Differential Eddy Current Probe for Multi-Depth Pipeline Defects
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Solution Overview
Problem
Eddy current nondestructive inspection methods face challenges in accurately inspecting buried and outer surface defects of pipelines due to the skin effect reducing penetration depth and high sensitivity leading to noise issues, making it difficult to quantify tiny defects.
Innovation Solution
A differential eddy current internal inspection probe with a single excitation coil and dual receiving coils, combined with direct current magnetization, allows for the inspection of inner, buried, and outer surface defects by utilizing the difference in induced magnetic fields to enhance signal-to-noise ratio and enable defect quantification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the excitation frequency of eddy current is increased to improve inspection accuracy, then the sensitivity is improved, but the penetration depth decreases due to skin effect
Solution Approach 1:
The probe is segmented into multiple receiving coils (first receiving coil and second receiving coil) with opposite winding directions, allowing independent signal acquisition from different depths. This segmentation enables the system to simultaneously detect both surface and buried defects by processing signals from different coil configurations
Solution Approach 2:
The patent changes the parameter of excitation frequency to a range that balances penetration depth and sensitivity. By optimizing the frequency parameter and combining it with differential signal processing, the system achieves both adequate penetration depth for buried defects and high sensitivity for defect detection
2Measurement precision
If the excitation frequency is increased to improve sensitivity, then the detection capability is improved, but the noise of the output signal increases making quantification difficult
Solution Approach 1:
The system uses differential feedback by comparing signals from the first and second receiving coils. The differential signal processing subtracts the noise components from both coils while preserving the defect signals, thereby reducing noise and improving signal-to-noise ratio for accurate quantification
Solution Approach 2:
The differential signal processing acts as an intermediary that filters out noise. By processing the signals through a differential amplifier or processing circuit, the system eliminates common-mode noise and enhances the useful defect signals, enabling accurate measurement and quantification
3Device complexity
If a single excitation coil is used, then the device complexity is reduced, but the ability to inspect multiple defect types is limited
Solution Approach 1:
The probe achieves multi-functionality by incorporating multiple receiving coils with opposite winding directions that can detect different defect types. The same excitation coil configuration can inspect inner surface defects, buried defects, and outer surface defects by appropriately selecting and processing signals from the receiving coils
Solution Approach 2:
The patent adds a dimensional aspect by introducing receiving coils with opposite winding directions (positive and negative polarity). This dimensional change in coil configuration enables the system to distinguish between different defect types and depths by analyzing the phase and amplitude characteristics of the received signals
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 probe achieves high sensitivity and noise reduction, enabling accurate inspection and quantification of tiny defects in pipelines, including cracks and corrosion, with improved penetration depth and reduced energy consumption.
Implementation Method 1
The excitation coil is used to be energized with an alternating current to generate induced eddy current fields in an inspected pipeline
Implementation Method 2
The excitation coil is used to be energized with an alternating current to generate induced eddy current fields in an inspected pipeline
Implementation Method 3
The first receiving coil is configured to receive an induced magnetic field generated by an induced eddy current field at a first position of the inspected pipeline and to output a first voltage signal
Implementation Method 4
The first receiving coil is configured to receive an induced magnetic field generated by an induced eddy current field at a first position of the inspected pipeline
Data Source
AI summary
A differential eddy current internal inspection probe, an arrayed probe, and a defect inspection device and method are provided. The probe includes an excitation coil, a first receiving coil, and a second receiving coil. The first receiving coil and the second receiving coil are symmetrically attached to both sides of the excitation coil, and bottom surfaces of the first receiving coil, the excitation coil and the second receiving coil are located in a same plane. When an inspected pipeline is subjected to direct current magnetization, the differential eddy current internal inspection probe is configured to inspect inner surface defects, buried defects and outer surface defects of the inspected pipeline. When the inspected pipeline is not subjected to direct current magnetization, the differential eddy current internal inspection probe is configured to inspect the inner surface defects of the inspected pipeline.