NDT Training & Inspection Consultant

A-Star Training & Consultancy Pte Ltd, a reputed automated NDT solution consultant offers training & inspection services in advanced NDT applications.

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The Basic Principles and Areas of Application of Ultrasonic Testing

The use of different kinds of NDT technologies in all level of construction and engineering works in Malaysia is getting huge acceptance. Non-destructive testing techniques can detect different types of flaws and each technique has their own advantages and usefulness. For effectively detecting differences in material characteristics and discontinuities, NDT techniques are irreplaceable.

Among all other non-destructive testing techniques, Ultrasonic Testing is becoming really popular testing method. Consists of different functional units like transducer, display devices, receiver and pulser.

The Principles of Ultrasonic Testing

It is an NDT technique in which beams of high frequency sound waves that are introduced into the material being tested are used to detect surface and sub-surface flaws. When there is a discontinuity (such as a crack) in the wave path, part of the energy will be reflected back from the flaw surface. The reflected beam is detected and analyzed to define the presence and location of flaws. The proper wavelength depends on the material type, material crystalline structure and probable defect shapes and sizes.

Flaws that can be detected using Ultrasonic Testing-

Shrinkage

Flakes

Cracks

Bonding Faults

Cavities

Pores

Laminations

Discontinuities

The applications of Ultrasonic Testing-

The area effective for the ultrasonic test is called the "sound beam" which is characteristic for the applied probe and material in which sound waves propagate. Every probe has a certain directive and cover a certain section of the test object. Ultrasonic Testing is widely used in different industries:

I. Military and defence sector II. Aerospace industries III. Offshore industries IV. Marine industries

During the Ultrasonic testing procedure, detailed images of the flaws can be detected with automated system that helps to get instantaneous results. In the view of the professionals of NDT technology in Malaysia, this NDT technique saves a huge amount of time and helps to complete a project on-time. The equipment used in this technique are portable and highly automated with the minimal part preparation.

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Why TOFD is the Most Accurate of all NDT Inspection Techniques

TOFD better known as Time of Flight Diffraction is one of the most trusted and widely used non-destructive testing methods. TOFD proved really useful and handy for in-service as well as pre-service inspection. Determining flawless assessment of welds is extremely vital in order to ensure top-class integrity and stability of welded structures. No other NDT method even come closer with TOFD when it comes to assess the health of a welded structure. It can be utilized independently along with other ultrasonic techniques.

Time of flight diffraction provides brilliant accuracy in measuring the critical through-wall size of crack-like-defects. The crack tips depth and defects can be easily calculated by utilizing the measured time of flight of the pulse in TOFD method. Nowadays, advanced NDT inspection method in Singapore is the preferred technique used in industries.

Some of the most common TOFD techniques are:

TOFD with pulse echo/creeping waves

Single group TOFD

TOFD with phased array

Multiple TOFD

The Basic Theory of TOFD

TOFD inspection is generally performed by employing two longitudinal waves as the primary detection method. The L-wave angle beam transducers arranged symmetrically opposite facing each other, straddling the weld or base material under test. One sensor releases ultrasonic beam into the material and the other sensor receives reflected and diffracted ultrasound from anomalies and geometric reflectors. A position encoder records the position of the weld and produces the real time digital image of the flaw. In the industry of replacement projects and the life cycle of new build, time of flight diffraction technique can save huge amount of time.

Areas of TOFD Application

Nozzle inspection

Root corrosion detection in piping vessels

Construction weld inspections

High temperature weld inspections of up to nearly 500°C

In service inspection at ambient or high temperatures

Inter granular stress corrosion cracking in welds

Examination of steam drums used in power generation

For the instant determination of weld quality, no other technique can come closer with TOFD. It is fast, reliable and cost-effective non-destructive testing method.

