Immersion Testing (5) Flashcards
What are the three types of Immersion Testing?
- Conventional
- Bubbler/Squirter
- Wheel Transducer
What is Conventional Immersion Testing?
Both the probe + material are submerged in liquid couplant (water)
Equipment for Conventional Immersion testing
- Tank
- Bridge/Carriage Assembly
- Search/Scanner Tube
- Manipulator
- Immersion Probe
- UT Unit
What is a Bridge/Carriage Assembly?
Allows the Scanner Tube to be moved (up/down, left/right)
What is a Manipulator?
Used to angle the probe + maximize the reflection
What is an Immersion Probe?
Probe with
- no wear plate
- thinner crystal
- properly sealed
- Straight beam unit (produces longitudinal or shear waves)
- can attach a spherical lens
What is a Search/Scanner Tube?
Supports the probe, can be moved up/down to adjust the amount of couplant (water column)
- connects manipulator to bridge
What is Water Distance?
Distance between the probe and the test material
Why is Water Distance So important?
Time required for the sound to travel into and back out of the part is less than the time for the sound to go through the couplant to the part surface
if water distance is too short, a second front surface signal will appear on screen before the back surface signal
Sound travels ____x slower in water than in metal
4x slower
Minimum water distance rule
The minimum water distance required for immersion testing is equal to 1/4 of the material thickness + 6mm (1/4 in)
What is Bubbler/Squirter Immersion testing?
A variation of Conventional Immersion testing that can be used with an automated system for high-speed scanning.
- Pulse-Echo or Through-Transmission
Water couplant is sprayed at the surface
What is Wheel-Transducer Immersion Testing?
A probe is suspended from an axel in a tire filled with liquid couplant.
- Longitudinal or Shear
Advantages of Immersion Testing
- limited dead zone
- increased surface resolution
- limited/no near surface effects
- easy angulation
- can use high frequencies (25MHz) increasing sensitivity
- even coupling
- automation adaptability
- high-speed
- no probe wear
- easy to inspect rough surfaces
- use of a spherical transducer (focused)
What is a Focused Transducer?
Described by its focal length
- point of focus can be adjusted by changing water distance
- better sensitivity and front surface resolution
- less scattering and rough surface effects
- limited depth
