Pundit PD8050 Ultrasonic Pulse User Manual

Pundit PD8050 Ultrasonic Pulse

Product Specifications

• Model: PD8050
• Channels: 8 (single handle 16 channel available)
• Technology: 8 channels with 3 transducer elements per channel connected in parallel
• Scan Surface: 21 cm
• Operating Principle: One channel transmits while the signal is received on the other 7 channels

Instrument Overview
The PD8050 system features various components including Digital TGC controls, AI positioning camera, laser pointer, tablet holder, WiFi module, and more. The modularity allows for flexibility in usage.

Recommended Workflow – Structural Assessment

To assess structures, follow these steps:

1. Concrete quality assessment using ultrasonic pulse velocity measurements
2. Verification of structural defects like voids, delaminations, and honeycombs
3. Check for voids inside tendon ducts
4. Start with recommended measurement settings and aim for a clean back wall image

Tips on Obtaining a Good Back Wall Image

If a back wall is not immediately visible, try these steps:

• Rotate the probe diagonally to reduce reinforcement influence
• Increase linear gain and digital TGC (auto gain function must be off)
• If still not visible, increase analog gain and TGC
• Consider using a lower frequency by adjusting depth or settings if necessary

Quick Reference

PD8050 System

Instrument Overview

Modularity

Accessories

UTH100 Universal tablet holder for Pundit PD
UHA100 Universal tablet holder with chest harness Can also be used as an iPad stand

Technology – 8 channels

Technology – Operating principle

Technology – B-scan

Technology – C-scan or Time Slice

Real-time imaging

Recommended Workflow

Tips on structural assessment.
Structural assessment with the PD8050 is typically done for the following cases:

1. Thickness measurement – e.g. tunnel lining thickness
2. Concrete quality assessment by means of ultrasonic pulse velocity measurements
3. Verification of the presence or absence of structural defects, in particular voids, delaminations and honeycombs.
4. Verification of the presence or absence of voids inside tendon ducts.

In all cases a good starting point is the recommended measurement settings

1. Case 1 – It is important to know the expected thickness of the tunnel and select the appropriate depth of field. This will usually be the intermediate range. Because of the large amount of reinforcement used in tunnels, it is typically not advisable to use the near field setting as this has a reduced transmission voltage.
2. Case 2 – In this case it is necessary to know the thickness of the element being tested and to set the appropriate depth of field.
3. Case 3 – For this investigation it is necessary to find out as much information as possible on the suspected default. Are there drawings of the structure available? How thick is the structure? What kind of defect is suspected? (e.g. a void caused by concrete not flowing freely due to dense reinforcement). Is the approximate depth of the suspected defect known? Have any destructive tests been carried out to confirm the presence of a defect? Once this is known, the starting point is to try and locate a position on the structure where there is a back wall echo clearly visible and then to compare this with the images taken at the suspected defect locations.
4. Case 4 – This technique involves locating the tendon duct with a GPR instrument and then carrying out a full 3D matrix scan along the duct to look for variations in amplitude which indicates the likely presence of voids. There are a number of guidelines available on this technique that the user is advised to consult for further information.
   Other than case 4, the best way to proceed is to try and detect a clean back wall image at some point on the structure.

Recommended Workflow

Tips on obtaining a good back wall image.

• Perform a provisional investigation. Without saving any data, move the sensor around the surface to try to locate a back wall echo.

If no back wall is immediately visible, try the following:

• Try rotating the probe diagonally to reduce the influence of reinforcement.

• Try increasing the linear gain and digital TGC if no back wall echo is immediately visible.
  (Note: in order to do this the auto gain function must be switched off.)

• If this fails, try increasing the analog gain and TGC.

• If this still does not work, then it may be necessary to use a lower frequency, either by setting the depth of field to far field, or by manually adjusting,
  Reasons why a back wall image may not be visible:

• Coating on the surface with de-bonding to the concrete. Typically results in a totally red reflection from the top of the scan.

• Near to surface defect. Typically results in a totally red reflection from near the top of the scan.

• The element is too thick. Typically, the scan will be completely blue if there are no objects present.

• There is too much reinforcement or poor concrete quality causes too much attenuation.

