PHASED ARRAY TESTING
Phased array tools provide us with the ability to perform inspections using ultrasonic beams of various angles and focal lengths using a single array of transducers.
Software control over beam angle and focusing is achieved by application of precisely controlled delays to both the emission pulse and received signal for each element in an array of transducers. Phased array improves on conventional UT by using a wide range of angles in a single scan.
ADVANTAGES INCLUDE:
1. The ability to sweep a range of angles from 40 - 70 degrees, and display the image in real time for the swept angles.
2. Steer-focus and scan beams with a single transducer assembly.
3. Detection of manufacturing flaws (lack of fusion, incomplete root penetration, porosity, toe and root cracks).
4. Detection of in-service flaws (fatigue cracking, stress corrosion cracking, corrosion, erosion, etc.) and parent material flaws (inclusions and laminations).
5. Efficient corrosion mapping by using a larger footprint of array probes to increase scanning areas.
6. Repeatability of inspections and reduced time required to perform inspections.
7. Creation of scan plans to visualize effectiveness of phased array setup.
TOFD TESTING
Time of flight diffraction (TOFD) detects flaws using the signals diffracted from the flaw's edges. When the sound wave strikes the tip of a flaw, it acts as a secondary emitter which scatters sound out in all directions, some in the direction of the receiving probe. The time difference between the lateral wave and the diffracted signal from the flaw provides a measure of its distance from the scanned surface, which makes TOFD excellent for defect measurement.
ADVANTAGES INCLUDE
1. Detection and sizing of all types of embedded flaws, especially those planar in nature. 2. Critical flaw sizing data for input to Engineering Critical Assessments. 3. Excellent at detecting and sizing volumetric type indications (i.e. slag, porosity, etc). 4. Ease of operation.