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Why Magnetic Particle Testing Is So Popular Among Other NDT Technologies

Magnetic Particle Testing or MPT is the most commonly used nondestructive testing method. This technique is used to identify discontinuities or defects in the ferromagnetic metals. It is an effective way to detect flaws in ferromagnetic metals like:

Steel

Cobalt

Iron

Nickel

How does Magnetic Particle Testing Work?

The method is only applicable to the metals which can be strongly magnetized. Through this process, a rotating or swinging magnetic flux is generated by utilizing a combination of two magnetic fields. The process can easily detect crack or hole in any orientation.

Step 1- Magnetized the object that is going to be inspected. Here a horizontal MT machine is used to magnetize the object. Step 2- The electric current (DC or AC) used in a waveform. Step 3- If there is a crack or hole in the metal object – the defect will cause a disruption in the magnetic field. Step 4- Iron particles, either in a wet or dry suspended form is applied to the surface of the magnetized part and form visible indication to locate the discontinuities.

Advantages of Magnetic Particle Testing

It is a high sensitive test method where even a small discontinuities can be located easily.

The entire process is fast, risk-free and relatively uncomplicated.

Magnetic Particle Testing requires minimal surface preparation without needing paint removal.

The procedure can be adopted for workshop or site use.

It is a low-cost method to where small or large objects can examined easily.

Comparing to Radiography, Magnetic Particle Testing is highly affordable and expensive.

Elaborate pre-cleaning is not required.

Makes it possible to see and measure the concentration of the particles for process control purposes.

Limitations of Magnetic Particle Testing

The process can only be adopted for testing ferromagnetic materials.

Only surface and near surface discontinuities can be detected.

In some cases two or more sequential inspections are needed with varied magnetizations to get the results.

Only a small area can be inspected at a time.

MPT is very popular among other testing procedures and heavily used in different NDT technologies in the industrial sector to test metal materials such as various metal machinery components and gas & oil pipelines to ward off accidents and mechanical failures.

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Useful Aspects of Non-Destructive Testing

Non-destructive testing (NDT) covers inspecting, testing, or evaluating materials, components or assemblies for discontinuities, or differences in characteristics without materially affecting the integrity of the unit under test. It is an important process to assure the safety and reliability of various industries such as:

Power Stations

Oil & Gas Refineries

Building and Construction

Transportation

Shipping

Biomedical

Aerospace

NDT service in Singapore is a quality assurance management tool which can give impressive results when used in a proper way. Different industries have different safety standards, and different types of machinery have to be regularly inspected at different intervals. But regardless of what has to be inspected, a non-destructive test will always be the most reliable option.

Different kinds of NDT techniques used in Industries

Visual Inspection

Liquid Penetrant Inspection

Acoustic Emission

Magnetic Particle Inspection

Eddy Current Inspection

Ultrasonic Inspection

Radiographic Inspection

Non-destructive Hardness Testing

Let us now have a look at the various benefits of non destructive testing services:

Provide more accurate and reliable inspection data with an improved PoD.

Non-Destructive Testing can help prevent accidents, which helps reduce costs associated with repairs, replacement, and equipment loss and business shut down.

NDT services would always remain the most economical of all.

All forms of non destructive testing allow operators to ensure absolute compliance with the necessary regulations.

NDT services in Singapore gives you the peace of mind that all your equipment are functioning at an optimum level and your workers are perfectly safe while doing their duty.

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Advanced NDT Inspection Services to Meet the Demands of Testing Excellently

The advancement of technologies and highly elegant innovations have led to the development of a number of solutions and excellent services, in every industry and sector. Every single industry and sector is now equipped with some alluring and appeasing technique that helps make the entire process smooth and ideal for all.

With such techniques being used in every industry, the different areas of science is also not left untouched by it. The four major areas of science, which include physics, chemistry, biology and mathematics require a special method of testing that leaves the matter or item under the test totally undisturbed and undamaged. It is done through the excellent method of non-destructive testing or NDT.

