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to ensure the soundness of the weld is use of DGS scales in Ultrasonic testing. order to bring the 3mm diameter disc on to curve II) then one uses the lines. Physics of NDT made clear by simulation · Ultrasonic Testing for Education · Eddy DGS (Distance Gain Size) or AVG (Abstand Verstaerkung Gröesse – in german) curves from manufacturer (Krautkrämer) are compared to simulation data for. block method the characteristic curve of the sound field is always determined before carrying out an ultrasonic test, whereas in the DGS method DGS diagrams.

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UT – FBH: DGS curves

The input signal frequency is 2. BINDT knows that you ultfasonic how information about you is used and shared and we appreciate your trust in us to do that carefully and sensibly. It is much more useful, however, to use direct reading scales which can be fixed to the UFD screen for immediate size estimation.

There is good agreement between simulation and measurement. Ultraslnic here hltrasonic unsubscribe Go. The information we learn from customers helps us personalise and continually improve the service we provide through our website and other channels. Specific DGS curves for individual probes can be produced and so both the distance axis and the reflector sizes can be in mm. Reflectors of the same size will have an echo height inversely proportional to the square of the beam path distance, assuming that the reflectors are in the far zone.

It is important for you to protect against unauthorised access ultrasonicc your password and to your computer. Please select the activities you want to receive information about: At longer beam paths, set the backwall to RE2 and add 8 dB.

It also shows a backwall echo BE to which the technician sets the backwall echo as the reference sensitivity. DGS using digital display courtesy Panametrics click photo to enlarge.

DGS scales are specific to each probe specification and test range. DGS is a sizing technique that relates the amplitude of the echo from a reflector to that of a flat bottom hold at the same depth or distance.


We reveal only the last five digits of your credit card numbers when confirming an order. Part Two Training Courses: This is a typical scale, and the shape of the curves and reference reflectors will depend on the test range, as well as the probe diameter and frequency. Aerospace Event About the event Information rgs Exhibitors CM About the conference Abstract and full paper submission Registration Key dates and participation Keynote speakers and structured session organisers Exhibitors booking form Dfs and accommodation Sponsorship packages Travel information Travel and attendance award Best student paper award About the organisers Curge of sponsors.

For more information on how to use a DGS diagram see: Ultrasonic Flaw Detection Tutorial. In the early days of development of the DGS approach ultrasoniv DGS sizing, it was necessary to employ this generalised approach. When this concept was first established, the general DGS diagram was developed as shown below:.

Our security procedures mean that we may occasionally request proof of identity before we disclose personal information to you. Information about our customers is an important part of our business and we are not in the business of selling it to others. The interaction model is the Kirchhoff model which is well suited to specular echoes. For small FBH above the focal spot the difference is up to 6 dB. In the general diagram the size of reflector is given as a ratio between the size of the disc and the size of the crystal.

Resonant inspection Stress measurement Thermography Ultrasonic methods Ultrasonic advanced methods Ultrasonic flaw detection Ultrasonic thickness gauging Visual inspection Other methods. The blue curves plotted show how the amplitudes obtained from different sizes of disc shaped reflector equivalent to a FBH decrease as the distance between the probe and the reflector increases.

These are called the reference echo curves, and are used to set the correct sensitivity from the backwall. As implemented in contemporary digital flaw detectors, DGS curves are typically plotted based on a reference calibration off a known target such as a backwall reflector or a flat bottom hole at a given depth.


The gain curvee be added can be then obtained by the difference on the Y-axis between the backwall curve at the backwall range and the curve of the disc reflector of the given size at the test range.

From that one calibration point, an entire curve ultraaonic can be drawn based on probe and material characteristics. The input signal frequency is 1. Traditionally this technique involved manually comparing echo amplitudes with printed curves, however contemporary digital flaw detectors can draw the curves following a calibration routine and automatically calculate the ERS of a gated peak.

Alternatively, the curves can be used ultrasonuc find the size of the disc shaped reflector which would give the same size echo as a response seen in the flaw detector screen. It is first used with great diameter reflectorsthen with FBH of different diameters at different depths in water:. In the example shown above:. For each FBH diameter, there is a very good agreement for the FBHs echoes amplitudes in the far field where the specular echo amplitude linearly decreases with the depth on the figures, but there are discrepancies for the highest diameters at the smallest depths.

DGS evaluation is a very convenient and reproducible technique, with a number of specific applications.

UT – FBH: DGS curves

The input signal frequency is 4. The curves show a good agreement between simulated and experimental data for FBH deeper than the focal depth. Now consider a probe scanning over three identical discontinuities at varying dga path lengths:. An example of a typical DGS curve set is seen below.

Rather than plotting the entire curve set, instruments will typically display one curve based on a selected reflector size registration level that can be adjusted by the user.