6: Inspection Flashcards
What are conducted regularly on UT instruments and transducers?
Performance tests
Who performs a performance test?
A level 2 or third party
Calibrations should be done a minimum of?
Every 2 hours
What are the two types of calibrations?
Time base and sensitivity
What does a time base calibration do?
Ensures material thickness and discontinuity depth are accurately displayed.
What reflectors in stand blocks are used to set reference levels?
Back wall, side drilled holes and FBH/notches
Why don’t you have a back wall reflection with angle beam testing?
When sound hits the surface it reflects away
What signals are shown in the screen in Angle-Beam testing?
Only the IP unless echo is received
How is the V Path calculated?
2T/cos theta
How can the skip distance be calculated?
2T x tan theta
What are the 4 types of scanning movements?
Traversing (perpendicular to weld), lateral (parallel to weld), rotational (spinning probe by axis) and orbital (moving probe around fixed point)
Where should you position the transducer from centre if weld to direct sound to root?
1/2 skip distance
How can surface distance be determined?
Surface distance = sound path x sin theta
How do you set mine depth is discontinuity found in the 1st leg?
Sound path x cos theta
How can the depth be determined if discontinuity found in 2nd leg?
2T - (sound path x cos theta)
What 2 performance tests must be done regularly on a UT instrument?
Horizontal linearity and vertical linearity.
What is a horizontal limit and linearity performance test used for?
It ensures the sweep circuit is working and that the material thickness and discontinuity depth will be displayed accurately.
What is the vertical limit and linearity performance test used for?
Verifies the receiver/amplifier are working and that height of signals will be displayed accurately.
important to evaluate defect size accurately
What are the 3 main reasons to manipulate a probe when scanning?
- Full coverage
- Detect all discontinuity, whatever their origin
- Obtain max amplitude from each reflector
In which case should you use the 6 db drop method for sizing?
When sizing discontinuities larger than sound beam
What is V-Path?
The angular distance from point of entry to point of exit for sound beam.
What is meant by surface distance when testing by Angle-Beam method?
Horizontal distance from index point to top of discontinuity
