Acoustic Emission testing

Acoustic emission monitoring of pipeline leakage

Update time：2014-02-03 09:11　　　 Viewed：次

Pipelines because the pipeline leaking due to aging or other material corrosion cracks or corrosion hole, the external force flow inside and outside differential pressure and make the pipes in the pipeline to outside leakage phenomenon. The fluid jet out through cracks or corrosion holes form the sound source, and then through interaction and pipeline, source radiation energy outward form sound waves, that is the pipeline leakage acoustic emission phenomenon. Through the instrument of the acoustic emission signal is caused by leakage data collection and analysis processing, can to determine leakage and its position.

Pressure pipeline leakage acoustic emission signal is generated by the generalized acoustic emission signal, the wall itself does not release energy, but only as a kind of communication media. Leakage in the process, the leak point due to the tube inside and outside differential pressure, fluid in the pipeline leak in the formation of multiphase turbulent jet, the jet not only make the normal flow of fluid happens disorder, and interact with the pipeline and the surrounding medium outward radiation energy, produces high frequency stress wave in pipe wall. The stress wave carrying the information leak (leak hole shape and size, etc.) along the wall to spread, on both sides of the acoustic emission signal acquisition and analysis processing, can be to determine leakage and their locations.

Pipeline leak when the acoustic emission signal has the following features:

(1) leakage acoustic emission signal is by the fluid medium in the pipe with pipe leakage and the surrounding media interaction, is a continuous signal, so the monitoring instrument does not need to use a higher sampling frequency.

(2) the leakage acoustic emission signal propagation along the pipe upstream and downstream, and analyze the reception, leakage source location information such as size can be obtained.

(3) the pipeline leakage acoustic emission signal is affected by many factors, such as leakage aperture size and shape as well as the liquid pressure, pipeline surrounding media, environmental noise and so on, therefore, acoustic emission signal in essence belongs to a kind of nonstationary random signal.

(4) according to the theory of guided wave leakage acoustic emission signal more modal characteristics, and dispersion phenomena existed during propagation in the pipe.
(Editor：admin)

Returns

Move>>