Summary: Evolution of Probe-Type MMO/DSA Anodes

1. Invention of MMO/DSA Anodes (1960s)

Inventor: Henri Bernard Beer.

Innovation: Mixed RuO₂–TiO₂ coatings on titanium substrates.

Purpose: Replace consumable anodes (graphite, lead, etc.) with stable, corrosion-resistant electrodes.

Initial Use: Chlor-alkali industry — achieving long life, dimensional stability, and reduced energy consumption.

2. Expansion into Cathodic Protection (1980s)

MMO/Ti anodes were adopted for impressed current cathodic protection (ICCP) systems, replacing sacrificial anodes (Zn, Al, Mg).

Advantages: Longer service life, lower maintenance, stable potential, and uniform current output.

Applications: Pipelines, offshore structures, tanks, and buried steel systems.

3. Emergence of the Probe-Type Design

Developed to solve installation and sealing challenges in confined or pressure-bound systems (e.g., pressure vessels, tanks, pipelines).

Engineering motivations:

Limited internal space → slim, through-wall installation.

High pressure or chemical containment → sealed probe structure (O-rings, epoxy).

Simplified electrical connection and stress mitigation.

4. Early Challenges

• Sealing issues (leakage, shorting, gas ingress).
• Mechanical stress from thermal/pressure fluctuations.
• Uneven current distribution reducing efficiency.
• Coating degradation due to poor adhesion or material mismatch.

5. Subsequent Improvements

• Sealing upgrades: High-grade elastomers, epoxy systems, pressure-rated fittings.
• Structural refinements: Optimized probe geometry, reinforced joints, stress-relief features.
• Coating/material advances: Improved Ti substrate purity and oxide composition (RuO₂, IrO₂, Ta₂O₅).
• Quality assurance: Long-term field validation, factory testing for sealing, insulation, and conductivity.

6. Typical Applications

• Oil and gas: Well casings, injection wells, pipelines (especially with through-wall connections).
• Water/oil storage tanks: Internal corrosion prevention at gas–liquid interfaces.
• Modern systems: Commercial probe-type MMO anodes (e.g., Jennings Anodes) for confined or high-pressure environments.

7. Evolutionary Significance

• The probe-type MMO anode is not a distinct invention but a refined evolution of MMO/DSA technology adapted to specialized cathodic protection challenges.
• It represents a practical response to spatial, sealing, and operational demands in modern corrosion control engineering.