It is through the use of the advanced and modern techniques and processes that the people and professionals from science sector can include and can experience the kind of solutions, which can allow them to use the items under test again.

NDT ensures that the items used for testing is not harmed or is damaged in any way. It ensures to protect and safeguard the items to its highest mode. This kind of testing is required for different sectors mainly heavy energy industries.

Why Non-Destructive Testing is Necessary?

NDT or Non-destructive testing is necessary in various sectors of science and also in sectors including the offshore industries. With the help of this kind of testing you will be assured of the integrity of the infrastructure and can also protect the precious items that you put down for testing. The heavy industries which include aircraft, trains, pipelines, oil rigs and others, make sure that they regularly undertake the NDT in order to examine their items' strength and its capabilities.

How to be Assured of the Quality of NDT?

Of course, none of the professionals from any of the above-mentioned industry can claim to be an expert of the NDT. It is because like every other industry, there are experts of the industry, who with their years of experience, their understanding of the sector and their knowledge, provide the best of their services.

It is extremely necessary for every industry who want to undertake the non-destructive testing to hire a professional company with skilled experts. It ensures them that the process is undertaken by expert hands and will include less or comparatively no harm to the premises and to the items as well.

Singapore, becoming a hub of the south-east trade and commerce, gradually, has a number of companies that promises to deliver advanced NDT inspection services in Singapore and nearby areas at the most affordable and reasonable rate. However, as well know, not all claims are true and thus one has to be always inquisitive about the quality and kind of services rendered. The companies with NDT inspection need to come up with customized inspection services or solutions, which would be flexible enough to suit the requirements of the clients. It also has to be equipped with necessary infrastructure and technologies that would make the entire process smooth and quick.

It is always feasible and important for all to hire a reliable inspection company before checking its background and its infrastructure as well.

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Professional NDT Training Courses for PCN and ASNT Certification

NDT Training courses in conventional and advanced non-destructive testing methods by professional teachers not only help the candidates in passing the PCN and ASNT certification examinations but also help them in developing confidence to carry out on-field challenges.

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The Importance of NDT Technology in Testing Solid Structures

It is extremely important to examine solid structures after the concrete has become hard because determining the feasibility of the structure is necessary. If the structure is not feasible, then it cannot be used for the purpose for which it was designed originally. Such testing should ideally be done without damaging the solid structure. There are different kinds of tests done to examine the structure. These range from entirely non-destructive tests to the ones that entirely damage the surface. The tests that causes damage to the structure must be totally avoided. The pull out and pull off tests are examples of tests that damage the object partially. The objects need repairing after such tests which is again expensive.

The range of properties that can be evaluated using NDT Technology in Malaysia and its surrounding regions is huge. The parameters for these tests include elastic, density, strength and modulus along with surface hardness and surface absorption. Also size, distance from the surface and reinforcement location also happen to be the parameters. In certain cases, it is also possible to evaluate the workmanship and structural integrity by the ability to identify faults, voids and cracking and delamination.

Application of NDT Techniques

Non-destructive testing can be applied to both old and new structures. The main applications for new structures include the test for quality and also to settle doubts about the quality of materials constructed. Whereas, the test for existing structures is done for assessment of structural integrity and adequacy. In either case, if destructive tests alone are used, for example, by eliminating cores for compression testing, the cost will be way more. Again, carrying out small tests for large structures can provide misleading results.

Following are situations where non-destructive techniques can be useful:

Quality control of precast units.

Eliminating uncertainties about the acceptability of supplied material.

Negating or confirming doubt about workmanship.

Monitoring strength development pertaining to curing cessation, load application and such application.

Determining crack location.

Determining position, quantity and condition of reinforcement.

Increasing the confidence level of smaller number of destructive tests.

Determining the extent of concrete variability in order to help in choosing sample location.

Confirming or locating suspected deterioration of solid resulting from such factors as overloading, external or internal chemical attack, fatigue, explosion, fire and environmental effects.

