Cp for Water Facility

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CATHODIC PROTECTION FOR PORT FACILITIES

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Contents
• • • • • • What causes corrosion What is CP and how does it work? Galvanic vs. impressed current Electrolytes (or where can I use CP) Marine applications Condition assessments

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What is Corrosion?

Corrosion is defined as the degradation of a material due to a reaction with it’s environment.
Metals require energy to process them from their native state to a usable material. Nature wants to reverse this.

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Corrosion Process

• Normal concrete has a very high pH (alkalinity) and this provides protection against corrosion of the embedded steel (passivation)
• Chlorides and other salts, over time can penetrate the concrete matrix reducing the pH causing the reinforcing steel to

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Good Concrete

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Corrosive Environment
De-icing salts, coastal chloride deposition, heat, humidity, CO 2, F/T

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• Coastal structures
• Highways, Bridges • Sea Walls and other Marine Structures • Industrial Facilities

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The Corrosion Process

• Once the chlorides penetrate to the reinforcing steel, the concrete’s high pH no longer passivates the steel. • A typical galvanic corrosion cell forms and corrosion can occur quite quickly.

_____________________________CORRTECH Corrosion Cell
Electrolyte Fe++ H0 H0 Conventional Current Flow H0 H0

H0

2eAnode
Electron Current Flow Metallic Path

Cathode

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The Corrosion Damage Begins
Rust expands volume 5-10x’s Internal stress + 5,000 psi
Electron Migration (e-)

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Corrosion Cell Elements
• • • • Anode Cathode Metallic path Electrolyte

Eliminate