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Home >News >Industry News >Applications of Fully Automatic Ultrasonic Inspection to Welding Seams of Carbon Steel Pipelines (Part Two)

Applications of Fully Automatic Ultrasonic Inspection to Welding Seams of Carbon Steel Pipelines (Part Two)

Posted: 10/27/2021 13:29:41 Hits: 22

3. Scanning tests of welding seams
(1) Calibration of AUT systems: The adjusted AUT scanning device was plated on the calibration block to calibrate one by one in accordance with the simulated focus law to ensure that the amplitude of the strip scan signal of each channel was between 70% and 99% in the dynamic calibration.
(2) Scanning of AUT welding seams: After the calibration was done, 5 artificially defective welding seams on a pipe with a diameter of 114.3 mm would be scanned one by one.
(3) Reference line drawing: Placed the AUT scanning device at the defect of the welding seam. Walked back and forth to find the highest wave position of the defect, and marked the highest wave position of the defect and travel direction of the AUT scanner with a marker; drew a reference line for the defect location. The reference line drawing is as shown in Figure 6.

Figure 6 The schematic diagram of the defect reference line
(4) Macro slicing: According to the defect reference line, 25 artificial defects detected by AUT were cut one by one, and the relevant defect slices were shown in Figure 7.

Figure 7 Slicing of related defects

4. Comparative analysis of data
Performed data analysis on the AUT scan map of 5 artificial defected welding seams one by one, and recorded the relevant starting point, length, height, depth, type and other parameters of the defect one by one. Compared and analyzed with the macro slicing data. Comparative analysis of AUT and macro slice data is shown in Table 2. It can be seen from Table 2 above that for the 5 artificial defected welding seams numbered W01, W02, W03, W04 and W05, there was a deviation between -1 mm and 0.8 mm for the defect height value evaluated by AUT and macro slicing evaluation. The minimum deviation value was 0.1 mm, and the maximum deviation value was 1 mm.

Table 2 Comparative analysis of AUT and macro slicing data

Welding items	Wall thickness	Defected items	Locations	AUT data						Slice data		Height
Welding items	Wall thickness	Defected items	Locations	Defected types	Starting point	Length	Height	Depth	US/	Height	Depth
W01	6.4	1	The cover surface	Lack of fusion	20	13	0.9	1	DS	0.7	1.2	0.2
W01	6.4	2	The cover surface	Lack of fusion	93	15	0.7	1	US	0.8	1.1	-0.1
W01	6.4	3	The cover surface	Lack of fusion	171	10	0.9	1	DS	1.1	2	-0.2
W01	6.4	4	The filling	Lack of fusion	236	23	2.9	4.2	US	2.2	3.6	0.7
W01	6.4	5	The filling	Lack of fusion	313	22	2.3	2.5	DS	2	3	0.3
W02	6.4	1	The filling	Lack of fusion	16	23	2.8	4	DS	2	3.4	0.8
W02	6.4	2	The root	Lack of fusion	95	13	1	6	C	1.3	6	-0.3
W02	6.4	3	The root	Lack of fusion	164	18	0.5	6	C	1.5	6	-1
W02	6.4	4	The root	Lack of fusion	241	16	0.5	6	C	1.2	6	-0.7
W02	6.4	5	The middle of the welding seam	Lack of fusion between layers	312	21	1.8	4.1	C/V	2.2	4.2	NA
W03	6.4	1	The middle of the welding seam	Lack of fusion between layers	23	7	0.9	4.2	C/V	2.9	4.2	NA
W03	6.4	2	The middle of the welding seam	Gas holes between layers	100	5	0.8	4.2	C/V	2.8	4.3	NA
W03	6.4	3	The cover surface	Lack of fusion	162	23	1.3	1.3	DS	0.9	1.4	0.4
W03	6.4	4	The cover surface	Lack of fusion	264	12	1.5	1.5	US	0.7	1.2	0.8
W03	6.4	5	The cover surface	Lack of fusion	371	13	1.2	1.2	D/S	0.9	1.3	0.3
W04	6.4	1	The filling	Lack of fusion	16	22	2.1	2.5	D/S	1.9	3.3	0.2
W04	6.4	2	The filling	Lack of fusion	92	17	2.5	4.2	US	1.8	3.9	0.7
W04	6.4	3	The filling	Lack of fusion	160	21	1.7	2.5	D/S	1.4	3.2	0.3
W04	6.4	4	The root	Lack of fusion	239	17	1	6	C	1.4	6	-0.4
W04	6.4	5	The root	Lack of fusion	315	14	0.7	6	C	1.2	6	-0.5
W05	6.4	1	The root	Lack of fusion	22	17	0.5	6	C	1.4	6	-0.9
W05	6.4	2	The middle of the welding seam	Lack of fusion between layers	92	21	1.5	4.8	C/V	1.9	4.1	NA
W05	6.4	3	The middle of the welding seam	Dense gas holes	173	12	1.5	5	C/V	1.3	4.0	NA
W05	6.4	4	The middle of the welding seam	Dense gas holes	236	16	1.1	4.4	C/V	1.4	4.2	NA
W05	6.4	5	The root	Lack of welding	313	17	0.6	6	C	1.3	6	-0.7

5. Conclusion
According to the requirements of relevant standards for inspecting carbon steel pipelines, the defect height and quantitative accuracy of AUT detection process does not exceed ±1 mm. In the experiment, AUT inspection, data analysis, and reference line drawing were carried out one by one for artificial defect welds of the processed 5 pipes with a diameter of 114.3 mm (4 inches) and a wall thickness of 6.4 mm in this article, and then the 25 artificial defects were subjected to a macroscopic slice test one by one. Through data analysis, AUT detection technology could effectively detect 25 artificial defects processed in a welding seam on thin-walled pipe with a diameter of 114.3 mm (4 inches) and a wall thickness of 6.4 mm, and the greatest quantitative deviation of the height of the defect was 1 mm, which met the requirement for the defect height quantitative accuracy required by the carbon steel pipeline's inspection standard (±1 mm). Therefore, the AUT detection technology can be applied to inspecting the thin-walled carbon steel pipeline of 4 inches.

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Teresa

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