Steel Tube Weld Toughness Assessment Using Greyscale Profiling
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Solution Overview
Problem
Current methods for evaluating the toughness of longitudinal welds in steel pipes, particularly those made by high-frequency induction or resistance welding, are either destructive or lack the ability to assess toughness non-destructively, especially in the presence of hydrogen or hydrogen/natural gas mixtures, and do not adequately address the low toughness issues in welds.
Innovation Solution
A system and method for non-destructive evaluation of weld toughness using image acquisition, processing, and analysis to categorize bond line toughness based on microstructural characteristics, including greyscale profiling and hardness assessment, without mechanical testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If destructive mechanical tests (Charpy test) are conducted to evaluate weld toughness, then measurement precision of toughness is improved, but the pipe is destroyed and productivity is reduced
Solution Approach 1:
The patent replaces destructive mechanical testing (Charpy impact tests) with non-destructive evaluation methods including visual inspection, ultrasonic testing, and eddy current testing to assess weld toughness and detect defects without destroying the pipe specimen, thereby maintaining productivity while achieving toughness evaluation
Solution Approach 2:
The patent creates visual and structural copies of the weld zone through imaging techniques (optical imaging, ultrasonic imaging, eddy current imaging) that replicate the physical and structural characteristics of the weld, allowing toughness assessment from these copies without damaging the actual weld
2Reliability
If high temperature heat treatment (normalizing or quenching+tempering) is applied to eliminate low toughness microstructure, then weld toughness is improved, but energy consumption and process complexity increase
Solution Approach 1:
The patent implements preliminary control of welding parameters (induction heating power, welding speed, coil positioning, material composition) to prevent the formation of low toughness microstructures in the first place, eliminating the need for subsequent complex heat treatment processes while ensuring weld toughness from the outset
Solution Approach 2:
The patent modifies welding process parameters including induction heating frequency, power density, welding speed, and material chemical composition to control the thermal cycle and resulting microstructure, achieving adequate toughness without requiring post-weld heat treatment
3Measurement precision
If comprehensive process parameter monitoring is implemented during welding, then measurement precision of weld quality is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs multi-functional sensors and imaging systems that simultaneously perform multiple functions: visual inspection of weld appearance, ultrasonic detection of internal defects, eddy current assessment of material properties, all integrated into a single evaluation platform that assesses multiple quality aspects without proportionally increasing complexity
Solution Approach 2:
The patent uses image processing algorithms and signal processing intermediaries that translate raw sensor data from multiple sources into integrated weld quality assessments, simplifying the complexity by providing a unified evaluation metric from multiple measurement streams
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 systematic and non-destructive evaluation of weld toughness, allowing for accurate categorization of pipes as PSL2, even in hydrogen environments, reducing the risk of accidents and improving quality control.
Implementation Method 1
image acquisition means configured to acquire, in use, at least a two-dimensional image of an outer or inner surface of the tube
Implementation Method 2
processing means configured to provide from the data associated with the microstructure of the tube in the analysis region, a greyscale profile with respect to the first dimension
Data Source
AI summary
A system and method for the evaluation of longitudinal welds in steel tubes, and more specifically, of longitudinal welds made by high frequency induction welding (HFW) or electric resistance welding (ERW) comprises a system for the evaluation of the toughness of longitudinal welds by high frequency induction or electric resistance welding in steel tubes and an associated method.