External Pipeline Weld Inspection Using Segmented X-Ray Source and Detector
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Solution Overview
Problem
Conventional methods for inspecting pipeline welds, especially when internal access is difficult or impossible, require extensive radiation exclusion areas and multiple exposures using broad beam x-ray or gamma-ray sources, which are inefficient and impractical for external inspection.
Innovation Solution
A method and apparatus for real-time external inspection of pipeline welds using independently mountable and movable x-ray source and detector assemblies on opposing external sides of the pipeline, eliminating the need for internal sources and film plates, and utilizing a highly sensitive CCD-based detector with synchronized movement to focus data collection on the weld area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a broad beam radioactive source is used to penetrate both walls of the pipeline, then the weld can be inspected from external side, but the radiation exclusion area becomes extensive and exposure time becomes long
Solution Approach 1:
The inspection system is segmented into two independent components: a radiation source on one side of the pipeline and a detector on the opposite side. This segmentation allows each component to be optimized independently, with the detector being highly sensitive to capture radiation that has passed through the pipeline walls and weld, thereby reducing the required radiation dose and exclusion area while maintaining external inspection capability
Solution Approach 2:
The system changes the detection parameter from conventional film-based detection to highly sensitive detector-based detection. This parameter change enables the use of lower radiation intensities and shorter exposure times, significantly reducing the radiation exclusion area required while maintaining the ability to inspect welds externally through pipeline walls
2Measurement precision
If multiple exposures are taken to obtain a complete image of the weld, then the entire circumferential weld can be inspected, but the inspection time and number of exposures increase
Solution Approach 1:
The system enables continuous inspection by moving the radiation source and detector together around the pipeline circumference. This continuous motion allows the entire weld to be inspected in a single continuous operation rather than requiring multiple discrete exposures, significantly reducing inspection time while maintaining complete coverage
Solution Approach 2:
The inspection system transitions from static multiple exposures to a dynamic moving system. The radiation source and detector are mounted on movable carriers that travel around the pipeline, allowing real-time continuous imaging of the weld as the components move, thereby reducing total inspection time while maintaining complete circumferential coverage
3Measurement precision
If internal access is obtained for weld inspection, then direct single-wall imaging is possible, but access is not possible in many situations such as pipelines beneath roads
Solution Approach 1:
Instead of placing the radiation source inside the pipeline and detector outside (the conventional approach requiring internal access), the system inverts the arrangement by placing the radiation source outside and the detector on the opposite side outside. This inversion eliminates the need for internal access while still enabling weld inspection through the pipeline walls
Solution Approach 2:
The pipeline walls themselves act as intermediaries that the radiation must penetrate. By using highly sensitive detectors, the system can detect the radiation signal after it has passed through both walls and the weld, making the walls transparent to the inspection process and eliminating the need for internal access while maintaining weld inspection capability
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 efficient and precise real-time external inspection of pipeline welds with reduced radiation exposure and improved sensitivity, comparable to single-wall film plate results, while allowing for inspection of welds without internal access and in small diameter pipelines.
Implementation Method 1
a radiation source which is an x-ray source
Implementation Method 2
a radiation detector which is a highly sensitive charge coupled device (CCD) based detector
Data Source
AI summary
An apparatus is provided for external inspection of a pipeline circumferential weld. This comprises a radiation source (5) and radiation detector (3). Both units are controllably movable around a drive band or track (7) which is fitted around the circumferential weld. To align the source with the detector the source and detector are moved with respect to each other clockwise and anticlockwise around an initial position while sampling the radiation detected at a number of positions. A position of maximum strength of the radiation signal detected can then be determined such that the center point of the radiation source may be located. The source and detector are then substantially aligned with each other and means are provided to move the source and detector circumferentially around the weld while remaining substantially in alignment.