Evaluation of FeCo magnetostrictive sensors for SHM of components operating in harsh environmental conditions (original) (raw)
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FeCo) was developed by Southwest Research Institute (SwRI ® )in early 2000 and has been used successfully in the petrochemical industry to inspe ct and monitor piping systems for corrosion and cracking. This technology generates a torsional mode guided wave that propagates in the pipe wall up to 500 feet from one location and can detec t d fects on the order of 0.5-1.0% of the total pipe wall cross section in the monitoring mode. The sensor consists of the ferromagnetic material (approximately 0.1 mm thick) by 25.4 mm wide bonded to the pipe and excited using an RF voltage passing through a ribbon cable. This provid es a low profile, inexpensive sensor that can be left in place on the pipe or component for many years. By using FeCo strips with appropriate bonding materials and coil components, the MsS tech nology can be used on piping and components up to approximately 300°C. Applications to piping, heat exchangers, and plate will be described. Results obtained from various example ...
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Guided wave testing is now a widely accepted method for detection of structural damage in many different types of components, from pipelines to pressure vessels to tanks. Torsional wave modes (T modes) in pipes and shear horizontal (SH) mode guided waves in plates are good candidates for finding areas with generalized corrosion, due to the absence of fluid coupling effects and their lack of dispersion. However, from our field test experience, certain types of defects are difficult to detect with conventional T mode or SH mode guided wave probes. Gradual wall thinning is one such type of defect; another is crack-like defects in or close to welds or penetrations in the pipe. Recently, Southwest Research Institute (SwRI) has developed a new sensor configuration and scanning system that overcomes these limitations. We have recently developed a linear scanning magnetostrictive transducer (MsT) probe system, in which a FeCo strip wound with radio frequency (RF) coils is attached to the st...
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The use of solar thermal power plants is considered a cost-effective alternative to produce renewable energy. Unlike other energy installations, in this type of plants the transfer and storage of energy has been solved by using molten salts. These salts run between two tanks through the steam generation system that feeds the turbine. Although the use of salts as a heat transfer fluid is considered an adequate solution, they are not without problems. One of them is the formation of blockages in the pipes due to a partial solidification of the salt, which leads to the shutdown of the installation, with the consequent economic losses. Fast location of these blockages in a minimally intrusive way is the objective pursued in this work. The method to achieve this is based on the use of a new magnetostrictive sensor that simplifies previous designs.
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In this paper a new method is described that allows estimating the 3d shape of defects identified in guided wave signals that were acquired with a magnetostrictive type sensor. The method is based on the evaluation of flexural components extracted from data sets acquired by a multitude of sensors distributed around the pipe circumference in a “collar” type configuration. In addition, to prove its efficiency, the method will be applied to a large number of simulated data and will finally be tested on signals acquired experimentally on real pipes with artificial defects.
Independently of the instrumentation which is used to generate and receive guided waves (GW) in pipes, wave propagation is affected by some factors like pipe geometry (T-branches, welded joints, U-bends), state of integrity (good state or heavily corroded), coating material (paint, PE, FBE, bitumen etc) or surrounding media (soil, water, air). Among other factors, wave attenuation (gradually loss of energy during guided wave propagation), has a remarkable influence on the performances of the guided wave technique. Sensitivity and range of investigation play a key role to describe the quality of Guided Wave non-destructive testing (GW-NDT) of pipes, particularly when the pipe to be tested is buried or coated with a material that produces a high attenuation effect on the propagating waves. In this paper the relationship between wave attenuation and inspection range and sensitivity is discussed considering measured attenuation values for unburied PE coated pipes, unburied bitumen coate...
New Magnetostrictive Transducer Designs for Emerging Application Areas of NDE
Materials (Basel, Switzerland), 2018
Magnetostrictive transduction has been widely utilized in nondestructive evaluation (NDE) applications, specifically for the generation and reception of guided waves for the long-range inspection of components such as pipes, vessels, and small tubes. Transverse-motion guided wave modes (e.g., torsional vibrations in pipes) are the most common choice for long-range inspection applications, because the wave motion is in the plane of the structure surface, and therefore does not couple well to the surrounding material. Magnetostrictive-based sensors for these wave modes using the Wiedemann effect have been available for several years. An alternative configuration of a sensor for generating and receiving these transverse-motion guided waves swaps the biasing and time-varying magnetic field directions. This alternative design is a reversed Wiedemann effect magnetostrictive transducer. These transducers exhibit a number of unique features compared with the more conventional Wiedemann sens...