Affiliations: [a] State Key Lab of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China | [b] School of Engineering and Computing Sciences, Durham University, Durham, UK
Correspondence:
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Corresponding author: Songling Huang, State Key Lab of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China. Tel.: +86 10 62772131; Fax: +86 10 62772131; E-mail:huangsling@tsinghua.edu.cn
Abstract: An increasing number of buried oil-gas pipelines are
generated in recent years and defects occur with higher probability in their
long-running process. This work proposes an electromagnetic ultrasonic
guided wave (EUGW) long-term monitoring scheme for buried oil-gas pipelines
and a data difference adaptive extraction method for the monitoring data.
The T (0,1) mode guided wave is selected because of its non-dispersive
characteristic. For the electromagnetic acoustic transducer (EMAT), a
circumferentially magnetized nickel strap is bonded on the pipe to provide
the bias magnetic field and the excitation coils are winded on the nickel
strap to provide the dynamic magnetic field. A detection stub is planted on
the ground and the connector of buried coils is installed in the stub. The
difference array is constructed and adaptive gain and attenuation are
performed in the data difference adaptive extraction method. The EUGW
long-term monitoring scheme is on-site applied for buried oil pipes in Jinan
city, Shandong province, China. The EMAT is installed and buried with the
pipe, and the periodical detection is conducted from December 2015 till now,
once per month. A pit is found and verified by excavation at the distance
9.25 m from the buried EMAT on the flow direction. On-site detection results
show that the data extraction method can dramatically improve the signal to
noise ratio of the monitoring data and accurately extract the difference and
variation of the pipe's structural health condition that occurred in the
long-term service. The EUGW long-term monitoring scheme is proved to be a
feasible method with prosperous prospect for the structural health
monitoring of buried oil-gas pipelines.
Keywords: Buried oil-gas pipeline, structural health monitoring, electromagnetic ultrasonic guided wave testing, data difference extraction
