NDT is a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component, or system without causing damage.
Non–destructive testing (NDT) is a mechanism used by engineers to detect defects in materials and structures, either during manufacturing or while in service. Typically, the methods used are ultrasonics, radiography, magnetic particle, eddy current, dye penetrant and visual methods
The six most used frequently used NDT methods are as follows
- Eddy Current
- Magnetic Particle
- Liquid Penetrant
- Radio graphic
- Ultrasonic
- Visual Testing
Eddy Current Tester: ECT is one of many electromagnetic testing methods used in NDT making use of electromagnetic induction to detect and characterize surface and sub-surface flaws in conductive materials.
The two major applications of eddy current testing are surface inspection and tubing inspections. Surface inspection is used extensively in the aerospace industry, but also in the petrochemical industry. The technique is extremely sensitive and can detect tight cracks. Surface inspection can be performed both on ferromagnetic and non-ferromagnetic materials.
Tubing inspection is generally limited to non-ferromagnetic tubing and is known as conventional eddy current testing. Conventional ECT is used for inspecting steam generator tubing in nuclear plants and heat exchangers tubing in power and petrochemical industries. The technique is extremely sensitive to detect and size pits. Wall loss or corrosion can be detected but sizing is not accurate.
A variation of conventional ECT for partially magnetic materials is full saturation ECT. In this technique, permeability variations are suppressed by applying a magnetic field. The saturation probes contain conventional eddy current coils and magnets. This inspection is used on partially ferromagnetic materials such as nickel alloys, duplex alloys, and thin-ferromagnetic materials such as ferritic chromium molybdenum stainless steel. The application of a saturation eddy current technique depends on the permeability of the material, tube thickness, and diameter
Applications:
Eddy current tester can be used for following applications,
- Petrochemical
- Energy
- Aerospace
- Heavy Industry
- Railway
- Other Industries
Advantages:
- Sensor arrangements and multiplexing tailored for optimal resolution and coverage
- Multiple modes available to work on different materials (ferro and non-ferro) to find various flaws (cracks, corrosion, pits, etc.)
- Dynamic acquisition with integrated encoder for defect localization
- Proven high Probability of Detection (PoD)
- Maximize coverage and speed
- Powerful software with data archiving
- Controlled human factor
- Data Repeatability
- Raw signal stability
- Less operator dependence
- Quick Calibration
Comparative Analysis:
