CorroZone: Fundamentals of Cathodic Protection

A plain-language audio walk through the fundamentals and design of cathodic protection — section by section, from CorroZone's Cathodic Protection course. From the core electrochemistry and CP concepts to current distribution, potential gradients and CP design principles. Free, no login. From CorroZone.Full courses here: https://corrozone.com/courses#udemy

30 episodes

2mo ago latest

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Episodes 30

Master the Fundamentals of Cathodic Protection — Course Introduction
3mo ago · 5:00
Full courses here: https://corrozone.com/courses#udemy A big-picture tour of the whole cathodic protection course — how its four sections build from the fundamentals, through core CP assessment concepts and current distribution, to design principles. What this course covers A comprehensive, end-to-end course on cathodic protection (CP), organised into four sections that build on each other. Section One, Fundamental Concepts, lays the groundwork — what CP is, free corrosion, how applying a current to a corroding surface changes things, how charge is transported through electrolytes, the two mai
01 · Introduction to Section 1: Fundamental Concepts
3mo ago · 7:00
Full courses here: https://corrozone.com/courses#udemy Introduces Section 1 by placing cathodic protection among corrosion-control strategies, explaining why corrosion matters, contrasting the sacrificial anode and impressed current approaches, and mapping the four sections ahead. What you'll learn Explain what cathodic protection is and why it's effective at the electrochemical level Place cathodic protection among the broad corrosion-control strategies and understand why it's used alongside coatings Distinguish between sacrificial anode and impressed current (ICCP) systems and their key comp
02 · What is cathodic protection?
3mo ago · 12:00
Full courses here: https://corrozone.com/courses#udemy Explains what cathodic protection is at the electrode level — shifting a metal's potential negative to suppress dissolution — and contrasts the two ways of doing it: self-powered sacrificial anodes and externally powered impressed current systems. What you'll learn Explain how a metal corrodes via a corrosion cell and settles at its mixed potential, E-corr Describe cathodic polarization — shifting the potential negative — as the core operating principle of CP, with a defined protective window Describe sacrificial anode CP and the common an
03 · Free Corrosion
3mo ago · 12:00
Full courses here: https://corrozone.com/courses#udemy Examines free corrosion — the natural, unprotected state of a metal in an electrolyte — covering the simultaneous anodic and cathodic reactions, the corrosion potential and current density they settle at, and the environmental and material factors that govern the rate of attack. What you'll learn Describe the simultaneous anodic (metal dissolution) and cathodic (oxygen reduction or hydrogen evolution) reactions at free corrosion Explain mixed potential theory — how the surface settles at the corrosion potential E-corr where anodic and cath
04 · Effect of Applying a Current to a Corroding Surface
3mo ago · 19:00
Full courses here: https://corrozone.com/courses#udemy Traces what happens when external current is applied to a corroding surface — how the anodic and cathodic rates rebalance, how cathodic polarisation shifts the potential negative, and how this yields three practical states: underprotection, adequate protection, and overprotection. What you'll learn Explain how applying external current raises the cathodic rate and shifts the potential negative to a new balance (E-on), defining cathodic polarisation Use the Evans diagram and the net-current relationship to relate applied current, potential
05 · Transport of Electrical Charge in Electrolytes
3mo ago · 21:00
Full courses here: https://corrozone.com/courses#udemy Follows the cathodic protection current the rest of the way around the loop — through the electrolyte. Covers how charge moves ionically through soil, seawater and concrete pore water, how conductivity and resistivity shape current distribution, and why the resulting IR drop and potential gradients drive voltage demand and distort measurements. What you'll learn Distinguish electronic conduction in metal from ionic conduction in the electrolyte, where cations and anions carry the current between anode and structure Use conductivity (sigma)
06 · Cathodic Protection Systems
3mo ago · 27:00
Full courses here: https://corrozone.com/courses#udemy Turns the principle of cathodic protection into hardware, comparing the two main industrial system types — sacrificial (galvanic) anode systems and impressed current systems. Covers their shared four elements, components, strengths and limitations, and how to choose between them. What you'll learn Identify the four elements every CP system shares — protected structure (cathode), anode, electrolyte and metallic continuity — and how they form a circuit Explain how a sacrificial anode system uses the galvanic potential difference of zinc, mag
07 · Measuring Potentials
3mo ago · 24:00
Full courses here: https://corrozone.com/courses#udemy Explains where the single voltmeter number behind every CP decision actually comes from. Covers why a measured potential is always a difference against a reference electrode, the main reference electrode types and their conversions, how to set up a field measurement, and the error sources — above all IR drop — that contaminate readings. What you'll learn Understand that a CP potential is always a potential difference — structure potential minus reference potential — so both terms must be controlled Select and maintain the right reference e
