Buried Iron Pipe Coating with Pore Sealing and Bactericidal Protection
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Solution Overview
Problem
Buried iron pipes face significant corrosion challenges due to heterogeneous soils and the presence of sulphate-reducing bacteria, which existing coatings fail to adequately address, especially in terms of cost-effectiveness and comprehensive protection.
Innovation Solution
A two-layer outer coating system for iron pipes, comprising a porous zinc-aluminum-copper alloy layer deposited by electric arc metallization and a porous organic resin-based paint layer applied without compressed air, with the latter capable of sealing pores and regulating electrochemical reactions, while incorporating bactericidal agents to inhibit bacterial activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer coating is used to protect buried iron pipes, then the coating structure is simple and cost is reduced, but the corrosion protection effectiveness is insufficient especially against sulfate-reducing bacteria
Solution Approach 1:
The coating is divided into two distinct functional layers: a porous metallized layer providing corrosion protection and a separate paint layer providing pore sealing and biocidal protection. This segmentation allows each layer to optimize its specific function, with the metallized layer offering sacrificial protection and the paint layer providing biological protection against sulfate-reducing bacteria, thereby resolving the contradiction between protection effectiveness and structural simplicity.
Solution Approach 2:
The invention uses a composite coating structure combining metallized material (zinc, aluminum, or their alloys) with an organic paint layer containing biocidal agents. This composite approach integrates the electrochemical protection of metals with the biological protection of organic coatings, achieving superior corrosion and biocorrosion resistance that neither material could provide alone.
2Reliability
If the paint layer is made impermeable to block all pores, then corrosion protection is improved, but the cost of materials and application increases
Solution Approach 1:
The paint layer is applied selectively to seal pores in the metallized coating where needed for corrosion and biocorrosion protection, rather than requiring complete impermeabilization of the entire pipe surface. This local quality approach focuses protective materials on the critical interface between the metallized layer and the environment, reducing overall material consumption while maintaining effective protection.
3Manufacturing precision
If conventional spray deposition is used for the paint layer, then application speed is high, but the coating quality and pore-sealing effectiveness deteriorate
Solution Approach 1:
The invention changes the application parameters by using deposition methods without compressed air (such as gravity feed or pump-based systems) rather than conventional spray deposition. This parameter change allows for better control of paint layer formation, ensuring proper pore sealing and coating quality while maintaining acceptable application rates through optimized deposition processes.
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 coating system provides enhanced corrosion protection, effectively blocking pores and inhibiting bacterial activity, while maintaining a competitive cost and facilitating application on both corrosive soil and water contact areas.
Implementation Method 1
deposition by metallization, preferably by electric arc, on the pipe element, of the first layer
Implementation Method 2
deposition by metallization, preferably by electric arc
Implementation Method 3
a second porous layer disposed on the first layer and capable of sealing pores of the first layer
Data Source
AI summary
The invention relates to an outer coating (9) for a buried pipe element (7) based on iron, especially cast iron, the outer coating comprising a first porous layer (11) and a second porous layer (13) arranged on the first layer (11) and able to block pores of the first layer. The first layer comprises substantially pure zinc or a zinc alloy or pseudo-alloy, the alloy or pseudo-alloy comprising, by weight, at least 50% of zinc, and preferably between 0.5% and 40% of aluminum. The second layer comprises paint based on at least one organic resin, the paint being either single-component in an organic solvent, or dual-component. At least one of the first layer and the second layer comprises a bactericide agent. The invention also relates to a corresponding coated pipe element and method for depositing the coating.