MT lv.1 Flashcards
Prior to the use of magnetic particles to detect flaws by magnetic methods, flaws could be located in iron pieces using
a) Hall detectors
b) ordinary magnetic compasses
c) electro scopes
d) electromagnetic resonance
b) ordinary magnetic compasses
The ampere is a unit of
a) electric current
b) electromotive force
c) electromagnetic force
d) magnetic intensity
a) electric current
Total current in two parallel conductors can be determined by knowing the distance between the conductors and the
a) dielectric constant of air
b) resistivity of the conductors
c) right hand rule
d) magnetic force exerted per unit length of wire
d) magnetic force exerted per unit length of wire
The units Webers per square metre (Wb/m^2) are used to quantify a:
a) magnetic induction field
b) magnetic dipole
c) magnetic monopole
d) magnetic force
a) magnetic induction field
Magnetic field lines are
a) always concentric rings
b) symbolic only, and used to indicate spatial direction of the field
c) a result of the van Allan belts
d) of uniform density
b) symbolic only, and used to indicate spatial direction of the field
A void in an otherwise homogenous magnetized material presents itself as a point magnetic dipole. This is the basis for
a) magnetic particle flaw detection
b) multi frequency eddy current
c) para-magnetism
d) de-magnetisation
a) magnetic particle flaw detection
Magnetic properties of materials are a result of
a) electric currents on the atomic and sub-atomic scale
b) the strong nuclear force
c) the ratio of protons to neutrons in the material
d) the weak nuclear force
a) electric currents on the atomic and sub-atomic scale
In a ferromagnetic material, a region where all the “atomic moments” are aligned parallel to each other is called a
a) magnetic zone
b) confederation
c) domain
d) magnetic junta
c) domain
When discussing magnetization and its effects the magnetic induction field is usually represented by the letter
a) B
b) H
c) M
d) Z
a) B
When discussing magnetization and its effects the magnetic field intensity, or as its also called, the magnetic field is represented by the letter
a) B
b) H
c) M
d) Z
b) H
The phenomenon whereby the magnetization of a ferromagnetic sample lags the applied cyclic magnetic field is referred to as
a) phase lag
b) Doppler effect
c) hysteresis
d) demagnetization
c) hysteresis
When a hysteresis curve is generated for a ferromagnetic material, a magnetic field remains in the material when the applied field is returned to zero. This field is called the
a) coercive force
b) induction field
c) residual induction
d) resultant vector
c) residual induction
The value of H applied to bring the residual value of B to zero is called
a) saturation field
b) demagnetization value
c) induction coercive force
d) phase reversal factor
c) induction coercive force
In order to be detectable by magnetic particle testing, a flaw must
a) be surface breaking
b) be no deeper than 1mm below the surface
c) produce a perturbation of the induction field at the test surface
d) all of the above
c) produce a perturbation of the induction field at the test surface
To detect a flaw by magnetic particle methods, techniques are developed to
a) maximize field perturbations in the region of a flaw
b) optimize retentivity of the material
c) propagate the flaw by Barkhausen jumps
d) all of the above
a) maximize field perturbations in the region of a flaw
Sensitivity of the magnetic particle method depends on the
a) absolute magnitude of the induced field perturbation
b) spatial gradient of the induced field perturbation
c) magnitude of the applied field
d) surface flux density of the test piece
b) spatial gradient of the induced field perturbation
Magnetic particle testing has an advantage over liquid penetrant testing because it can
a) be used on ferromagnetic materials
b) locate surface defects
c) locate subsurface defects
d) be cheaper to use
c) locate subsurface defects
Magnetic particle testing is a practical test method to inspect.
a) glass
b) ceramics
c) aluminum castings
d) none of the above
d) none of the above
Which is not an essential step in magnetic particle testing?
a) establish a suitable magnetic flux in the test piece
b) application of magnetic particles
c) examination of test piece
d) post cleaning of test piece to remove magnetic particles
d) post cleaning of test piece to remove magnetic particles
Inherent discontinuities are formed during
a) initial melting and refining of the metal
b) primary processing
c) secondary processing and manufacturing
d) in-service use
a) initial melting and refining of the metal
When a discontinuity causes the magnetic field lines to be forced out of the specimen into the air, the field in the air is called a
a) force field
b) leakage field
c) flux field
d) flaw field
b) leakage field
Magnetic particles are available in many colours to
a) indicate degree of permeability
b) optimize visibility
c) indicate degree of rententivity
d) permit the inspector to choose a colour that will not clash with his/her clothing
b) optimize visibility
The deeper a subsurface defect gets below the surface
a) the greater the flux leakage it produces
b) the harder it gets to magnetize the part
c) the larger it must be to be detectable
d) all of the above
c) the larger it must be to be detectable
In order to detect a flaw by magnetic particle testing the magnetic field must
a) alternate
b) pulse
c) run parallel to the principal plane of the flaw
d) intercept the principal plane of the flaw
d) intercept the principal plane of the flaw
The cgs unit of magnetizing force (H) is the
a) Oersted
b) Gauss
c) Tesla
d) Weber
a) Oersted
The cgs unit of flux density (B) is the
a) Oersted
b) Gauss
c) Tesla
d) Weber
b) Gauss
If the ends of a long bar magnet are bent to form a circle and the ends perfectly fused together the result will be
a) the magnet will no longer attract ferromagnetic material
b) a circular magnetic field
c) no magnetic flux leakage field
d) all of the above
d) all of the above
A bar magnet would be considered to be
a) circularly magnetized
b) longitudinally magnetized
c) electromagnetically poled
d) cross-polarized
b) longitudinally magnetized
Which of the following is not a characteristic of magnetic flux lines?
a) they attract each other
b) they form continuous loops
c) they do not cross each other
d) they decrease in intensity with distance from the surface
a) they attract each other
Inside a bar magnet magnetic flux lines are considered to flow from
a) north to south
b) south to north
c) east to west
d) west to east
b) south to north
The direction of magnetic lines of force around a current carrying conductor is
a) parallel to the conductor
b) at right angles to the conductor
c) 45 degrees out of phase to the applied current
d) parallel or perpendicular to the conductor depending on which current flow convention is used
b) at right angles to the conductor
If a nail is brought to a bar magnet it is held by the magnet. If another nail is now brought to touch the first nail it is held to the first nail. Subsequent nails can be held in a long chain. This is a result of
a) induced magnetism
b) nail bonding
c) domain transfer
d) natural attraction of nail points to nail heads
a) induced magnetism
The end of the compass needle that points towards the northern region of the earth is called
a) the north seeking pole
b) the magnetic north pole
c) the magnetic south pole
d) both a and b
d) both a and b
The magnetic north pole is located
a) at 90ø north latitude
b) somewhere in northern Canada
c) at the north geographic pole
d) at Greenwich England
b) somewhere in northern Canada
A single line of force represents the unit of magnetic flux in a field. This is called a(n)
a) oersted
b) gauss
c) weber
d) maxwell
d) maxwell
A magnet can lose its magnetism by
a) heating
b) hammering
c) both a and b
d) no known means
c) both a and b
Removal of magnetism from a part is termed
a) domain scattering
b) demagnetization
c) stress relieving
d) the Hall effect
b) demagnetization
A permanent magnet configured such that both north and south poles are adjacent is usually termed a
a) longitudinal magnet
b) circular magnet
c) parallel magnet
d) horseshoe magnet
d) horseshoe magnet
The “image” of a magnetic field produced by placing a magnet under a paper and sprinkling iron fillings on the top of the paper is called
a) magnetic projection
b) magnetic holography
c) a magnetograph
d) flux painting
c) a magnetograph
Magnetic lines of force are
a) isolated mono-poles
b) elongated bi-poles
c) manifestations of the “string-theory”
d) imaginary concepts for mapping magnetic fields
d) imaginary concepts for mapping magnetic fields
Electric current which at regular intervals reverses its direction of flow is called
a) AC
b) DC
c) alternating
d) both a and c
d) both a and c
In direct current flow electric circuits the unit of current is the
a) ampere
b) ohm
c) mho
d) volt
a) ampere
In alternating current electric circuits the unit of current flow is the
a) ampere
b) ohm
c) volt
d) deci Bell
a) ampere
Opposition to electric current flow in a D.C. circuit is termed
a) ohmage
b) resistance
c) reactance
d) reluctance
b) resistance
The unit of electrical resistance is the
a) ampere
b) coulomb
c) ohm
d) volt
c) ohm
The unit of potential difference in an electric circuit is the
a) ampere
b) ohm
c) volt
d) Coulomb
c) volt
A ferromagnetic material surrounded by a current carrying coil becomes
