23 Jun Electromagnetic Testing – ASNT Level 3 Certification

What is Electromagnetic Testing Inspection?

Electromagnetic testing inspection is one among the nondestructive testing (NDT) which make use of electromagnetic induction techniques  to identify and characterize surface and subsurface defects in conductive materials.

This inspection mainly contains three types of testing such as Eddy Current testing , Remote Field testing and Alternating Current Field Measurement. These techniques use the induction of a magnetic field or electric current into a conductive part and those results are recorded and evaluated.

In this method, electromagnetic energy is used to evaluate the condition of a sample object. In which the energy interacts with the material and a picture of the interaction process is analyzed to evaluate the condition of the material. 

Principle of  Electromagnetic Testing

The principle behind the electromagnetic testing is that a coil made of conductive wire is induced with an alternating current. This creates a small current around the magnetic flux field. The oscillation of the magnetic field has the same frequency of the current running through the coil. This coil is then advanced to a conductive material. The opposed current in the coil is then induced into the material in circular paths which is called Eddy Currents.

The presence of the defects is analysed by understanding the changes in the flow pattern, phase and intensity of the Eddy Currents which is caused due to the variation in the magnetic permeability and electrical conductivity of the sample object. Also , there can be a change in the amplitude and the phase of the coupled magnetic field which can be detected by evaluating the impedance changes in the coil. This points to the presence of defects which is known as telltale sign which also points to the basis of the standard Eddy Current Testing.

Advantages and disadvantages 

Advantages

• Sensitive to surface defects or small cracks
• Fast results
• Portability
• Minimal pre-cleaning required
• Can penetrate through external coatings
• Can detect complex shapes and through several layers
• Accurate conductivity measurements
• Test can be automated and the result can be stored
• No contact is required with sample object
• Can inspect inaccessible structures 

Disadvantages

• Can perform only on conductive materials
• Not suitable for large areas
• Susceptible to magnetic permeability changes
• Defects parallel to surface cannot be detected
• External training or skills required for Signal interpretation
• Depth of penetration is limited
• Permanent record is not there unless automation is performed

Applications of Electromagnetic Testing

• Used for detection of Cracks 
• Used for measuring of coating thickness
• Used for measuring material thickness
• For material identification, heat damage detection, heat treatment monitoring to identify the conductivity
• Used in airline industry for testing of aircraft skins (surface testing)
• Used in nuclear power industry for testing heat exchanger tubing (volumetric testing

Enroll for 1 month preparatory classes for ASNT level 3 Electromagnetic Testing Certification

Gamma NDT academy offers NDT preparatory classes for candidates who intend to appear for the ASNT 3 Electromagnetic Testing Certification exam. 

We will cover all the syllabus under ASNT for Electromagnetic Testing and conduct mock tests to prepare you best for the certification exam. We will also share study materials and sample questions which you need to revise. We have a 100% success rate for NDT level 2 and 3 certification courses.

Gamma NDT academy training institute is located in Kerala, India. We provide online classes for candidates who cannot attend our training sessions in-person.