08 · Introduction to Section 2: Core CP Concepts
3mo ago · 7:00
Full courses here: https://corrozone.com/courses#udemy Sets the scene for Section 2, the bridge between Section 1's electrochemical theory and CP engineering practice. Maps the six interrelated concepts that define real-world CP assessment: ohmic effects/IR drop, near-surface reactions, Pourbaix thermodynamics, protection criteria, overprotection, and potential transients with OFF-potential measurement. What you'll learn See how Section 2 bridges Section 1's electrochemical theory to the practical assessment of whether a CP system is doing its job Understand why ohmic effects and IR drop must
09 · Ohmic Effects
3mo ago · 21:00
Full courses here: https://corrozone.com/courses#udemy Examines ohmic effects — IR drop — that sit underneath almost every CP potential measurement. Shows why the ON potential isn't the true polarised state, how the soil voltage gradient biases readings more negative, the four factors that control IR drop magnitude, and the practical rules and instant-off technique for honest assessment. What you'll learn Define IR drop as Ohm's law (V = I R) applied to the resistive electrolyte path between the reference electrode and the structure surface Understand that the measured ON potential equals the
10 · Electrochemical reactions and their effects
2mo ago · 18:00
Full courses here: https://corrozone.com/courses#udemy Cathodic protection isn't only an electrical intervention — it actively changes the chemistry at the protected surface. This episode unpacks the cathodic reactions (oxygen reduction and hydrogen evolution), the local pH rise and calcareous deposits they cause, and the resulting risks of cathodic disbondment and hydrogen damage. What you'll learn Identify the two dominant cathodic reductions in CP environments — oxygen reduction (ORR) and hydrogen evolution (HER) — and what sets the balance between them (dissolved oxygen, potential, pH, tem
11 · Thermodynamic Perspective on Cathodic Protection
2mo ago · 22:00
Full courses here: https://corrozone.com/courses#udemy Where does a 'safe' cathodic protection potential actually come from? This episode works through the thermodynamics — Gibbs free energy, the Nernst equation and the Pourbaix diagram's immunity, passivation and active-corrosion regions — to show why CP works, where the minus 850 mV criterion comes from, and where the thermodynamic view falls short. What you'll learn Distinguish thermodynamics (is corrosion possible?) from kinetics (how fast?), and explain why immunity guarantees protection while kinetics only sometimes saves you State the t
12 · Protection Criteria
2mo ago · 25:00
Full courses here: https://corrozone.com/courses#udemy Applying current isn't the goal — reaching a measurable, verified condition is. This episode lays out the three dominant CP protection criteria (the -850 mV vs CSE potential, the 100 mV polarisation shift, and the 100 mV depolarisation test for reinforced concrete), why IR drop must be removed via instant-off measurements, and how criteria are applied at commissioning and in routine surveys. What you'll learn Explain why a measured potential indicates corrosion control, and how cathodic polarisation past the immunity threshold suppresses d
13 · Overprotection
2mo ago · 21:00
Full courses here: https://corrozone.com/courses#udemy Going more negative isn't always safer. This episode covers overprotection — driving the structure potential below the safe protection window — its causes, the three principal damage mechanisms (coating disbondment, excessive hydrogen evolution, and hydrogen embrittlement), how to recognise it in the field with IR-drop-free measurements, and how to prevent it through potential control, anode placement and coating selection. What you'll learn Define overprotection and the protection window — the floor near -850 mV vs CSE and a ceiling commo
14 · Potential Transients
2mo ago · 22:00
Full courses here: https://corrozone.com/courses#udemy A CP potential is more than a single meter reading — the revealing part is how it behaves the moment you switch the current on or off. This episode explains the potential transient: the capacitive double layer, the three switch-off regimes (IR elimination, double-layer discharge, chemical relaxation), why instant-off must be caught within milliseconds, and how transient shape diagnoses coating condition. What you'll learn Explain why the potential doesn't change instantly when current is switched — the metal-electrolyte interface behaves l
15 · OFF Potential Measurement
2mo ago · 21:00
Full courses here: https://corrozone.com/courses#udemy How the OFF potential measurement removes the IR-drop error from cathodic-protection readings. Covers why ON potentials overstate protection, what the instant-off represents electrochemically, how to capture it in the field, and how to use ON-versus-OFF data to assess protection. What you'll learn Explain why the ON potential overstates protection: it equals the true polarised potential plus the IR drop through the electrolyte, an error that varies with soil resistivity, current magnitude, electrode placement and distance to the anode Desc
16 · Introduction to Section 3: Current Distribution and Potential Gradients
2mo ago · 6:00