a) diamagnetic
b) magnetized
c) an electromagnet
d) both b and c
d) both b and c
The unit of inductance is the
a) farad
b) henry
c) Coulomb
d) abvolt
b) henry
The ability of a material to emit visible light while being irradiated by UV light is called
a) fluorescence
b) phosphorescence
c) iridescence
d) Birefringence
a) fluorescence
The typical duration of a coil shot is
a) a fraction of a second
b) 1 second
c) 2 seconds
d) 5 seconds
a) a fraction of a second
The clamping contacts on a large stationary magnetic particle testing unit are called
a) prods
b) heads
c) poles
d) shunts
b) heads
When a part is magnetized such that the flux lines run essentially parallel to the long axis of the part it is called
a) parallel magnetization
b) circular magnetization
c) longitudinal magnetization
d) a long shot
c) longitudinal magnetization
In magnetic particle testing prods are
a) hand held electrodes
b) never used
c) used for longitudinal magnetization
d) substitutes for the central conductor
a) hand held electrodes
The relationship relating electric current flow, voltage and resistance in electric circuits is
a) relativity
b) Ohm’s law
c) Snell’s law
d) Kirchoff’s law
b) Ohm’s law
In electric circuit terminology the usual symbol for current is
a) A
b) E
c) I
d) C
c) I
In electric circuit terminology, the usual symbol for voltage is
a) E
b) I
c) V
d) both a) and c) are used
d) both a) and c) are used
The common unit of electric power is
a) amperes
b) volts
c) watts
d) horsepower
c) watts
To determine the direction of magnetic field lines in a conductor (assuming - to + current flow) you can use
a) the left hand rule
b) the right hand rule
c) a Galvanometer
d) a Wheatstone bridge
a) the left hand rule
For a single straight conductor, assuming modern theory current flow, the fingers on the left hand point
a) in the direction of the magnetic field lines
b) against the magnetic field lines
c) in the directions of the electron flow
d) opposite to the electron flow
a) in the direction of the magnetic field lines
In the left hand rule as applied to a solenoid, the fingers point in the direction of
a) north
b) south
c) current flow
d) force on the conductor
c) current flow
In the left hand rule, as it applies to a solenoid, the thumb point in the direction of
a) north
b) south
c) current flow
d) force on the conductor
a) north
The relative amount of flux linkage between two coils (as in a transformer) is called
a) mutual inductance
b) figure of merit
c) coupling coefficient
d) flux factor
c) coupling coefficient
In order to operate as a transformer, two coils must be linked by a(n)
a) iron core
b) air core
c) alternating magnetic field
d) copper wire
c) alternating magnetic field
The difference between a yoke and prods in magnetic particle testing is
a) a yoke produces a circular field and prods a longitudinal
b) a yoke produces a longitudinal field and prods a circular
c) a yoke produces a longitudinal field and prods a parallel
d) none, the both produce circular fields
b) a yoke produces a longitudinal field and prods a circular
As one increases the size of the MPI test system from small yokes and portable units to large bench units the single most significant difference is
a) length of piece that can be tested
b) the ability to use liquid suspensions in the big units
c) the amount of magnetizing current available
d) type of magnetic field that can be generated
c) the amount of magnetizing current available
When single phase AC is halfwave rectified it is sometimes called half wave direct current. The reference to direct current is because
a) Lenz’s law applies
b) current amplitude does not change
c) current flow direction does not change
d) all of the above
d) all of the above
A part that has been magnetized by ________ requires demagnetization.
a) mechanical means
b) magnetic particle testing
c) a magnetic chuck
d) none of the above
d) none of the above
Demagnetization of a part is usually required when the part is
a) used near magnetically affected instruments
b) part of a moving assembly
c) to be finish machined
d) all of the above
d) all of the above
The Curie point is
a) 320øC.
b) 1650øF.
c) varies with the position on the earth relative to the north magnetic pole
d) varies for each ferromagnetic alloy
d) varies for each ferromagnetic alloy
The number of reversals normally required to properly demagnetize a part using electromagnetic means is
a) 1
b) 2-5
c) 10-30
d) 50-100
c) 10-30
Demagnetization can be accomplished using
a) A.C.
b) D.C.
c) a yoke
d) all of the above
d) all of the above
The advantage of using reversing D.C. for demagnetization is
a) low heating effect
b) deep penetration
c) only one reversal is needed
d) all of the above
b) deep penetration
The magnetic flux in a part increases as applied field is increased. The flux moves along the virgin curve of the hysteresis curve
a) once each cycle of applied A.C. field
b) twice each cycle of applied A.C. field
c) only once when the part is completely demagnetized
d) for paramagnetic materials only
c) only once when the part is completely demagnetized
For demagnetizing large parts, field reversals are usually _________.
a) lower frequency than for small parts
b) higher frequency than for small parts
c) the same frequency as for small parts
d) not needed
a) lower frequency than for small parts
For best demagnetization results using a coil with A.C. and passing parts through it you should
a) pass the part through with its long axis parallel to the coil axis
b) hold the part close to the coil
c) both a and b
d) switch the current on only when the part is centered along its length in the coil
c) both a and b
Small parts can be demagnetized in multiple lots by passing them through an A.C. coil provided they are
a) stacked in a basket
b) apart in single layer
c) oriented long axis parallel to coil axis
d) both b and c
d) both b and c
For rings and hollow parts a handy means of A.C. demagnetization is
a) using a yoke
b) a central conductor using decreasing current
c) surge pulses through prod contacts
d) swinging field technique
b) a central conductor using decreasing current
The most likely tool you would use to determine if a part has been adequately demagnetized is the
a) Hall detector
b) field meter
c) electrogram
d) magnetometer
b) field meter
A problem with doing a head shot on a ball bearing is
a) arc burns damage the surface
b) no defects are found
c) the field is distorted too much
d) they cannot be demagnetized
a) arc burns damage the surface
The two classifications of media in MPI are
a) fluorescent and non-fluorescent
b) wet and dry
c) magnetic and para-magnetic
d) high temperature and low temper
b) wet and dry
What shape is used for the particles used in magnetic particle testing?
a) acicular (elongated)
b) spherical and flake
c) irregular
d) all of the above
d) all of the above
Which is a type of particle available for magnetic particle testing?
a) wet visible particles
b) dry fluorescent particles
c) dry visible particles
d) all of the above
d) all of the above
What is the result if magnetic particles are made of a material of high coercive force?
a) decreased mobility
b) high background
c) masking of defects
d) all of the above
d) all of the above
Large sized particles are not used in wet magnetic particle testing because
a) they drop from suspension too quickly
b) they form misleading indications called drainage lines
c) circulation pumps cannot move them off the tank bottom
d) both a and b
d) both a and b
The purpose of large particles in the dry powder mix is to
a) detect large defects
b) reduced background by “sweeping”
c) locate subsurface defects
d) both a and b
d) both a and b
The reason agglomerations of fine magnetic particles tend to move through the liquid they are suspended in is
a) increased mass
b) increased field strength
c) both a and b
d) the fluid dynamic shape that is taken on
c) both a and b
Maximum particle mobility is had for dry magnetic particles with _______ shape.
a) spherical
b) elongated
c) flake
d) irregular
a) spherical
The reason for adding a portion of spherical shaped magnetic particles to a batch of elongated shaped dry powder magnetic particles is to
a) increase density
b) increase mobility
c) increase sensitivity
d) increase contrast
b) increase mobility
The difference in colour between an MPI indication and the background colour of the part tested is critical in evaluation of a part. The colour difference is referred to as
a) contrast
b) lumens
c) luminosity
d) indication intensity
a) contrast
Dry magnetic particles should be applied so they have a minimum velocity when they reach the test part. The reason being
a) to avoid a peening effect on the part
b) to ensure they can be caught by leakage fields
c) so pigments are not knocked off
d) all of the above
b) to ensure they can be caught by leakage fields
The choice of colour of dry magnetic particle to use depends on
a) colour of part being tested
b) ambient light at the test location
c) type of defect required to be found
d) both a and b
d) both a and b
What is the name of the technique whereby a part is magnetized first and the particles applied after the magnetizing force is removed?
a) residual method
b) leakage field method
c) time lapse MPI
d) delay technique
a) residual method
What is the name of the MPI technique whereby the magnetic particles are applied to a part only during the time the magnetizing force is applied?
