#ultrascans

From aerospace to hydrocarbon exploration, Ultrasonic testing is used in multiple industries to detect flaws in a material or metal workpiece. It is an effective and proven method of identifying defects. This process helps manufacturing or mechanical companies make more targeted maintenance plans to save money and time. Industrial units and companies leverage ultrasonic technology for their non-destructive testing requirements. Understanding how Ultrasonic testing works and how this technology has evolved over the years can help industries decide how this non-destructive testing technique can be utilised. 

Ultrasonic Testing At A Glance

In Ultrasonic testing, high-frequency sound waves are moved through a material to identify defects and flaws. The sound waves encounter the material using a transducer and send different signals when they come across a defect in the material. A returned sound wave displays the existence of any crack, decay, or other defects. The high-frequency sound wave sends back a signal in 3D visualisation form, determining the distance between each discontinuity. By utilising ultrasonic flaw detector, the inspection operator can easily visualise the defects and discontinuities in a tested material. 

For instance- it is used to inspect whether a welded material or metal workpiece is welded rightly or not. Such testing is effective with iron or non-iron-based materials. Moreover, this technique is also suitable for those materials that are not entirely accessible or within reach. The ultrasonic methods can detect those finer and flatter flaws that can not be easily found with radiographic testing. 

Ultrasonic Testing In The History 

Ultrasonic testing can be found back in history since the study of acoustics was initiated. It fascinated the globally acclaimed mathematician Pythagoras (600 BC) due to the utilisation of sound waves and how they collide with the materials. 

In the modern age, ultrasonic testing was introduced after the Titanic sank in The North Atlantic Ocean in 1912. As a consequence, the marine engineers were looking for techniques to identify icebergs before they came across ships’ routes. Moving echoes of sound waves through the water were supposed to be the most optimistic technique to identify objects that can be dangerous. 

In further years, ultrasonic testing was utilised extensively but for unfortunate causes. During the First World War, this technique was used to find and sink enemy submarines and other combat ships, leading to broad research on the sound wave and ultrasonic testing field. 

Sergei Y. Sokolov, a Soviet scientist, had shown a way to identify defects in metals in 1928. Later in 1940, British engineers researched to find out the use of ultrasonic waves for steel and other metals. Ultrasonic testing equipment manufacturers in the United States and Japan had developed ultrasonic flaw detector for industrial use. The initial ultrasonic testing equipment included the massive vacuum tubes consuming high energy, and it took a lot of human effort to set them up and make them work. During the 1960s, engineers finally developed portable ultrasonic testing equipment using solid-state circuitry.

The Ultrasonic Testing Technique Today 

Modern ultrasonic testing equipment is slightly similar to old yet bulky ultrasonic flaw detector. Though they both follow the same principle, modern UT devices are advanced in precise measurement of flaws, imaging defects, calibration stabilisation, and data sharing. 

In today’s scenario, ultrasonic testing: 

Identifies both surface and subsurface discontinuities 

Needs a single side of the surface to collide 

Needs nominal part preparation 

Delivers instant results 

Allows to share outcomes easily 

Can be automated to save user’s energy and time

The precision of ultrasonic testing results needs expertise and training to be understood and interpreted. Therefore, a well-trained flaw inspector can easily handle ultrasonic testing equipment. 

How Does The Ultrasonic Indicator Work?

In ultrasonic testing, a piezoelectric transducer is linked to an Ultrasonic flaw detector. Generally, the defect finders are made of a pulse receiver and a display to show oscillations. The transducer is attached to the object to be tested with gel, oil, or water to move over it. A couplant (a material that enables the transmission of ultrasonic waves from the transducer) is essential to move the sound energy to the transducer to get the outcomes. However, the couplant is not required if we use non-contact methods like laser excitation or electromagnetic acoustic transducer.

Types of Ultrasonic Testing

There are multiple types of Ultrasonic testing used for different causes in different industries and sectors, and some are mentioned below. 

1. Automated Ultrasonic Backscatter Testing 

AUBT is an ultrasonic testing technique to detect damage or defects caused by high-temperature Hydrogen attack. Generally, this technique is used to inspect pipes and pressure vessels. In this inspection technique, a high-frequency probe and an oscilloscope are used for frequency calculation. 

2. Phased Array Ultrasonic Testing 

PAUT is an ultrasonic testing technique that uses an ultrasonic probe made of different small elements. Each element utilised in a PAUT system is capable of pulsing separately. This is done through the phasing process with computer-calculated timing.

