Eddy Current Testing

NDT course on Eddy Current Testing

Computer Based Training Course on EDDY CURRENT TESTING
Prodotti
CONTENIDO DETALLADO: Eddy Current Testing
(see Contents )



1. METALLURGY OF STEEL
1.1. Steel
- Introduction
- Components
- Solidification
- Iron-carbon diagram
1.2. Heat treatments
- Introduction
- Annealing
Normalisation
1.3. Production of carbon steels
- Manufacturing process
- Classification of products
1.4. Study of defects
- Discontinuities in steel
- Discontinuities in forged pieces
- Discontinuities in castings
- Discontinuities in rolled plates
- Discontinuities in pipes
- Discontinuities in welded joints

2. BASIC PHYSICAL PRINCIPLES
2.1 Electricity
1. Electric charge
2. Electric field
- Work of the electric field
- Electric potential energy
- Electric potential
- Potential difference
3. Electric current
- Intensity and direction of the current
- Electric current density
4. Electromotive force
5. Electrical resistance
- Resistivity and conductivity
- Resistivity and temperature
6. Direct current
- Ohm's Law
7. Alternating current
- Alternating current parameters
- Skin effect
- Vector representation
8. Electric power
9. Thermal effect of the current (Joule effect)
2.2 Magnetism
1. Magnets
2. Magnetic Field
3. Ferromagnetism
4. Magnetic Induction
- Magnetic permeability
- Normal magnetisation curve
5. Magnetic Hysteresis Loop
6. Magnetic Flux
- Conservation of magnetic flux
2.3 Electromagnetism
1. Magnetic field produced by current
- Rectilinear Conductor
- Circular loop
- Coil
- Solenoid
- Toroidal coil
2. Magnetic circuits
- Hopkinson's law
- Analogies with electrical circuits
3. Electromagnetic induction
- Faraday's law of induction
- Eddy Current or Induced current
- Lenz's law
- AC voltage generator (Alternator)
4. Self-induction
- Self-induced electromotive force
- Coefficient of self-induction (or inductance)
- Inductive circuit
5. Mutual induction
- Coefficient of mutual inductance
- Coupling coefficient
6. Alternating current circuits
- Purely resistive circuit (Ohmic circuit)
- Purely inductive circuit(L circuit)
- Resistor - Inductor circuit (RL circuit)
2.4 Measurement units
1. Electromagnetic quantities
2. Base Units
3. Derived units

3. METHOD PRINCIPLES
3.1 Eddy current method
1. General description
2. Typical applications
3. Advantages
4. Limitations
3.2 Eddy current properties
1. Introduction
2. Eddy currents paths
- Surface coil (surface probe)
- Encircling coil
- Inside diameter coil
3. Penetration depth
- Standard penetration depth
- Calculation of standard depth
- Eddy currents densities
- Frequency dependence
- Penetration curves
- Effective penetration depth
4. Phase shift with depth
- Calculating phase angle
5. Calculation expressions
3.3 Factors affecting the eddy current
1. Introduction
2. Material properties
- Conductivity of the material
- IACS system
- Magnetic permeability
3. Part geometry
- Thickness of the workpiece
- Surface shape
4. Presence of discontinuities
- Shape and orientation of discontinuities
- Depth of discontinuity
5. Eddy current coupling
- Lift-off
- Fill factor
6. Supply frequency of the coil
7. Edge effect
3.4 Impedance changes
1. Introduction
2. Coil impedance
3. Impedance plane
4. Conductivity curve
5. Decoupling curve (lift-off curve)
6. Frequency effects
7. Material thickness effect
8. Non-conductive coating
9. Conductive coating
10. Discontinuity signals
11. Effect of magnetic permeability
3.5 Impedance diagrams
1. Normalized impedance
2. Normalized frequency
3. Diagram: coil on surface
- Influence of normalized parameters
4. Diagram: external coil with bar
- Influence of normalized parameters
5. Diagram: external coil with tube
- Influence of normalized parameters