a) the inertial technique
b) the continuous method
c) the synchronized method
d) the time-metered method
b) the continuous method
The localized overheating of a part being magnetic particle tested, arising from high resistance or sparking at the electrical contact point is
a) burning (or arcing)
b) coagulation
c) feedback
d) background noise
a) burning (or arcing)
The general appearance of the test surface on which indications are to be viewed is termed
a) purple haze
b) backdrop
c) background
d) carrier
c) background
The purpose of contact pads placed on the electrodes used in MPI is
a) ornamental
b) to redirect flux patterns
c) top secret
d) to improve electrical contact
d) to improve electrical contact
The buildup of magnetic particles due to excessive magnetization of the part under test is called
a) furring
b) fall-out
c) magnetic hair
d) magnetic writing
a) furring
A “split-coil” attachment for MPI use is used for
a) varying the number of turns in a coil
b) varying the magnetizing current strength in the part
c) positioning over a part with no free ends for normal coil access
d) both a and b
c) positioning over a part with no free ends for normal coil access
A five turn coil on a bench unit is 30cm diameter. If 2000amps are passed through it will result in
a) 10,000 ampere turns
b) 12,000 ampere turns
c) 60,000 ampere turns
d) unknown
a) 10,000 ampere turns
The process whereby the magnitude and significance of an indication is determined is termed
a) examination
b) interpretation
c) evaluation
d) rejection
c) evaluation
A “keeper” is used on a permanent magnet to complete the magnetic circuit. The purpose of this is to
a) prevent loss of magnetism
b) provide an intensification of flux
c) provide longitudinal magnetization
d) provide circular magnetization
a) prevent loss of magnetism
Parallel magnetization is
a) not possible
b) not a recommended practice for MPI testing
c) the same as longitudinal magnetization
d) a substitute for overall magnetization
b) not a recommended practice for MPI testing
The non-relevant indication resulting when the surface of a magnetized part comes in contact with another piece of ferromagnetic material is
a) bearding
b) furring
c) magnetic writing
d) break lines
c) magnetic writing
Which of the following materials has the highest relative permeability
a) iron
b) vacuum
c) air
d) gold
a) iron
The two basic decisions made before an MPI test is carried out are
a) minimum size of defect to find and type of current to use
b) minimum size of defect to find and type of particle to use
c) type of current and type of particle to use
d) which code to use and how fast to perform the test
c) type of current and type of particle to use
To detect a flaw in a low carbon steel shaft, if you suspect the flaw is about 6mm (1/4”) below the surface which method would you use?
a) A.C.
b) half wave rectified A.C.
c) an A.C. yoke
d) a pair of permanent magnets
b) half wave rectified A.C.
Which is the best material for detecting defects wholly below the surface using MPI tests?
a) dry powder
b) wet fluorescent
c) wet visible
d) all are about equal for the same current
a) dry powder
Low carbon steels must have the continuous method of MPI testing used on them due to
a) the skin effect
b) the Hall effect
c) low retentivity
d) carborization occurring from the residual method
c) low retentivity
The magnetizing current in the continuous wet method, when the bath is applied by flooding from a nozzle, is usually applied
a) during the whole time it takes to wet the part
b) immediately after flooding is stopped
c) after the bath stops dripping from the part
d) both before and after bath application
b) immediately after flooding is stopped
The normal duration required for a magnetizing “shot” in the continuous wet method is about
a) 1/4 to 1/2 second
b) 1/2 to 1 second
c) 1 to 2 seconds
d) 2 to 5 seconds
a) 1/4 to 1/2 second
Prods or clamps are used to produce which type of magnetization?
a) longitudinal
b) circular
c) parallel
d) swinging field
b) circular
When a central conductor is used inside a tube the type of magnetization employed for the testing of that tube is
a) longitudinal
b) circular
c) parallel
d) swinging field
b) circular
Generally an electromagnetic yoke is considered to be used for producing
a) longitudinal magnetization
b) circular magnetization
c) field distortions
d) either a or b depending on if it is an A.C. or D.C. yoke
a) longitudinal magnetization
Field strengths of the magnetic field produced by a solenoid (or coil) can be changed by
a) changing the number of coil loops
b) changing the current in the coil
c) both a and b
d) none of the above
c) both a and b
For the same diameter, length and current used, the difference between using a non-magnetic and a ferro-magnetic central conductor is
a) magnitude of magnetic field on the outside surface of the conductor
b) directions of defects detected
c) both a and b
d) no difference
a) magnitude of magnetic field on the outside surface
When performing MPI using prods, the current used depends on
a) prod spacing
b) part thickness
c) prod diameter
d) both a and b
d) both a and b
The guideline to use 40 amperes of magnetizing current per mm of part diameter applies to
a) head shots
b) coil shots
c) central conductor shots
d) de-magnetization
a) head shots
If using the rule of thumb of 40 amps per mm of part diameter for a head shot, what current is required to magnetize a 20mm diameter copper bar?
a) 400 amp
b) 800 amp
c) 1600 amp
d) none of the above
d) none of the above
If 24000 ampere turns are required for coil shot using a 5 turn bench coil, what should your current setting be?
a) 2400 amps
b) 4800 amps
c) 12000 amps
d) 24000 amps
b) 4800 amps
In what way does surface roughness hinder the MPI test on a part?
a) hindrance of particle migration
b) reduction in contrast
c) distortion of the magnetic field
d) all of the above
d) all of the above
What do the following cleaning methods all have in common? Shot blasting, sand blasting, wire brushing and scraping
a) none are used for precleaning a part for MPI
b) none require electricity
c) all are mechanical methods
d) all are environmentally friendly
c) all are mechanical methods
Which cleaning method is not likely to be used to remove oil films prior to an MPI test?
a) vapour degreasing
b) wire brushing
c) steam cleaning
d) ultrasonic cleaning
b) wire brushing
The magnetic field produced by a yoke made of permanent magnets is _______ between the poles.
a) longitudinal
b) circular
c) both a and b
d) constantly varying
a) longitudinal
The swinging field MPI technique is used with
a) sequenced D.C.
b) combined D.C. and A.C. fields
c) combined A.C. fields
d) all of the above
d) all of the above
The advantage of the swinging field or multidirectional magnetization technique is
a) cost of equipment
b) detection of small defects
c) time saving because it is single step test
d) both b and c
d) both b and c
When permeability of a material is quoted without an additional qualifying term the permeability referred to is
a) initial permeability
b) incremental permeability
c) maximum permeability
d) osmotic permeability
c) maximum permeability
Current for circular magnetization of a part whose maximum permeability is 500 will be ___________ compared to a part with maximum permeability of 4000.
a) more
b) less
c) about the same
d) it depends if A.C. or D.C. is used
a) more
In MPI a handy rule of thumb relating current flow and suspected flaw orientation is; current flow should be directed _______ major axis.
a) under suspected defects’
b) parallel to suspected defects’
c) perpendicular to suspected defects’
d) diagonally to suspected defects
b) parallel to suspected defects’
The strength of a circular magnetic field is not diminished by ________ of a part.
a) permeability
b) diameter
c) length
d) any of the above
c) length
A 2cm diameter pipe and a 2cm diameter bar of the same steel alloy are each circularly magnetized by a 1000 amp D.C. head shot. The strongest magnetic field will occur on the surface of the __________-.
a) bar
b) pipe
c) pipe if its wall is less than 0.5cm
d) none of the above, fields will be equal
d) none of the above, fields will be equal
When a hollow non-magnetic central conductor is used to induce a circular magnetic field in a ferro-magnetic cylinder maximum field strength is at the
a) central conductor’s outside surface
b) central conductor’s inside surface
c) magnetic material’s inside surface
d) magnetic material’s outside surface
c) magnetic material’s inside surface
When A.C. is used instead of D.C. for a head shot on a steel tube, the field on the inside surface of the tube is
a) much less
b) much more
c) nearly the same
d) both are exactly zero
d) both are exactly zero
The best way to determine magnetizing current required for irregularly shaped pieces is
a) length to diameter ratio equations
b) 40 amps per mm of part thickness
c) empirically (trial and error)
d) finite element analysis
c) empirically (trial and error)
When using the prod method of MPI, defects are normally looked for
a) between the prods
b) under the prods
c) in circles about 4” (100mm) radius from the prods
d) in all of the above locations
a) between the prods
In order to maintain the same field strength at the midpoint of prods spaced 8 inches apart as was had with a 6 inch spacing you must
a) increase the magnetizing current
b) decrease the magnetizing current
c) use D.C. instead of A.C.
d) use larger diameter prod electrodes
a) increase the magnetizing current
Which is not a consideration when choosing current type to use for prod inspection methods of MPI?
a) particle mobility
b) safety
c) power consumption
d) heating effects on equipment
b) safety
Capacitive discharge methods of producing a magnetizing current do so for only a short duration.
