ELECTROMAGNETIC TESTING ( ECT,RFT,MFL,IRIS)
1. When an inspection coil induces eddy currents into a test specimen the induced eddy currents in the
specimen
❑
will not affect the impedance of the test coil.
❑
will affect the impedance of the test coil.
❑
will not balance the impedance of the test coil.
❑
will not cancel the impedance of the test coil.
2. At a fixed test frequency, in which of the following materials will the eddy current penetration be least?
❑ Aluminum (35 percent IACS conductivity)
❑ Brass (15 percent IACS conductivity)
❑ Copper (95 percent IACS conductivity)
❑ Lead (7 percent IACS conductivity)
3.The induced magnetic field have a direction.
❑
90 degree to the primary changing magnetic field
❑
aligned with the primary changing magnetic field
❑
opposite to the primary changing magnetic field
❑
any of the above
4.For the E.C.T to be carried out the most important property for the material under test shall be that it is:
❑
Conductive
❑
Non-conductive
❑
magnetic
❑
both a & c
5. In a properly designed RFT probe, the detector coil is positioned in the
❑ direct field zone
❑ transition zone
❑ remote field zone
❑ junction between remote field zone and transition zone
6. Compared to a conventional eddy current probe, a typical RFT probe
❑ has a larger inter-coil spacing
❑ requires more protection from vibration
❑ generates greater adhesion forces to the tube wall
❑ requires a greater fill-factor
7. To make eddy currents more sensitive to ID defects when performing a test with an encircling probe , its
frequency must be :
❑ increased.
❑ decreased.
❑ kept constant.
❑ none of the above.
8. The three properties of the coil that affect the strength of the eddy currents induced in a test specimen are
❑ fill factor, edge effect and coersivity.
ELECTROMAGNETIC TESTING ( ECT,RFT,MFL,IRIS)
❑ permeability, dimension and conductivity.( Coil size and shape)
❑ permeability, impedance and conductivity.
❑ inductance, resisitivity and conductivity.
9. The ease with which a material can be magnetized is known as :
❑
lift off.
❑
permeability.
❑
conductivity.
❑
inductivity.
10.The total opposition to the flow of alternating current in a circuit with different electrical components is called :
❑ permeability.
❑ conductivity.
❑ impedance.
❑ inductance.
11. In a circuit having only pure inductance the current lags behind the voltage by :
❑
0 deg.
❑
180 deg.
❑
270 deg.
❑
90 deg.
12. The Voltage Plane displays
❑ the phase and amplitude in polar coordinates
❑ the frequency and drive voltage along the x and y axes, respectively
❑ the probe air-signal placed at the origin
❑ probe lift-off noise along the x-axis
13.What is the relation of phase & voltage in ECT
❑ depth & length
❑ time & depth
❑ depth & metal loss
❑ distance travelled by the probe & volumetric metal loss.
14.Device used to remove the noise
❑ amplifier
❑ filter
❑ analyser
❑ discriminator
15. RFT Systems are highly effective in inspecting thin wall, type 304 stainless steel tubes
❑ True
❑ False
❑ Only true if magnetic saturation probes are used
16. The symbol ‘μ’ stands for:
❑ magnetic permeability
❑ Conductivity
❑ Resistivity
❑ Standard depth of penetration
ELECTROMAGNETIC TESTING ( ECT,RFT,MFL,IRIS)
17.Due to the materials it is commonly used in, RFT frequencies are
❑ usually higher than conventional eddy current
❑ usually lower than conventional eddy current
❑ similar to conventional eddy current
18.A prime frequency has
❑ Equal sensitivity towards OD & ID discontinuities
❑ Maximum sensitivity towards OD discontinuities
❑ Maximum sensitivity towards ID discontinuities
❑ Optimized sensitivity towards OD discontinuities
❑ Both a & d
❑ Both c & d
19.The inductive reactance of the coil is measured in;
❑ mhos
❑ ohms
❑ henrys
❑ gauss
20.For a frequency applied a self differential bobbin coil is more sensitive to;
❑ Crack on the tube ID
❑ Crack on the tube OD
❑ Crack cannot be detected .
❑ internal thickness changes.
