Two-Component Magnetic Flux Leakage Detection for Oil Tank Corrosion
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Solution Overview
Problem
Current magnetic flux leakage (MFL) detection systems are velocity dependent and unable to reliably pinpoint flaws at or toward the top or bottom side of a plate in a single pass, especially in horizontal arrangements, which can lead to missed or incorrectly located corrosion flaws in above-ground oil tanks.
Innovation Solution
A two-component MFL detection system using a combination of horizontal and vertical magnet-sensor arrangements with GMR or Hall effect sensors, where the horizontal arrangement detects top or bottom flaws and the vertical arrangement differentiates between top and bottom flaws, allowing for accurate location determination without operator skill dependence and coating removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If induction coil sensors are used for MFL detection, then the system can detect magnetic flux changes, but the signal response becomes velocity dependent and requires operator skill
Solution Approach 1:
The patent replaces induction coil sensors with giant magnetoresistive (GMR) sensors that utilize quantum mechanical effects (giant magnetoresistance) instead of electromagnetic induction. This substitution eliminates velocity dependence because GMR sensors measure magnetic field strength directly rather than measuring changes in magnetic flux, thereby removing the need for operator skill in maintaining optimal sensing velocity.
Solution Approach 2:
The patent changes the sensing parameter from measuring magnetic flux change (velocity-dependent) to measuring magnetic field strength directly (velocity-independent). By using GMR sensors that respond to the magnitude of the magnetic field rather than its rate of change, the system achieves reliable detection without dependence on sensing velocity or operator skill.
2Reliability
If a single horizontal magnet-sensor arrangement is used, then the system can detect flaws, but it cannot reliably pinpoint whether the flaw is at the top or bottom side of the plate
Solution Approach 1:
The patent divides the detection system into two separate detection components: a horizontal magnet-sensor arrangement for detecting the presence of flaws, and a vertical magnet-sensor arrangement for determining flaw location (top vs. bottom side). This segmentation allows each component to specialize in its specific function, achieving both reliable flaw detection and precise location determination.
Solution Approach 2:
The patent adds a vertical dimension to the detection system by introducing a vertical magnet-sensor arrangement in addition to the horizontal arrangement. This dimensional addition enables the system to differentiate between top and bottom side flaws by sensing magnetic flux patterns in the vertical direction, thereby achieving three-dimensional flaw localization capability.
3Measurement precision
If vertical magnet-sensor arrangement is used alone, then top side flaws generate large response, but bottom side flaws are often missed
Solution Approach 1:
The patent merges the horizontal and vertical magnet-sensor arrangements into an integrated detection system where both components work together. The horizontal arrangement provides reliable detection of both top and bottom flaws, while the vertical arrangement enhances top side flaw detection sensitivity. By combining their outputs, the system achieves both high sensitivity for top flaws and reliable detection for bottom flaws.
Solution Approach 2:
The patent uses the output from the vertical magnet-sensor arrangement to provide feedback that helps interpret the horizontal arrangement's data. When the vertical sensor detects a strong response, it confirms a top side flaw; when it shows minimal response, it suggests a bottom side flaw. This feedback mechanism allows the system to reliably distinguish between top and bottom flaws while maintaining high sensitivity for both.
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 system provides a velocity-independent, accurate, and portable method to detect and locate corrosion flaws in oil tanks, eliminating the need for operator skill and coating removal, and enabling reliable top or bottom side differentiation in a single pass.
Implementation Method 1
A GMR sensor sees a large change in resistance when a magnetic field is applied. The sensor does this by sandwiching a 10-angstrom layer of copper between two layers that have particular electron spin.
Implementation Method 2
The first layer polarizes the passing electrons and the second layer spins similarly, opposite, or somewhere in between depending on the alignment and strength of the magnetic field.
Implementation Method 3
A Hall effect sensor responds to changes in magnetic flux by generating a voltage
Implementation Method 4
a coil or solenoid that generates and applies a magnetic field generally perpendicular to the material being tested
Data Source
AI summary
A device, system and method for detecting flaws in a magnetic material includes a wheeled scanner having two detectors and arranged for travel over a flat surface. The first detector is a horizontal magnet-sensor arrangement that generates a magnetic field in a direction generally parallel to a central horizontal axis of the scanner. The second is a vertical magnet-sensor arrangement that generates a magnetic field in a direction generally perpendicular to the central horizontal axis of the scanner. A set of computer executable instructions uses data collected by the first detector to detect a flaw in the magnetic material and data collected at a same time by the second detector to determine a location of the detected flaw relative to a top and bottom surface of the magnetic material.