a) typically 1 to 2 seconds
b) typically 0.5 to 1 seconds
c) typically 10 to 100ms
d) typically 5 to 55 æs
c) typically 10 to 100ms
Pre-cracked magnetic steel plates are an effective means of
a) qualitative analysis of MPI bath concentrations
b) quantitative analysis of MPI bath concentrations
c) calibrating ammeters on MPI bench units
d) sizing unknown MPI indications
a) qualitative analysis of MPI bath concentrations
Typical pocket sized magnetic field indicators are used to measure
a) magnetizing force in a coil
b) external residual fields
c) internal residual fields
d) circular field strength during current flow
b) external residual fields
A low cost rugged tool used to measure residual magnetic field strength of ferromagnetic parts is a
a) residu-meter
b) shunt meter
c) magnetic field indicator
d) Helmholtz coil
c) magnetic field indicator
A good magnetic field indicator (MFI) should have which characteristic?
a) rugged supports to prevent damage to the pointer needle
b) not be easily demagnetized by strong external fields
c) not induce magnetic poles of the parts they test
d) all of the above
d) all of the above
Excessive background in wet fluorescent MPI testing results from
a) excessive current density
b) excessive particle density
c) excessive black-light intensity
d) both a and b
d) both a and b
The standard steel ring 7/8” thick having a 1 1/4” diameter central hole and 12 0.007” diameter holes arranged with increasing depth from the outside edge of the ring is called a(n)
a) annular ring
b) Ketos ring
c) ASME ring
d) DIN ring
b) Ketos ring
Probability of seeing a wet fluorescent MPI indication
a) increases with increasing blacklight intensity
b) increases with decreasing white light background
c) increases with decreasing blacklight intensity
d) both a and b
d) both a and b
Although settling time prior to measuring wet fluorescent magnetic particle concentration is now increased to 1 hour for most standards, complete settling usually takes
a) 15 minutes
b) 30 minutes
c) 2 hours
d) 24 hours
d) 24 hours
When viewing the oil carrier of wet fluorescent particles (i.e. the liquid without the particles) under black-light it usually has a _________ tint.
a) yellowish
b) bluish
c) yellow/green
d) reddish
b) bluish
The purpose of adding an antifoaming agent to wet MPI bath is to
a) reduce suds resulting from agitation
b) eliminate phosphates for environmental protection
c) prevent fluorescent material from disbonding from the oxides
d) all of the above
a) reduce suds resulting from agitation
Indications from medium to deep surface breaking seams found using A.C. MPI
a) are not possible to find
b) usually look alike
c) require extra large particles
d) form double indications
b) usually look alike
Fastest particle settlement in an MPI bath would occur for
a) small dense particles in a low viscosity liquid
b) small dense particles in a high viscosity liquid
c) larger dense particles in a low viscosity liquid
d) all of the above would settle about the same rate due to the Bernoulli effect
c) larger dense particles in a low viscosity liquid
MPI indication width tends to increase for increasing
a) defect width
b) defect depth
c) magnetizing current strength
d) all of the above
d) all of the above
Because in general, there exists a direct relationship between indication width and seam (defect) depth, a minimum magnetizing current level can be set to
a) maintain uniform indication widths
b) detect significant flaws
c) both a and b
d) none of the above
b) detect significant flaws
Very fine MPI particles which fall into a crack opening can cause the flux lines to remain in the part, this could result in
a) over estimating crack depth
b) over estimating crack length
c) missing the crack altogether
d) missing the crack all together if non-fluorescent particles are used
d) missing the crack all together if non-fluorescent particles are used
When lighting requirements are specified for a blacklight viewing of fluorescent MPI, 20 lux whitelight intensity is
a) a recommended maximum
b) a recommended minimum
c) only a rough estimate
d) must be strictly met to ensure visibility of indications
a) a recommended maximum
What method is used to ensure proper magnetization levels are used?
a) formulae (rules of thumb)
b) test pieces
c) gauss/tesla meter
d) all of the above
d) all of the above
An advantage of MPI over LPI (Liquid Penetrant Inspection) is that ___________ using MPI.
a) ceramics can be tested
b) ferromagnetic materials can be tested
c) coated surfaces can be tested
d) it is always more environmentally friendly
c) coated surfaces can be tested
The difference between magnetic particle testing and magnetic flux leakage testing is
a) the type of sensor used to detect fields
b) the type of magnetizing current used
c) the thickness of part that can be tested
d) none, they are exactly the same
a) the type of sensor used to detect fields
The “standard depth of penetration” resulting from the skin effect is caused by
a) hysteresis
b) alternating current
c) direct current
d) Hall detectors
b) alternating current
To understand magnetic particle indication formation you should consider
a) discontinuity parameters
b) magnetic field parameters affecting the external flux leakage
c) how the magnetic particles react to passing through the leakage fields
d) all of the above
d) all of the above
The main purpose of a ferrite core in the coil type flux sensitive devices for magnetic field testing is
a) reduction of electrical noise
b) to amplify the flux density
c) enhancement of the Hall effect
d) all of the above
b) to amplify the flux density
In addition to flux density amplification, ferrite cores in coil type flux sensitive devices provide
a) support for the wire turns
b) minimizing of detrimental eddy current effect
c) both a and b
d) no useful purpose
c) both a and b
The crystals used in Hall detector type flux sensitive devices are
a) piezoelectric
b) pyroelectric
c) magneto-strictive
d) semiconductors
d) semiconductors
The main advantage of the Hall detector as a flux sensing device is
a) the small size of its active area
b) the low voltage required to run it
c) its direct readout of field
d) its ability to be used in both northern and southern hemispheres
a) the small size of its active area
The main disadvantage of a Hall detector as a flux measuring device is
a) its small size
b) variability between units
c) high cost per unit
d) poor temperature characteristics
b) variability between units
A ferro-probe (or Foerster microprobe) has a high frequency alternating current in a coil mounted on a _______ core.
a) ferrite
b) diamagnetic
c) hard
d) paramagnetic
a) ferrite
The bulk magnetic indicator is not used for measuring
a) uniform magnetic induction fields in air
b) uniform magnetic field strength in air
c) the existence of a magnetic field external to a part
d) leakage fields from discontinuities
d) leakage fields from discontinuities
Daylight fluorescent dry magnetic particles
a) require a standard blacklight for viewing
b) require a special filter on the blacklight
c) fluoresce brightly in visible light
d) have no place in NDT
c) fluoresce brightly in visible light
In MPI testing using dry powder, mechanical blowers can be used for
a) particle application
b) removal of background particles
c) pre cleaning of gritty surfaces
d) both a and b
d) both a and b
Dry magnetic particle powders must be handled with care because
a) the ferrous powders and pigments are considered nuisance dusts
b) exposure to skin can cause acute melanoma
c) inhalation can result in silicosis
d) both b and c
a) the ferrous powders and pigments are considered nuisance dust
For sensitive wet method magnetic particle testing, coloured particles are typically 5 to 15 æm diameter. Unpigmented ferromagnetic oxides for the same sensitivity would be
a) 0.5æm to 1.5æm
b) 50 æm to 150æm
c) 0.5mm to 1.5mm
d) useless
a) 0.5æm to 1.5æm
Which materials are not used to make wet method particles for MPI testing?
a) finely divided iron
b) red iron oxide
c) black iron oxide
d) brown iron oxide
b) red iron oxide
Most non-fluorescent magnetic particles used in the wet method are
a) red iron oxide
b) unpigmented ferromagnetic iron oxides
c) fluorescent particles viewed without a blacklight
d) not reusable
b) unpigmented ferromagnetic iron oxides
For a given mass of fluorescent magnetic particles, 60æm sized particles would be more visible by containing more fluorescent pigment than 125æm particles. The reason for this is the smaller particles
a) less binding resin is needed
b) have a stronger chemical affinity for fluorescent pigments
c) have more surface area
d) all of the above
c) have more surface area
Which is not an advantage of oil based vehicles versus water based vehicles of wet magnetic particles?
a) low corrosivity to ferrous alloys
b) low fire hazard
c) low electrical hazard
d) reduced risk of causing hydrogen embrittlement
b) low fire hazard
Which is not an advantage of water based vehicles versus oil based vehicles of wet magnetic particles?
