MPI Flashcards
When conducting an MPI on a nodal weld, which of the following techniques would be used?
a. Evenly-spaced coils
b. Permanent magnet
c. Close-wrapped coils
d.AC parallel loops
Answer: Close-wrapped coils
On which of the following materials can MPI be carried out?
a. Bismuth
b.Cobalt
c.Palladium
d. Antimony
Answer: Cobalt
The opposition that a material shows to the establishment of a magnetic field is known as its?
a.Remanence
b.Retentivity
c.Coercivity
d.Reluctance
Answer: Reluctance
During MPI, defects can be detected due to?
a. Flux leakage
b. Hysteresis
c.Tesla losses
d.Eddy currents
Answer: Flux leakage
BS EN ISO 9934-2 is the standard for which of the following?
a. Ultra-violet lights
b. Electro-magnets
c. Ferrous oxide inks
d. Permanent magnets
Answer: Ferrous oxide inks
AC current is more preferred for finding surface-breaking defects because?
a. AC equipment is cheaper to deploy than DC equipment
b. The domains are agitated by the rapid change in direction
c. The ink fluoresces brighter with AC than it does with DC
d. A greater volume of flux lines are produced with AC
Answer: The domains are agitated by the rapid change in direction
AC current is more preferred for finding surface-breaking defects because the alternating nature of the current causes a phenomenon known as the “skin effect.” This effect concentrates the magnetic field at the surface of the component, making it more effective for detecting surface discontinuities. The rapid change in the direction of AC agitates the magnetic domains only near the surface, which is ideal for surface defect detection
Which of the following is a paramagnetic material?
a. Concrete
b. Oxygen
c. Nickel
d. Bismuth
Answer: Oxygen
Which of the following is a true statement?
a. UVB is much safer than UVA
b. UVA is safer than UVB
c.UVA wavelength is 300-360nm
d.UVB wavelength is 365-400nm
Answer: UVA is safer than UVB
1000µw/cm2 is?
a. The power required to produce one Tesla
b. The strength of the electro-magnetic yolk
c. The maximum strength of the ambient light
d. The minimum power output of the UV light
Answer: The minimum power output of the UV light
The Skin Effect describes which of the following?
a. The condition of a test material’s surface
b. The type of magnetic field achieved using AC
c. The type of magnetic field achieved using DC
d. The tension induced by the flux lines on a metal
Answetr: The type of magnetic field achieved using AC
Which of the following would acquire the most lines of flux if all were subjected to the same amount of magnetising force?
a. Nickel
b. Platinum
c. Bismuth
d. Antimony
Answer: Nickel
Among the options given, nickel would acquire the most lines of flux when subjected to the same amount of magnetizing force. Nickel is a ferromagnetic material, which means it has a high magnetic permeability and can strongly attract and concentrate magnetic field lines
Magnetic flux lines traveling from steel into iron would do what?
a. Spread further apart
b. Gather closer together
c. Retain their formation
d. Stop at the interface
Answer: Gather closer together
When magnetic flux lines travel from steel into iron, they would gather closer together. This is because iron is a ferromagnetic material, which means it has a high magnetic permeability and can strongly attract and concentrate magnetic field lines.
This behavior is due to the ferromagnetic properties of iron, which cause it to strongly attract magnetic fields, resulting in a denser concentration of magnetic flux lines
The type of magnetism produced by a horseshoe magnet is?
a. Circumferential
b. Semi-circular
c. Longitudinal
d. Semi-arched
Answer: Longitudinal
14.
The volume of a settlement flask sample for MPI ink is?
a.10ml
b.100ml
c. 60ml
d. 600ml
Answer: 100ml
Which of the following is a 3.2u diver allowed to perform that a 3.1u diver is not?
a. Taking wall thickness measurements with a DTM
b. Photographing crack-like indications found with MPI
c. Remedial grinding of defects found during MPI/CVI
d. Conducting a CVI of a nodal weld prior to an MPI
Answer: Remedial grinding of defects found during MPI/CVI
Which of the following would cause a spurious indication in MPI?
a. Grinding mark
b. Dirt or scale
c. Toe undercut
d. Poor cap profile
Answer: Dirt or scale
In the formula I = 16 x r ÷ N, what does the ‘I’ stand for?
a. RMS current DC
b. RMS current AC
c. Peak current DC
d. Peak current AC
Answer: Peak current AC
By multiplying the RMS figure by 1.414, the sum will be a value of?
a. The average voltage
b. The peak voltage
c. The peak current
d. The useable current
Answer: The peak voltage
By multiplying the RMS (Root Mean Square) figure by 1.414 (which is the square root of 2), the resulting value will be: The peak voltage.
This calculation is used to convert from RMS voltage to peak voltage in an AC (alternating current) waveform.
When an MPI inspection is carried out on a nodal weld using close wrap coils, where would the Burmah Castrol Strip be placed when checking for flux density?
a.Longitudinally along the weld cap
b.Transversely across the weld cap
c.Longitudinally on the chord side HAZ
d.Longitudinally on the brace side HAZ
Answer: Longitudinally along the weld cap
During an MPI inspection of a nodal weld using an AC yoke, which of the following would not be detected?
a. Star cracking within a crater in the weld cap
b. A crack in the HAZ running at 45° to the weld
c. A longitudinal crack in the chord weld toe
d. A lamination running parallel with the weld
Answer: A lamination running parallel with the weld
The nodal joint below is to be inspected with MPI, complete the drawing to show how the coils would be applied and where you would take the Burmah Castrol Strip readings, prior to commencing the inspection.
(Draw a diagram)
The drawing below shows a permanent magnet, complete the drawing to show the direction of the line of flux, and in which orientation are defects must likely to be found
(Draw a diagram)
The diagram below shows the current flow prods, complete the diagram to show the following:
The direction of the magnetic field
The orientation of the prods should be applied to a weld to reveal longitudinal defects.
- Rods induce a circular magnetic field by sending a high amperage current (typically 1000A) through the test piece.
- The high amperage can cause arcing between the electrodes and test surface.
- Contact points must be carefully cleaned, and electrode materials chosen to prevent contamination of the test piece.
- Prods produce a distorted circular magnetic field with defects showing at a maximum when orientated along a line between the prod tips.
- particular care has to be taken to avoid surface damage of the component under test due to arcing or contamination.
What is the main disadvantage of the MPI technique using prods?
The high amperage can cause arcing between the electrodes and test surface.
