Caliper Pig Sensor Arms Using Hall-Effect Deflection Sensing

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Solution Overview

Problem

Existing caliper pigs for pipeline inspection lack high-resolution, low-power sensor systems capable of detecting geometrical deformations such as dents, ovalities, and bend radius with high-frequency response, which is essential for maintaining pipeline integrity during the transportation of oil and gas over long distances.

Innovation Solution

A caliper pig equipped with a sensor arm assembly featuring a primary caliper sensor ring and circumferentially distributed sensor arms, each with a magnet and sensing unit that detects changes in the magnetic field to generate an output indicative of the angle of deflection, utilizing a dual-axis Hall-effect IC and a diametrically magnetized magnet to provide accurate deformation measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional sensor systems are used in caliper pigs, then the device complexity is reduced, but the measurement precision and frequency response are insufficient for detecting geometrical deformations

Engineering Contradiction:

Improvedeformation detection resolutionVSAvoidsensor arm assembly complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical sensors with a magnetic field-based sensing system. A magnet is mounted on the sensor arm, and a Hall effect sensor detects changes in the magnetic field as the arm deflects. This substitution eliminates complex mechanical linkages and contact points while achieving high-resolution measurement of geometrical deformations through non-contact magnetic field detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the sensor arm deflection and the detection system. The magnet mounted on the sensor arm creates a magnetic field that varies with arm position, and the Hall effect sensor measures these variations. This intermediary enables high-precision measurement while keeping the sensor arm assembly relatively simple and avoiding direct mechanical contact with the pipeline surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If high-power sensor systems are used to improve signal strength, then the detection reliability is improved, but the power consumption increases which is unacceptable for inline inspection

Engineering Contradiction:

Improvedetection reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The magnetic field-based sensing system inherently requires minimal power compared to conventional electrical or mechanical sensors. The Hall effect sensor is a solid-state device with low power consumption, and the passive magnet requires no power source. This substitution maintains high detection reliability through precise magnetic field measurement while dramatically reducing power consumption suitable for battery-powered inline inspection devices.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If mechanical contact sensors are used to detect pipeline deformations, then the measurement accuracy is improved, but the wear and damage to the pipeline surface increases

Engineering Contradiction:

Improvedeformation measurement accuracyVSAvoidpipeline surface damage

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical contact sensors with a magnetic field-based sensing system. The Hall effect sensor detects the position and deflection of the sensor arm through changes in the magnetic field generated by a magnet, without requiring physical contact with the pipeline surface. This eliminates wear and damage to the pipeline while maintaining high measurement accuracy for detecting geometrical deformations such as dents, ovalities, and bends.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 proposed caliper pig achieves high-resolution, low-power deformation detection with high-frequency response, enabling accurate monitoring of pipeline geometrical deformities, ensuring pipeline integrity and safety during operation.

Implementation Method 1

utilizing a dual-axis Hall-effect IC and a diametrically magnetized magnet to provide accurate deformation measurements

Methodology Applied

Scientific EffectHall effect: Hall Effect

Data Source

PatentUS11598475B2Caliper pig for detecting geometrical deformation of a pipeline

Publication Date: 2023.03.07 INDIAN OIL CORP LTD

AI summary

A caliper pig for detecting geometrical deformation of a pipeline is disclosed. The caliper pig includes a body and a first sensor arm assembly. The first sensor arm assembly includes a primary caliper sensor ring adapted to be mounted on the body. Further, the first sensor arm assembly includes a plurality of sensor arms adapted circumferentially distributed on the primary caliper sensor ring. Each of the plurality of sensor arms includes a sensing arm adapted to be in contact with an internal surface of the pipeline and a pair of magnets adapted to rotate along the sensing arm. Each of the plurality of sensor arms includes a sensing unit configured to detect a change in magnetic field based on the movement of the sensing arm. The sensing unit is configured to generate an output indicative of an angle of deflection of the sensing arm while traversing on the internal surface of the pipeline.