a) cost
b) speed of indication formation
c) lower electrical hazard
d) lower fire hazard
c) lower electrical hazard
When fine fluorescent magnetic particles are seen floating on the surface of their water carrier like dust and no amount of mixing disperses them it indicated
a) particle breakdown
b) insufficient or lack of wetting agent
c) excessive pump speed
d) the particles require demagnetization
b) insufficient or lack of wetting agent
Rust inhibitors placed in MPI water baths
a) provide only short term corrosion protection
b) are neutralized by fluorescent particles
c) double as antifoaming agents
d) all of the above
a) provide only short term corrosion protection
Mineral seed oil is sometimes added to a part after MPI testing with water or oil based baths to provide
a) a demagnetizing effect
b) wash off excess magnetic particles
c) both a and b
d) longer term rust prevention
d) longer term rust prevention
Water used in preparing a water based MPI bath
a) must be de-aerated
b) must be demineralized
c) both a and b
d) can be straight tap water provided it is free from dirt particles
d) can be straight tap water provided it is free from dirt particles
The best way to control oil contamination of MPI baths is
a) use only oil for bath vehicles
b) effective precleaning of parts
c) organic osmotic type filters
d) inorganic micron sized filters
b) effective precleaning of parts
When preparing a bath from dry concentrated MPI particles, in either oil or water vehicle, if the tank is not equipped with a re-circulation pump uneven distribution resulting from hand
stirring can be avoided by
a) premix the quantity into a paste in a blender or small container before adding to the bath
b) presoak the correct quantity in wetting agent or emulsifier
c) mounting an egg-beater on the tank
d) wrapping 3 turns of coil around the tank and applying maximum A.C. to the coil when adding the powder
a) premix the quantity into a paste in a blender or small container before adding to the bath
Settling volume determination used to establish MPI bath particle concentrations usually uses which implement?
a) a pipette
b) a centrifuge tube
c) a ph meter
d) a mass indicator (triple beam balance)
b) a centrifuge tube
Bath concentrations for magnetic particle testing are usually specified as having
a) a maximum value
b) a minimum value
c) a range of values
d) the same values for visible and fluorescent particles
c) a range of values
The result of vibrating a sample of magnetic particle bath being tested for concentration is to
a) increase setting speed
b) decrease apparent concentration by compaction
c) increase apparent concentration by fluffing
d) none of the above
b) decrease apparent concentration by compaction
The source of contaminants that can cause erroneous concentration readings for MPI baths is
a) dirt from the test piece
b) dirt form the atmosphere
c) salts precipitating from hardwater
d) all of the above
d) all of the above
The practical upper limit temperature of the part surface performing MPI on a part using a water vehicle is
a) 20øC.
b) 80øC.
c) 100øC.
d) 212øC.
c) 100øC.
Blacklight intensity in post 1990 specifications nearly always quote minimum irradiance in
a) lux
b) footcandles
c) candela
d) æW/cm
d) æW/cm
The unit of illuminance used to quantify white light for visual inspections is
a) lux
b) candle power
c) æW/cm
d) milliphotos
a) lux
The SI that is now used as the standard measure of the wavelength of light is the
a) m (meter)
b) nm (nanometer)
c) mm (millimeter)
d) A (angstrom unit)
b) nm (nanometer)
As light intensity decreases in the visible range the retina’s cone shaped cells shut down and the ______ shaped cells assume the role of light collection.
a) round
b) square
c) rod
d) pyramidal
c) rod
The cells commonly referred to as the “cone shaped cells” and the “rod shaped cells” are to be found in the
a) eye
b) ear
c) nose
d) penitentiary or asylum
a) eye
Eye glasses with blue-absorbing filters are used to view fluorescent indications because
a) higher levels of blue-violet light can be used without diminishing contrast
b) higher levels of blue-violet light can be used to enhance fluorescence
c) both a and b
d) none of the above
c) both a and b
Maximum contrast when viewing magnetic particle indications would occur for
a) bright daylight conditions
b) subdued daylight conditions
c) darkened conditions as for blacklight viewing
d) none of the above, contrast is a constant
a) bright daylight conditions
In MPI testing, the difference between the amount of light reflected by the surface of a test piece and the amount reflected by an MPI indication is called
a) colour contrast
b) brightness contrast
c) resolution
d) signal to noise ratio
b) brightness contrast
If two objects, such as an MPI indication and its background test surface have the same apparent brightness but reflect light at different wavelengths they would exhibit
a) colour contrast
b) brightness contrast
c) photo harmonics
d) good resolution
a) colour contrast
Eyeball fluorescence results in
a) cataracts
b) lens deterioration
c) an unpleasant but harmless sensation
d) permanent colour blindness
c) an unpleasant but harmless sensation
To reduce the discomfort of eye fatigue when performing fluorescent MPI you can
a) take breaks at regular intervals
b) wear yellow-green tinted glasses (of the appropriate filtering ability)
c) both a and b
d) increase dark adaption time
c) both a and b
The purpose of the deep purple filter used on the mercury vapour lamp is to
a) block most visible light given off the arc
b) block most UV light below 300nm given off the arc
c) absorb only a narrow band of energies centered around 365nm
d) both a and b
d) both a and b
Dark adaption from bright daylight to full darkened conditions for a blacklight viewing booth will require about
a) 30 seconds
b) 2 minutes
c) 5 minutes
d) 10 minutes
b) 2 minutes
In automated scanning systems used for defect detection in MPI testing unwanted background lighting is illuminated by
a) diodes
b) filament rectifiers
c) filters
d) lenses
c) filters
Which of the following can result in an increased output from a blacklight?
a) bulb aging
b) line variations in voltage supply
c) dirt on the filter
d) none of the above
b) line variations in voltage supply
Which of the following can result in a non-relevant MPI indication?
a) sharp corners
b) holes drilled near the surface
c) shrink fits
d) all of the above
d) all of the above
Which is not a source of a false indication in MPI testing?
a) a scratch
b) a shrink fit
c) scale
d) a burr
b) a shrink fit
The purpose of running the circulation pump prior to performing the MPI settling test is to
a) eliminate residual fields
b) permit the skimmer to remove high density contaminants
c) ensure even particle distribution
d) degasify the suspension
c) ensure even particle distribution
The first thing you would do if your mercury arc blacklight did not have adequate intensity when tested is
a) re-calibrate the meter
b) clean the filter
c) replace the bulb
d) put a voltmeter at the receptacle to determine line voltage
b) clean the filter
Cracked blacklight filters are
a) replaced
b) useable if the opening does not exceed 25æm
c) can be used on manual but not automated systems
d) OK to use as long as they stay in the holder and the edges do not present a cutting hazard
a) replaced
An MPI gage cannot be used to estimate adequacy of
a) circular magnetization
b) longitudinal magnetization from a coil
c) the direction of the magnetic field
d) any of the above
b) longitudinal magnetization from a coil
Which is a means of determining if the applied magnetic field is in the correct orientation?
a) pie gages
b) shim gages
c) Hall detectors
d) all of the above
d) all of the above
In a totally automated MPI system, the bath concentration
a) is not important
b) is monitored by continuously measuring opacity
c) required continuous addition of particles
d) is monitored by an employee taking samples for the settling test at one hour intervals
b) is monitored by continuously measuring opacity
In the wet MPI method, timing of the magnetizing current with respect to the flowing of bath over a test piece is especially important if the test piece is of low retentivity because
a) a safety hazard exists if the shot is too long
b) de-polarization of the particles can occur
c) indications could be washed off if flow continues after the shot
d) both a and c
c) indications could be washed off if flow continues after the shot
The primary advantage of the television imaging systems over flying spot systems used for MPI scanning systems is
a) cost and availability
b) resolution
c) depth of field
d) simplicity of electronics
a) cost and availability
The glass commonly used as a filter for blacklights is Kopp 41 (Kopp Glass Inc. Pittsburg, PA.,USA). It effectively
a) blocks all visible light
b) blocks all UV light
c) transmits “soft” UV light over 330 nm wavelength
d) both a and c
d) both a and c
Automated scanning systems rely on the _______ to establish if an MPI indication is real or not.
a) intensity of fluorescence
b) linear nature or patterns of defects
c) absence of background noise
d) type of laser light used
b) linear nature or patterns of defects
The problem with using drawings or written descriptions as a means of recording an MPI indication is
a) they are highly dependent on the writing or drawing skills of the inspector
b) background condition cannot be determined
c) it is not considered a permanent record
d) all of the above
a) they are highly dependent on the writing or drawing skills of the inspector
The tape transfer method of recording an MPI indication is easiest to use with
a) oil vehicle wet fluorescent MPI
b) water vehicle wet visible MPI
c) dry magnetic particle method
d) water vehicle wet fluorescent MPI
c) dry magnetic particle method
A major problem with trying to take a tape transfer of an MPI indication where the vehicle was oil instead of water is
a) longer drying time
b) loss of fluorescence
c) residual oils break down the tape
d) none of the above, oil vehicle wet MPI indications are easier to transfer than water vehicle
a) longer drying time
Which method of recording MPI indications is different from the others?