3. Long Range Ultrasonic Testing 

This ultrasonic testing technique is formed to test a big volume of material from a single checkpoint. In this method, transducer rings are fixed around a pipe to generate a sequence of low-frequency waves to inspect the complete range of the pipelines. 

4. Internal Rotating Inspection System

IRIS is an ultrasonic technique developed to identify the decay in pipelines and tubes. This method utilises an internally fixed probe to generate sound waves. The probe moves through the flooded pipeline for scanning defects and other related inspections.  

5. Time Of Flight Diffraction 

TOFD is an ultrasonic technique to find defects in welds. It determines the position of a reflector by measuring the TOF (time of flight) of an ultrasonic pulse. A pair of ultrasonic transducers are used to determine the TOF in this method. The transmitter sends out low-frequency waves that travel at an angle, and they only diffract back to the receiver if they come into contact with a flaw.

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What are the types of…

Jun152021

Ultrasound is the sound above the human hearing range having shorter wavelengths. Though ultrasound starts at 20 KHz and above most ultrasonic transducers start from 200 KHz. The ultrasonic transducers are sensors that work by using ultrasonic sound waves. These transducers convert the electrical signals to ultrasonic waves or vibrations which are focused on the intended object. Once the ultrasonic waves reach back to the transducer, the distance between the objects can be measured by the intensity of sound. Transducers are used in a variety of fields. The shorter wavelengths generated by ultrasonic transducers are used for measuring materials and distances and for non-destructive testing. The ultrasonic probes or transducers are the necessary part of any ultrasonic test. Transducers can be used for sensitivity or resolution. Sensitivity is the transducer’s ability for detecting small defects in materials while the resolution is the ability to separate signals. 

How Ultrasonic Transducers Work

When electricity is supplied to the transducer, it vibrates at a certain frequency and an ultrasonic sound wave is produced having a frequency of 40 kHz. The sound waves are focused and travel in a certain direction, if there is any obstacle in the path an echo will be produced, and the sound waves will bounce back and reach the transducer which will convert the echo into an electrical signal. The transducer can calculate the distance between the object and the transducer by the time interval between when the original sound wave was released and when the echo from the obstacle was received. These ultrasonic probes or transducers have an advantage over infrared sensors as they are not affected by black particles or smoke in the surroundings and are better at suppressing interference from the background than infrared ones. These transducers are generally used for calculating the distance by the use of ultrasonic waves. 

The Formula for Measuring the Distance 

D = ½ * T * C

Where D= Distance

T=Difference in time between sending and receiving ultrasonic waves

C= Sonic speed 

Ultrasonic transducers types

These transducers are of many different types depending on the factors like piezoelectric crystal arrangement, frequency, and footprint. Ultrasonic transducer price is dependent on the type of transducer. Some of them are given below.

a. Linear Transducers – These transducers have a linear piezoelectric crystal arrangement. Piezoelectric crystals include some types of ceramics, Rochelle salt, and quartz crystals. These transducers are versatile and generally used everywhere. 

b. Standard Transducers – Also called convex transducers, these have curved piezoelectric crystals. These are best for in-depth examinations. 

c. Phased Array Transducers – These are low-frequency transducers of center frequency between 2 MHz to 7MHZ with small footprints. 

d. Straight Beam Contact Transducers-These are used to introduce longitudinal waves into a material. Straight Beam Contact Transducers are used for direct contact with the material being tested. 

e. Angle Beam Transducers-These types of transducers are used to produce longitudinal waves in the material to be tested. 

f. Dual Element Transducers- These transducers use different elements for transmitting and receiving ultrasound signals. These are used to detect irregular defects mainly caused by pitting and corrosion.

g. Immersion Transducers- These types of transducers are better than contact-type transducers. There is a reduction in variations in sensitivity due to their uniform coupling. These are also faster due to their automated scanning ability. Also, these are better posed to detect small defects.

h. Some other transducers are Contact transducers, Air coupled ultrasonic transducers, and Delay line transducers among others.