Providing information for any proposed alternations for change of use of a particular structure for insurance or for change in ownership.

Evaluating long-term changes in solid properties

Assessing the potential durability of the solid structure.

Application of NDT technique with the help of NDT equipment in Malaysia and other regions can be very useful when testing solid structures. They can help to find out the quality and the concerns. NDT testing is safe and is definitely less time consuming along with being less expensive for the industries using it.

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Some Powerful NDT Technology Techniques to Detect Concealed Flaws

NDT technology or nondestructive testing technology ensures flaw detection on an assembly line before being put to use. Faulty welds always exist in the manufacturing industry. And there should be an effective way to determine those faults. Faults could lead to issues some of which could be extremely dangerous based on the items being welded. For instance, gas pipeline and oil pipeline are difficult to be welded and contain lots of faults. Weld connections also suffer from fatigue and wear and tear during their lifetime and that could lead to failure if they do not meet the standard goals. NDT technology in Malaysia works towards maintaining the quality of the welds.

Nondestructive technology can identify both surface and sub-surface deficiencies while the welding procedure in midway. When you know about the flaws, you will also know about the techniques that can be employed to determine the flaws. Some of the most conventional NDT techniques sued presently include:

Visual Inspection

Magnetic Particle Testing

Liquid Penetrant Testing

Ultrasonic Testing

Radiography

Magnetic particle, visual, liquid penetrant testing methods are used today in detecting surface defects like gaps, cracks, inconsistent weld bead profiles, undercut and sometimes even convex and concave welds. Radiography and ultrasonic are powerful tools to detect sub-surface flaws.

Some Techniques for Weld Verification

Some of the NDT techniques that are applied for weld verification:

Visual Testing- Visual testing or inspection is the most cost-effective technique to locate welded flaw specimen as it employs very few equipment. It typically, uses a hand-held mirror, pocket ruler, weld gauge and most probably a straight edge. Visual inspection can be done before, during or after welding. In some industries, it is used once before any other using any other methods. This is done because it is the most cost-effective technique which uses few equipment. If this technique detects flaws, then there will be no need to apply other sophisticated methods to be used.

Radiographic Testing- Radiography uses X-Ray and is quite an effective non-destructive technique. It uses X-rays and radioactive isotopes to find out the internal soundness of welds in a similar way in which the doctor uses X-rays to detect any kind of damaged incurred by the human body. It is one of the highly valued, versatile and widely used techniques among all the nondestructive methods.

Magnetic Particle Testing- This is also known as MT and is used to detect cracks at or near the surface of pipes. This technique uses a magnetic field doubled up as the application of fine magnetic particles to locate flaws. This technique is applied to plate edges before welding and also after welding evaluation and repairs.

These 3 methods are often used and are deemed some of the most accurate result-driven and cost-effective methods for detecting flaws. On these pillars stands the NDT technique series and also the manufacturing and welding industries.

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NDT Service - The Most Reliable Techniques to Detect Faults in Components

Nondestructive Testing or NDT plays a vital role in assuring good performance from mechanical and structural components in the manufacturing unit. The testing is cheap, reliable and tests functionality of a component in a proper way. The NDT performs necessary tests to spot indicators and discontinuities resulting from failures or shut downs in technical systems. The tests are completely safe and they are done in a way in which the usefulness of the objects remain intact. Since, the usefulness remains intact, the name ‘nondestructive’. NDT allows for meticulous and detailed material evaluation without the requirement for deconstruction. This is the biggest advantage of NDT.

So many manufacturing units are opting for NDT service in Singapore and Malaysia because of the above mentioned features. Since, the process is completely safe and prevents damage to the object, it is so popular across industries. It is not a process that is just used in the end of product manufacturing. It is also used throughout the various stages of part’s life cycle. NDT can be used before the use of component for its purpose for the sake of quality control. This is actually a method of quality control. Components that have sustained wear, fatigue, corrosion, stress and other things affecting reliability should undertake this technique following NDT.