• There are voids or honeycombs in the path. Typically, the objects will be visible as significant red, orange, yellow echoes.

• There are delaminations not visible due to destructive interference which block the path to the back wall. This occurs when the delaminations or voids have very rough surfaces which scatter the reflections. The scan may appear totally blue in this case, even though there may be large defects visible. This has been known to occur in steel fibre-reinforced concrete and verified by destructive testing.

Recommended Workflow

Recommend Measurement Settings

Initial settings recommended to give a reasonable image on concrete without the need to calibrate the pulse velocity on the test object.

Initial settings recommended to give a reasonable image on concrete without the need to calibrate the pulse velocity on the test object.

Depth of Field – Custom Settings

If desired the depth of field settings can be individually adjusted

Analog Gain and TGC

• For most test objects it is recommended to leave the Analog Gain and TGC at the default values and to use the digital gain and TGC in Image Processing to obtain a good image.
• TIP – double tap on the slider to reset to the defaults (36, 0)
• However, particularly for deep objects it may be desirable to increase the analog gain and TGC.
• In total there is 80 dB of gain available.
• NOTE! If analogue gain and TGC are adjusted, remember to reset to the default values on completion of the test.

Advanced Settings – Half Cycle

Can help to distinguish near surface objects that are close to each other.

Advanced Settings – Image Stabilizer

• Used to reduce flicker on the real time B-scan image
• The image displayed on screen is a combination of the latest real-time image data combined with a percentage of the previous image data. The percentage is determined by the slider.
• Slider set to 1 = no stabilization – Image presentation is immediate but it flickers
• Slider set to 8 = maximum stabilization – Image takes longer to build up, but there is no flicker

Advanced Settings – Pulse Delay

Used for accurate depth estimations

Advanced Settings – Raw Data Offset
Introduces a delay between transmission pulses. Functionality used for research.

Pulse Velocity Calibration – 1st and 2nd Back Wall Echo

This method provides the most accurate depth information. It requires two clear back wall echoes and must be carried out at a location of known depth

Pulse Velocity Calibration – 1st and 2nd Back Wall Echo

Pulse Velocity Calibration – Only One Back Wall Echo

A 2nd back wall echo is not always available. If only one back wall echo is available, then this method is recommended.

Workflow – Line Scan – Data Collection

Scan parallel to the long axis of the sensor. Combine B-scans with or without an overlap to create a line scan.

Workflow – Line Scan – Default Spacing

Unless AI positioning is being used, it is necessary to set the X spacing, i.e. how far you wish to move the sensor between snapshots.

Workflow – Line Scan – X Spacing Overlap

Smoother images can be achieved by overlapping B-scans. In this case it is necessary to set the number of channels you wish to overlap.

Workflow – Line Scan – X Spacing > 21 cm

For quicker scans over greater distances it is possible to leave a gap between B-scans. Particularly useful when scanning over large distances when looking for larger defects.

Workflow – Full 3D Matrix – Data Collection

Scan parallel to the short axis of the sensor.

Workflow – Full 3D Matrix – Image Creation

B-scans are interpolated to create 3D images up to 1.5m in length.

Workflow – Full 3D Matrix – First Snapshot

Gain and TGC can be adjusted before the first snapshot is taken. Switch to the B-scan view to adjust the transmission parameters as required before commencing with the scan.

Unless AI positioning is being used, it is necessary to set the Y spacing, i.e. how far you wish to move the sensor between snapshots.

Workflow – Time Slice View – Detai

Unless AI positioning is being used, it is necessary to set the Y spacing, i.e. how far you wish to move the sensor between snapshots.

Workflow – Full 3D Matrix– 2nd Snapshot

The maximum length of a Full 3D Matrix scan is 1.5m.

Workflow – Full 3D Matrix – Review Mode

Workflow – Full 3D Matrix – 8 channel / 16 channel

Multiple 3D Matrix scans can be combined to create larger volume scans using the optional Pundit Vision Software.

Workflow – Post-processing and Analytics Software

Advanced visualization and analysis of ultrasonic pulse-echo data.

Workflow – AI Positioning

Enables faster and more precise data acquisition.

