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Inspection is a task carried out at various stages in the life cycle of a product or structure. Products and structures are inspected during manufacture for quality control purposes. Typically this can be weld inspection in an oil rig fabrication yard or a laybarge, inspection on an automobile production line, inspection carried out during the manufacture of aircraft components or structures, or inspection during manufacture of compressors and turbines and their component parts.
However, to maximize the useful lifetime of a product or asset, to optimize the efficiency of a product or structure in operation, and to ensure that products and assets continue to operate safely, it is vital that intelligent in-service inspection is carried out.
Unfortunately, when a product or structure is installed in its working location, inspection often is not quite as simple as it was during manufacture. Welds can be hidden behind other pipework and machinery, gearboxes can be on top of towers and combustion engines are crammed into increasingly tight engine compartments.
As a result, today’s in-service inspection equipment needs to be able to be used in difficult-to-access locations and offer extreme portability.
By the very nature of in-service inspection tasks, portability of equipment always has been a desired feature. The in-service inspector typically has to fit himself with the tools and instruments necessary to perform his daily inspection tasks.
Moreover, the department or contractor responsible for overall inspection has to ensure that all inspectors are provided with the correct tools for the job, whether this is eddy current equipment to detect surface cracking, remote visual inspection equipment for difficult access and internal examinations, or ultrasonic equipment for weld and corrosion inspection.
Naturally, the prime requirement of an inspector’s equipment must be its functional suitability for the task at hand. That is, will it supply accurate results that can be relied on to allow the correct decisions to be made in terms of maintenance requirements, life assessment and fitness for purpose?
This functionality also covers a range of additional features including clarity of display, ease of result interpretation, the ability to record results for subsequent analysis and connectivity to allow data sharing. At the same time, the equipment also must offer portability to allow its multiple functions to be used in difficult access situations and allow the equipment to be transported to inspection points. This, then, has been one of the important challenges faced by inspection equipment manufacturers: to reduce the size and weight of in-service inspection equipment while at the same time increasing and enhancing functionality.
Eddy CurrentIn-service inspection has been a major employment sector for eddy current since eddy current became an inspection tool. As a result, portability has long been a design feature for a range of eddy current instrumentation. For example, in the aerospace sector this is a necessary feature as it is often the case that the equipment needs to be taken to the aircraft. Consequently, the trend in recent years has been to pack even more functionality into already portable instruments.
Typical of this trend is a family of flaw detectors that brings enhanced data display into portable eddy current inspection. The instruments have a large color screen, with color-coding to highlight specific data, to allow easier interpretation of displayed signals, as each channel is assigned its own color.
Color-coding can be used to differentiate between stored and active signals and it is possible to use color to differentiate the graticule from the signal. The range also has an onscreen menu that allows all functions and parameters to be set, stored in the memory and recalled as required. Even so, all this functionality has not sacrificed portability, as the range and instruments are roughly the size of a hardback book. As a result they are easy to carry to site and to use on site.
Remote Visual InspectionAlthough video borescopy has become increasingly portable during the past few years, true portability always has been denied because of the need to carry an associated drive or processing instrument connected to the borescope by cable.
Recent developments have allowed the introduction of a portable video borescope, which is totally self-contained, requiring no cable connections. Powered by a lithium ion battery, the video borescope uses LED technology to transmit high-quality light by a fiber optic bundle to the camera head and a VGA LCD screen provides high-resolution data display.
Embedded file manager software supports file and folder creation to allow systematic data management, while a VGA port allows easy connection for external video viewing.
UltrasonicsIn many ways, ultrasonic flaw detectors have set the standards for portability in inspection, even though many of the early “portable” models were only truly portable by operators trained in Olympic weightlifting. Today’s typical portable flaw detector weighs just more than 2 kilograms, incorporates long-life batteries and has easy-to-read color displays. However, true portability often is limited by the need to carry different probes for different jobs and functionality is often restricted to A-scan displays.
During the past few years, phased array technology has made its way from the laboratory to the factory shop floor and eventually to the portable flaw detector. The first portable flaw detectors offering phased array were seen just a couple of years ago, allowing inspection professionals an integrated cross-sectional visualization through multiple beams of different angles, or multiple shots of the same angle, using the same phased array probe. Phased array also brought improved imaging to ultrasonic inspection with the advantage of a full-color, real time B-scan sector display.
Today’s in-service inspection equipment offers a well judged balance between portability and functionality, which has been achieved by a combination of field experience, advances in microelectronics and the development of new inspection technologies.
No doubt these same facilitators will continue to ensure that inspection equipment continues to improve in its functionality, portability and, above all, fitness for purpose. NDT
Dave Jankowski is eddy current business leader of GE Sensing & Inspection Technologies (Billerica, MA). For more information, call (717) 447-1562, e-mail email@example.com or visit www.geinspectiontechnologies.com.