Distributed Sacrificial Anode Coating for Subsea Cathodic Protection
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Solution Overview
Problem
Conventional sacrificial anode systems for cathodic protection of subsea metallic structures require significant anode mass, leading to increased weight and complexity, and are prone to issues like blistering and separation due to corrosion, especially in multilayer coating systems.
Innovation Solution
A cathodic protection system utilizing a distributed sacrificial anode (DSA) approach, where a metallic second-layer coating with an open circuit potential equal to or more negative than the first-layer coating is applied over the entire surface, reducing the total cathode area and anode mass, while maintaining equivalent protection levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sacrificial anode systems are used for cathodic protection, then adequate corrosion protection is provided, but significant anode mass is required leading to increased weight and complexity
Solution Approach 1:
The patent divides the sacrificial anode function into two separate layers: a first layer providing corrosion protection and a second layer providing sacrificial anode function. This segmentation allows each layer to be optimized independently, reducing the total anode mass required while maintaining adequate corrosion protection through the distributed architecture.
2Reliability
If conventional sacrificial anode systems are used, then corrosion protection is achieved, but the system becomes more complex with multilayer coating systems
Solution Approach 1:
The patent merges the corrosion protection function and sacrificial anode function into a single integrated coating system with two layers. This combination eliminates the need for separate anode attachments and complex wiring, reducing overall system complexity while maintaining reliable corrosion protection through the coordinated action of both layers.
3Reliability
If multilayer coating systems are used with conventional anodes, then corrosion protection is provided, but blistering and separation occur due to corrosion
Solution Approach 1:
The patent applies preliminary protective action by having the first layer corrode in controlled manner before the substrate is affected. This preliminary corrosion of the first layer creates a protective environment that prevents blistering and separation, maintaining coating integrity while providing effective corrosion protection to the underlying structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The DSA system significantly reduces anode mass by up to 92% and minimizes defects, improving current distribution and reducing Ohmic drop, while maintaining effective corrosion protection, as demonstrated by reduced corrosion and calcareous deposit formation in subsea environments.
Implementation Method 1
A sacrificial anode in the form of a metallic second-layer coating distributed over the first-layer coating, the second layer coating having an open circuit potential that is equal to the metallic first-layer coating or being anodic to the first-layer coating
Implementation Method 2
a metallic first-layer coating which is anodic to the substrate, bonded to the component or substrate and electrically conductive
Data Source
AI summary
A method to reduce the total anode mass of a cathodic protection system by reducing or eliminating the total cathode area is disclosed, the system comprising: a metallic first-layer coating which being anodic to the component or substrate to be protected, bonded to the component or substrate and electrically conductive. A sacrificial anode in the form of a metallic second-layer coating is distributed over the first-layer coating. The second layer coating has an open circuit potential that is equal to the first-layer coating or being anodic to the first-layer coating and to the substrate, the second-layer coating electrically conductive, bonded to the first-layer coating and exposed to the surrounding environment.