a) a photograph
b) tape transfer
c) alginate impression or magnetic rubber
d) fixing coatings
a) a photograph
When using fixing coatings to adhere MPI indications to the test piece surface the part is usually dried. What is the reason for this?
a) to allow time for the indication to form at the flux leakage point
b) to allow time for the background to clear off
c) to allow the coating to adhere to the part
d) all of the above
c) to allow the coating to adhere to the part
Which of the following methods of recording MPI indications is different from the other 3?
a) magnetic rubber
b) tape transfer
c) fixing coatings
d) alginate impressions
a) magnetic rubber
The magnetic rubber method of producing permanent records of MPI indications
a) is only used in laboratory experiments
b) requires very long duration magnetization shot
c) must be photographed immediately as the rubber breaks down within 24 hours
d) is the fastest and easiest recording methods for MPI indications
b) requires very long duration magnetization shot
The recommended way to make high quality recordings of MPI indications is by
a) tape transfer methods
b) magnetic rubber
c) photography
d) cast ceramic molds
c) photography
The magnetic particle method does not work if the magnetic flux density is below
a) 100 tesla
b) 10 tesla
c) 1 tesla
d) none of the above, there is no sudden cut off point below which MPI does not work
d) none of the above, there is no sudden cut off point below which MPI does not work
When the central conductor MPI method is used to inspect a ring shaped object, or short cylinder
a) only inside diameter surface flaws can be found
b) only outside diameter surface flaws can be found
c) both inside and outside surface and subsurface flaws can be found if the wall thickness is not too great
d) none of the above, central conductors cannot be used for ring shaped objects
c) both inside and outside surface and subsurface flaws can be found if the wall thickness is not too great
Rating of yokes is either by the force needed to pull one leg off the specimen or by the lifting power of the yoke. The lifting force of a yoke is
a) half the pull off force
b) twice the pull off force
c) 18 kg.
d) 4.5 kg.
b) twice the pull off force
When lifting power of an A.C. yoke is specified in kg. you must also specify a minimum
a) current draw
b) test piece thickness
c) prod spacing
d) coil length
c) prod spacing
When rotating field MPI techniques are used it is required that you use
a) fluorescent particles only
b) the wet method
c) dry powder
d) straight D.C. magnetization
b) the wet method
On which of the following surfaces would you not likely use the dry MPI method?
a) hot surface up to 300øC.
b) undressed weld surfaces
c) wet or oily surfaces
d) rough casting surfaces
c) wet or oily surfaces
The region outside a magnet, where the magnet exerts its influence is the
a) magnetic field
b) Barkhausen region
c) Lorentz zone
d) de-magnetized zone (DMZ)
a) magnetic field
The following are properties of what? 1) they begin and end on poles, 2) they appear to repel each other, 3) their direction is that in which a free north pole would travel.
a) electrons
b) magnetic lines of force
c) gravitons
d) strong nuclear forces
b) magnetic lines of force
If a ferromagnetic material is not taken to magnetic saturation on its hysteresis loop it will follow ________ when the applied field is reversed.
a) the virgin curve
b) a minor loop
c) straight line
d) none of the above, it will be stuck at the termination point
b) a minor loop
In a unmagnetized ferromagnetic specimen the net (macroscopic) magnetization is
a) zero
b) greater than 0.1 Oersted
c) greater than 1.0 Oersted
d) at least 10.0 Oersted to be considered ferromagnetic
a) zero
During magnetization of an initially unmagnetized specimen the total number of domains in the specimen
a) remains constant
b) increases
c) decreases
d) first decreases and then increases at saturation
c) decreases
Steels used in transformer cores and electromagnets would have which characteristics?
a) relatively small areas are enclosed by the B-H curve
b) small field intensities cause large flux densities
c) relatively low coercive force
d) all of the above
d) all of the above
The super magnets, such as samarium-cobalt and neodymium-iron are virtually impossible to de-magnetize by any means other than raising their temperature over the curie point because of
a) low retentivity
b) low coercivity
c) high coercivity
d) high retentivity
c) high coercivity
As compared to inspecting at the middle of a long tube, when inspecting the end of a tube using the longitudinal MPI method, ______ are required of the coil.
a) higher fields
b) lower fields
c) longer shots
d) shorter shots
a) higher fields
For field applications, in order to induce a longitudinal field in a section of piping, if a fixed coil or split coil is not available, you would probably use
a) prods
b) several turns of welding cable around the pipe
c) a yoke
d) two shots using circular magnetization
b) several turns of welding cable around the pipe
As paint coating thickness increases on a ferromagnetic plate, the force required to pull the yoke off the plate
a) increases
b) decreases
c) remains constant
d) may increase or decrease depending on type of paint
b) decreases
How are circular magnetizations applied to cylindrical specimens?
a) rotating yokes
b) central conductors
c) passing current along the part
d) all of the above
d) all of the above
The purpose of a silicon controlled rectifier (SCR) in the circuitry for pulsed or capacitor discharge magnetization is
a) to ensure the pulse in unipolar
b) a safety feature
c) to act as a filter to eddy currents
d) a delay line device
a) to ensure the pulse in unipolar
What is the disadvantage of doing MPI by the residual method when looking for sub-surface indications?
a) lack of particle motion
b) excessive surface noise can mask small indications
c) the time it takes for eddy currents to die down
d) all of the above
b) excessive surface noise can mask small indications
Which could be considered “sub-surface flaw”?
a) external pitting on tubes’ OD surfaces
b) internal pitting on tubes’ ID surfaces
c) laminations or porosity
d) all of the above
d) all of the above
“Banding” of magnetic particles when using the dry powder method with prods indicates
a) insufficient current
b) excessive current
c) particle size is too small
d) particle size is too big
b) excessive current
Most portable field indicators, such as the “pie” gage are used to
a) accurately determine relative sensitivity
b) quantitatively determine field strength
c) indicate general direction of surface fields
d) all of the above
c) indicate general direction of surface fields
Irregularly shaped parts that have been magnetized are demagnetized by
a) suspending it in an east-west orientation and beating lit
b) passing it through a long coil (solenoid) using decreasing A.C.
c) both a and b
d) there is no effective way to completely demagnetize an irregular part other than heating over the curie temperature
d) there is no effective way to completely demagnetize an irregular part other than heating over the curie temperature
Soft iron bars placed across the pole ends of horseshoe magnets are called
a) stoppers
b) keepers
c) reflectors
d) magneto-strictors
b) keepers
To detect radial cracking on a bolt flange 2cm thick, 30cm diameter with an inside diameter of 25cm you could probably use
a) 2 head shots
b) a central conductor for circular magnetization
c) a yoke
d) prods
b) a central conductor for circular magnetization
The most important factor in MPI for detectability of a defect is
a) current strength
b) strength of induced magnetism
c) direction of induced magnetic field
d) all of the above are equally important
c) direction of induced magnetic field
Welding machines, magnetic chucks, contact with electromagnetic lifting devices and permanent magnets are the cause of what problem?
a) magnetic writing
b) unwanted residual magnetism in ferromagnetic parts
c) false indications
d) arc burns
b) unwanted residual magnetism in ferromagnetic parts
In general, likelyhood of flaw detection by MPI is statistical and increases with
a) flaw size
b) age of inspector
c) current used
d) amount of power (or ink) used
a) flaw size
Which is not a factor that will affect the level of magnetic flux leakage from a flaw?
a) defect size
b) defect shape
c) part thickness
d) applied field strength
c) part thickness
What is the purpose of limiting the flux density generated in a piece being MPI tested?
a) reduce the occurrence of false reporting of flaws
b) prevent arcing
c) ensure saturation is not achieved
d) provide more particle mobility
a) reduce the occurrence of false reporting of flaws
For precise delineation of the contour and extent of a magnetic particle indication is required the best way to record it is
a) photography
b) tape transfer or lacquer
c) etching
d) hand sketches
b) tape transfer or lacquer
Flow lines found by MPI in a steel forging are
a) always rejectable
b) non-relevant indications
c) seen only with the aid of a microscope
d) evidence for magnetic domains
b) non-relevant indications
When photography of fluorescent indications is performed ____________ are used to prevent overexposure of film.
a) F-stops
b) fish-eye lenses
c) special filters
d) black and white film
c) special filters
For photography of MPI indications the use of a tripod is recommended. Why?
a) the camera with all the attachments is too heavy
b) exposures are long and camera movement would ruin the shot
c) to facilitate a mount for the light meter
d) none of the above-tripods are never used
b) exposures are long and camera movement would ruin the shot
Photographs of fluorescent indications require which type of film?