Full courses here: https://corrozone.com/courses#udemy A short bridge into Section 3, which extends CP assessment from a single measurement point to the whole structure. It explains why current distribution is the master idea and previews the four lectures ahead: potential gradients, remotely placed anodes, stray current corrosion, and potential decay. What you'll learn Recall what Section 2 equipped you with: reading potentials correctly despite IR drop, the electrochemistry of protection, protection criteria, overprotection risks, and getting meaningful OFF potentials Explain why single-poin
17 · Potential Gradients in the Environment
2mo ago · 20:00
Full courses here: https://corrozone.com/courses#udemy How cathodic-protection current leaves a potential-gradient footprint in the electrolyte, why that gradient is the physical origin of IR drop, and how it drives non-uniform protection. Covers E = rho*J, the gradient around hemispherical and cylindrical anodes, what a reference electrode actually samples, and the three controlling variables. What you'll learn Derive the potential gradient from Ohm's law in the electrolyte, E = rho * J, and explain why it is steep where current density is high (at the anode, at coating holidays) and shallow
18 · Remotely Placed Anodes
2mo ago · 21:00
Full courses here: https://corrozone.com/courses#udemy Why engineers often place CP anodes far from the structure: remote placement is a geometric strategy for uniform current distribution that also helps current get around shielding. Covers the distance trade-off against circuit voltage, groundbed design and types, distributed anode systems, and how to verify performance. What you'll learn Explain why a close anode causes non-uniform protection (local overprotection plus remote underprotection) and how remote placement makes the arriving current density far more uniform along the structure De
19 · Stray Current Corrosion
2mo ago · 20:00
Full courses here: https://corrozone.com/courses#udemy Stray current corrosion: damage driven by external DC currents that leave their intended circuit and flow through buried metal. Covers the entry (cathodic) and exit (anodic) zones, Faraday's-law metal loss, the worsening effect of coating holidays, the main sources, how to detect it, and how to mitigate it. What you'll learn Explain the mechanism: stray current follows the path of least resistance into buried metal, creating a cathodic (protected) entry zone and an anodic (corroding) exit zone, often tens to hundreds of metres apart Quanti
20 · Potential Decay
2mo ago · 30:00
Full courses here: https://corrozone.com/courses#udemy Why a structure's potential keeps rising after you switch cathodic protection current off — and how to read that decay curve as a diagnostic of coating condition, interference, and how well protected you really are. What you'll learn Explain potential decay as the sequential relaxation of stored polarisation — double-layer discharge (ms to seconds), concentration-gradient relaxation (seconds to minutes), and calcareous-deposit reversal (hours to days) Read the decay curve from the instant-off potential to the fully depolarised E_corr, and
21 · Introduction to Section 4: CP Design Principles
2mo ago · 7:00
Full courses here: https://corrozone.com/courses#udemy The turning point of the course: where assessment ends and design begins. This Section 4 introduction reframes the same CP science from reading measurements backward to a diagnosis toward reasoning forward from a requirement to a system specification. What you'll learn Distinguish CP assessment (start from measurements, work backward to a diagnosis) from CP design (start from a required outcome over a design life, work forward to a specification) Recall what Sections 1–3 built up: corrosion fundamentals and system types, the quantitative t
22 · Anode Materials and Their Properties
2mo ago · 27:00
Full courses here: https://corrozone.com/courses#udemy What an anode should be made of, and why it matters. A walk through the sacrificial alloys (zinc, magnesium, aluminium) and impressed-current materials (MMO, high-silicon cast iron, graphite, platinised titanium/niobium), the four electrochemical properties that compare them, and how to match a material to environment and system type. What you'll learn Describe how a sacrificial anode works through driving voltage (delta E), and contrast zinc, magnesium and aluminium alloys by open-circuit potential, capacity, efficiency and suitable envir
23 · Mass of Anode Material
2mo ago · 30:00
Full courses here: https://corrozone.com/courses#udemy Once you've chosen the anode metal, how much of it do you actually need? Building from Faraday's law to the working design equation — mass = I_p × T / (C_e × u_f) — with design life, electrochemical capacity, utilisation factor, coating breakdown, and three worked examples. What you'll learn Derive the anode-mass design equation, mass = Ip × T / (Ce × u_f), from Faraday's law linking dissolved mass to charge passed Distinguish theoretical from practical electrochemical capacity via current efficiency — roughly 90–95% for zinc and aluminium
24 · Anode's Resistance
2mo ago · 24:00
Full courses here: https://corrozone.com/courses#udemy The one number that can make or break an impressed-current design — the anode (groundbed) resistance. How current spreading sets it, the Dwight and Sunde formulas that quantify it, the factors that control it, and how it dictates the rectifier voltage and caps the current you can deliver. What you'll learn Explain anode (groundbed) resistance as a spreading resistance set by electrolyte resistivity and anode geometry, illustrated by the spherical-anode result rho/(2pir0) Apply the Dwight formula for a single vertical cylindrical anode (wit

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CorroZone: Fundamentals of Cathodic Protection

Episodes 30

Master the Fundamentals of Cathodic Protection — Course Introduction

01 · Introduction to Section 1: Fundamental Concepts

02 · What is cathodic protection?

03 · Free Corrosion

04 · Effect of Applying a Current to a Corroding Surface

05 · Transport of Electrical Charge in Electrolytes

06 · Cathodic Protection Systems

07 · Measuring Potentials

08 · Introduction to Section 2: Core CP Concepts

09 · Ohmic Effects

10 · Electrochemical reactions and their effects

11 · Thermodynamic Perspective on Cathodic Protection

12 · Protection Criteria

13 · Overprotection

14 · Potential Transients

15 · OFF Potential Measurement

16 · Introduction to Section 3: Current Distribution and Potential Gradients

17 · Potential Gradients in the Environment

18 · Remotely Placed Anodes

19 · Stray Current Corrosion

20 · Potential Decay

21 · Introduction to Section 4: CP Design Principles

22 · Anode Materials and Their Properties

23 · Mass of Anode Material

24 · Anode's Resistance

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Episodes 30

Master the Fundamentals of Cathodic Protection — Course Introduction

01 · Introduction to Section 1: Fundamental Concepts

02 · What is cathodic protection?

03 · Free Corrosion

04 · Effect of Applying a Current to a Corroding Surface

05 · Transport of Electrical Charge in Electrolytes

06 · Cathodic Protection Systems

07 · Measuring Potentials

08 · Introduction to Section 2: Core CP Concepts

09 · Ohmic Effects

10 · Electrochemical reactions and their effects

11 · Thermodynamic Perspective on Cathodic Protection

12 · Protection Criteria

13 · Overprotection

14 · Potential Transients

15 · OFF Potential Measurement

16 · Introduction to Section 3: Current Distribution and Potential Gradients

17 · Potential Gradients in the Environment

18 · Remotely Placed Anodes

19 · Stray Current Corrosion

20 · Potential Decay

21 · Introduction to Section 4: CP Design Principles

22 · Anode Materials and Their Properties

23 · Mass of Anode Material

24 · Anode's Resistance