Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Millwright Level 4 > NDT Testing > Flashcards

NDT Testing Flashcards

1
Q

Destructive testing tests include:
- tensile testing
- compressive testing
- torsion testing
- fatigue testing
- hardness testjng
- impact testing
What are the five most common non destructive testing methods?

A
  • visual inspection
  • dye penetrant
  • magnetic particle
  • ultra sonic
  • radiography

Eddy current is not the top five most common but it is frequently used for automatic production line inspection.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Welding process can cause internal stress of the parts or the ______ condition of the manufactured component. And must be NDT tested.

A

Operating conditions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Liquid dye penetrant (LDT) is used to?

A

Detect discontinuities open to the surface of solid and non porous materials.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What type of NDT testing uses capillary action, blotted to the surface with a developing agent and viewed under a ultra violet light or white light?

A

Liquid penetrant testing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

LPT testing can be done on a wide variety of materials such as:

Some advantages are?

A

Metals, glass, ceramics and plastics

Portable and can be applied on small and large surfaces

  • in practice it is relatively simple and less costly
  • good for detecting flaws in non-magnetic materials and inspecting items made from non-ferromagnetic steels
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Limitations of liquid penetrant?

A
  • can only detect imperfections that are open to the surface
  • rough or porous surfaces will produce false indications
  • temperature sensitive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Liquid penetrant process?

A

1: clean area, must be free of oil, water or other contaminants. For atleast 1” beyond the area being inspected.
2: apply a penetrating coloured liquid dye to the surface of the test piece. Should be left on long enough to along sufficient penetration. (Dwell)
3: Remove all surplus dye. Type of dye will dictate cleaning method. Make sure not to over clean
4: apply thin coat of developer to the surface to provide a contrasting background.
5: inspect with good white light or or black light depending on the penetrant.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Two type of liquid penetrants?

A

Fluorescent - visible Under ultraviolet light

Visible - red penetrant produces vivid red indications in contrast with the light background

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Non flammable cleaners usually contain halogenated solvents which make them unsuitable for some applications. How come?

A

High toxicity and have undesirable effects on some materials.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fluorescent dye penetrant test detects surface imperfections such as?

A
  • Surface cracks in in castings, welds and carbide tools
  • shrinkage in castings and hot forgings
  • cracks in turbine blades and ceramic insulators
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Liquid penetrant is widely used in?

A

Welded thin walled vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Magnetic particle testing (MT) is used to detect surface and subsurface discontinuities usually at depths not greater than?

A

6mm (1/4”)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Magnetic partial testing is commonly used on?

A
  • welds
  • Large forgings
  • castings
  • other parts with rough surfaces
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

To detect the flaws with magnetic particle testing magnetic field must be orientated in which direction of the defect?

A

90 degrees

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Limitations of magnetic particle testing?

A
  • thin coatings of paint make less sensitive
  • non-ferromagnetic materials cannot be tested
  • demagnetizations is often required afterwards
  • exceedingly large currents are sometime needed
  • ## wide cracks may not produce a particle pattern
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Three types of unbalance

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What current is used for Magnetic particle testing?

A

Ac - should not be used for searching for subtracted discontinuities.

And

Dc - generally penetrate the cross section of the part.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Two types of magnetic yokes are?

A

Permanent

Electromagnetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Radio graphic testing (RT) is?

A

Penetrating radiation is used to produce a film image of the internal structure of a specimen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Two different radio graphic testing sources are?

A

X-ray - accelerating electrons

Gamma ray - radio active materials

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Two criteria for measuring the quality of the radio graph are ?

A

Contrast - different degrees of darkening on the film

Definition - sharpness of the image projected on the film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Radio graphs can pick up:

A
  • gas pockets or porosity
  • slag inclusions Or slag lines
  • lack of penetration or fusion
  • internal or external undercuts
  • burn throughs or cracks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the best testing method for checking an engine or compressor cylinder head casting for interior cracks?

A

X-ray

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Ultrasonic inspection (UT) has two main types of ultrasonic waves for testing welds?

A

Longitudinal

Shear waveforms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Which NDT method can measure the length of a stud, locate and measure defects deeper and more accurately and less expensive?

A

Ultra sonic testing

Most widely used NDT methods of testing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

The NDT testing can measure thickness of materials within 1% accuracy?

A

Ultrasonic thickness gauging

Can test any thickness over 1/8”

27
Q

Sending transducer does?
Receiving transducer does?

A

Sending transducer - emits a beam of ultrasonic waves when burst of alternating voltage is applied

Receiving transducer - accepts and converts the output of ultrasonic waves from the test piece to corresponding burst of alternating voltage

28
Q

Advantages of ultrasonic testing:

A
  • portable
  • superior penetrating power 20ft
  • high sensitivity
  • greater accuracy
  • only needs access to one surface
  • operation is electronic
  • volumetric scanning
  • not hazardous
  • can measure wall thickness
  • can test on almost any kind of metal of any size
29
Q

Disadvantages of ultrasonic testing?

A
  • manual operation by experienced techs
  • exclusive technical knowledge
  • rough irregular shapes are hard to inspect
  • discontinuities right below surface may not be detected
  • reference standards are needed
30
Q

Eddy current testing applications?

A
  • used as an alternative to magnetic Particle and dye penetrant testing because it is able to detect surface and subsurface cracks beneath even a thick layer of paint.
  • ideal for testing non magnetic conductive materials such as copper, bronze, aluminum and Austenitic stainless steels
  • economical because of speed of inspection
  • used in marine, aerospace, high pressure, high temperature, and corrosive applications where failure of a part would be disastrous
  • parts are scanned by moving test probes or passing them through test coils
31
Q

Disadvantages of Eddy current testing?

A
  • laminar flaws not detected
  • must be electrically conductive
  • testing is best done at or near the surface
32
Q

Causes of imbalance?

