Steam generator small bore piping socket weld inspection using the phased array ultrasonic technique

Figures & data

Figure 1. Phased array ultrasonic technology generating multi-angle ultrasonic.

Figure 2. Socket weld configuration (ASME Section III 4542.9-1).

Figure 3. Ultrasonic sound field modeling results at (a) 45° and (b) 80° refraction angles at a 0.4-mm pitch.

Table 1. Phased array probe and wedge specifications.

Item	Parameter	Design value
Probe	Frequency	3.5 MHz
	Number of elements in primary axis	16
	Primary axis pitch	0.4 mm
	Inter-element spacing	0.05 mm
	Element width	7.0 mm
	Total active length	9.5 mm
Wedge	Wedge angle	35°
	Wedge length	18 mm
	Wedge width	11 mm
	Sound velocity	2337 m/s
	Contour	12.7 mm

Figure 4. Phased array ultrasonic transducer and wedge for SG small bore piping socket weld inspection.

Figure 5. Manually operated ring-type encoded scanner for the small bore socket weld piping of steam generators.

Figure 6. Manufactured flawed specimen of SG drain line socket weld.

Table 2. Flaws introduced to specimens (unit: mm).

			Flaw size
No.	Orientation	Flaw type	Length	Depth
1	Circ.	Crack	7.06	3.53
2	Circ.	Crack	8.26	2.41
3	Circ.	VLOF	6.38	4.52
4	Circ.	Crack	6.20	2.13
5	Circ.	HLOF	5.16	6.17
6	Circ.	Crack	6.73	3.78
7	Circ.	Crack	6.27	3.35
8	Circ.	HLOF	8.08	6.91
9	Circ.	Crack	4.83	2.01
10	Circ.	Crack	6.96	6.53
11	Circ.	VLOF	6.15	4.50
12	Circ.	Crack	7.06	3.45

Figure 7. Experimental configuration of the phased array ultrasonic system.

Table 3. Phased array system parameters for experimental.

Parameter	Setting value
Gain	40 dB
Digitizing frequency	50 MHz
Inspection mode	Pulse-echo
Steering angle	35°–80°
Angle resolution	1°
Voltage	80 V

Figure 8. Signals from the valve side weld of flawed specimens with 1:1 leg length ratio.

Figure 9. Valve side weld signal of flawed specimens with 1:2 leg length ratio.

Table 4. Flaw length sizing results of flawed specimens (unit: mm).

No.	Type	Actual	Measured	Deviation
1	Crack	7.06	8.00	0.94
2	Crack	8.26	8.50	0.24
3	VLOF	6.38	5.50	−0.88
4	Crack	6.20	7.50	1.30
5	HLOF	5.16	6.50	1.34
6	Crack	6.73	7.50	0.77
7	Crack	6.27	8.50	2.23
8	HLOF	8.08	9.00	0.92
9	Crack	4.83	4.50	−0.33
10	Crack	6.96	5.50	−1.46
11	VLOF	6.15	7.00	0.85
12	Crack	7.06	7.00	−0.06

Figure 10. SG drain pipe socket weld inspection.

Figure 11. SG “A” drain line valve socket weld inspection result.