NDT methods/weld defects Flashcards
Inspection, testing and qualification are growing part of _______ in manufacturing and maintenance.
quality control
The ______ is the person who begins quality control by being satisfied only with quality welding.
welder
The welder starts the inspection in the process of welding, making immediate adjustment in response to what is being observed in the ______.
weld pool
Factors that affect quality of weld bead include….
Changing amperage, travel speed, or arc length
Finally, the welder give the completed weld a final _____ to look for any defects that could not be seen while welding.
visual inspection
What are the common methods used in NDE?
VT, MT, Liquid Dye PT, UT, LT (air/water pressure testing)
What is VT?
Visual inspection, a NDT process, examination with the eye. Only able to detect surface discontinuities.
What is the advantage of VT?
Inexpensive equipment and wage, no power required, portable
What is the disadvantage of VT?
requires training/experience, good eye sight, can’t detect subsurface defects, no permanent records, human error
What are the 5 steps of VT?
- Definite procedure
- Inspection prior to welding
- Inspection during welding
- Inspection after welding
- Mark/make repairs
What are the 7 VT equipment for welding?
Flashlight, magnifying glass, protective lenses, weld gage, hammer/chisel, temperature indicating devices, magnet
What is inspected with VT before welding?
Drawing, position of welds, welding symbols, welding procedure
Specifically paying attention to root face, root gap, bevel angle, and joint/fitup
Proper ____ will prevent discontinuities from occurring.
Fit up
______ will be used to slow the cooling rate and prevent distortion.
Pre-heat
What is inspected with VT during welding?
Electrodes, root pass, subsequent passes, crater formation, weld size/sequence
What is inspected with VT after welding?
Compare weld to standard, weld size, contour/finish, cracks, overlap, undercut, spatter
Testing companies provide an important service because they _____
help manufacturers produce safe and durable goods/structures that consumers can live with.
What are two methods of testing?
Non-destructive and destructive
What are the 4 common NDT methods?
MT, PT, UT, RT
What are the 6 steps of PT?
1 .surface prep
- penetrant application
- excess penetrant removal
- developer application
- inspection/ evaluation
- post cleaning
If dye color of defect is deep and not never red, defect is ______.
shallow
What is referred to as magnaflux?
MT
Magnetic particle test begins when _____ electric charges is passed between two poles. Force line up until there is a break in these magnetic lines of force.
Direct Current (DC)
In MT, defects appear as a ___ in the lines of force.
break
The magnetic particles become attracted to the defect, which develops ______ at the edge of the defect, outlining the defect.
north and south poles
What defects are detected with MT?
surface discontinuities, cracks, porosity, slag inclusions, incomplete fusion
What are the disadvantage of MT?
Magnetic materials only, surface roughness may distort field, no permanent record
To enable the formation of a proper magnetic particle pattern for defect indications, the _____ of the defect and magnetic field must be taken into account.
orientation
What are the 2 methods of magnetizing the weld zone?
Yoke method, prode method
What does the yoke method use?
An electromagnet
What does the prode method use?
Electrode are applied to the specimen to allow current to flow in specimen.(Can’t apply to high tensile steel which can resemble an arc strike. Effective to detecting defects not exposed but existing near the surface)
What are two methods of magnetizing the weld zone?
- yoke method uses an electromagnet
2. Prode method uses electrode applied to specimen to allow current to flow in the specimen
What are the 2 types of magnetic particles?
Fluorescent, and non-fluorescent type
What are the two methods of particle application for MT?
Wet method and dry method.
Magnetic particle testing shall not be performed with nonmagnetic coating in place that exceed _______ in thickness, or ferrous magnetic coating that exceed ______ in thickness.
- 003” (0.08mm),
0. 001” (0.03mm)
half-wave rectified ___ is best for dry particle method.
AC
Defects open to the surface use ____ only.
AC
When using wet particle method for subsurface defects, use full-wave rectified ___.
AC
If you are dragging an AC yoke you are not magnetizing you are_____
demagnetizing.
To correctly magnetize an object, position the yoke and apply magnetizing force for _____ seconds before moving the unit to the next position.
2-5 seconds
UT- what is a oscilloscope?
Machine that generates and receives ultrasonic waves.
UT- what is a cathode ray tube?
where the traveling distance and intensity of reflected wave are measured to locate and determine the size of the defect.
What are two transducers (probe) in UT?
Straight beam,
What does the letters NDE mean ?
Nondestructive examination
The method most often used to check for leaks as small as one part per million (PPM) from gas line or cylinder is the ____ method.
mass spectrometer
True of false, magnetic particle testing can only be done on materials that can be magnetize.
true
True or false. Dye penetrate inspection can only be used on non-magnetic material.
false
True or false. x-rays can only be used to locate flaws at or near the surface of a weld.
false
True or false. Virtually all welds have flaws.
True
True or false. MT can only detect flaws at or near the surface.
True
