Capacitive Holiday Detection Robot Without Grounding Wire
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional robotic systems for inspecting internal coatings in large diameter pipes face issues such as the need for grounding wires that can tangle or break, and the use of rotating arms that are prone to mechanical problems, leading to delays and increased costs in pipeline construction.
Innovation Solution
A robot-based electrical system that uses a metal brush/capacitive pad combination to detect holidays without a grounding wire, employing a capacitive method with a microprocessor to detect changes in capacitance and potentially featuring a wireless grounding system or a circumferential brass brush for continuous inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grounding wire is used to complete the electrical circuit for holiday detection, then the conductivity measurement can be performed, but the wire is subject to tangling or breaking which causes delays and increased costs
Solution Approach 1:
The patent extracts and eliminates the grounding wire from the system by using the robot's own conductive structure as the reference electrode. The capacitive coupling between the conductive brush and the pipe coating allows holiday detection without requiring an external grounding wire, thereby removing the source of tangling and breaking problems.
Solution Approach 2:
The patent introduces capacitive coupling as an intermediary mechanism between the conductive brush and the pipe. Instead of direct electrical contact requiring a grounding wire, the system uses capacitive coupling through the coating to detect holidays, eliminating the need for physical wire connections while maintaining detection capability.
2Reliability
If a rotating arm with conductive brush is used for inspection, then the coating can be swept and tested, but the rotating arm is prone to mechanical problems leading to delays
Solution Approach 1:
The patent replaces the mechanical rotating arm system with a simpler conductive brush arrangement that relies on capacitive coupling rather than mechanical rotation. The inspection is performed by moving the robot linearly through the pipe, eliminating complex rotating mechanisms and reducing mechanical failure points.
Solution Approach 2:
The patent extracts and removes the rotating arm mechanism from the system, retaining only the essential conductive brush element. The brush is positioned to contact the pipe coating during linear robot movement, eliminating the mechanical complexity of rotation while maintaining inspection functionality.
3Reliability
If conventional robotic systems with grounding wires and rotating arms are used, then holiday detection can be performed, but the system complexity and potential for mechanical failure increase
Solution Approach 1:
The patent extracts and eliminates both the grounding wire and rotating arm from the system, leaving a simplified configuration where the robot body itself serves as the reference and the conductive brush performs capacitive coupling with the coating during linear movement, greatly simplifying operation.
Solution Approach 2:
The robot system serves itself by using its own conductive structure and power supply to perform holiday detection without requiring external grounding wires or complex mechanical accessories. The system is self-contained and eliminates dependencies on external components that could fail.
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 rapid and efficient detection of coating imperfections throughout the pipe length without the need for grounding wires or rotating arms, reducing downtime and costs associated with pipeline construction.
Implementation Method 1
a capacitor will be formed with the internal coating acting as the dielectric. If a holiday is not present, there will be no (or little) current observed. When the brush encounters a holiday, the capacitance formed will be momentarily shorted
Implementation Method 2
a capacitor will be formed with the internal coating acting as the dielectric
Implementation Method 3
such an imperfection will typically also manifest itself as a spark between conductive brush and the pipeline wall, thereby providing a further indication of a holiday
Data Source
AI summary
There is provided herein a robot-based electrical system for locating holidays within coated pipe that does not utilize a grounding wire. In a preferred arrangement, the robot will carry a metal rotating brush/capacitive pad combination and changes in the capacitance in the brush/pad circuit will be used to identify imperfections in the interior coating of the pipe and especially those located proximate a girth weld. In another preferred embodiment, a circumferential brush will be used that allows testing of the integrity of the internal coating throughout the length of the pipe as the robot travels the pipeline.