• Can be used both with Line scan and Full 3D Matrix scan
• Up to 10 tapes can be connected in series for longer line scans up to 15 m.

AI positioning tape accessory 32730418S (Set of 10x 1.5 m tapese

Workflow – AI Positioning

Faster scans – does not require constant spacing or careful placement of the sensor. As long as the tape is visible in the camera window, the B-scan will be placed in the correct position.

Workflow – AI Positioning – Multiple Tapes

When working with multiple tapes it is necessary to inform the system which tape is being used. E.g. Swipe left with two fingers to move to the next tape

Workflow – AI Positioning – 16 channel tape position

When using AI positioning for Full 3D Matrix scans with the 16 channel instrument, there is a difference between the PD8000 and PD8050 versions

Workflow – Grid Scan– Data Collection

One measurement is made in each cell to create a colour-coded heat map of back wall depth or pulse velocity Useful for uniformity testing and for identifying weak or suspect areas

Workflow – Grid Scan – Set-up

The grid that you set up here corresponds to a real grid defined on the structure

Workflow – Grid Scan – Additional Set-up Pulse Velocity

In order to calculate the pulse velocity, it is necessary to enter the known back wall depth. Note; for structures of varying depth it is possible to adjust individual cells later.

Workflow – Grid Scan – Measurement Screen

The grid scan relies on an AI function to automatically detect the back wall echo. If it is unable to detect the back wall, the user may set the tag manually.

Workflow – Grid Scan – Measurement Screen Actions
When a measurement is taken, the next cell automatically becomes the active cell unless the user wishes to change this manually.

Workflow – Grid Scan – Re-open a saved file

Grid scans can cover very large areas. It is possible to take a break from scanning, then re-open the file and continue where you left off.

Workflow – Grid Scan – Review Modes

Workflow – Grid Scan – Review Screen

Workflow – Grid Scan – Adjust Colour Slider

The colour slider allows you to quickly highlight weak spots and suspect areas. Useful for setting a minimum thickness or an acceptable pulse velocity.

Workflow – Augmented Reality

Augmented reality allows the scan to be projected onto the surface of the test object

Workflow – Augmented Reality – Marker Position

Workflow – Augmented Reality

Image Interpretation – Understanding Echoes – Colour Coding

The echoes are colour coded to make image interpretation simpler.
Strong echoes occur when there is a boundary between two materials with differing acoustic impedances. The strongest echoes are from a concrete / air boundary.

Image Interpretation – Reflections at Boundaries

The main boundaries encountered in reinforced concrete are concrete / air and concrete / steel.
The strongest echoes are from the concrete / air boundary which occur at the back wall and at defects such as voids, honeycombs and delaminations.

Image Interpretation – Multiple Echoes

The ultrasonic wave bounces backwards and forwards within an element. So particularly for thinner elements, it is quite common to see multiple echoes of the back wall and other large objects such as large voids and delaminations.

Image Interpretation – Multiple Echoes – Explanation

The image below shows the path travelled by the signal to create the 1st, 2nd and 3rd back wall echoes.

Image Interpretation – Crack Detection

Cracks or delaminations that run more or less parallel to the scanning surface can be detected. Cracks that are vertical or at a steep angle cannot be detected.

Image Interpretation – Shadowing

Larger objects create shadows on the back wall. Likewise, a shadow on the back wall most likely indicates the presence of an object, even if it cannot be seen directly.

Image Interpretation – Grouting Defects

Voids inside tendon ducts due to grouting defects, cause stronger echoes than those from fully grouted ducts.
This principle has been successfully used to locate grouting defects. (Note! It is always advisable to confirm by drilling and performing a visual inspection.

For more information on the product use of the product, please refer to the PD8050 documentation
It is available for download on

https://www.screeningeagle.com/en/products/pundit-pd8050

For safety and liability information, please download at https://www.screeningeagle.com/en/about-us/gtc-and-certificates Subject to change. Copyright © 2022 by Proceq SA, Schwerzenbach. All rights reserved.

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References

• Screening Eagle Technologies - Protect The Built World - Protect The Built World
• Certificates and General Terms & Conditions (GTC) - Protect The Built World
• Pundit PD8050 | Pundit Ultrasonic Pulse and Echo Technologies

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