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Phased Array Auto Ultrasonic (UT) System Conventional ultrasonic transducers for NDT commonly consist of either a single active element that both generates and receives high – frequency sound waves, or two paired elements, one for transmitting and one for receiving. Phased array probes, on the other hand, typically consist of a transducer assembly with 16 to as many as 256 small individual elements that can each be pulsed separately, these can be arranged in a strip ( linear array), 2D matrix, a ring ( annular array), a circular matrix ( circular array), or a more complex shape. As is the case with conventional transducers, phased array probes can be designed for direct contact use, as part of an angle beam assembly with a wedge, or for immersion use with sound coupling through a water path. Transducer frequencies are most commonly in the 2 MHZ to 10 MHZ range. A phased array system also include a sophisticated computer-based instrument that is capable of driving the multi element probe, receiving and digitizing the returning echoes, and plotting that echo information in various standard formats. Unlike conventional flaw detectors, phased array systems can sweep a sound beam through a range of refracted angles or along a linear path, dynamically focus at a number of different depths, thus increasing both flexibility and capability in inspection setups. In most basic sense, a phased array system utilizes the wave physics principle of phasing. It varies the time between a series of outgoing ultrasonic pulses in such way that the individual wave fronts generated by each element in the array combine with each other. This action adds or cancels energy in predictable ways that effectively steer and shape the sound beam. This is accomplished by pulsing the individual probe elements at slightly different times. Frequently the elements are pulsed in group of 4 to 32 in order to improve effective sensitivity by increasing aperture, which then reduces unwanted beam spreading and enables sharper focusing. Software known as a focal calculator establishes specific delay times for firing each group of elements in order to generate the desired beam shape, taking into account probe and wedge characteristics as well as the geometry and acoustical properties of the test material. The programmed pulsing sequence selected by the instrument's operating software then launches a number of individual wave fronts in the test material. OCTG pipe inspection system using phased array consists of Five water wedges, each Water Wedge (WW) in the inspection head performs one type of inspection. The inspection head assembly allows the inspection for Longitudinal defects, Oblique defects, Transverse defects, Lamination defects, Wall thickness measurements. The inspection of oblique angles will vary according to the system's configuration. Control of pipe rotation with the inspection head translation is required, using encoders for translation and rotation position feedback. The translation speed is synchronized with the rotation speed (gearing in motion control servo module). Movements in the systems are controlled by servomotors. The Phased Array System for Pipe Body Inspection adds unprecedented flexibility for pipe inspection. The main advantages are:  Sensitivity to small defects and holes by optimizing the beam dimension and shape of the anticipated defects. Adaptability of the beam coverage and inspection overlap of specified requirements. Optimization of the focal length and spot size for wall thickness and geometry. Versatility: the system can be quickly reconfigured to different inspection configurations to optimize productivity and detection capabilities. Flexibility: Aperture size and overlapping between apertures are optimized to fit the inspection requirements and improve repeatability (smaller defects, drilled hole, lamination, etc.) Enhanced Inspection Quality. Automatic calibration per aperture with detailed data reporting Highest documented repeatability in the industry Automatic check calibration Accurate defect positioning Detailed alarms reporting: Complete data reporting wall thickness mapping.System Performance Reference Standards: The following reference standards are used to evaluate the capability and productivity of the system according of the inspection configuration. 1. Notches Orientation- Longitudinal (L) - Transverse (T) - ±11° Oblique (Ob 11°) - ±22° Oblique (Ob 22°) - ±45° Oblique (Ob 45°) Location: ID and OD Depth: 0.012 in (0.3 mm) or 5% of nominal wall thickness (N5) ( whichever is higher). Width: 0.02 in ( 0.5 mm) Length:- Longitudinal: 1” (25.4mm) 1/2” (12.7mm) - Transverse: 1” (25.4 mm) 3/8” (9.5 mm) - Oblique: 1” (25.4 mm) 1/2” (12.7 mm) 2. Threw drilled Holes (TDH) Diameter: 1/16” (1.6 mm) & 1/8”(3.2 mm) for Wall Thickness 4.4 to 16 mm. Diameter: 3/16”( 4.7 mm) for Wall Thickness bigger that 16 mm3. Flat bottom Holes (FBH) Diameter: 6.35mm Location : ID FBH 1- Remnant Wall Thickness: 50% of nominal wall thickness. FBH 2- Remnant Wall Thickness: 2mm FBH 3-Remnant Wall Thickness - Nominal Wall Thickness - 2mm.4. Wall Thickness Reduction (WTR) Depth: 12.5% of nominal wall thickness Length: 25.4 mm Width: 6.35 mm Location: ID Orientation: Axial
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