4 EXAMINATION EQUIPMENT
4.1 Examination system
1. Parts of the system
2. Eddy current probe
3. Eddy current instrument
4.2 Probes
1. Probe classification
2. Coils configuration
- Encircling probe
- Internal probe
- Surface probe
- Probes with ferrite core
- Shielded probes
3. Probe operating mode
- Single coil probe
- Reflection probe
- Absolute probe
- Differential probe
- Transmission probe
- Induction bridge
4. Structure of the coil
- Calculation inductance
4.3 Instruments
1. Instruments of exam
2. Oscillator
3. Measuring circuit
- Bridge measuring circuit
- Maxwell-Wien bridge
- Measuring with absolute probes
- Measuring with compensated probes
- Measuring with differential probes
- Measuring with reflection probes
4. Phase analysis
5. Phase rotation
6. Band-pass filters
- Frequency response
- Types of filters
- Effect of the filters on the signal
7. Display device
- Digital displays
- Settings
8. Eddy current instruments
- Meters instruments
- Portable instruments
- Multi-frequency instrument
4.4 Reference standards
1. Generality
2. Conductivity samples
3. Calibration reference standards
- Samples with natural discontinuities
- Samples with artificial discontinuities
4. Lift-off samples

5. EXAMINATION PROCEDURE AND RESULTS
5.1 General examination
1. Introduction
2. Sensitivity to defects
- Lift-off
- Penetration depth
- Coil parameters
3. Signal phase discrimination
4. Frequency selection
5. Defect effects on the signal
- Defect orientation
- Minimum defect length
- Defect depth
6. Effectiveness of test
- Lift-off variations
- Surface conditions
- Surface coating
- Test piece temperature
- Test piece geometry
- Probe orientation
- Probe wobble
- Scanning speed
7. Equipment
8. Reference blocks
9. Testing of ferromagnetic materials
5.2 Surface inspections
1. Introduction
2. Examination system
- Instrument
- Probes
- Calibration block
3. Equipment calibration
- Check sensitivity
- Calibration procedure
- Phase adjustment
- Gain settings
4. Inspection technique
5. Evaluation of signals
6. Sub-surface discontinuities
5.3 Welding inspection
1. Introduction
2. Examination system
- Instrument
- Probes
- Calibration block
3. Equipment calibration
- Check sensitivity
- Phase adjustment
- Gain settings
- Coating thickness measurement
- Coating thickness compensation
4. Inspection technique
- a) Inspection of the HAZ and parent metal
- b) Inspection of the welded surface
5. Evaluation of signals
6. Other examination techniques
5.4 Tube inspetions with an internal probe
1. Introduction
- Tube Bundle Heat Exchangers
2. Examination system
- Instrument
- Internal probes
- Calibration reference standards
3. Equipment calibration
- Differential bobbin coil
- Absolute bobbin coil
4. Inspection technique
5. Evaluation of signals
- Estimate depth of discontinuities
6. Ferromagnetic tubes
5.5 Tube and bar inspections with an external probe
1. Inspection technique
- Inspection with encircling coil
- Inspection with surface probe & rotating workpiece
- Inspection with surface probe for sectors
2. Calibration reference standards
- Example of block reference
3. Equipment calibration
4. Inspection method
5. Evaluation of signals
5.6 Measuring thickness
1. Measurable thicknesses
2. Thickness of non-conductive coatings
- Factors affecting the measurement
- Instruments
- Calibration reference standards
- Instrument calibration
- Thickness measurement
3. Thickness of conductive coatings
- Factors influencing the measurement
- Instrument and calibration reference blocks
- Instrument calibration
- Thickness measurement
4. Thickness of thin metal sheet
- Thickness curves
- Construction of thickness curves
5.7 Measuring conductivity
1. Conductivity measuring
- Factors affecting the measures
2. Instruments
3. Conductivity meters
- Instrument calibration
- Measurement execution
4. Measurement by general purpose meters
- Instrument calibration
- Choice of operating frequency