Lecture 16: ICCP and Anodic Protection

• ICCP Principle and Applications
• Anodic Protection
• Comparison of Protection: Cathodic or Anodic?
• Summary
• Reading Assignments

                            [Previous Lecture] [Course Outline] [General Info] [Study Guide]

ICCP Principle and Application

In Impressed Current Cathodic Protection, electrons from an external DC power source are pumped into the steel structure and cathodically polarise it by typically 200 mV below the corrosion potential (like the case in sacrificial anode cathodic protection).

ICCP can be used to protect

• buried pipelines
• offshore structures
• ship's hull

Combined use of cathodic protection with paints is ideal for steel structure as

(1) defects in paints will be cathodically protected against corrosion

(2) most surface area is painted thus the required cathodic protection current is small

Anodic Protection
In anodic protection, the metal to be protected is made the anode

corrosion products protective

active-passive metals/alloys

Cathodic Protection or Anodic Protection? -The Comparison

	Cathodic Protection	Anodic Protection
Advantages	can be used for all metals installation cost is low corrosion rate can be reduced to zero	can be used in extremely aggressive environment applied current is direct measure of corr rate operating conditions can be easily controlled operation cost low
Limitations	can only be used in weak to moderate environment operating conditions must be determined by empirical testing.	only applicable to active-passive metals installation cost is high

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Summary

ICCP cathodic protection differs from sacrificial anode cathodic protection in that an external current is applied from a power source. In anodic protection, the metal to be protected is made the anode by making the potential more positive (above the corrosion potential).

Reading Assignments

To reinforce learnings in this lecture read pages 393-404 (textbook)
To prepare yourself for the next lecture read pages all previously cited (textbook)

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