Different Applications

Transducers are used in various fields including industrial and medical fields. Ultrasonic waves generated by them help find the specified targets, measure the distance between the targets and the transducers, finds the levels or depths, and finds the exact location of an intended target. 

a. Application in Medical Field

Ultrasonic probes are used for diagnostic tests, testing of internal organs like heart, eyes, and uterus, and even in oncology. Doppler motion study is only possible due to the use of these types of transducers. Ultrasound generated by transducers helps in reducing joint pains and cauterizing tumors which require localized heating. Ultrasonic transducers are also helpful in removing bladder and kidney stones due to the vibrations it produces.

b. Application in Industrial Field

Transducers are used in production line management, detecting broken down wires, for counting of workers, assessment of liquid levels, detecting vehicles, and measuring the distance between certain objects among others. 

c. Ultrasonic transducer for cleaning purposes

These transducers are used for cleaning purposes too. These transducers emit ultrasonic vibrations in liquid tanks where objects are placed for cleaning, these vibrations and liquid cavitation due to ultrasound result in turbulence in liquid, and thus cleaning is achieved. Ultrasonic cleaning is mainly done for cleaning jewelry, small machinery, surgical instruments, dentures and for degreasing too. Ultrasonic cleaners are also being employed in assembly lines for large-scale cleaning.

d. Chemical uses

The cavitation that happens due to ultrasound by transducers results in an electric discharge. Thus, ultrasound acts as a catalyst in chemical reactions like polymerization and depolymerization, oxidation and reduction, molecular rearrangement, and hydrolysis. Due to ultrasound acting as a catalyst, many chemical processes are efficiently done at low temperatures at a far greater speed than was possible before. 

Advantages of Ultrasonic Transducers

Some advantages of transducers are given below.

a. These transducers can sense and are able to measure in a wide variety of materials.

b. These transducers are impervious to dust, water, and temperature variations.

c. Well suited for work in any type of environment.

d. These transducers can measure high distances too.

Conclusion

So, this was a brief description of ultrasonic transducers types. These devices are used for wide-ranging purposes main among them being measuring the distance between different objects in a variety of micro and macro environments which helps in completing the task efficiently.

Modsonic Instruments has in its range a variety of Transducers as standard and custom in different configurations of Frequency, Element Diameter, Connector Styles etc. 

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What Are The Different Types…

May102021

There are more than one NDT methods. Non-destructive testing or NDT is an analysis and testing-based technique that is used by industry for evaluating the properties of a component, structure, material, or system for welding defects or characteristic differences and discontinuities without causing any damage to its original part. NDT is also called Non-destructive Inspection (NDI), Non-destructive Evaluation (NDE) or Non-destructive Examination (NDE).

Different Types of NDT Testing Methods

The current NDT testing methods include the following.

1. Acoustic Emission Testing (AE)

Acoustic Emission Testing is a type of passive NDT technique that depends on detecting the short bursts of the ultrasound waves that are emitted from the active cracks under a load. The sensors that are dispersed over the structural surface detect AE. AE can also be detected with the help of ultrasonic flaw detectors from plasticization in stressed surfaces before the crack forms.

2. Electromagnetic Testing (ET)

The method of Electromagnetic Testing makes use of a magnetic field or an electric current that is passed through a conductive part. There are three different kinds of Electromagnetic Testing that include Eddy Current Testing, Remote Field Testing (RFT), and Alternating Current Field Measurement (ACFM).

3. Ground Penetrating Radar (GPR)

Ground Penetrating Radar is a geophysical NDT method that uses an ultrasonic flaw detector machine to send radar pulses through the material’s surface. The waves either get reflected or refracted when they come across a material boundary or a buried object having different electromagnetic properties.

4. Laser Testing Methods (LM)

The Laser Testing Method is divided into three categories that include laser profilometry, holographic testing and laser shearography.

Laser profilometry makes use of a high-speed rotating laser light source along with miniature optics for detecting pitting, cracks, corrosion and erosion when it detects the changes in the surface through a 3D image generation via surface topography.

Holographic testing incorporates a laser for detecting the changes in the surface of the material that is subjected to pressure, vibration or heat.

Laser shearography uses laser light for making the image even before the surface is subjected to stress and creates a new image.

5. Magnetic Flux Leakage (MFL)

The method of Magnetic Flux Leakage makes use of a powerful magnet for creating magnetic fields that saturate the structure of steel such as storage tanks and pipelines. A sensor is used for detecting the changes in the magnetic flux density that shows any kind of reduction due to erosion, corrosion or pitting.

6. Magnetic Particle Testing (MT)

The Magnetic Particle Testing method uses magnetic fields for finding the discontinuities near or at the surface of the ferromagnetic materials. This magnetic field is generated either through a permanent magnet or an electromagnet.

