This presentation from ECNDT 2018 reviews the following topics: Why is scan planning required? Basic scan plan requirements Basic methodology—example Complementary method to phased array

1. June 2018 12t h ECNDT – Gothenburg, Sweden 2018
Phased Array Scan Planning and Modeling
for Weld inspection
Thierry Couturier Olympus Europa

2. Advanced Scan Plan Methodologies for Weld Inspection
§ Why is scan planning required?
§ Basic scan plan requirements
§ Basic methodology—example
§ Complementary method to phased array

3. § Before any phased array inspection is performed, a scan plan should be built
§ Like conventional ultrasonic testing—considered by the operator during a manual
scan
Why Is a Scan Plan Required ?

4. Why Is a Scan Plan Required?
LINEAR scan =
Same angle
Different elements along the long probe
SECTORIAL scan =
Different angles with the
Same elements
Linear scan
Sectorial scan

5. COMPOUND scan = a mix of LINEAR and SECTORIAL scans
The angle changes as the beam moves along the long probe
Why Is a Scan Plan Required?
Sectorial scan
angle:
increasing
Linear scan
elements:
increasing

6. COMPOUND scan = a mix of LINEAR and SECTORIAL scans
The angle changes as the beam moves along the long probe
Why Is a Scan Plan Required ?
Sectorial scan
angle:
increasing
Linear scan
elements:
increasing

7. Why Is a Scan Plan Required?
§ “The coverage is there, so my inspection is correct”

8. § You may have the coverage and not have the inspection be correct; the wrong
angle might be used
– The wrong angle versus the indication angle, and the response does not
come back to the probe
Why Is a Scan Plan Required?
Dessin
de
soudure

9. § Another potential error is that you might select the wrong number of elements
– The focus point is not far enough
– The beam spread is too wide at the area of interest
– Detection will be very poor
Why Is a Scan Plan Required?

10. Scan Plan Definition
A scan plan is a documented inspection strategy to
provide repeatability for weld inspections

11. Importance of Scan Plans for Phased Array
PROBLEM
How do we deal with the different variables
of a phased array examination?

12. Importance of Scan Plans for Phased Array
§ Sectorial, linear, or compound scanning
§ Distance to the weld center line
§ Thickness
§ Material
§ Encoded vs. manual
§ Transducer selection—frequency and beam considerations
§ Aperture determination
§ Multichannel / grouping
§ Focusing effects
§ Angle selection

13. Scan Plans and Codes
§ Existing codes
– ASME
– API 1104
– AWS
– ISO17640
– EN 13588 - Nondestructive testing of welds
§ Codes
– They require a scan plan be built
– Nothing in the codes about how to build a scan plan

14. § Carbon steel
§ Thickness = 25 mm
§ Single-V design
§ 30° bevel
30°
25 mm
Scan Plan Example

15. Scan Plan Example
§ Typical areas of concern and their defects
1. Root: most critical area
– Lack of penetration
– Root or ID crack
2. Fusion zone
– Lack of side wall fusion (LOSWF)
– Side wall crack
3. Heat affected zone
– Cracking
4. Volume: typically omni-directional
reflectors
– Slag
– Porosities

16. How to Deal with a Scan Plan
§ Essential variables
– Transducer selection
– Frequency
– Aperture size
– Focusing
– Coverage and beam angle selection

17. Example
Transducer Selection: Frequency
§ Position of N0 (near field distance) of the equivalent flat transducer
2.25 MHz 5 MHz
7.5 MHz
Active aperture =
10 mm × 10 mm
For round transducers
N0
NDT SetupBuilder

18. Same frequency = 5 MHz
10 × 16 mm
aperture
10 × 10 mm
aperture
Example
Transducer Selection: Aperture Size
§ Position of N0 (near field distance) of the equivalent flat transducer
For round transducers
N0

19. With
electronic
focusing
7.5 MHz
18 × 18 mm
5 MHz
10 × 16 mm
Example
Transducer Selection: Frequency and Aperture Size
§ Position of N0 (near field distance) of the equivalent flat transducer
For round transducers
N0
Focal
Point

20. § On an indication 3 mm high
à Aperture 10 × 10 mm, unfocused beam, wide beam
à Measurement = 5 mm
à Aperture 10 × 30 mm, focused beam, narrow beam
à Measurement = 3 mm
Phased Array: Electronic Focusing
Same side wall lack of fusion
3 mm
5 mm
No electronic focusing possible
ELECTRONIC FOCUSING
DEMO 1

