Phased Array Leseprobe

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1 Introduction 1.1 Why an IIW Phased Array Handbook? Industrial phased arrays have been in development for decades, following medical phased arrays and other areas like radar, sonar and geophysics. In the past, a small market, difficult data manipulation, crude software, and extensive training and experience requirements have hampered the wide use of phased arrays for industrial applications. The first industrial commercial phased array systems appeared in the early 1990’s, but were large, expensive, and required good software skills. Most of these units were used in the nuclear industry on specific advanced applications. Currently, the phased array industry is maturing rapidly and phased arrays are becoming pervasive in inspection markets worldwide. This is true both for industrial field applications as well as for more academic applications in universities and research institutes. From a technical perspective, this is being driven by the flexibility that phased arrays bring to an inspection task, with their ability to generate a wide range of ultrasonic beam characteristics with one phased array unit. This has allowed phased arrays to displace other inspection techniques, and in many instances provide inspection data that is superior. From a practical perspective, the new phased array systems are relatively easy to use and are portable, thus allowing easy access to the inspection location. This is in sharp contrast to older phased array systems that are large, immobile and thus difficult to deploy. Lastly, from the commercial perspective these systems have now come down in price to a level that they can be used by organizations that span many different fields. This has also led to a corresponding lowering of rates that has allowed their usage in many new commercial applications. It is these factors acting together that have driven the large increase in phased array usage. 1.2 IIW The IIW is an independent organization that brings together experts from a number of different industries and countries to work together on projects that are relevant for welded components [1]. Within the IIW there are over fifty member countries that work within sixteen Commissions and a number of other sub groups. Commission V of the IIW deals with NDT issues; within this Commission, there are 4 sub-commissions that are focused on different aspects of NDT and report to the IIW through Commission V. Sub-commission VC is focused on ultrasonic inspection and in the past has been involved with publishing Handbooks on a number of different ultrasonic inspection techniques. Examples of this are the Handbook on the Ultrasonic Examination of Austenitic and Dissimilar Welds, Handbook Automated Ultrasonic Testing Systems and this Handbook on Phased Arrays. The intent of this Handbook is to provide a best practices document that can be used by practitioners of phased arrays as a guideline when configuring and performing inspections. This same Sub-commission also designed the IIW calibration block that is now ubiquitous in the field of ultrasonic inspection. This IIW Phased Array Handbook was compiled by a group of experts, and thus represents a wide consensus across different industries, with varying academic and industrial perspectives on the state of the art in industrial phased array inspection. 1
1.3 Handbook layout The Handbook is laid out in the following format: Chapter 1 provides an introduction to the Handbook. Chapter 2 covers Ultrasonic Phased Array Principles and Design; this chapter describes the basic physics required for an understanding of phased arrays, how arrays are manufactured, and some inherent limitations. Chapter 3 covers Scanning Patterns and Ultrasonic Views; this chapter shows the basic scan patterns used for data acquisition, plus some advanced scans primarily of academic interest. Many different combinations of common data views are also described, with the addition of some less common special views. In addition, this chapter includes a brief description of TOFD (Time of Flight Diffraction), which is a complementary technique to pulse echo phased array inspection. Chapter 4 covers Codes and Calibration; this chapter provides an update of phased array code developments, plus indications of future trends with codes. Calibration of phased arrays is also described, as it specifically relates to code inspections. Chapter 5 covers Modeling and Imaging; this chapter describes four different levels of computer modeling to optimize inspections, starting at a basic geometric model and going to a full beam propagation model. The latest methods of data plotting showing two-dimensional and threedimensional defect data superimposed on the component being inspected are also shown. Chapter 6 covers Construction Weld Inspections; this chapter is a series of application specific descriptions for pipelines, process piping, pressure vessels, butt welds, seamless pipe, T joints, ERW pipe, superaustentics and friction stir welds. These are highly regulated inspections, and the examples show how phased arrays fulfill the code requirements. Chapter 7 covers In-Service Weld Inspections; this chapter is a series of application specific descriptions for detecting in-service weld defects in heavy-walled reactors, core shrouds, environmental cracking and transverse defects. These inspections are often less regulated than construction weld inspection, so imaginative use of phased arrays is possible. Chapter 8 covers Non-Weld Inspections; this chapter is a series of application specific descriptions that demonstrate how phased arrays can be applied to non-weld applications, such as railway wheels and axles, bridge pins, turbines, fasteners, and thickness measurements. Lastly, the Handbook presents a Glossary of phased array terms. As phased arrays were developed in different countries and industries, some functions have multiple terms (like S-scans), while other terms have two very different meanings (e.g. linear scanning). All the common terms have been collected. References [1-1] See the IIW Web site (www.iiwelding.org) or contact the member country welding society for more details. 2
Seite 2 und 3: Moles Sjerve Phased Array IIW Hand
Seite 4 und 5: Foreword IIW Commission V - NDT and
Seite 8 und 9: 2 Ultrasonic phased array principle
Seite 10 und 11: 2.2.1 Delay laws In what follows, f
Seite 12 und 13: wedges with a single phased array p
Seite 14 und 15: element diameter in Equation 2-5 wi
Seite 16: the sound field exhibits a complex

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