| Title |
Detection and assessment of defects in pipelines using high order symmetrical modes / |
| Authors |
Cirtautas, Donatas ; Samaitis, Vykintas ; Mažeika, Liudas ; Raisutis, Renaldas |
| Full Text |
|
| Is Part of |
International ultrasonic testing conference 2021 (UT-online 2021) "Novel methods and applications in ultrasonic testing": 1-30 November 2021: UT-online 2021 preface & abstract book.. Bad Breisig : NDT.net. 2021, p. 12-13 |
| Keywords [eng] |
ultrasonic testing (UT) ; guided waves ; mode-selective excitation ; structural health monitoring ; screening ; pipeline corrosion ; high order modes |
| Abstract [eng] |
Monitoring and detection of defects in pipe structures can prevent hazardous accidents and unexpected losses. Ultrasonic guided waves showed good potential detecting various defects in pipeline networks at sufficiently large distances. However, in practise usually low order fundamental guided waves are used for non-destructive testing along pipe structures due to relatively easy setup and analysis of transmitted or reflected signals. Despite long range coverage such waves have less sensitivity to localized corrosion that mostly lead to a sudden leakage. Hence, more advanced ultrasonic testing techniques with capabilities to detect such defects are required. Such techniques are usually based on high order guided wave modes that offer better sensitivity and resolution at a cost of propagation distance and complicated signal analysis. There are number of issues that must be solved in order to develop successful NDT technique for inspection of pipe-wall defects using high order modes, i.e. mode selection, wave excitability, detectability, sensitivity to a defect, propagation losses and overlapping with co-existing modes. In this research novel medium range guided wave screening method was developed that uses high order symmetrical modes for detection of localized and uniform defects in the cross section of the pipelines. A comprehensive analysis was performed in order to select most suitable mode for inspection taking into the account the excitability and detectability of the mode; displacement profile; sensitivity to a defect; leakage and propagation losses; group velocity and geometrical features of the considered defects. The investigations demonstrated that S3 mode at 1MHz has high group velocity, sufficiently short wavelength and low leakage losses which made it a good candidate for inspection of localised defects in pipes. Different techniques based on phased array excitation were tested in order to excite S3 mode into the structure without generating undesired waves. Finally, the interaction between the S3 mode and structural defects were investigated, revealing which signal parameters assist in detecting the defects and assessing defect parameters. In contrast to existing approaches, the proposed screening technique offer increased sensitivity, allow to assess pipes with circumference up to 2m and can be used with conventional UT equipment. |
| Published |
Bad Breisig : NDT.net |
| Type |
Conference paper |
| Language |
English |
| Publication date |
2021 |
| CC license |
|