a) instant black and white
b) regular black and white
c) regular colour
d) any of the above, generally no special film is needed
d) any of the above, generally no special film is needed
In photography of NDT indications filters are often incorporated as part of the lens optics, why?
a) to remove unwanted light
b) to balance colour of light used
c) both a and b
d) none of the above, filters are forbidden
c) both a and b
If a UV filter used for photography of fluorescent indications was made of fluorescent material what would the effect be?
a) cause fogging of the image
b) change the colour of the indication
c) change the colour of the background
d) both b and c
a) cause fogging of the image
When taking photographs of NDT indications it is often advised to take several exposures of the same view but using different f-stops. The reason is
a) to get several copies for multiple reports
b) to compensate for unforeseen conditions
c) to give the appearance of being professional
d) not all cameras have the same aperture for a given f-stop
b) to compensate for unforeseen conditions
What is the advantage of photography of MPI indications over other archival methods?
a) highest resolution reproduction possible
b) the indication in relation to the test object is shown
c) storage life is nearly indefinite
d) all of the above
d) all of the above
The problem with de-magnetizing a piece by raising its temperature to over the curie point is it
a) is often impractical
b) is only effective for surface demagnetization
c) doesn’t work for circular magnetization
d) doesn’t work for longitudinal magnetization
a) is often impractical
Ferromagnetic materials that contain very high residual fields are
a) very hard to demagnetize
b) very easy to demagnetize
c) cannot be demagnetized
d) none of the above, retenitivity has nothing to do with ease of demagnetization
d) none of the above, retenitivity has nothing to do with ease of demagnetization
Ferromagnetic materials having very high coercivity have
a) very high retentivity
b) very low retentivity
c) no retentivity
d) none of the above, coercivity is not determined by the magnitude of residual field
d) none of the above, coercivity is not determined by the magnitude of residual field
When using reversing D.C. to demagnetize a part about 30 reversals of decreasing amperage are used in a time of
a) 2 seconds
b) 15 seconds
c) 30 seconds
d) 120 seconds
c) 30 seconds
The best way to demagnetize a long tube would be
a) reversing D.C. with a central conductor
b) pulsating A.C. with a central conductor
c) a portable yoke
d) passing the tube through an A.C. coil
a) reversing D.C. with a central conductor
In most cases A.C. demagnetization methods are adequate for parts having a cross-section of not more than
a) 5mm
b) 50mm
c) 100mm
d) 150mm
b) 50mm
The coil 30 point step down D.C. demagnetization is not an acceptable method for
a) small sized soft steel objects at low production rates
b) medium sized medium hardness steel objects at medium production rates
c) small sized, soft steel objects at high production rates
d) none of the above
c) small sized, soft steel objects at high production rates
Field strength within a magnetizing coil
a) greatest at the coil’s center
b) greatest near the inside wall of the coil
c) evenly distributed across the coil’s area
d) opposite to that found in a demagnetizing coil
b) greatest near the inside wall of the coil
Which of the following is an acceptable practice for demagnetization?
a) pass small parts through demag coils while stacked in baskets
b) pass short objects through demag coils end to end in a chain
c) use ferromagnetic trays or baskets to convey parts through the demag coil
d) all of the above are common good practice
b) pass short objects through demag coils end to end in a chain
Operator safety as it concerns MPI testing equipment usually concerns the
a) electrical and mechanical parts of the MPI equipment
b) petroleum distillates
c) inherent risks of the test site
d) both a and b
d) both a and b
The safety hazard associated with petroleum distillates used as vehicles for MPI is
a) fire and explosion upon ignition by arcing
b) dermaititis (skin irritation/infection)
c) inhalation of toxic fumes
d) all of the above
d) all of the above
When working over tanks of petroleum distillates used for MPI particle vehicles the safety precaution that would be taken is
a) grounding all motors
b) only work in the presence of blacklight to see any splashed oils on your person
c) ensure proper ventilation
d) post all material hazards documents near by
c) ensure proper ventilation
Even a cool well ventilated environment, there is still a safety risk of explosion when performing fluorescent MPI. What is the source of this risk?
a) battery packs
b) transformer surges
c) high intensity discharge lamps
d) spontaneous combustion of vapours
c) high intensity discharge lamps
The ultraviolet light used in NDT for viewing fluorescent indications is called
a) long wave ultraviolet
b) blacklight
c) UV-A
d) all of the above
d) all of the above
Some blacklights come with thin outer glass filter envelope around the discharge lamp. Should this outer shell break the inner lamp continues to work. If the outer shell cracks you should
a) replace the whole bulb unit at the end of the shift
b) turn it off and discard it immediately
c) check the intensity with a meter and continue only if still within permissible working range
d) not worry unless a piece of glass falls off
b) turn it off and discard it immediately
Prior to the main electrodes arcing what must occur in the mercury vapour blacklight lamps?
a) argon gas must be transferred to the outer glass envelope
b) the starter resistor must shut off
c) the mercury must vaporize
d) the main electrodes must heat up
c) the mercury must vaporize
The purpose of the aluminized surface on the inside surface of the outer glass bulb of the mercury vapour lamp is to
a) increase the heating rate on the vapour
b) produce a spot profile of light
c) protect the operator from excessive heat
d) filter out the UV-C radiation
b) produce a spot profile of light
When voltage drops more than 15% or power has been switched off to the blacklight the arc ceases and attempts to immediately restart it will fail because
a) the ballast capacitor takes time to build up its starter charge
b) the “heater” electrode is still cold
c) mercury vapour pressure must reduce by cooling before the arc will re-start
d) the re-set switch has been tripped
c) mercury vapour pressure must reduce by cooling before the arc will re-start
Bulb radiance output from a mercury vapour blacklight can rise suddenly as a result of
a) line voltage surge
b) steady vibration of the ballast
c) cleaning the filter
d) both a and c
a) line voltage surge
The phosphor coating on the glass filter envelope of blacklight tubes emits
a) infrared radiation
b) UV-A and visible light
c) UV-B radiation
d) UV-C radiation
b) UV-A and visible light
The reason blacklight tubes are not used for critical fluorescent viewing is
a) their irradiance is mush lower than the medium pressure mercury vapour lamps
b) they must be arranged in banks so present a safety hazard
c) the UV-A to UV-B ratio is insufficient
d) none of the above, blacklight tubes are equal to or better than medium pressure mercury vapour lamps
a) their irradiance is mush lower than the medium pressure mercury vapour lamps
In MPI testing (and any work with electric apparatus) risk of dangerous electric shock is increased in the presence of water or moisture on or around the body because
a) water is a good insulator
b) Ohm’s law breaks down in presence of water
c) the body’s electrical resistance is lowered allowing higher currents to flow
d) water increases the voltage entering the body
c) the body’s electrical resistance is lowered allowing higher currents to flow
From an MPI safety point of view, if you cannot eliminate the possibility of a spark occurring you should
a) not perform the test
b) control the environment so an explosion cannot occur
c) only use D.C. yoke
d) only use an A.C. yoke
b) control the environment so an explosion cannot occur
Adherence to the empirical rules set down for MPI will
a) ensure the smallest detectable flaw is always found
b) indicate reference standards are not required in MPI
c) often lead to over magnetization and poor coverage
d) always satisfy code requirements
c) often lead to over magnetization and poor coverage
The purpose of the ketos tool steel ring is to
a) determine the effectiveness of the magnetic particle system’s performance, especially the particles
b) establish the length of defect that can be found
c) calibrate the ammeter
d) determine the current required on test objects
a) determine the effectiveness of the magnetic particle system’s performance, especially the particles
Which of the blocks listed below is not a magnetic particle inspection reference standard?
a) spilt prism test block
b) magnetized test block
c) I.I.W. calibration block
d) tool steel ring standard
c) I.I.W. calibration block
The number of holes 0.07mm diameter found in the ketos tool steel ring standard is
a) 3
b) 10
c) 12
d) 15
c) 12
Raised cross indicators and pie gages are
a) the same thing
b) MPI field direction indications
c) quantitative flux meters
d) permeability indicators
b) MPI field direction indications
In MPI testing the pie gage is read by
a) slots perpendicular to the flux lines producing distinct indications
b) slots parallel to the flux lines producing distinct indications
c) digital read-out
d) both a and b
a) slots perpendicular to the flux lines producing distinct indications
When viewing parts with blacklight both direct and reflected blacklight striking the eye should be avoided because
a) dark adaption is lost
b) cone sensors are “killed”
c) vision becomes clouded due to ocular fluorescence
d) vision becomes over-sensitive
c) vision becomes clouded due to ocular fluorescence
The mercury found in the mercury vapour lamp in its cold or off state is
a) vacuum deposited on the quartz tube walls
b) condensed droplets of liquid mercury
c) vapourized and blended with an inert gas
d) actually mercurous oxide powder which acts as a phosphor
b) condensed droplets of liquid mercury
Blacklights used for fluorescent indication viewing are usually mounted in fixtures for what reason?
