Non-destructive testing (NDT) of heat exchangers is a widely accepted practice for detecting failures and cracks that could lead to leaks and subsequent system failure.
The principle of NDT for heat exchangers is based on the fact that materials will experience changes in their physical properties when subjected to external stressors, including temperature, pressure, and corrosion. By using various inspection methods and techniques, engineers can identify these changes in the material and determine if they pose a threat to the integrity of the heat exchanger.
There are several methods of non-destructive testing, of which ultrasonic testing is one of the common methods.
According to some basic characteristics of ultrasound propagation in the material, in the propagation to the heterogeneous interface will occur reflection, transmission, refraction and waveform conversion, etc., ultrasound propagation in the material will undergo attenuation; and after these changes in the ultrasound and the detection equipment to receive, and in an appropriate manner to display, analyse the characteristics of the received ultrasonic signals and based on the results of the test and the characteristics of the workpiece, you can Analyse the characteristics of the received ultrasonic signals and, based on the results and the characteristics of the workpiece, assess the material itself and the defects present within it.
(1) It can be applied to the inspection of various metal materials and some non-metal materials;
(2) It can be applied to the inspection of machined parts, forgings, castings, welded parts and composite components.
(3) It can be applied to the inspection of plate, bar and pipe.
(1) Strong penetration, both for the detection of thinner materials, but also for the detection of a larger range of thickness of materials.
(2) High sensitivity.
(3) Can measure the location of defects more accurately.
(4) The equipment is lightweight and harmless to the human body and the environment.
(1) Easy to miss detection of defects located on and near the surface.
(2) Whether the shape of the specimen is regular or not, the size of the surface roughness, the radius of curvature, etc. have a greater impact on the reliability of ultrasonic testing.
(3) The internal structure of the material, grain size, composition phase, homogeneity, densification, etc. will affect the sensitivity and signal-to-noise ratio of ultrasonic testing.
(4) The operator's human factors have a greater impact on the detection results.