The magnetic field shows any sorts of discontinuities as the magnetic flux lines show leakage that can be seen easily via magnetic particles that are drawn towards the discontinuities.

7. Neutron Radiographic Testing (NR)

Neutron Radiography NDT technique makes use of low beam energy neutrons for penetrating the workpiece. While the beam remains transparent in the metallic materials, most of the organic materials allow this beam to be visible. This helps the internal and structural components to be examined and viewed for detecting flaws.

8. Radiographic Testing (RT)

The technique of Radiographic Testing incorporates radiations that are passed through the test piece for detecting the defects. X-rays are generally used for less dense or thin materials whereas gamma rays are used for denser or thicker objects. The results are then processed by using computed radiography, film radiography, digital radiography, or computed tomography. Whatever method is used, the radiations would show discontinuities in the material because of the higher strength of the radiations.

9. Ultrasonic Testing (UT)

The method of Ultrasonic Testing transmits high-frequency sound into an object for interacting with the features present within the material that attenuate or reflect it by using ultrasonic crack detection. The method of Ultrasonic Testing is broadly classified into Through Transmission (TT), Time of Flight Diffraction (ToFD) and Pulse-Echo (PE).

Choosing the right NDT method is crucial to optimize the performance of the NDT inspection. Since there are so many different kinds of techniques and ultrasonic flaw detectors with each having its distinct characteristics, some are perfectly suited for certain applications while they can be ineffective in the rest of the cases.

Modsonic, specializing in the area of Portable Ultrasonic Flaw Detector, features EINSTEIN-II DGS, an ultrasonic flaw detector that helps in evaluating the flaw size effectively with its built-in DGS/AVG curves and Time Controlled Gain.

Modsonic has also come up with the New Arjun Series Ultrasonic Flaw Detectors that have three different models, Arjun10, Arjun 20 and Arjun 30.

Out of all, Arjun30 is the most advanced ultrasonic flaw detector machine that brings in revolutionary changes in the field of conventional flaw detection through its recordability as well as offline analysis, which wasn’t available in the past.

Despite its smaller size and less weight, the functions and features of Arjun30 meet all the requirements of modern conventional ultrasonic testing.

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Introduction to Ultrasonic Thickness Gauges

May42022

Like an ultrasonic flaw detector, an ultrasonic Thickness Gauge is also non-destructive testing equipment used to measure a component’s thickness. This testing device can assess the thickness of a workpiece by calculating the time sound waves take to move from the transducer through the material and its reflection time back to the transducer. Then the gauge estimates the thickness of the material on the basis of sound waves’ velocity. This equipment can monitor corrosion, evaluate wall thickness, and mould thickness testing. 

Quality control professionals use ultrasonic flaw detectors to detect flaws in industrial structures and ultrasonic thickness gauges to assess the thickness of different products utilised in multiple industries for decades. Over the years, the world has witnessed tremendous growth in hardware development and so the ultrasonic thickness gauge has become a potent yet user-friendly tool. Wondering how it works? We have explained it in the simplest way possible. 

What Are The Usages of Ultrasonic Thickness Gauge?

However, ultrasonic thickness gauges are commonly used to measure a material’s thickness when a quality inspection professional can’t access both sides of the component. Apart from that, it has multiple significant usages to determine the wellness or integrity of workpieces that are likely to have erosion or corrosion such as ship hulls, boilers, pipelines, tankers, and pressure vessels. Be it TM210 Plus or Edison 10, every advanced ultrasonic thickness measuring device has different usages.  Some of the common usages of ultrasonic thickness gauges are mentioned below.

1. To Measure The Thickness Of Tube Wall Or Metal Pipe 

The ultrasonic thickness gauge is extensively used to examine the wall thickness of a pipe or tube, and it helps determine inevitable circumstances in an industrial unit. A non-destructive thickness assessment through a gauge isn’t limited to the accessible ends of pipes or tubes. It can measure the concentration of pipes or tubes automatically without shutting down the process or cutting the pipes. The ultrasonic thickness gauge measures thickness over the whole length of tubes or pipes when the process is on the go. 

2. To Inspect The Wellness Of A Ship Hull 

This is one of the most critical uses of the ultrasonic thickness gauge. As it is difficult to inspect the wholeness of a ship’s hull through eyes because a protective coating is applied on the hull’s outer surface to extend its life. The protective layer makes it difficult to evaluate the wellness of the ship hull. But, the thickness gauge assesses the metal thickness and detects the corrosion spot instantly without removing the protective coating. The tool figures the metal density by measuring the delay in the echo. 

