EMAT Sensor Array for Corrosion Mapping
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Solution Overview
Problem
Existing EMAT technologies face challenges in accurately measuring the wall thickness of pipes with significant corrosion, as corrosion patches scatter ultrasonic energy, making it difficult to detect the minimum useful wall thickness.
Innovation Solution
The development of EMAT sensors with a smaller sensing footprint and increased magnetic field density, allowing for more focused ultrasonic energy and improved detection of small, deep corrosion pits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional EMAT with larger sensing footprint is used, then coverage area is improved, but detection precision of small corrosion patches deteriorates
Solution Approach 1:
The patent divides the sensing area into multiple discrete sensor elements arranged in an array. Each element has a small individual footprint, but collectively they provide broad coverage. This segmentation allows the system to maintain large area coverage while each element contributes to precise localization and characterization of small corrosion patches through their individual small sensing areas.
Solution Approach 2:
The patent transitions from a single large-area sensor to a two-dimensional array of small sensor elements. This dimensional change allows simultaneous achievement of large coverage area (through array extent) and high detection precision (through small individual element footprint), effectively resolving the contradiction by adding spatial distribution as an additional dimension.
2Adaptability or versatility
If EMAT is used on thin-walled pipes, then adaptability to different pipe types is improved, but measurement reliability deteriorates due to signal burial in main bang
Solution Approach 1:
The patent segments the ultrasonic signal reception across multiple sensor elements in the array. By distributing the reception function across many elements, the system can process signals from thin-walled pipes more effectively, as the segmented reception allows for better signal separation and processing that reduces the main bang interference problem.
Solution Approach 2:
The patent replaces conventional piezoelectric transducers that require mechanical coupling with electromagnetic acoustic transducers that operate through electromagnetic induction. This substitution eliminates the need for couplants and reduces mechanical contact issues, improving reliability on thin-walled pipes where coupling is particularly problematic.
3Adaptability or versatility
If conventional EMAT is used on corroded pipes, then general inspection capability is maintained, but measurement precision deteriorates due to ultrasonic energy scattering
Solution Approach 1:
The patent uses a segmented array of small sensor elements that can individually resolve scattered ultrasonic energy from corrosion patches. The segmentation allows the system to maintain general inspection capability across the pipe surface while the small individual element footprints provide the precision needed to distinguish true wall thickness measurements from scattering effects of corrosion.
Solution Approach 2:
The patent applies local quality by having each sensor element in the array with a specific small sensing footprint optimized for precise local measurement. This local optimization allows the system to maintain adaptability for general inspection while achieving high measurement precision even in the presence of corrosion-induced scattering, as each element's localized sensing is less affected by scattered energy from adjacent areas.
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 approach enhances the sensitivity and accuracy of wall thickness measurements in corroded pipes, enabling better detection of small corrosion patches and improving the assessment of pipe fitness for service.
Implementation Method 1
When the alternating current (AC) flows in the coil 12, the AC current in the coil 12 generates eddy currents in the solid material 6
Implementation Method 2
The magnetic field of the permanent magnet 10 interacts with these eddy currents (through, for example, Lorentz force or magnetostriction) to produce ultrasonic waves
Implementation Method 3
The magnetic field of the permanent magnet 10 interacts with these eddy currents (through, for example, Lorentz force or magnetostriction) to produce ultrasonic waves
Implementation Method 4
At the receiving EMAT (not shown), the interaction of the reflected ultrasonic waves with the magnetic field of the receiving EMAT induces eddy currents in the material of the specimen, which in turn induce electrical currents in the receiving EMAT coil circuit
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Systems and methods for detecting corrosion in pipes are disclosed herein. In one embodiment, an apparatus for detecting corrosion in an object includes an electromagnetic acoustic transducer (EMAT) having a ferromagnetic core and a plurality of permanent magnets arranged peripherally around the ferromagnetic core. The permanent magnets are arranged to produce a magnetic field through the ferromagnetic core. The apparatus also includes a coil between the ferromagnetic core and the object.