Here are some Nondestructive Technologies:

Radiography- Radiographic evaluation uses radioactive isotopes that is gamma rays on materials to peer qualitatively for indications similar to what a doctor looks for while treating fractures or other medical conditions within the body. Radiation is directed through a part and projected onto a film. Digital detection device is used leaving an image that can be examined by the qualified radiographer.

Visual Optical Testing- Visual optical testing or VT is an extremely effective way to identify surface imperfections that could adversely affect a portion or whole of a component. Visual examiners utilize the knowledge of how a portion is manufactured; the function of the human eye; lighting needs and precise measuring tools to evaluate materials.

Ultrasonic Testing- UT or ultrasonic testing utilizes high-frequency sound waves that are transmitted into an object to find discontinuities or spot alterations in material characteristics. Sound is introduced into the component being tested and reflections from internal imperfections. Zones of acoustic impedance or differing geometrical surfaces are returned to a receiver.

There are other techniques like MT or Magnetic Particle Testing and PT which is Penetrant testing. All these techniques provide accurate results that too keeping the original composition of the component intact. In fact, these testing methods are tried and tested to produce positive results and in cheap price. The best part about employing these techniques is its cheap price. However, most of these techniques require knowledgeable technicians to carry it on. Some of these techniques are conventional while others are non-conventional; but all of them provide excellent results.

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ToFD - The Accurate Result Driven Ultrasonic NDT Technique

ToFD or Time of Flight Diffraction is a technique of ultrasonic testing which is a sensitive and accurate method for welds. The method originated from tip diffraction techniques and was first used in 1975 by Silk and Liddington. Later on, it became a popular technique for nondestructive testing. This technique works with the help of ultrasonic wave and hence is a part of ultrasonic testing method. It works in a manner in which the tips of the fissure when struck by a wave will diffract signals back to the other spot on the surface. The depth of the concerned tips can be ascertained from the diffracted energy.

Time of Flight Diffraction in Singapore is quite a unique technique which was first used as a research tool in UK. It enabled the crack sizes to be measured precisely. This helped the manufacturers to increase the shelf-life of expensive components by detecting the cracks.

How Does ToFD Function?

Measuring the extent of a crack with the help of reflected signal is not a full proof method  of nondestructive testing. There are defects occurring in the measurement because the extent depends on a large extent to the orientation of the crack. Hence, instead of extent, ToFD utilizes the time of flight aspect of an ultrasonic pulse to determine the size and location of the reflector. In this mechanism, a pair of ultrasonic probes is placed on opposite sides of a weld. There is a transmitter and a receiver. When the ultrasonic pulse is sent through the transmitter, the receiver detects it on the other end.

In a solid pipe without defects, the receiver picks up 2 waves- one that reflects off the far wall and one that travels along the surface. However, when a crack is detected there is diffraction of the ultrasonic wave from the tip giving out the size of the crack. Utilizing the measured time of flight of the pulse, the degree of cracks can be measured. Trigonometry is used to calculate the crack’s measurement.

ToFD is applied to the manufacturing of pipeline welds. This industry utilizes this system optimally.

How Reliable is ToFD?

ToFD is largely reliable except for the fact that it has a “dead zone” created by lateral wave signal just beneath the inspection surface. The dead zone does not allow flaw detection and is around 5mm in measurement.

Features of ToFD

It has computerized system for automated weld inspection.

Probes a placed on a buggy traveling along a weld that records data on the go.

ToFD measures the dimensions of cracks almost accurately.

ToFD has a dead zone and in order to prevent flawed detection, it must be supplemented with pulse-echo exam.

It requires trained ultrasonic professionals

Thus, ToFD or Time of Flight Diffraction is a largely successful mechanism but ha sits flaws. The flaws can however, be covered up by supplementation. A majority of industries are depending on Time of Flight Diffraction technique to measure cracks in their manufactured object.