The ultrasound thickness gauge transmits multiple echoes to get a precise image. It measures and determines the thickness of the protective coating by the first echo. The device automatically logs the determinations, overlooking the material delay of the protective coating for the next two echoes. The hull inspectors use these figures to determine the ship’s wellness allowing them to make an informed decision related to the ship’s maintenance. 

3. To Examine Weathering Steel Structures 

Weathering steels encounter continuous decay due to extended corrosion. Therefore, industrial units use thicker steel and closely monitor corrosion. The ultrasonic thickness gauge measures the leftover steel through the rust layer. In this testing technique, transducers are not required to travel the sound waves through the steel. The device not only measures the thickness of the remaining steel but the thickness of the rust layer as well. 

Different Materials That Can Be Measured With An Ultrasonic Thickness Gauge?

However, other techniques and methods have limitations as they can be used to measure the thickness of certain materials, an ultrasonic thickness gauge has varied applications for different materials for numerous purposes. Some of them are mentioned below: 

1. Erosion 

The ultrasonic thickness measuring device assesses the thickness of a coated material that is applied to a component due to erosion. Different parts of industrial structures, nuclear reactors, jet engines, water turbines, and boilers are prone to erosion.

2. Corrosion 

When metals are exposed to natural factors such as atmospheric moisture, they frequently corrode. An ultrasonic thickness gauge, on the other hand, is a precise non-destructive inspection instrument that can determine the level of corrosion in concealed interior metal parts through a single checkpoint.

3. Metals 

Ultrasonic thickness gauges are frequently used to gauge duplicate, machined, wadded, cast, or extruded metal components with thicknesses ranging from 0.2mm to 500mm, depending on grain formation.

4. Ceramic 

The ultrasonic thickness gauge is used to inspect the integrity of all structural and electronic ceramics including ceramic pipes and valves, coatings, containers, and turbine blades. Apart from that, the tool is used to calculate the absolute value of elasticity through sound velocity measurement.  

5. Other Materials 

Because of their ability to measure general metals and plastics, ultrasonic gauges are utilized to measure an extensive range of different materials such as elastic polymers, porcelain, crystal soft contact lenses, wax patterns, and biological specimens including soft tissues.

Type Of Ultrasonic Thickness Gauges

The ultrasonic thickness gauges come in different types on the basis of their usages and transducers. Though, the most extensively used gauges are – 

1. Corrosion Gauges

These are application-based gauges that are used to measure the corrosion in metals through the travel time gap of sound waves between the two sides of the material’s wall. Also, they are widely used to determine the time between two consecutive sound waves. 

2. Precision Gauges

Apart from metals, precision ultrasonic thickness gauges are frequently used for materials such as plastics, porcelain, ceramics, crystals, and other materials utilized in industrial units. The term comes from the fact that these gauges can accurately and precisely measure a broad range of wall thicknesses ranging from 0.2mm to 500mm.

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Thickness Gauge Or Flaw Detector:…

May262022

Thickness gauge and flaw detector are two preferred techniques used for equipment testing. If you are into industrial equipment manufacturing, you might be familiar with these two, but do you know the difference between thickness gauge or flaw detector? While both devices are similar in some ways, they are used for different purposes. In this post, we will elaborate on the difference between thickness gauge and ultrasonic flaw detector and which one is best for your application.

The similarities between thickness gauge and ultrasonic flaw detectors

Ultrasonic thickness gauge and flaw detector are two equipment testing devices. They both use transducers to generate sound waves. Whether you use a thickness gauge or a flaw detector, both devices measure the time a sound wave takes to leave a transducer, travel through the test piece, cross the reflectors and return to the transducer. 

The thickness Gauge and flaw detector use the basic equation of-

Distance = (Velocity * Time) / 2

This equation is divided by two because the one-way time measurement to the reflector is enough to measure the effectiveness of the material.

The reflection and transition of high-frequency sound waves–also known as ultrasound waves—had long been an effective and reliable method for evaluating the integrity of welds. Apart from the leakage and structural changes, these two techniques are preferably used for testing structural metals, pipes and tanks, boiler tubes, railroad rails, aerospace equipment, and many other industrial applications. Further in this post, we will enumerate how to pick a suitable testing device for your application.

Ultrasonic testing equipment devices continue to be popular for their accuracy and availability. Being among the top Ultrasonic Thickness Gauge Manufacturers in India, Modsonic offers a range of equipment testing devices that are;

Cost-effective, quick, and reliable

It can be utilised with no test piece other than wetting with couplant

It has minimal safety hazards or regulatory licensing requirements so that you can use it right away

If you are juggling between ultrasonic thickness gauge and flaw detector and wondering which is the right pick for you, let us assist you. Though selecting between these two largely depends on your purpose of testing, you can easily pick the right one based on their advantages. Before we discuss the key differences between ultrasonic thickness gauges and flaw detectors, let’s take a look at their use throughout the years.

History of ultrasonic testing devices

Ultrasonic testing equipment has been used for industrial applications for over six decades. Initially, the ultrasonic devices were released in the 1940s; most of those were flaw detector testing devices.

The very first digital thickness gauge (also known as “D Metres”) was released in the 1960s. However, the use of an ultrasonic flaw detector to measure thickness was more popular and preferred until the 1980s. But right after the ultrasonic thickness gauge started displaying an ongoing waveform, flaw detectors got an alternative. 

Nowadays, these small yet powerful devices come in either standard waveform or a software option. At Modsonic, we have the EDISON-1 thickness gauge device, which comes with a large 4-digit LCD display, and Einstein II DGS is an ultrasonic flaw detector device that has built-in DGS/AVG curves to provide time-efficient flaw size evaluation. Read on to know more about the capabilities of thickness gauge and ultrasonic flaw detectors and discover how they can be used for your application.

What is an ultrasonic thickness gauge?

Simply put, an ultrasonic thickness gauge is designed to accurately measure the thickness of the material and identify the surface corrosion/erosion from either side of the test piece. It can be used on almost any engineering material of metal, plastic, composites, fibreglass, and chemical, unless it is an engineering marvel.

Modsonic’s ultrasonic thickness gauge testing equipment can measure the thickness of a wide range of materials and products such as plastic tubes, aircraft turbine blades, pipes, or tanks.

Advantages of thickness gauge

Here are some of the advantages you can score with Modsonic’s thickness gauge testing devices.

Easy to operate and can be utilised for any sort of equipment testing

Provide a more consistent and accurate time of flight to ensure the accurate measurement of the total thickness of the test piece

Equips with a large four-digit LCD display

Operates on just two AA-size batteries

One-step calibration saves time

Measures a full range of probes for all applications across all industries

What is an ultrasonic flaw detector?

An ultrasonic flaw detector locates and sizes manufacturing defects such as cracks, voids, porosity, and disbonds in various materials and welded joints as well. Flaw detector devices can be used to measure any standard engineering material. However, most tests are done on steel and other structural metals, but ultrasonic flaw detectors can be used on plastics, composites, and fibreglass as well.

An ultrasonic flaw detector can also reasonably measure material thickness accurately; however, it is not designed for precision thickness.

Advantages of flaw detector

Take a sneak peek at the advantages of Modsonic’s ultrasonic flaw detector.

It comes with built-in DGS/VGS curves to simplify measurement and get accurate flaw size evaluation

Features TCG, which slows down decay with distance 

Dynamic DAC curves change test range and gain after measurement

Equips a built-in software in the assessment as per AWS standard

Features specialised sizing defects;

Distance amplitude correction (DAC)

Time varied gain (TVG)

Distance gain sizing (DGS)

Suggestions to pick a thickness gauge or flaw detector

From aerospace to hydrocarbon exploration, Ultrasonic testing is used in multiple industries to detect flaws in a material or metal workpiece. It is an effective and proven method of identifying defects. This process helps manufacturing or mechanical companies make more targeted maintenance plans to save money and time. Industrial units and companies leverage ultrasonic technology for their non-destructive testing requirements. Understanding how Ultrasonic testing works and how this technology has evolved over the years can help industries decide how this non-destructive testing technique can be utilised. 

Ultrasonic Testing At A Glance

In Ultrasonic testing, high-frequency sound waves are moved through a material to identify defects and flaws. The sound waves encounter the material using a transducer and send different signals when they come across a defect in the material. A returned sound wave displays the existence of any crack, decay, or other defects. The high-frequency sound wave sends back a signal in 3D visualisation form, determining the distance between each discontinuity. By utilising ultrasonic flaw detector, the inspection operator can easily visualise the defects and discontinuities in a tested material. 

For instance- it is used to inspect whether a welded material or metal workpiece is welded rightly or not. Such testing is effective with iron or non-iron-based materials. Moreover, this technique is also suitable for those materials that are not entirely accessible or within reach. The ultrasonic methods can detect those finer and flatter flaws that can not be easily found with radiographic testing. 

Ultrasonic Testing In The History 

Ultrasonic testing can be found back in history since the study of acoustics was initiated. It fascinated the globally acclaimed mathematician Pythagoras (600 BC) due to the utilisation of sound waves and how they collide with the materials. 

In the modern age, ultrasonic testing was introduced after the Titanic sank in The North Atlantic Ocean in 1912. As a consequence, the marine engineers were looking for techniques to identify icebergs before they came across ships’ routes. Moving echoes of sound waves through the water were supposed to be the most optimistic technique to identify objects that can be dangerous. 

In further years, ultrasonic testing was utilised extensively but for unfortunate causes. During the First World War, this technique was used to find and sink enemy submarines and other combat ships, leading to broad research on the sound wave and ultrasonic testing field. 

Sergei Y. Sokolov, a Soviet scientist, had shown a way to identify defects in metals in 1928. Later in 1940, British engineers researched to find out the use of ultrasonic waves for steel and other metals. Ultrasonic testing equipment manufacturers in the United States and Japan had developed ultrasonic flaw detector for industrial use. The initial ultrasonic testing equipment included the massive vacuum tubes consuming high energy, and it took a lot of human effort to set them up and make them work. During the 1960s, engineers finally developed portable ultrasonic testing equipment using solid-state circuitry.

The Ultrasonic Testing Technique Today 

Modern ultrasonic testing equipment is slightly similar to old yet bulky ultrasonic flaw detector. Though they both follow the same principle, modern UT devices are advanced in precise measurement of flaws, imaging defects, calibration stabilisation, and data sharing. 

In today’s scenario, ultrasonic testing: 

Identifies both surface and subsurface discontinuities 

Needs a single side of the surface to collide 

Needs nominal part preparation 

Delivers instant results 

Allows to share outcomes easily 

Can be automated to save user’s energy and time

The precision of ultrasonic testing results needs expertise and training to be understood and interpreted. Therefore, a well-trained flaw inspector can easily handle ultrasonic testing equipment. 

How Does The Ultrasonic Indicator Work?

In ultrasonic testing, a piezoelectric transducer is linked to an Ultrasonic flaw detector. Generally, the defect finders are made of a pulse receiver and a display to show oscillations. The transducer is attached to the object to be tested with gel, oil, or water to move over it. A couplant (a material that enables the transmission of ultrasonic waves from the transducer) is essential to move the sound energy to the transducer to get the outcomes. However, the couplant is not required if we use non-contact methods like laser excitation or electromagnetic acoustic transducer.

Types of Ultrasonic Testing

There are multiple types of Ultrasonic testing used for different causes in different industries and sectors, and some are mentioned below. 

1. Automated Ultrasonic Backscatter Testing 

AUBT is an ultrasonic testing technique to detect damage or defects caused by high-temperature Hydrogen attack. Generally, this technique is used to inspect pipes and pressure vessels. In this inspection technique, a high-frequency probe and an oscilloscope are used for frequency calculation. 

2. Phased Array Ultrasonic Testing 

PAUT is an ultrasonic testing technique that uses an ultrasonic probe made of different small elements. Each element utilised in a PAUT system is capable of pulsing separately. This is done through the phasing process with computer-calculated timing.

3. Long Range Ultrasonic Testing 

This ultrasonic testing technique is formed to test a big volume of material from a single checkpoint. In this method, transducer rings are fixed around a pipe to generate a sequence of low-frequency waves to inspect the complete range of the pipelines. 

4. Internal Rotating Inspection System

IRIS is an ultrasonic technique developed to identify the decay in pipelines and tubes. This method utilises an internally fixed probe to generate sound waves. The probe moves through the flooded pipeline for scanning defects and other related inspections.  

5. Time Of Flight Diffraction 

TOFD is an ultrasonic technique to find defects in welds. It determines the position of a reflector by measuring the TOF (time of flight) of an ultrasonic pulse. A pair of ultrasonic transducers are used to determine the TOF in this method. The transmitter sends out low-frequency waves that travel at an angle, and they only diffract back to the receiver if they come into contact with a flaw.

Conclusion