Pipeline Coating Condition Estimation Using Phase-Locked Loop Interference Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for detecting and characterizing coating disbonds in pipelines require direct contact, necessitating excavation, which is costly and burdensome, and are affected by interference from power-line ground-return current and soil conditions like subsurface saltwater, making them impractical.
Innovation Solution
The implementation of a phase-locked loop method to reduce interference from power-line ground-return current, a dual-magnetometer method to combine interfering signals, and the use of synthetic disbonds in pipeline coating samples for field calibration, allowing for remote measurement and improved accuracy in coating condition estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If EIS is used to detect coating disbonds, then measurement precision is improved, but device complexity increases due to the need for excavation and direct contact
Solution Approach 1:
The patent introduces a magnetic field as an intermediary to enable non-contact measurement. Instead of directly contacting the coating through excavation, the system uses magnetic field coupling to induce currents in the pipeline, which then interact with the coating interface to provide EIS measurements remotely.
Solution Approach 2:
The patent replaces the mechanical excavation and direct physical contact system with an electromagnetic field-based system. The magnetic field induces currents that enable electrical measurements without mechanical intrusion into the soil or direct contact with the pipeline coating.
2Ease of operation
If MEIS is used to measure on-pipe current, then ease of operation is improved, but reliability decreases due to interference from power-line ground-return current
Solution Approach 1:
The patent extracts and removes the harmful power-line ground-return current interference from the measurement signal. By identifying and separating this interfering component, the system can isolate the true on-pipe current signal for accurate coating assessment.
Solution Approach 2:
The patent converts the harmful power-line interference into a useful reference signal. By measuring the interference component and using it for calibration or subtraction, the system transforms the previously detrimental signal into a tool for improving measurement accuracy.
3Measurement precision
If traditional EIS methods are used, then coating condition detection is accurate, but loss of time increases due to excavation requirements
Solution Approach 1:
The patent replaces time-consuming mechanical excavation with rapid electromagnetic field-based measurements. The system can assess coating conditions in real-time without disturbing the soil or exposing the pipeline, dramatically reducing inspection time.
Solution Approach 2:
The patent enables continuous monitoring of coating conditions without interruption from excavation or physical access requirements. The electromagnetic measurement system can operate continuously along the pipeline, providing ongoing assessment without disrupting pipeline operation or requiring soil disturbance.
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
Enables non-invasive, cost-effective detection and characterization of coating disbonds, reducing excavation needs and improving measurement accuracy across various soil conditions.
Implementation Method 1
generating a signal to cancel or suppress the interfering current signal
Implementation Method 2
measuring on-pipe currents... using a magnetometer
Implementation Method 3
measuring on-pipe currents at two locations along the structure... using a magnetometer
Data Source
AI summary
Methods are provided for reducing interference from stray currents in buried pipelines/metal structures during MEIS testing or other current-sensing applications in the pipeline. Methods are also provided for measuring bulk complex electrical impedance between a buried pipe and the soil, thereby rendering an indication of the quality of the anti-corrosive coating. Methods are also provided for measuring the complex propagation constant of AC voltages propagating along an attenuative pipeline. This information is useful for assessing the general condition of the anti-corrosive coating involved, or to enhance MEIS inspection of the pipeline. Methods are also provided for enhancements to MEIS testing, including (a) canceling magnetometer offset effects associated with the Earth's magnetic field after the magnetometer is positioned for measurement, (b) implementing a separate sensing connection to the pipe so as to avoid interference from voltage loss in the pipe feed-line connection, (c) providing a power amplifier to excite the pipe with large-amplitude signals.