Cathodic Protection Corrosion Control System

Explore the fundamentals of corrosion, including electrochemical and chemical reactions, and learn how anode, cathode, and electrolyte drive degradation and the main corrosion forms.

Explore how electrode potential acts as the driving force in corrosion, forming galvanic cells between anode and cathode in electrolytes. Learn about reference electrodes and field measurements.

Explore reference electrodes such as saturated calomel and silver chloride, potentials versus standard hydrogen electrode, and how temperature and concentration corrections use Nernst equation to assess corrosion via Faraday's law.

The Pourbaix diagram illustrates stability boundaries for water and iron species, showing hydrogen and oxygen lines and regions of corrosion, passivation, and immunity.

Explore polarization in cathodic protection, including activation and concentration polarization from kinetics and thermodynamics, open circuit potentials, and the event diagram of current versus potential.

Explore how cathode and anode polarization vary with current and voltage. Learn how reactant concentration, dissolved oxygen, hydrogen ions, temperature, agitation, surface area, coating integrity, and currents drive charge transfer.

Analyze how increasing polarization at the anode and cathode influences driving voltage, current, and corrosion in a cathodic protection system, considering circuit resistance, time, and EMF effects.

Apply cathodic protection to convert the protected metal to a cathode. Inject current to polarize toward the anode's open circuit potential, reducing corrosion.

This lecture explains cathodic protection criteria, defining -850 mv vs copper sulfate as the potential criterion and 100 mv polarization shift, measurement methods, and temperature and sulfate-reducing bacteria adjustments.

Describe galvanic sacrificial anode systems and semi-inert anodes with a power supply, including core components and how a sufficient potential difference protects steel structures.

Explore galvanic (sacrificial) anode systems, including anode backfill in soil and water, alloyed electrodes, wiring, to provide ionically conductive paths, minimize resistance, and protect offshore structures and underground storage tanks.

Explore the impressed current cathodic protection system, detailing anode types, carbon backfill, power supplies, wiring, and the contrasts with galvanic anodes to prevent corrosion.

Learn cathodic protection design fundamentals, choosing galvanic or current systems and calculating current requirements, ground-bed layout, and power needs from pipeline and environmental factors.

Explore calculating cathodic protection current for coated and bare steel, using coating percentage, environment, and field tests, including minimum voltage drop, coating resistance, and polarization methods.

Calculate cathodic protection current and circuit resistance by analyzing structure and cable resistances, anode and cathode potentials, and vertical or horizontal anode layouts with backfill.

Calculate cathodic protection system capacity and lifetime by linking electrochemical capacity to current requirements, anode weight, and efficiency factors; apply galvanic and improvised current design methods with example calculations.