21. § Size of the transducer
– Conventional UT
– 8 × 9 mm
– 14 × 14 mm
– 20 × 22 mm
– Frequency 4 MHz, 2 MHz
– Angles 45°, 60°, 70°
§ Flat transducers
§ Used in the far field
Transducer Selection: Refer to Conventional UT

22. § Transducer Selection Suggestion
– Frequency: 5 MHz
– 64 elements
– Pitch: 0.6 mm
– Elevation: 10 mm
– Number of elements for active aperture: 27
– No electronic focusing = the far field of the equivalent flat transducer is used
5 MHz
10 × 16 mm
aperture
Active aperture per beam
10 × 16 mm
Scan Plan Example
NDT SetupBuilder

23. § Beam plot—beam coverage—beam angles
– Root zone: better with 1st leg inspection
Scan Plan Example
Sectorial Scan

24. § Beam plot—beam coverage—beam angles
– Fusion zone
50°
70°
60°
Scan Plan Example
Sectorial Scan

25. § Beam plot—beam coverage—beam angles
– Root zone + fusion zone
50°
70°
60°
Scan Plan Example
Sectorial Scan

26. § Beam plot—beam coverage—beam angles
– Heat affected zone + fusion zone thanks to overlap
50°
70°
60°
45°
70°
Scan Plan Example
Sectorial Scan

27. § Beam plot—beam coverage—beam angles
– Volume already covered
50°
70°
45°
70°
Scan Plan Example
Sectorial Scan

28. § Linear scan
– Best for side wall lack of fusion along the weld face
– Reduced coverage requiring a bigger phased array probe (more elements)
– Additional scans (linear or sectorial) are required to cover the 4 zones
properly
Linear scan at 60°
-
Reduced coverage
Scan Plan Example

29. § Compound scan—suggested solution
– Same angle range compared to sectorial à more coverage à inspecting thicker
materials in a single pass
– Better angle orientation à higher probability of detection (POD)
– Fewer groups
– Faster inspection speed
– Shorter setup and calibration time
– Faster data analysis
– Smaller file size
Scan Plan Example

30. § Compound scan versus sectorial on weld
– Fewer angles for the same coverage = higher perpendicularity = higher POD
– Shorter sound path for weld root = higher signal-to-noise ratio (SNR) = higher POD
Scan Plan Example

31. § Compound scan versus sectorial on weld
– Fewer angles for the same coverage = higher perpendicularity = higher POD
– Shorter sound path for the weld root = higher SNR = higher POD
Scan Plan Example

32. § Beam plot—beam coverage—beam angles à skip distance change
– What happens if the scan is not performed perfectly straight?
Scan Plan Example

33. Scan Plan: Additional Variables
§ Additional parameters to complete the scan plan
– Parameters of the electronic equipment (filters, voltage)
– Encoded scan
– Additional technique?

34. Scan Plan: Phased Array and Time-of-Flight Diffraction (TOFD) at the
Same Time

35. Scan Plan: TOFD
§ TOFD and phased array pulse-echo techniques
Phased array could miss misoriented indications (such as a center line crack
for a double V-joint)
TOFD could miss indications located at the top or bottom surface
§ But the 2 techniques complete each other
Phased array can pick up indications located close to the top or bottom
surface thanks to the corner effect and provide additional information on the
location of the indications
TOFD can pick up an indication whatever its orientation and help with height
sizing

36. Scan Plan: Phased Array and TOFD at the Same Time

37. Scan Plan: Additional Variables
§ To complete the inspection procedure
– Certification and training of personal
– Calibration
– Analysis process
– Qualification program, if required

38. Importance of Scan Plans for Phased Array
§ Sectorial, linear, or compound scanning
§ Distance to weld center line
§ Thickness
§ Material
§ Transducer selection—frequency and beam considerations
§ Encoded vs. manual
§ Aperture determination
§ Multichannel / grouping
§ Focusing effects
§ Angle selection

39. Scan Plan: Conclusion
§ Phased array is not magic
– Select your transducer
– Select sectorial, linear, or compound scan
– Think about defect orientation
§ Please consider these essential variables
– Frequency, aperture size, focusing
– Coverage and beam angles
§ Following these steps, you should get a good scan plan

40. Thank You