Cathodic Protection of Pipeline ( corrosion )

1 - principles of corrosion

• Introduction
• 1.1 importance of corrosion studies
• 1.2 Examples of Catastrophic Corrosion Damage
• 1.2.1 Sewer explosion, Mexico
• 1.2.2 Loss of USAF F16 fighter aircraft
• 1.3 corrosion definition
• 1.3.1 THE CONSEQUENCES OF CORROSION
• 1.4 corrosion principles
• 1.5 classification of corrosion

2. Forms of corrosion

• 2.1 Uniform corrosion or general corrosion
• 2.1.1 Mechanisms
• 2.1.2 Prevention or Remedial Action
• 2.2 Galvanic
• 2.2.1 Mechanism
• 2.2.2 Important factors in galvanic corrosion
• 2.2.3 Prevention or Remedial Action
• 2.3 crevice
• 2.3.1 MECHANISM
• 2.3.1.2 Stage two of a crevice formation (Restricted Convection)
• 2.3.1.3 Stage three of a crevice formation(Obstruction and Electromigration)
• 2.3.2 Prevention
• 2.4 Pitting
• 2.4.1 Characteristics of Pitting Corrosion
• 2.4.2 Mechanisms
• 2.4.3 Prevention or Remedial Action
• 2.5 Stress-corrosion cracking (SCC)
• 2.5.1 Mechanisms
• 2.5.2 Prevention
• 2.6 intergranular corrosion
• 2.6.1 Mechanisms
• 2.6.2 Prevention
• 2.7 selective leaching
• 2.7.1 Mechanisms
• 2.7.2 Prevention
• 2.8 Erosion Corrosion
• 2.8.1 Mechanism
• 2.8.2 Prevention or Remedial Action

3. Environment Effects

• 3.1 Atmospheric Corrosion
• 3.1.1 Types of atmospheres and environments
• 3.1.2 Important practical variables in atmospheric corrosion
• 3.1.2.1 Time of wetness
• 3.1.2.2 Sulfur dioxide
• 3.1.2.3 Chlorides
• 3.1.2.4 Nitrogen compounds
• 3.1.2.5 Temperature
• 3.2 Corrosion By Water
• 3.2.1 Effect OF Electrolyte Composition
• 3.2.1.1 Conductivity
• 3.2.1.2 Hydrogen Ion Concentration (pH)
• 3.2.1.3 Dissolved Gases
• 3.2.1.3.1 Oxygen
• 3.2.1.3.2 Carbon Dioxide
• 2.1.3.3 Hydrogen Sulphide
• 3.2.1.3.4 Chloride Ions
• 3.2.2 PHYSICAL VARIABLES
• 3.2.2.1 Temperature
• 3.2.2.2 Pressure
• 3.2.2.3 Velocity
• 3.2.2.4 Erosion/Velocity
• 3.3 Soil in the Corrosion Process
• 3.3.1 The Corrosion Process in Soil
• 3.3.2 Properties of Soils Related to Corrosion
• 3.3.3 Types of Soil Moisture

4. corrosion protection

• 4.1 FACTORS THAT CONTROL THE CORROSION RATE
• 4.2 Material selection
• 4.2.1 Alloy steels
• 4.2.2 Stainless steels
• 4.2.1.2 Low-alloy weathering steels
• 4.3 Corrosion Prevention
• 4.3.1 Conditioning the Metal This can be sub-divided into two main groups:

(a) Coating the metal, in order to interpose a corrosion resistant coating between metal and environment. The coating may consist of:

Coating type

• 1. Internal Lining
• 2. Fusion Bonded Epoxy (FBE) Powder Coating
• 3. Dual Fusion Bonded Epoxy (D-FBE ) coating
• 4. Bitumen / Asphalt Enameln (AE) Coating
• 5. Three Layer Polypropylene (3LPP) Coating
• 6. Three Layer Polyethylene (3LPE) Coating
• 7. Concrete Weight Coating (CWC)
• 8. Polyurethane Insulation Coating
• 9. Polypropylene Insulation Coating

(b) Alloying the metal

• 4.3.2 Conditioning the Corrosive Environment
• 4.3.3 Electrochemical Control

5. preparation of pipeline

• 5.1 Stringing
• 5.2 Trenching
• 5.3 Pipe Bending
• 5.4 Welding
• 5.5 Coating
• 5.6 Lowering In
• 5.7 Backfilling
• 5.8 Hydrostatic Test
• 5.9 Restoration
• 5.10 Open Cut River and Stream Crossings
• 5.11 Directional Drilling
• 5.12 Wetlands
• 5.13 road Bores