Deconvolution imaging of weak reflective pipe defects using guided-wave signals captured by a scanning receiver

Area of Science:

• Non-destructive testing
• Ultrasonic guided waves
• Signal processing

Background:

• Guided-wave testing is crucial for inspecting pipelines.
• Coherent noise and low axial resolution hinder defect interpretation.
• Existing methods struggle with weak reflective defects.

Purpose of the Study:

• To develop a deconvolution imaging method for guided-wave signals.
• To enhance axial resolution and signal-to-noise ratio for pipe defect imaging.
• To validate the method's effectiveness on artificial defects.

Main Methods:

• A compact transducer circumferentially scans the pipe for data acquisition.
• Synthetic focusing and deconvolution reconstruct defect images.
• Noise suppression techniques improve signal-to-noise ratio.
• High circumferential sampling density (up to 72 spots/lap) is achieved.

Main Results:

• The method successfully reconstructed images of pitting and attached iron piece defects.
• A pitting defect image achieved a 5.87 dB signal-to-noise ratio.
• High circumferential sampling density was found critical for inspection sensitivity.
• A modified full width at half maximum criterion evaluated inhomogeneous defects.

Conclusions:

• The proposed deconvolution imaging method enhances axial resolution and signal-to-noise ratio for guided-wave pipe inspection.
• Achieving high circumferential sampling density is vital for improved inspection sensitivity.
• The method offers a promising approach for detecting and characterizing weak reflective pipe defects.