 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
||||||||||||||
|
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
 |
 |
 |
 |
 |
 |
 |
|
||||||||
 |
|
|
PHASED ARRAYPhased array is a groundbreaking industrial ultrasonic inspection technique. Modern systems are battery operated, computerized, and light enough that they are hand carried and placed next to the components being inspected. Phased array examinations:
- Give a computerized image and records of the inspection results.
- Allow easier interpretation of the ultrasonic signals associated with weld geometry (when compared to traditional ultrasonic inspection techniques).
- Facilitate characterizing lack of fusion defects since the large number of sound beam angles match better with the weld bevel angles.
- Are typically more expedient than other imaging ultrasonic inspection techniques. In many cases, an entire weld can be inspected with a single pass of the phased array probe.
- Are used for entire shift durations since they have more than one battery system.
As well as staple ultrasonic inspection techniques, phased array:
- Can detect planar flaws (cracks) of various orientations with respect to the weld outer surface.
- Can provide detailed analysis flaw depths and orientations within the weld.
- Does not entail the radiation hazards associated with radiography.
Phased array probes sharply contrast with the more traditional fixed beam angle piezoelectric elements, they:
- Have 16 or more elements generating or receiving ultrasound.
- Can have sound beams engineered to fit specific applications by pulsing different combinations of the individually controllable elements.
- Can generate sound beams of variable angles and focal properties to match the component being inspected.
- Can pulse multiple and varied beam angles as the probe is moved along a weld. This results in fast inspections that obtain high-resolution weld images.
Phased array is now used for inspecting as fabricated piping and pressure vessel welds. For piping inspection, it is used in lieu of radiography or manual ultrasonic inspection. Weld acceptability is determined based on the:
- ASME B31.3 specified rejection criteria for piping.
- ASME Code Case 2235 for pressure vessels.
Phased array is also used for in-service weld inspection. The flaw image obtained with multiple angles and beams gives a more accurate flaw characterization than conventional ultrasonic inspection. This in turn facilitates fitness for service modeling and predictions.
Phased array can give some significant advantages over standard ultrasonic inspection when inspecting parts with difficult geometries. Consequently, bolts and turbine components are inspected with phased array techniques; the complex shape of these parts makes interpretation of manual ultrasonic inspections very difficult.
The reports are prepared from standard laptops after the data has been transferred via a memory stick. The data is then CD archived for possible future inspection comparison. The reports are normally presented to the customer at the end of the shift before the crew has left the site; a formal report is issued later after peer quality assurance reviews.