A
  • Corrosion or abrasion
  • distortion
  • eccentricity
  • bent shaft
  • clearances
  • keys and keyways
  • non homogenous machined parts
  • asymmetry
  • material buildup
  • shaft flexing
  • shifting parts
  • temperature
33
Q

What are the three types of imbalance?

A

Static - shafts weight is evenly distributed along its length but unevenly from side to side

Dynamic imbalance - extra weight unevenly distributed

Couple imbalance - extra weight at each end of the shaft but opposite sides of the shaft

34
Q

What is a major result of imbalance?

A

Vibration

35
Q

Static equalibrium

A

8oz x 2” = 16
2oz x 8” = 16

Parts can balance

36
Q

Imbalance shows up at how many times the rpm?

A

1x

37
Q

Why should rotors operate at RPM’s 20 to 30% outside of the critical speed?

A

Equipment will experience resonance. (Marked increase/implication in vibration) once out of this critical speed range (above/below) vibration will lesson again

38
Q

Vibration in rotating equipment is?

A

The result in any force that moves a shaft from its reference

39
Q

By changing the mass or stiffness of an object you will change its?

A

Vibratory signature

40
Q

What are the three terms/meaning to describe vibration?

These are a series of forms called sine waves.

A

Frequency - how often an event happens in a unit of time or cycle.
- cycles per second (Cps, HZ)
- cycles per minute (cpm)

Amplitude - how much the machine is vibrating. Three
- imperial measurement 1mil = .001”
- metric measurement 1micron = .001mm

Phase - the relationship between displacement, velocity and acceleration

41
Q

Frequency on a signature is?

A

The most prominent frequency is the one with the spike. (This is the predominant or fundamental frequency.

42
Q

What are the three measurements of amplitude?

A

Displacement - total distance a vibrating part moves either side of its neutral axis

Velocity - rate of change of displacement for a given time

Acceleration - rate of change in velocity for a given time

43
Q

Displacement (see image)

A

Imperial measurement 1mil=.001”
Metric 1 micron = .001mm

44
Q

Velocity see image

A

Imperial inches per second (in/sec or IPS)
Metric millimetres per second (mm/s)

Best overall indicator of machine condition

45
Q

Acceleration (see image)

A

Measure in g forces

46
Q

Natural frequency?

A

A frequency at which an object or system naturally vibrates when a forcing function has been introduced

47
Q

Resonant frequency?

A

The system amplifies the energy from the forcing function frequency causing large amplitude. RESONANCE OCCURS IN ANY SYSTEM IF THE FORCING FUNCTION FREQUENCIES ARE NOT KEPT AT ATLEAST 20% outside the natural frequency’s range

48
Q

Critical speed?

A

Critical speed of a shaft or rotor occurs when the rotor rotates at or near its natural critical speed. At critical speed the rotor reaches a point of resonance and there is a marked increase in vibration. This will damage the machine and should be kept 20-30% outside of the critical speed

49
Q

Synchronous vibration?

A

Correspond to a frequency that is a whole multiple of the rotating speed (velocity) of the machine. These are phase locked to the rpm of the machine such as: 1x rpm and 2x rpm

50
Q

Non-synchronous vibration

A

Frequencies that are not whole multiples of the rotating speed of the machine

51
Q

Sub-synchronous vibration?

A

Frequencies that occurs at less than the rotating speed of the machine

52
Q

What are some tools for measuring vibration?

A
  • vibration pencils
  • portable handheld meters
  • portable vibration meters with graphs
  • monitors
  • analyzers
53
Q

Most important part of any vibration measurement system is the?

A

Transducer

If the transducer gives the analyzer immaculate information the analyzer cannot give a accurate analysis.

54
Q

Three basic categories of transducers are:

A
  • displacement transducers
  • velocity transducers
  • acceleration transducers

Each has different degree of sensitivity at various frequencies. No single type is able to reliably measure all parameters of amplitude over all the frequency ranges.

55
Q

Displacement transducers?

A

Non contact Eddy current transducers measure the relative resistance bearing housing and bearing journal.

They do not generate their own power. And need a high frequency dc electical signal

56
Q

Velocity transducers?

A

Used for general vibration measurements and balancing.

Generate their own power

Primarily used to measure velocity but the analyzer can differentiate or interstate the signal making it capable of measuring displacement and acceleration through the machine

57
Q

Acceleration transducers (Accelerometers)

A

Most common used with vibration analysis equipment.

Generate their own power but often use an amplifier to increase signal strength.

58
Q

What are the pickup mounting locations for the transducers?

A

HVA or XYZ

59
Q

Water in oil can?

A

Change viscosity, lubricity and load carrying characteristics. The chemical properties of fluid can also be affected by water.

Water can cause additive depletion, which creates oxidation due to the formation of acids from chemical reaction

60
Q

The main cause of oxidation is heat. That are the effects of the products oxidation creates?
Gum and varnish
Sludge
Acids

A

Gum and varnish - sticky valves

Sludge - blocked pilot passages

Acids - corrosion of parts

61
Q

Where should the sample of oil be taken from in a circulating oil system?

A

At a point where the fluid is well mixed. A live zone sample

Live zone should have a quick coupler or a valve to take the sample without allowing contamination to enter

62
Q

Oil taken for sampling on a circulating oil system is taken from the live zone when the machine is?

A

Running at its normal operating temperature, pressure, speed and load

  • from live zones in the piping
  • downstream of system components
  • upstream from filters or separators
63
Q

When getting an oil sample from a non circulating system(ring oilers, splash lubricated gear box) how do you get it?

A

Use a short tube that extends inward and up into the sump.

Make sure not to collect fluid from dead legs (where fluid is not moving)

Millwright Level 4 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions