Ultrasound technology uses sound energy with high frequency that even humans cannot hear. However, dolphins and bats can use these high-frequency sound waves. It was about 60 years ago that humans started taking the benefits of ultrasound, which led to the ultrasonic testing equipment coming into existence.
Nowadays, a lot of industries are using ultrasonic quality control techniques in a variety of applications. It helps in measuring the thickness and other properties of a material. You can get fast and accurate measurements of a material’s outer or inner flaws without cutting or slicing them.
In ultrasonic testing, materials pass through the ultrasonic sound waves. The waves provide complete properties of the material and its flaws. UT testing uses a short pulse wave that ranges between 0.1-15 MHz. The common application of this is when we measure the material’s thickness while reviewing its corrosion.
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How does Ultrasonic Inspection Work?
Ultrasonic testing uses a piezo-electric transducer along with a fault detector that provides an oscilloscope display and pulse receiver. The transducer is then moved above the testing material while the test object is coated with water, oil, or gel. This couplant sends the sound waves from the transducer into the testing material.
In contact-less testing techniques, there is no need for the couplant. Such situations require laser excitation or an electromagnetic acoustic transducer.
Why Use Ultrasonic Testing?
Ultrasonic testing belongs to the non-destructive testing (NDT) family. It is the best method for identifying faults and defects without damaging the testing object. Regular ultrasonic testing is done to check corrosion and to know the reasons for damages. It prevents the malfunctioning of an asset, component, or even the tiniest part. It is used widely in automotive, aerospace, construction, manufacturing, and metallurgy industries.
What Materials can be Tested using Ultrasonic Methods?
Ultrasonic testing is favorable for various materials, and so it is used in a wide range of industries. Usually, UT is done in the testing of heavy, crystalline structures like metals. Materials like plastics, ceramics, concrete, and composites can also be tested. However, lower resolutions are used to test these materials because of their fragile nature.
The medical industry has been successfully using ultrasonic technology for many decades now. It is a preferred option for both medical researches as well as diagnostic image testing. It is considered an ideal solution as it does not emit ionizing radiation.
Advantages of Ultrasonic Testing
Following are some advantages of ultrasonic testing:
- Higher penetration capabilities allow the detection of faults deep inside an object.
- Higher sensitive testing allows detection of even the minutest of faults.
- It’s easy to test an object even if only one side of it is reachable.
- UT has more accuracy as compared to other non-destructive testing techniques. UT is more preferred for assessing the depth of internal faults and thickness of objects.
- You can determine the shape, size, nature, and orientation of the defects through UT.
- Capable to ascertain the alloy formations of objects with different sound properties.
- Completely safe to close materials, equipment, and people.
- Portable and highly automatic testing is possible through UT.
- UT gives immediate results, which allows quick decision-making.
Limitations of Ultrasonic Testing
Along with advantages, there are a few limitations of UT, which are as follow:
- Only experienced and well-trained technicians can perform UT for the best results.
- In some cases, the geometry of the object and some slight irregularities can give false-positive results, also termed Spurious signals.
- Materials that are irregular in shape, rough, very thin, or too small are hard to test.
- Rust scaling or loose paint should be cleaned out before the start of the test. However, clean and smooth surfaces can be left intact.
- In a conventional ultrasonic test, the use of couplant is mandatory.
- UT has lower sensitivity for volumetric faults when compared to radiograph testing.
Ultrasonic Testing Applications
Ultrasonic testing techniques have a range of applications around many industries. It also includes the reliability tests of various materials and components. UT is also used to check for the discontinuities present in welded areas.
UT can be done on ferrous as well as non-ferrous objects. It is feasible to test the thicker sections and also objects that are accessible from one side only. Minute defects and planar faults are also detected through UT over radiographic testing.
The scope of UT applications goes throughout these industries
- Automotive
- Aerospace
- Rail
- Construction
- Oil and Gas
- Manufacturing
- Medical
- Metal and metallurgy
- and many more
Ultrasonic Testing – A Reliable and Accurate Testing Technique
There are many advantages of UT, the most important is that the materials tested are not damaged during the process. It gives a scope of replacing them after repairs or after analysis. Ultrasonic testing ensures accurate results and is also a safer testing method when compared to radiographic techniques. That’s why it is said that Ultrasonic Testing belongs to the Non-destructive Testing (NDT) family.
