TOFD Reference Block Stepped Notch Design
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Solution Overview
Problem
Conventional ultrasonic testing methods, particularly TOFD in B-scan direction, face challenges in detecting reheat cracks in hydrogen reactor vessels due to their small size, vertical orientation, and the ASME Code's inadequacies in sensitivity and calibration, leading to unreliable detection and limited coverage of wide weld widths.
Innovation Solution
The development of ultrasound time-of-flight diffraction reference blocks with stepped notches, fabricated from steel, that simulate reheat cracks and are positioned to minimize signal interference, allowing for improved detection and calibration of TOFD setups by correlating signal strength with actual crack sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ultrasonic testing methods are used, then detection capability for general flaws is adequate, but detection sensitivity for small reheat cracks is insufficient
Solution Approach 1:
The patent changes the geometric parameters of the calibration block flaws from round side-drilled holes to flat-bottom holes with dimensions and orientations that match reheat crack characteristics. This parameter change allows the calibration block to accurately replicate the acoustic response of actual reheat cracks, thereby improving detection sensitivity and measurement precision for these specific flaws.
Solution Approach 2:
The patent creates a copy of the actual reheat crack geometry and acoustic response in the calibration block. By fabricating flat-bottom holes that replicate the size, shape, and orientation of reheat cracks, the calibration block provides an accurate reference for detecting and measuring these flaws in actual welds.
2Reliability
If side-drilled holes are used in calibration blocks, then calibration can be performed, but the round acoustic interface reflects energy back to receiving probes rather than generating diffracted waves
Solution Approach 1:
The patent replaces the symmetric round side-drilled holes with asymmetric flat-bottom holes that have a planar base and vertical sides. This asymmetric geometry eliminates the circular acoustic interface that causes harmful reflections, instead creating a flaw shape that generates diffracted waves similar to actual reheat cracks.
Solution Approach 2:
The patent converts the harmful reflection effect into a beneficial diffraction effect by changing the flaw geometry. The flat-bottom hole design ensures that ultrasonic energy is diffracted rather than reflected back to the probes, transforming the problematic reflection into the desired diffraction response that characterizes reheat cracks.
3Quantity of substance
If drilled holes are arranged directly above each other in calibration blocks, then multiple flaws can be tested, but signals merge and cause confusion
Solution Approach 1:
The patent arranges multiple flat-bottom holes in a stepped configuration along the length of the calibration block, positioning them at different locations rather than directly above each other. This spatial arrangement in multiple dimensions prevents signal merging and allows clear distinction between responses from individual flaws while still testing multiple flaws.
4Ease of manufacture
If ASME Code calibration blocks are used, then standard compliance is achieved, but the blocks fail to replicate the response observed from actual reheat cracks
Solution Approach 1:
The patent modifies the flaw parameters in the calibration block from the ASME Code's round side-drilled holes to flat-bottom holes with specific dimensions (e.g., 0.25 inch diameter holes with 0.5 inch deep flat bottoms) and orientations that match reheat crack characteristics. This parameter change enables accurate replication of actual reheat crack responses while maintaining standard compliance through proper block design and testing procedures.
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 more accurate and confident detection of reheat cracks by replicating the signal characteristics and geometry of actual cracks, enhancing the sensitivity and coverage of TOFD setups, thereby improving the reliability of ultrasonic testing.
Implementation Method 1
Two 5 MHz ultrasonic transducers positioned on opposite sides of each notch are coupled to the block
Implementation Method 2
ultrasound time-of-flight diffraction sensitivity demonstration
Implementation Method 3
ultrasound time-of-flight diffraction sensitivity demonstration
Data Source
AI summary
An ultrasound time-of-flight diffraction reference block has a plurality of notches that extend into the block to simulate cracks, wherein the notches have a normal and transverse orientation with respect to a test path formed on the block.