NDT calculators · PAUT

Phased Array UT calculators.

Aperture, steering, focal laws, wedges and the acquisition arithmetic behind an encoded scan. Each of the 29 shows the governing formula, a worked example and the standard it comes from.

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PAUT · Phased array and TFM 29 calculators

index = g/2 + t · tan θ

Worked example 25 mm wall, 3 mm gap, 30° bevel, 60° root index 44.80 mm cap width 29.56 mm

PAUT weld bevel coverage

Phased array and TFM

29 calculators

Core calculations first. Pick a topic or search to narrow them down.

Phased array and TFM 29

Aperture, steering, focal laws, wedges and the acquisition arithmetic behind an encoded scan.

  • PAUT Sensitivity, scanning and data

    Maximum PAUT scan speed

    Highest encoded scan speed that still records every acquisition point, from the frame rate and the scan axis resolution.

    General engineering Free

  • PAUT Wedges and weld coverage

    PAUT wedge geometry and refracted angle range

    Natural refracted angle of a phased array wedge and the refracted angle range reachable with a given amount of electronic steering.

    General engineering

  • PAUT Sensitivity, scanning and data

    TCG point gain

    Gain needed at a TCG point relative to the reference point, from the far field reflector law and material attenuation, with a headroom check.

    Engineering reference

  • PAUT Focal laws and focusing

    Maximum focal depth

    Checks a requested focal depth against the near field length of the aperture and gives the element count needed to focus there.

    Engineering reference

  • PAUT TFM and FMC

    TFM grid sizing

    Maximum TFM pixel pitch from the wavelength, the resulting grid dimensions for a zone, and the delay-and-sum load per frame.

    ASME V

  • PAUT Wedges and weld coverage

    PAUT weld bevel coverage

    Bevel geometry, the angle that strikes the fusion face square, and the probe index positions needed to cover root and cap in leg 1 and leg 2.

    ASME V · ISO 17640

  • PAUT Wedges and weld coverage

    Skip distance and probe stand-off

    Half skip, full skip and the exit point stand-off needed to place a shear beam on a reflector at a given depth in leg 1 or leg 2.

    General engineering

  • PAUT Focal laws and focusing

    Beam width at the focus

    The −6 dB beam width at a focal depth, compared with the narrowest width the same aperture reaches unfocused.

    Engineering reference

  • PAUT Focal laws and focusing

    Focal law delays

    Per-element transmit delay for a direct contact or immersion linear array steering and focusing at a chosen angle and depth.

    General engineering

  • PAUT Sensitivity, scanning and data

    Reference sensitivity and scanning gain

    Gain that puts a reference reflector at the required screen height, plus transfer correction and the code scanning gain addition.

    ASME V · ISO 17640

  • PAUT TFM and FMC

    TFM amplitude fidelity

    Worst case amplitude fidelity loss from TFM grid sampling, and the coarsest pixel pitch that still meets a 2 dB limit.

    ASME V

  • PAUT Array and aperture

    Dead element tolerance

    Checks inactive elements in an aperture against the usual 25 percent and no-two-adjacent limits, with the resulting sensitivity loss.

    ISO 18563-3 · ASME V

  • PAUT Array and aperture

    PAUT active aperture

    Active aperture size of a phased array group from element count and pitch, with the aperture expressed in wavelengths.

    General engineering

  • PAUT Array and aperture

    PAUT near field length

    Near field length of a rectangular phased array aperture using the k factor for the active to passive aperture ratio.

    Engineering reference

  • PAUT Array and aperture

    PAUT steering limit

    Maximum useful steering angle set by the directivity of a single element, and the sensitivity lost at a chosen steering angle.

    Engineering reference

  • PAUT Sensitivity, scanning and data

    PAUT acquisition rate

    Frames per second from the pulse repetition frequency, law count and averaging, with the PRF ceiling set by the sound path.

    General engineering

  • PAUT Array and aperture

    Grating lobe free pitch

    Maximum element pitch that keeps grating lobes out of the propagating field over a required steering range.

    General engineering

  • PAUT Array and aperture

    Grating lobe angle

    Angle at which grating lobes appear for a given pitch and steering angle, so ghost indications can be recognised and plotted.

    General engineering

  • PAUT Wedges and weld coverage

    Curved surface wedge fit

    Gap between a flat wedge and a curved surface, whether contouring is required, and the pipe size band a contoured wedge covers.

    ISO 17640

  • PAUT Sensitivity, scanning and data

    PAUT data file size

    Raw file size of an encoded phased array scan from samples per A-scan, law count, scan length and resolution.

    General engineering

  • PAUT Sensitivity, scanning and data

    Encoder resolution

    Pulses per millimetre for a wheel encoder from wheel diameter, pulses per revolution and quadrature multiplier.

    General engineering

  • PAUT Wedges and weld coverage

    First element height, wedge delay and exit point

    Wedge path, wedge delay and beam exit point for an active group on an angle wedge, from the first element height and the wedge angle.

    General engineering

  • PAUT Array and aperture

    Passive aperture beam spread

    Elevation beam spread and width of a linear array, set by the fixed passive aperture that cannot be steered or focused.

    Engineering reference

  • PAUT Wedges and weld coverage

    Linear (E-scan) law count

    Number of focal laws, index resolution and coverage width for an electronic raster scan stepping a fixed aperture along the array.

    General engineering

  • PAUT Focal laws and focusing

    Depth of field of a focused beam

    Axial extent of the −6 dB focal zone of a focused array beam, from the normalised focal depth.

    Engineering reference

  • PAUT Wedges and weld coverage

    Wedge attenuation and steering loss

    Extra gain needed at a steered refracted angle relative to the wedge natural angle, from the longer wedge path and the element directivity.

    General engineering

  • PAUT TFM and FMC

    TFM frame rate

    TFM frame rate from the delay-and-sum load and from the full matrix capture time, showing which of the two is the limit.

    General engineering

  • PAUT Wedges and weld coverage

    Scan line count and index offsets

    Number of parallel scan lines and the index offset between them to cover a required width with a specified overlap.

    General engineering

  • PAUT Wedges and weld coverage

    Sectorial scan law count

    Number of focal laws in a sectorial sweep from the angular range and step, including multiple focal depths and groups.

    General engineering

Formulas are the standard engineering forms. Values taken from codes — IQI classes, allowable stress, dwell tables, acceptance limits — are stated with the edition they come from.

Use at your own risk — verify before you act

These calculators support, and never replace, the judgement of qualified NDT and engineering personnel. Results are provided as is, without warranty of any kind, express or implied, and must be independently verified against the governing code edition named in your contract before being used in any inspection, acceptance, rejection, radiation-safety or fitness-for-service decision. By using them you accept full responsibility for how the results are applied; NDT Inspect, its owners and contributors accept no liability for any loss, damage, injury or death arising from their use or from reliance on them. If a result matters to safety, check it by hand and have it reviewed by a competent person.

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