Eddy current testing is a widely used non-destructive testing technology for pipelines, which can be divided into conventional eddy current testing, transmission eddy current testing and far-field eddy current testing. Conventional eddy current detection is affected by the skin effect, only suitable for detecting surface or subsurface defects in pipelines, while transmission eddy current detection and far-field eddy current detection overcomes this defect, and its detection signal has the same detection sensitivity for the inner and outer walls of the pipe. Among them, the far-field eddy current method has the features of easy automated detection (electrical signal output), fast detection speed, suitable for surface detection, wide range of application, safety and convenience as well as minimum consumption of goods, etc., which has been widely valued in developed countries and is widely used for in-service pipeline inspection.
Advantages of eddy current detection technology:
High detection speed, low detection cost, easy to operate;
The probe and the inspected workpiece can be non-contact, without the need for coupling medium;
Detection can be obtained at the same time as the results of the direct output of the electrical signal indication, can also be achieved on-screen display;
Can achieve high-speed automated detection, and can achieve permanent records.
Disadvantages of eddy current detection technology:
Only for conductive materials, difficult to use for complex shaped specimens;
Can only detect the surface of the material or workpiece, near-surface defects;
Detection results are not intuitive, it is also difficult to identify the type and nature of defects, as well as the shape, size and so on;
Detection of more factors affected by interference, easy to produce pseudo-display.