Capacitance Tomography Inspection Pig for Pipeline Deposit Detection
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Solution Overview
Problem
Existing methods for inspecting pipelines are mechanically complex and cannot distinguish between different factors influencing the tubular condition profile, making them inefficient for detecting deposits and other anomalies within the pipeline.
Innovation Solution
A method using an inspection pig equipped with a substantially circumferential inside-out capacitance tomography sensor arrangement with a diameter smaller than the nominal inner diameter of the pipe, allowing for measurements to be taken along the pipe length and deriving information about the pipe's inner surface, including deposits, without scraping them off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a known inspection apparatus with caliper assemblies is used to detect tubular condition, then data about debris, deposits, protrusions, joints and bends can be collected, but the apparatus is mechanically complex and cannot distinguish between different factors influencing the tubular condition profile
Solution Approach 1:
The patent replaces the mechanical caliper assembly system with an electromagnetic field-based capacitance sensing system. Instead of using mechanical arms that physically contact the pipe wall to detect anomalies, the invention uses capacitance sensors that measure changes in electrical field distribution caused by different materials (deposits, protrusions, bends). This substitution eliminates mechanical complexity while enabling differentiation between various tubular condition factors through their distinct electromagnetic signatures.
Solution Approach 2:
The invention changes the measurement parameter from mechanical displacement (caliper arm movement) to electrical capacitance values. By measuring capacitance changes at multiple sensor locations and analyzing the pattern of these changes, the system can distinguish between different types of tubular conditions. Each factor (deposits, protrusions, bends) produces a characteristic capacitance signature that can be identified and differentiated.
2Measurement precision
If radioactive inspection technologies are used to detect deposits from the outside, then deposit detection is possible, but the process requires clamping, de-clamping, re-positioning and re-clamping which is complex, tedious and expensive
Solution Approach 1:
The patent inverts the inspection approach by placing the sensors inside the pipeline rather than outside. The inspection pig travels through the pipe with capacitance sensors positioned on its outer surface, allowing direct measurement of the inner pipe wall conditions. This eliminates the need for external clamping and positioning equipment, as the sensors are already in direct contact with or close to the inspection surface during normal pipeline operation.
Solution Approach 2:
The inspection pig is propelled through the pipeline by the existing fluid flow or by its own propulsion mechanism, eliminating the need for external positioning systems. The capacitance sensors continuously measure tubular conditions as the pig moves autonomously through the pipeline, providing self-contained inspection capability without requiring external support equipment for positioning or data collection.
3Productivity
If an inspection pig with diameter equal to nominal inner diameter is used, then continuous measurement is possible, but the risk of the inspection pig getting stuck increases
Solution Approach 1:
The patent implements a nested structure where the capacitance sensor arrangement is positioned inside a protective housing or pig body. The sensor array with diameter smaller than the nominal inner diameter is nested within the inspection pig structure, allowing the pig to navigate through the pipeline while maintaining measurement capability. This nested configuration provides clearance between the pig outer surface and the pipe wall, reducing the risk of getting stuck while preserving continuous measurement through the inner sensor arrangement.
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 improved inspection of pipeline interiors by distinguishing between different factors and providing detailed information about deposits and anomalies, reducing the risk of the inspection pig getting stuck and allowing for continuous measurement without requiring the pipe to be submerged in liquid, thus enhancing the accuracy and efficiency of pipeline condition assessment.
Implementation Method 1
conducting measurements with the sensor arrangement at a plurality of locations along the length of pipe and deriving, for each of the plurality of locations, information about a deposit formed on an inner surface of the pipe wall
Implementation Method 2
substantially circumferential inside-out capacitance tomography sensor arrangement
Data Source
AI summary
A method of inspecting a length of pipe having a pipe wall and a nominal inner diameter, comprising providing an inspection pig configured for passing along the length of pipe, wherein the inspection pig is provided with a substantially circumferential inside-out capacitance tomography sensor arrangement having a diameter smaller than the nominal inner diameter; passing the inspection pig along the length of pipe thereby defining an annular space between the sensor arrangement and the pipe wall; conducting measurements using the sensor arrangement at a plurality of locations along the length of pipe, and deriving, for each of the plurality of locations, information about an interface surrounding the inspection pig from the measurements. Further provided is an inspection pig for inspecting a length of pipe, wherein the inspection pig is provided with an inside-out capacitance tomography sensor arrangement.