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PIPE CORROSION

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									PIPE CORROSION

  GVHD: Thầy Nguyễn Vĩnh Khanh
  SVTH: Phan Thị Vân Anh-60500073
        Trịnh Tôn Thanh Hòa-6050
        Ngô Văn Quốc-6050
•   Introduction
•   Corrosion mechanism
•   Factors influencing corrosion
•   Methods of corrosion control
                    Introduction
• The corrosion of a metal is a
  chemical process by which the
  metai is oxidized. The tendency
  to corrode in a given
  environment varies with the
  particular metal.
• Corrosion is the result of a
  chemical reaction between a
  metal and its surroundings
  during which the metal is
  oxidized
                  Problem
• Cause increased economic costs.
• Cause serious health problems if toxic
Problem
Corrosion mechanism
         Corrosion mechanism
There are two basic mechanisms by which
 metals in electrolytes corrode

  • Electrolytic Corrosion

  • Galvanic Corrosion
         Corrosion mechanism
• Electrolytic Corrosion
        Corrosion mechanism
• Galvanic Corrosion
Corrosion mechanism
Corrosion mechanism
      Factors influencing corrosion

•   Type of metal used in pipe construction
•   The amount of exposed area to the water
•   The amount of dissolved oxygen in the water
•   Qualities of the water flowing through and
    around the system
    Methods of corrosion control
•   Materials resistant to Corrosion
•   Protective coatings
•   Cathodic protection
•   Corrosion Inhibitors
  Materials resistant to Corrosion
• Application Of Corrosion Performance Data To
  Selection Of Materials.
      • Materials Selection as Part of the Design
        Process.
      • Designing to Fit Available Materials.
• Use of Corrosion Resistance Data.
           Protective coatings
• A means for separating the surfaces that are
  susceptible to corrosion from the factors in the
  environment which cause corrosion to occur
• Examples of common coatings are asphalt,
  concrete, epoxies, polyvinyl chloride (PVC),
  and polyethylene
Protective coatings
Protective coatings
          Cathodic protection
• Cathodic protection is an electrical method of
  preventing corrosion on metallic structures
  which are in electrolytes such as soil or water
• Two basic methods of Cathodic protection
     • cathodic protection with galvanic anodes
     • impressed current cathodic protection
cathodic protection with galvanic
             anodes
cathodic protection with galvanic
             anodes



                           ZINC OR
                           MAGNESIUM
                           ANODE
impressed current cathodic protection
impressed current cathodic protection
       Corrosion Inhibitors
• a substance which retards corrosion when
  added to an environment in small
  concentrations”

                       Corrosion Inhibitor

                       • Amine, Amide and Imidazoline.
                       • Contains a volatile corrosion inhibitor
                       and an oil dispersible-water dispersible
                       persistent film forming inhibitor
                       • Recommended for CO2 Gas
Corrosion Inhibitors
Corrosion Inhibitors
        Corrosion Inhibitors
• Corrosion Inhibitor function by one or more
  of these mechanisms:
     • adsorption as a thin film on the surface of a
       corroding material
     • By inducing formation of a thick corrosion product
     • By forming a passive film on the metal surface
     • By changing characteristics of the environment
       either by producing protective precipitates or by
       removing or inactivating an aggressive constituent.
       Corrosion Inhibitors
The most important corrosion inhibitors
 are passivating, cathodic, organic,
 precipitate-inducing, and vapor-phase
 corrosion inhibitors.
                 References
• “Corrosion At Pipe Supports Causes & Solutions” -
  Jim Britton, InterResources Inc.
• “Corrosion and Cathodic Protection Theory” -
  James B. Bushman, P.E Principal Corrosion
  Engineer, Bushman & Associates, Inc Medina, Ohio
  USA
• “Corrosion protection” - Edited under the HSE
  Technical Support Agreement by BOMEL Ltd
• “Offshore Cathodic Protection 101:what Is It And
  How Does It Work?” - Dick Baxter & Jim Britton

								
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