What is Ultrasonic Testing?

Similar to the ultrasonic principles used by an OB/GYN during pregnancy and naval SONAR, the ultrasonic non-destructive testing method uses high frequency sound waves traveling through a part to detect discontinuities. If the sound traveling through a part hits material with different acoustical impedance, some of the sound will reflect back. Once received by the sending unit, it will represent as an indication on the screen. Knowing the velocity at which sound travels through a part, along with the time of travel, will allow the technician to determine the distance to the indicated material with a change in acoustic impedance.

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Sound waves are introduced to the part via a transducer made up of a piezoelectric crystal that converts electrical current to sound waves. The two most commonly used types of sound waves are Compression (Longitudinal or Straight Beam) and Shear wave (Transverse or Angle Beam).

What are the Advantages and Disadvantages of Ultrasonic Testing?

Advantages of Ultrasonic Testing Techniques:

• Portability
• Consistent
• Detects surface and subsurface defects
• Only limited access needed
• Instant results

Disadvantages of Ultrasonic Testing Techniques:

• Training is more extensive than other methods
• More expensive than other methods
• Difficult to use on thin materials
• Part Geometry can cause complications
• Needs relatively smooth surface to couple transducer
• Must know velocity of part and have a reference to calibrate against for equipment set-up

TXNDT facilitates an in-depth ultrasonic testing training course. Our sole aim is for trainees to receive quality ultrasonic inspection training.

Top 11 Advantages of Ultrasonic Testing

Companies in asset-centric industries like power generation, oil and gas, transportation, and manufacturing depend on large, expensive pieces of equipment or machinery in order to generate returns. In order to keep large assets operational, companies rely on nondestructive testing regimens to determine the need for maintenance or repairs. This extends asset lifespan, reducing the need for capital investment to replace integral equipment. It also prevents operational failures: while an airline without a working airplane is a harmless joke, an airline with airplanes that stop working mid-flight is a nightmare.

The primary advantage of ultrasonic testing and other NDT methods is preventing costly, tragic asset failures. 

How Ultrasonic Fits Among Nondestructive Testing Methods

There are many types of nondestructive testing, each with advantages and disadvantages. One of the most common, useful, and cost-effective methods is ultrasonic testing. Ultrasonic testing equipment can quickly, effectively, and inexpensively generate an image of the material&#;s internal structure. 

The basic premise is simple&#;like bats or dolphins, ultrasonic probes pulse high-frequency sound waves through physical media. As bats with air and dolphins with water, UT equipment transmits waves through metals or composite materials. By capturing and analyzing the reflection (or transmission) of sounds waves, the UT instrument can generate an image of irregularities and anomalies in the medium. This allows UT technicians to detect and report flaws in the material that can lead to asset failure. 

Several methods of nondestructive testing are currently used, from the most basic to the highly complex. In its simplest form, visual, auditory, olfactory, and tactile inspections are all basic means of testing assets without needing to take them apart; if something doesn&#;t look, sound, smell, or feel right, it&#;s time to call maintenance. Obviously, these inspections have limits, as do eddy current, radiography, magnetic particle, and liquid penetrant testing. 

Ultrasonic testing likewise has limitations. A surface must be accessible, technicians must be skilled, and references must be used. Certain materials, like cast-iron, are difficult to inspect, and some flaws, especially linear cracks parallel to the sound beam, are not easily detected. Yet for all this, ultrasonic testing remains widely used and deeply beneficial, thanks to the method&#;s many advancements and advantages. 

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Advantages of Advanced Ultrasonic Testing

Ultrasonic testing of metals has been in development for at least 90 years, and built on the principles of sonar before it. The technology has improved dramatically and continually over this time, and remains in use due to its numerous advantages. Companies rely on ultrasonic testing for: 

1. Speed. Advanced ultrasonic techniques like phased array (PAUT) and time of flight diffraction (TOFD) can provide immediate results. As soon as the probe passes over the surface of the material, the instrument&#;s software displays a visual image of its interior. Technicians can cover large areas during a shift, and informed decisions on scan results can be made instantly. Phased array probes significantly increase inspection speed, by scanning larger areas at once. 
2. Ease of Use. While ultrasonic testing does require training and certification, modern software and instruments render the process smooth and intuitive. In addition, scans require little preparation, and lightweight, cordless instruments are easy to carry. Only a single side of the material needs to be accessible when using pulse-echo techniques. 
3. Depth. Ultrasonic scans thin and thick materials at the same effective rate. They travel more deeply through materials than other NDT methods, enabling greater flaw detection. 
4. Accuracy and Sensitivity. Ultrasonic testing that applies advanced techniques and proven software algorithms can determine the size, shape, and position of most flaws in the right materials with better persistent accuracy than other NDT methods. UT is also sensitive to surface flaws, as well as those which lurk below. 
5. Portability. Lightweight, handheld, self-contained instruments enable technicians to travel to a job site and cover serious ground during a shift. Better yet, technicians who aren&#;t physically tired from lugging around heavy equipment are less likely to become mentally fatigued and make mistakes, even at the end of a long, hot day. 
6. Imaging Power. Software provides powerful visualization tools. Images can be inspected from multiple angles, filters can be used to screen noise or enhance features, and zoom features allow small details to be examined minutely. 
7. Versatility. More versatile ultrasonic products can be used across a broad swath of asset-centric industries, to ensure materials integrity and production quality. It has other uses, such as thickness measurement, in addition to flaw detection. All this means less equipment needed and more efficient inspections. 
8. Software. In addition to high-speed processing and imaging options, industrially proven software also streamlines inspection documentation and reporting. Tests can be stored locally on the instrument, or transmitted to a central system, where they can be used for research or provided to regulators. 
9. Durability. Built with field conditions in mind, ultrasonic testing equipment can withstand temperature, humidity, vibration, and dust. Hot-swappable batteries also inspections to continue throughout the day, without returning to base. 
10. High-Resolution Touchscreen. Learning from modern tablets and phones, ultrasonic instruments are now built with high-resolution touchscreens, enabling far more function than older, button-driven only models. 
11. Safe and Clean. Ultrasonic technology is self-contained and poses no hazards to technicians or workers in the area. This improves on other NDT methods like radiology, which releases radioactive particles in the vicinity, and liquid penetrant, which requires cumbersome fluid containment systems. 

Taking Advantage of UT&#;s Benefits

While advanced ultrasonic testing is not the only effective NDT solution available, it is a common, powerful, and broadly useful technology in many industries. Without ultrasonic testing, companies expose themselves to the risk of unplanned asset downtime, dangerous accidents, and legal, regulatory, and reputational damage. 

Often, ultrasonic testing is used in combination with other NDT methods, like eddy current testing, so each can cover the ground the other cannot. Both alone and as part of a comprehensive NDT strategy, ultrasonic testing is an inarguably valuable asset to the companies who employ it successfully. 

Zetec has provided ultrasonic testing solutions for asset-centric industries for half a century. To find the perfect ultrasonic solution for your operation, contact us today.

Zetec&#;s designers are industry-leading experts in ultrasonic and eddy current technologies, and we can help you navigate any of our NDT testing solutions or devices.

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