a) prevent transmission of visible light
b) support the filter
c) allow the beam to be directed to the inspection surface
d) all of the above
d) all of the above
The advantage of tubular style UV lamps is
a) quick starting
b) cool operating temperature
c) cheap to buy and operate
d) all of the above
d) all of the above
UV lamps used for viewing fluorescent indications tend to operate under higher than optimum design conditions. As a result
a) output is constantly higher b) output is constantly lower
c) life expectancy is lower than manufactures’ estimates
d) life expectancy is higher than manufacturers’ estimates
c) life expectancy is lower than manufactures’ estimates
The unit of light intensity is the lux or footcandle which is based on the human eye’s response to light. Why is it an inappropriate unit for UV radiation?
a) UV radiation is not sensed by the eye
b) UV radiation for NDT is filtered
c) because the fluorescence of the meter interferes with the reading
d) none of the above-the lux value is easily and accurately had by subtracting the filtered from the unfiltered readings
a) UV radiation is not sensed by the eye
The reason high quality UV light filters, having well defined upper and lower limits, are not used for measuring UV intensities in NDT applications is primarily because
a) they are not available
b) of cost
c) they cannot be fitted to standard meters
d) none of the above
b) of cost
UV meters should be calibrated about every six months, this is because
a) it is stipulated in all QA manuals
b) sensors can deteriorate
c) UV filters can deteriorate d) both a and b
d) both a and b
If coatings are left on a part to be MPI tested you must
a) demonstrate detectability through the maximum costing thickness
b) get a Level II to ok the work
c) get a Level III to sign the report
d) both b and c
a) demonstrate detectability through the maximum costing thickness
To detect fatigue cracks in a field weld you would most likely use
a) a D.C. yoke
b) an A.C. yoke
c) permanent magnets
d) all of the above work well for fatigue cracks
b) an A.C. yoke
For crack detection on a painted steel surface that has had the paint removed, MPI as compared to Liquid Penetrant testing is
a) not as good
b) far better
c) only slightly better
d) about the same
b) far better
Particle concentrations for magnetic particles applied from aerosol cans are
a) always constant-hence their advantage
b) known and accurate only when the can is full
c) never determined
d) not important as they are never used for critical work
b) known and accurate only when the can is full
The prism block standard in MPI testing is used to evaluate
a) total system sensitivity
b) yoke strength
c) particle suspension effectiveness
d) all of the above
c) particle suspension effectiveness
When welds are required to have only partial penetration use of HWDC yokes often give rise to nonrelevant indications. This can be overcome by
a) using A.C.
b) increasing leg spacing
c) reducing magnetizing current
d) using a pie gage
a) using A.C.
When using dry fluorescent powders outdoors, ambient lighting must be
a) maximized
b) minimized
c) augmented by UV lamps
d) not less than 4,500 lux
b) minimized
When performing MPI with A.C, the resulting eddy currents provide
a) a demagnetizing effect
b) all the particle mobility
c) a means of performing 2 NDT test at one time
d) both b and c
a) a demagnetizing effect
In order that they be held by weak leakage fluxes, dry magnetic particles must have
a) mobility
b) high permeability
c) high retentivity
d) all of the above
b) high permeability
Acceptance or rejection of a discontinuity found in a test object is controlled by
a) the Level I inspector
b) the Level II inspector
c) the defect length
d) the service requirements of the part
d) the service requirements of the part
Which of the following would risk erroneous test results for an MPI test?
a) magnetizing current meter reads too high
b) magnetizing current meter reads too low
c) bath suspension concentration is too high
d) all of the above
d) all of the above
If the magnetizing current ammeter on your bench unit is no longer reading current when you hit the “on” switch for the current, the problem is
a) a coil is burned out on the transformer
b) a loosened or broken connector
c) both a and b could cause the problem
d) the meter has been de-gaussed
c) both a and b could cause the problem
The decision an inspector makes as to whether or not an indication is to be accepted is
a) interpretation
b) evaluation
c) dispensation
d) disposition
b) evaluation
Rejecting all parts in an MPI inspection which contain relevant indications is
a) costly
b) not always necessary
c) required by code
d) both a and b
d) both a and b
Which of the following flaws in a highly stressed steel component is most likely to be cause for concern?
a) a shallow vee shaped scratch
b) a small surface breaking pore
c) a medium sized sub-surface pore
d) 4 small subsurface aligned pores separated by no less than 6mm
a) a shallow vee shaped scratch
Characteristics of discontinuities determine
a) their detectability by NDT
b) their possible role as defects
c) materials’ properties
d) both a and b
d) both a and b
MPI indication formation for dry powder methods will best be formed on _______ surfaces.
a) coarse, horizontal
b) rough and slightly inclined
c) smooth, flat (horizontal)
d) smooth, vertical
c) smooth, flat (horizontal)
For dry powder MPI methods, inspection on flat horizontal surfaces is preferred because
a) particles are not pulled off by gravity
b) less powder is needed to form indications
c) only then can subsurface defects be located
d) all of the above
a) particles are not pulled off by gravity
Cold working steel can result in non-relevant MPI indications, these result from
a) micro fractures
b) permeability changes from increased harness
c) concentration of carbon into banded regions
d) none of the above, cold working does not produce non-relevant indications
b) permeability changes from increased harness
Although a welding machine can be used to supply many amps of current it is not used for practical MPI testing for which reason?
a) welding machines cannot supply D.C.
b) voltages are too high
c) currents available are never sufficient
d) all of the above
b) voltages are too high
Which NDT method would you use to locate shrinkage in a steel casting?
a) magnetic particle
b) liquid penetrant
c) radiography
d) ultrasonics
c) radiography
Which NDT method would you use to detect tight cracks in tungsten forgings
a) magnetic particle
b) liquid penetrant
c) ultrasonics
d) radiography
b) liquid penetrant
Which NDT method would you use to locate defects in 15mm diameter monel tubing?
a) magnetic particle
b) liquid penetrant
c) ultrasonics
d) radiography
c) ultrasonics
Which of the following NDT methods would be best suited to inspect thin wall (1mm) 15mm diameter monel tubing?
a) liquid penetrant
b) magnetic particle
c) eddy current
d) radiography
c) eddy current
Magnetic flux lines intercepted by a discontinuity lying just below the surface flow
a) across the discontinuity
b) around the edges of the discontinuity
c) through the air above the discontinuity
d) all of the above
d) all of the above
Austenitic steels are
a) non-magnetic
b) used for super magnets
c) used as magnetic keepers
d) all of the above
a) non-magnetic
The most likely cause of no current reading when you apply a prod shot to a rough casting (assuming you have turned the unit on) is
a) insufficient current setting b) to great a prod spacing
c) poor prod/casting contact d) incorrect current type (AC/DC)
c) poor prod/casting contact
Dry magnetic particle techniques would not be well suited to finding
a) transverse cracks in welds
b) grinding cracks
c) subsurface non-fusion in welds
d) unfused chaplets in castings
b) grinding cracks
The maximum demagnetizing current used is always
a) AC
b) DC
c) greater than that used for the MPI test
d) less than that used for the MPI test
c) greater than that used for the MPI test
When the contact heads of an MPI bench unit are used to direct current along cable to test a large or remote piece, the spacer placed between the heads is
a) ferro-magnetic
b) copper
c) an insulator
d) none of the above
c) an insulator
Horseshoe permanent magnets have their advantage in
a) high flux density available
b) portability
c) the variety of sizes they are available in
d) being able to test stainless steels
b) portability
“Dam” structures are used in MPI testing using _______ techniques.
a) wet
b) dry
c) magnetic rubber
d) swinging field
c) magnetic rubber
In MPI, the settling test is used to determine
a) dry particle density
b) bath strength
c) bath condition (degree of contamination)
d) both b and c
d) both b and c
Magnetic particles used in wet methods have _________ to prevent clumping and high background buildup.
a) low coercivity
b) low retentivity
c) low permeability
d) both a and b
d) both a and b
Low retentivity and low coercivity are requirements for magnetic particles to
a) promote clumping
b) increase subsurface detectability
c) decrease background
d) all of the above
c) decrease background
In MPI testing the dry powder equivalent to the wet particle pressurized sprayer is the
a) squeeze bulb
b) powder blower
c) particle shaker
d) static-discharge applicator
b) powder blower
