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Using Ultrasonic NDT to Identify Wear & amp; Corrosion

Monitoring equipment for damage and potential flaws is vital Mining equipment is under constant operational stress due to the harsh working environments present in mines and quarries and the weight of the materials involved. This can cause wear and corrosion which can become dangerous, resulting in loss of productivity and even injury or potential death of operators. The mining industry also has to adhere to various industry Standards and regulations which requires regular testing of equipment. In order to accomplish the necessary testing with minimal downtime and without causing any damage to the area under test, ultrasonic NDT testing is carried out.

Ultrasonic NDT testing provides crucial information about the equipment’s condition Capable of non-destructively measuring a wide variety of materials – including metals, rubber and plastics, ultrasonic thickness gauges are ideal for monitoring corrosion and erosion, or
checking for defects in complex, manufactured components. Testing mining equipment using ultrasonic thickness gauges allows operators to quickly and easily determine whether the equipment is fit for purpose or what action needs to be taken if
corrosion has occurred.

Ultrasonic Material Thickness Gauges The Elcometer MTG range of ultrasonic material thickness gauges can measure both uncoated
materials up to 500mm thick, and coated materials up to 25mm thick, whilst ignoring the coating, using a dual element transducer.
Dual element transducers consist of two independent crystals, separated by an acoustic barrier. The two elements are angled so that when one crystal emits an ultrasonic pulse, the energy path creates a “V” shape, entering the material via ultrasonic couplant, hitting the back-wall of the material, and echoing towards the other crystal, where it is detected.
The gauge then uses the speed of the pulse and the time taken to travel from one crystal to another (from pulse to echo), to calculate the thickness of the material – with the acoustic barrier preventing any sound from reaching the receiver directly from the emitter, before the pulse has completed its path.

Choosing a Material Thickness Gauge
Ultrasonic thickness gauges come in many forms, each with different features. In the Elcometer MTG range, the standard gauge, the Elcometer MTG2, is simple and low cost. It is ideal for taking thickness measurements on steel and can take four readings per second.
The MTG4 gauge also takes four readings per second whereas the MTG6 and MTG8 gauges are faster, and are able to take four, eight or 16 readings per second whilst displaying the thickness value. The MTG6 and MTG8 feature a high speed ‘scan’ feature which allows the user to “scrub” the probe over the surface, continuously displaying the thickness values at a rate of 16 readings per second. When the probe is removed from the surface, the thinnest thickness value that was measured is displayed, showing the most potential point for failure.
The top of the range gauge, the MTG8 features ‘Differential Mode’ and ‘Limits’. In Differential Mode, a target thickness can be entered into the gauge and when measuring, the gauge will display the variance from that value. Similarly, the ‘Limits’ mode also allows a target value to be entered into the gauge. If a reading is taken below this value, an alarm will sound and the red LED on the keyboard will light.

Data Logging
The MTG6 and MTG8 gauges both have data logging capabilities, allowing readings to be saved in the gauge memory and then downloaded via USB or Bluetooth ® to PC, iOS or Android ™ devices for further analysis and reporting. The MTG6 gauge can store up to 1,500 readings and the MTG8 can store up to 100,000 readings in up to 1,000 batches. A batch is a group of readings, which can be saved sequentially or into a grid format, the Elcometer MTG8 can store multiple batches which can represent multiple locations around the
asset being inspected.
To help undertake and report grid-based corrosion inspections quickly and easily; the Elcometer MTG8 comes with a ‘Grid Batching’ feature, which allows readings to be saved instantly into a grid making it easy to complete and report the inspection.
Using a grid is ideal when inspecting large areas as it clearly marks and identifies areas of concern, and helps to identify exactly where the corrosion is occurring. By repeating grid-based inspections in the same location over time, corrosion rates are able to be predicted and
preventative maintenance can be performed to avoid a breakdown.

Inspection Reporting
When it comes to inspection reporting, typically a report would be created manually, either by hand or using word processing or spreadsheet software, which can be both time consuming and open to human-error.

However, if when the Elcometer MTG6 or MTG8 is connected, via USB or Bluetooth, to ElcoMaster ® , Elcometer’s free software application, readings can be transferred, with full statistics, calibration information and limits, to a smart phone, tablet or PC. Once the data and any additional notes and photographs have been uploaded, the software is able to instantly create a professional inspection report that can be exported to PDF, printed or sent elsewhere via email.
ElcoMaster ® software can also be used during the inspection process. The software’s ‘Collects’ feature allows the inspector to follow a template live from an Android or Apple mobile device showing exactly where to inspect. To do this, a picture of the inspection area should be
uploaded to the ElcoMaster ® mobile app and specific locations that need to be inspected are added. Once the area is inspected, the app will instantly show, on the image, exactly where the corrosion is occurring, which can be used in the final inspection report.

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