Composite Magnetic Field Layout for Axial Pipeline Flaw Detection
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Solution Overview
Problem
Existing MFL and EMAT technologies for pipeline inspection face design constraints due to complex geometries in helical magnet arrangements, limiting their application and increasing fabrication and servicing costs, while traditional axial magnetic fields fail to detect axial pipe flaws effectively.
Innovation Solution
A composite magnetic field system is arranged circumferentially around the ILI tool body, using multiple magnetic circuits to produce a resultant angled field, with magnets oriented in the axial direction and sensors aligned similarly, allowing for a simpler magnet design and smaller mechanical footprint, enabling detection of axial pipe flaws without the need for complex helical geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If helical magnet arrangements are used to produce angled fields, then axial pipe flaws can be detected, but device complexity and fabrication costs increase
Solution Approach 1:
The patent divides the single helical magnet arrangement into multiple separate magnetic circuits (typically three circuits spaced 120 degrees apart). Each circuit produces a magnetic field component that, when combined with the tool's rotation, creates the desired angled field effect. This segmentation simplifies the geometry of individual magnet assemblies while maintaining the functional equivalence of the helical arrangement.
Solution Approach 2:
The patent introduces the rotational dimension of the inspection tool as a new degree of freedom. Instead of creating angled fields through complex spatial arrangements of magnets in a static tool, the invention uses the tool's rotation combined with simpler magnetic circuit geometries to achieve the same effect. This transforms the problem from a spatial arrangement challenge to a temporal/rotational control problem.
2Measurement precision
If helical magnet arrangements are used to produce angled fields, then axial pipe flaws can be detected, but fabrication and servicing costs increase
Solution Approach 1:
By segmenting the helical arrangement into multiple independent magnetic circuits, each circuit can be manufactured and tested separately using standard fabrication processes. This modularity reduces tooling costs, simplifies quality control, and enables easier replacement or repair of individual circuits without affecting the entire system.
Solution Approach 2:
The magnetic circuits are designed with universal geometries that can be manufactured using standard industrial processes. The segmented design allows the same circuit patterns to be replicated multiple times around the tool, achieving economies of scale in manufacturing and reducing per-unit costs.
3Device complexity
If traditional axial magnetic fields are used, then device complexity is reduced, but detection of axial pipe flaws is limited
Solution Approach 1:
The patent transforms the static axial field configuration into a dynamic system where the tool's rotation plays an active role in creating the effective angled field. The magnetic circuits remain geometrically simple and axially aligned, but their functional effect changes over time as the tool rotates, creating the necessary field angles for detecting axial flaws without complicating the magnet geometry.
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 enables the detection of axial pipe flaws with a more compact and cost-effective design, improving sensor density and arrangement, and reducing fabrication and servicing costs, while allowing for the use of angled fields that traditional technologies cannot achieve.
Implementation Method 1
each composite magnetic field system containing two magnetic circuits arranged relative to one another to provide a resultant magnetic field (C) at an angle α relative to an axial direction
Implementation Method 2
two magnetic circuits arranged relative to one another to provide a resultant magnetic field (C) at an angle α
Implementation Method 3
sensor coil circuit configured for magnetic flux leakage ('MFL') implementations
Implementation Method 4
magnetostrictive electro-magnetic acoustic transducers ('EMAT') implementations
Data Source
Figure 1~3
Figure 4~5
Figure 6
AI summary
Embodiments of an inline inspection ("IL1") tool (10) of this disclosure include a plurality of composite field systems (20) arranged circumferentially about the body of the IL1 tool, each composite field system including multiple magnetic circuits (60) to produce a composite or resultant angled field C relative to the target, along with a sensor array or circuit (40) configured for magnetic flux.leakage ("MFL") or magnetostrictive electro-magnetic acoustic transducers ("EMAT" ) implementations. In embodiments, the pole magnets (61) of the magnetic circuits are oriented in the axial direction of the tool body rather than in the direction of the resultant angled field. The same is true of the sensors (43). This composite field system approach provides options to design -geometries that were not previously possible in prior art single-circuit helical MFL designs and EMAT designs.