Pipeline Cathodic Protection Using Pre-formed Metallic Rings
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Solution Overview
Problem
Conventional methods for providing cathodic protection to pipelines, such as using sacrificial anodes connected via welding, are prone to hydrogen-induced stress cracking and lack assurance of fixation, especially when pipelines need to be bent or reeled for laying.
Innovation Solution
A pipeline system featuring pre-formed metallic rings around pipes with electrical connections to sacrificial anodes, allowing for cathodic protection without welding, ensuring secure fixation and compliance during bending or reeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sacrificial anodes are connected to the pipeline by welding, then electrical connection is achieved, but hydrogen induced stress cracking occurs at the weld toe
Solution Approach 1:
A metallic ring is introduced as an intermediary component between the sacrificial anode and the pipeline. The ring is fitted around the pipeline and provides a connection point for the anode, eliminating direct welding to the pipeline while ensuring electrical continuity for cathodic protection.
Solution Approach 2:
The connection system is divided into separate components: the pipeline, the metallic ring, and the sacrificial anode. This segmentation allows the anode to be connected to the ring rather than directly welded to the pipeline, avoiding stress concentration at the pipeline wall.
2Reliability
If long sleeves are used to protect the pipeline, then corrosion protection is improved, but the sleeves become difficult to bend and ree l onto drums
Solution Approach 1:
The protective structure is divided into short metallic rings instead of long continuous sleeves. Each ring is independently fitted around the pipeline at specific locations, providing corrosion protection while allowing the pipeline to be bent and reeled without compromising the integrity of the protective elements.
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
This solution prevents hydrogen-induced stress cracking and ensures reliable cathodic protection without the need for welding, enabling the pipeline to be effectively laid and reeled while maintaining structural integrity.
Implementation Method 1
one or more electrical connections attached to the or each metallic ring and to at least one sacrificial anode to allow an electrical current to flow between the pipeline and one or more of the sacrificial anodes
Implementation Method 2
the addition of anodes, in particular sacrificial anodes, made from a metal which degrade preferentially to the pipe material
Data Source
AI summary
A pipeline comprising one or more pipes, the pipeline having: one or more sacrificial anodes to provide cathodic protection; one or more pre-formed one-piece integral metallic rings around at least one pipe; and one or more electrical connectors attached to the or each metallic ring and to at least one sacrificial anode to allow an electrical current to flow between the pipeline and one or more of the sacrificial anodes. Each metallic ring has a one-piece form and can be fitted to the pipe without welding.