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How to use Ultrasonic Thickness Gauge?

In this blog post, you’ll read:Do you know how to use ultrasonic thickness gauge effectively? Here are some considerations, including preparing the surface, checking temperature fluctuations, selecting the right transducer or probe, choosing the right couplants, and making necessary calibrations.

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Does the thought of using an ultrasonic thickness gauge ever get you frustrated?

This feeling can arise when you miss a step in the operating procedures of the ultrasonic thickness gauge. Sometimes, moving from using another thickness measurement method to the ultrasonic gauge method can also be the reason for this frustration.

However, the ultrasonic thickness gauge offers so many benefits that it has become the standard for most technicians, especially corrosion and erosion assessment. Hence, it is important that inspectors and technicians understand its workings and effectively use it for accurate material thickness assessment. 

This post aims to give you all the information you need to efficiently use the ultrasonic thickness gauge. So, without further ado, let’s dive into it. 


I. How does the Ultrasonic Thickness Gauge Work?

An ultrasonic thickness gauge works by calculating how long it takes a sound vibration from an ultrasonic transducer to travel through a test sample and give feedback on the sample’s interior. This sound wave is often deployed for measuring defects. However, the inspection can give the thickness and other details of the object under inspection. Furthermore, the result of the measurement is displayed on a computerized screen.

The compactness of this device permits on-site inspection and allows for re-inspection in case a defect is detected. Additionally, the promptness in the result of tested materials makes it an essential tool that cannot be undervalued.


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II. Considerations for Correct Usage on Ultrasonic Thickness Gauge

To use the ultrasonic thickness gauge efficiently, you must satisfy certain criteria. Here are some of these criteria below. 

  • Select the Correct Transducer: In selecting the right transducer to be deployed for testing, there are other factors still to be considered, and they include the type of material to be tested, the surrounding physical limitations in the environment, the temperature of the material, and other technical factors around the test object such as the uniformity of the surface or if there exists a bend.
  • Choose the right couplant: A couplant represents a fluid that guarantees that there’s no gap between the test instrument, which is the transducer, and the test material, which is the object being measured. A little quantity should be administered on the surface before you can accurately calculate. Consequently, failure to verify a sufficient seal will translate to irregular results.
  • Make Calibration: This is necessary when implementing piping or tubing tests, as the diameter of the pipe ascertains what kind of testing technique is to be applied. For example, the testing could require either perpendicular or parallel testing. Bigger diameters with ten centimeters and above require the measurement with the transducer perpendicular to the lengthy axis. It would be best to take a perpendicular measurement and an additional parallel one for smaller diameters. But the lower measurement is the recorded measurement.
  • Prepare the Surface: When the surface of the tested object is uneven or rough, the reliability of the results is shortened. Therefore, it is advisable to clear any scale, rust, or debris found on the surface of the test material either with sanders, grinders, or a wire brush.
  • Take care of Temperature Fluctuations: It is a fact that sound waves are slower on hot material. Therefore, it is also advisable to utilize transducers suitable for such temperatures to have an accurate result and avoid expansion on the test object’s surface. It must also be kept on the surface only for the time required to perform the test.


III. What Materials can be Measured by Ultrasonic Thickness Gauge?

The ultrasonic thickness gauge has specific use cases, and its most common applications are highlighted below. 

  • Measuring Pipe and Tubing: The ultrasonic thickness gauge is applicable in measuring piping and tubing equipment, especially in detecting the escape of industrial gas pressure pipes and vacuum systems. Leaks of constricted air and gas systems, in particular, can be very disadvantageous because extra energy has to be generated to make up for the loss.
  • Measuring Hot Surfaces: Ultrasonic thickness gauging does not measure cool materials at normal temperatures but can also measure the thickness of the surface of the material as high as five hundred degrees. This is possible because the ultrasonic gauge is instant in measurement and only requires a brief contact with the test object’s surface.
  • Measuring Laminated Materials: Ultrasonic Thickness Gauge is not limited to measuring pipes and tubes or hot surfaces. It also measures laminated materials, which are distinctive because their thickness may differ significantly from one object to another. Laminated materials can also reveal a detectable difference in sound velocity over a single surface. But it can be accurately measured by performing a calibration procedure on a sample part of known thickness.


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IV. What is the Measuring Procedure of Ultrasonic Thickness Gauge?

The measuring procedure for an ultrasonic thickness gauge is quite simple, easy, and quick. All necessary preparations must be completed before implementing the measuring procedure, which is listed in quick, easy steps.

The first thing is to turn on the ultrasonic transducer, then select the appropriate function for the operation, i.e., in/mm to set the inches and millimeters to be measured. You can then apply a little couplant to the test object’s surface. Briefly place the probe on the couplant covered surface, and then take readings of the tested material displayed on the digital screen. The displayed reading is the actual measurement of the tested object, and that reading would be the last before the instrument is turned off.

Ultrasonic Thickness gauges are widely utilized in various industries such as the oil and gas, manufacturing, petrochemical, and energy industries. They are likewise crucial in ensuring the durability of different structures and equipment components.


V. How to use an Ultrasonic Thickness Gauge?

Sound energy comprises a wide range of frequency spectrum, and perceptible sound occurs at a low-frequency range. But with Ultrasound, its sound energy is at a higher frequency, past the limit of human hearing. Most ultrasonic testing is discharged at a frequency range between 500 kHz and 20 MHz, even though some customized instruments go as low as 50 kHz or lower and as high as 100 MHz.

Irrespective of what frequency, sound energy comprises a pattern of organized mechanical pulse transmitting via a channel such as air or steel. Ultrasonic thickness gauges work by accurately measuring the length of time it takes a sound vibration generated by a small probe referred to as an ultrasonic transducer to travel all over a test object and return feedback from the interiors.

The transducer accommodates a piezoelectric component charged by a short electrical impulse to produce a surge of ultrasonic waves. The sound waves are integrated into the test material and descend across the test object until it clashes with a back wall or other boundaries. The backscattering then travels back to the transducer, converting the sound energy into electrical energy.


How to use an Ultrasonic Thickness Gauge


➤ Related Article: How to Choose an Ultrasonic Thickness Gauge?



In conclusion, an ultrasonic thickness gauge listens for echo as it travels at the speed of sound. It then measures the thickness using the relationship between the velocity and sound travel time in the test material. 

It is also clear that an ultrasonic thickness gauge has applications, including measuring laminated surfaces and materials, piping and tubing equipment, and hot surfaces.

And finally, considerations for accurate usage of the ultrasonic thickness gauge include preparing the surface, checking temperature fluctuations, selecting the right transducer or probe, choosing the right couplants, and lastly, making necessary calibrations.

Following the procedures highlighted in this post will help you efficiently use an ultrasonic thickness gauge without any headaches.

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