling will occur if a galvanic cell is formed, recall that a basic corrosion cell consists
of four parts, if one part is eliminated corrosion ceases.
Corrosion control is achieved by Avoid by direct contact between two metals by means insulating or by applying
protective coating.
In good design practice all joints should be designed to permanent and watertight

8. 2-DEPOSIT AND IMPURITIES
Deposit and impurities must be not allowed because they are caused formation of differential aeration
cells and allows the adsorption of moisture from air which lead to corrosion the passive surface of
steel may be destroyed by such deposit
3-CREVICES
Any point at which two metals surfaces are separated by a narrow gap is a possible cell ,moisture
enters the gap often in by capillary action , when the liquid is in contact with air the oxygen is
replenished but the centre of the water film becomes impoverished in oxygen and corrosion occur at
that poin

10. CATHODIC AND ANODIC CORROSION PROTECTION
The corrosion rates of submerged or buried metals can be controlled by both cathodic and anodic protection.
Cathodic protection is the most commonly used of these two methods, and it is widely used on carbon-steel
structures as well as on other structural metals. Anodic protection is used on occasion in the chemical-process
and mining industries where extremely aggressive environments are encountered. Anodic protection is most
commonly applied to stainless steels and other corrosion-resistant metals which need additional corrosion
resistance in certain environments.
Cathodic Protection
Definition
"The reduction or prevention of corrosion by making metallic structure as cathode in the electrolytic cell is
called cathodic protection“
Since there will not be any anodic area on the metal, corrosion does not occur.
There are two methods of applying cathodic protection to metallic structure.
(i) Sacrificial anodic protection (galvanic protection)
(ii) Impressed current cathodic protection

11. Sacrificial anodic protection method
• In this method, Metallic structure is connected to more anodic metal.
• Hence the corrosion is concentrated at the active metal only.
• And the active metal gets corroded slowly.
• The parent structure (cathodic part) is thus protected.
• The more active metal so employed is called sacrificial anode
• . Sacrificial anodes are commonly as Mg, Zn, Al and their alloys.
Anodic Protection
Anodic protection (AP) is a technique to control the corrosion of a metal surface by making it the anode of an
electrochemical cell and controlling the electrode potential in a zone where the metal is passive. The
application of anodic current to the structure decrease the rate of hydrogen evolution. To anodically protect the
structure, potentiostat is required. Potentiostat is an electronic device that maintains a metal at a constant
potential. The use of potentiostat is to shift corrosion potential into passive potential so that the corrosion of the
metal is stopped. The potential range depends upon the relationship between the metal and the environment.

12. Environmental control
In aeronautics, an environmental control system (ECS) of an aircraft is an essential component
which provides air supply, thermal control and cabin pressurization for the crew and passengers.
Additional functions include the cooling of avionics, smoke detection, and fire suppression.