21. A carbon steel tube with thick internal scales need to be inspected for general wall loss. The best inspection
method would be:
❑ IRIS
❑ RFT
❑ MFL
❑ ECT
22. A carbon steel tube with thick internal scales need to be inspected for pitting. The next most effective step
will be:
❑ Using a optimum fill factor probe for RFT.
❑ To perform IRIS
❑ To perform adequate cleaning by analyzing the type of scale.
❑ To perform MFL.
23. An exciter & receiver coil concept is applicable to ;
❑ RFT
❑ ECT
❑ IRIS
❑ MFL
24. A trail & lead coil concept is applicable to; (conform again)
❑ RFT
❑ ECT
❑ IRIS
❑ MFL
ELECTROMAGNETIC TESTING ( ECT,RFT,MFL,IRIS)
25.Transition zone is a term used in;
❑ RFT
❑ ECT
❑ IRIS
❑ MFL
26.The term frequency compensation is used in:
❑ RFT
❑ ECT
❑ IRIS
❑ MFL
27. What does a change in TSP signal in RFT indicate:
❑ We are inspecting at the middle of the bundle
❑ The mechanical tolerance given during the tube manufacturing is causing the shift.
❑ The material permeability change.
❑ Defect under support plate.
❑ Both a & d
❑ All of the above.
28. A signal analysis with a phase 60 degree in MFL indicates:
❑ A 60% deep defect
❑ A 60-70 % deep defect
❑ A taper flaw
❑ Through hole
❑ None of the above is correct.
C
29. If 1 & 2 are coils
A
❑ Identify the absolute signal from the exciter coil.
:_______________
❑ Identify the absolute signal from the receiver coil.
:_______________
1
❑ Identify the differential signal from the receiver coil.
:_______________
2
B
Pulling Direction
Fig:1.1
❑ Identify the signal which is generated by the combined effect of two coils:___________
30.The best inspection method to detect defects in finned aluminum tube:
❑ RFT
ELECTROMAGNETIC TESTING ( ECT,RFT,MFL,IRIS)
❑ ECT
❑ IRIS
❑ MFL
31.The best inspection method to detect defects in non-ferromagnetic tubes:
❑ RFT
❑ ECT
❑ IRIS
❑ MFL
32.The figure 1.2 indicates the inspection method:
❑ RFT
❑ ECT
❑ IRIS
❑ MFL
2
1
Differential
Signal
Fig 1.2
33. By referring to the fig 1.2 place true or false against the below statements ( I am not sure)
❑ 1 has a thicker cross section than 2: __________True/false
❑ 2 represents a defect free signal: __________True/false
❑ 1 & 2 may indicate corrosion & general pitting: __________True/false
❑ 1 & 2 may indicate corrosion under tube support plate.: __________True/false
34. Direct field defines;
❑ Electromagnetic field present around the receiver
❑ Electromagnetic field present around the Exciter
❑ Field present at a distance of 2.5 times Outer diameter of the tube.
❑ None of the above.
35.A graphical representation of the output voltage from a coil to its polar co-ordinates representing skin depths
, best defines:
❑ Current Plane
❑ Impedance plane
❑ Voltage plane
❑ All of the above.
36.The reference calibration point for a differential type defect in RFT is;
❑ A FBH with 80% through wall depth
❑ A FBH with 60% through wall depth
❑ A FBH with 100% through wall depth
❑ None of the above ( we need 20,40,60,80)
37.Frequency compensation best defines:
❑ Changing frequency to detect the taper defects
❑ Changing frequency to balance the bundle effect.
ELECTROMAGNETIC TESTING ( ECT,RFT,MFL,IRIS)
❑ Changing frequency to have enough spread for output signal.
❑ Both a & b
38.The coil which can detect Inside diameter pitting in MFL:
❑ The Trail coil
❑ The Lead coil
❑ The absolute coil
❑ Both Lead & Trial
39..A magnetically saturated tube wall have internal pits. which of the following results in a drop in signal voltage;
❑ A fast pulling speed ( Sudden change in speed)_
❑ A slow pulling speed
❑ A pit with sudden change in edge dimension
❑ A pit with 80% or more metal loss in depth.
40.General pulling speed with MFL is:
❑ 2m/s
❑ 1 m/s
❑ 0.3 m/s
❑ 0.1 m/s
ELECTROMAGNETIC TESTING ( ECT,RFT,MFL,IRIS)