Acoustic Resonance Technology is an acoustic

Acoustics

Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...

 inspection technology developed by Det Norske Veritas

Det Norske Veritas

Stiftelsen Det Norske Veritas is a classification society organized as a foundation, with the objective of "Safeguarding life, property, and the environment". The organization's history goes back to 1864, when the foundation was established in Norway to inspect and evaluate the technical condition...

 over the past 20 years. ART exploits the phenomenon of half-wave resonance, whereby a suitably excited resonant target (such as a pipeline wall) exhibits longitudinal resonances at certain frequencies characteristic of the target's thickness. Knowing the speed of sound in the target material, the half-wave resonant frequencies can be used to calculate the target's thickness.

ART differs from traditional Ultrasonic Testing: although both are forms of nondestructive testing

Nondestructive testing

Nondestructive testing or Non-destructive testing is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage....

 based on acoustics, ART generally uses lower frequencies and has a wider bandwidth. This has enabled its use in gaseous environments without a liquid couplant.

ART has been used in field tests at Gassco

Gassco

Gassco is a Norwegian state owned company that operates of natural gas pipes transporting annually of 88.5 billion cubic meter of natural gas from the Norwegian continental shelf to Continental Europe and the United Kingdom....

's Kårstø

Kårstø

Kårstø is an industrial facility located in Tysvær, Norway. The site features a number of natural gas processing plants to refine natural gas and condensate from the fields in the northern parts of the North Sea, including Åsgard, Mikkel and Sleipner...

 facility.

Main features of ART

• Uses lower frequencies than Ultrasonic Testing
• Effective in gases and liquids (i.e. requires no liquid couplant)
• Can be used to characterize multi-layered media (e.g. pipelines with coatings)
• Can penetrate coatings
• Can measure inside and outside metal loss

RUV (Resonance Ultrasonic Vibrations)

In a closely related technique, the presence of cracks in a solid structure can be detected by looking for differences in resonance frequency, bandwidth and resonance amplitude compared to a nominally identical but non-cracked structure. This technique, called RUV (Resonance Ultrasonic Vibrations), has been developed for use in the photovoltaics industry by a group of researchers from the University of South Florida, Ultrasonic Technologies Inc. (Florida, USA), and Isofoton S.A. (Spain). The method was able to detect mm-size cracks in as-cut and processed silicon wafers, as well as finished solar cells, with a total test time of under 2 seconds per wafer.