SAM Testing for Brazed Plate Heat Exchangers
views：41
author：admin
source：Hiwave
time：2025-10-24
catogory：Industry News
Scanning Acoustic Microscopy (SAM), also known as C-mode Scanning Acoustic Microscopy (C-SAM), is a non-destructive testing technique widely used in electronic packagi……
Scanning Acoustic Microscopy (SAM), also known as C-mode Scanning Acoustic Microscopy (C-SAM), is a non-destructive testing technique widely used in electronic packaging, materials science, and industrial non-destructive inspection. For critical heat exchange equipment such as Brazed Plate Heat Exchangers (BPHEs), SAM technology plays an important role in quality control and failure analysis.
Principle
SAM utilizes high-frequency ultrasound (typically 10 MHz to 230 MHz) to penetrate materials. When the ultrasound encounters interfaces between different media (such as metal-air, metal-adhesive, or metal-defect), reflection and scattering occur. By analyzing the amplitude and time delay of the reflected signals, the system can construct two-dimensional or three-dimensional images of the internal structure, thereby identifying the location, size, and morphology of internal defects.
Main Inspection Targets (for BPHEs)
Brazed plate heat exchangers are fabricated by vacuum brazing multiple layers of corrugated stainless steel plates together using copper- or nickel-based filler metals. Common internal defects include:
Poor bonding (Non-brazing or Lack of Bonding): The filler metal fails to fully wet or fill the joint area, resulting in ineffective connections between plates, affecting heat transfer and pressure resistance.
Porosity: Small voids formed by trapped gases during the brazing process, which reduce weld strength and may become leakage paths.
Cracks: Micro-cracks caused by thermal or mechanical stresses, which may propagate during operation and lead to leakage.
Inclusions: Oxides or other impurities entrapped in the brazing material, weakening the integrity of the bond interface.
Delamination: Separation occurring between the plate and brazing layer, or within the plate itself.
Scanning Acoustic Microscopy is a powerful tool for inspecting the internal weld quality of brazed plate heat exchangers, particularly effective in identifying critical defects such as minor unbonded areas, porosity, and delamination.
