Radiographic Testing

Radiographic testing is an NDE technique, which involves the usage of either gamma rays or x-rays as radiation sources in order to examine the internal structure of a test component. These sources use shorter wavelength and hence higher energy level versions of electromagnetic waves. RT has been proved to have more advantages compared to various other non-destructive examination techniques. It can be used on a wide variety of materials, highly reproducible and the gathered data can be stored and reused for analysis later on. It is widely used in petrochemical industry to inspect machinery, inspect weld repairs and to detect flaws.

 

Types In Radiography

RT techniques are broadly classified as conventional radiography and various forms of digital radiographic techniques. Each one has their own benefits and limitations.

Conventional Radiography

A sensitive film is used in conventional radiography that reacts to the radiation emitted for capturing an image of the test piece. This image is used to identify the flaws or damages. The greatest disadvantage of this technique is that these films cannot be reused and consumes a lot of time to interpret the results.

Digital Radiography

Digital radiography does not require any usage of films unlike conventional radiography. It instantaneously displays the radiographic images using digital detector on a computer screen. The exposure time involved is much shorter and hence the images can be more quickly interpreted. In addition, digital images offer much higher quality which enables it to be employed in flaws identification in a material, existence of any foreign objects, weld repairs and in inspection for corrosion under insulation.

Computed radiography, real-time radiography, direct radiography, and computed tomography are the four most commonly used digital radiography techniques in the chemical processing, oil and gas industries. Computed radiography employs a phosphor imaging plate in the place of the film in conventional radiography technique. This technique is comparatively quicker than conventional radiography but slower compared to direct radiography. Direct Radiography (DR) is very similar to computed radiography but differs only in the method of image capturing. This technique offers higher quality images besides being fast. However, it is much expensive compared to computed radiography. Real-time radiography (RTR) works by emitting radiation through the test object. The resultant digital image can be viewed and analyzed in real time. These digital images are easier to be stored, transferred and archived for further reference. But RTR has limited image resolution and a lower contrast sensitivity which impacts the image quality. Computed tomography (CT) collects hundreds to thousands of 2D radiographic scans, which are later super imposed to create a 3D radiographic image. CT images readily provide the characteristics of the internal structure of the test object such as dimensions, internal defects, shape and density.

Benefits and Limitations

Radiographic testing is extensively used on welding and castings. It is well suitable for testing broken wires, cracks, foreign material, unsoldered connections and misplaced components in semiconductor devices. Non-metallic materials, ferrous alloys and composites as well can be radiographed.

Radiography is comparatively expensive than the other NDT methods. Radiographic laboratories require relatively large space allocations and capital investments. Operating personnel should be heavily shielded for protection from high activity sources. Even with proper orientation, tight cracks in thick objects are undetectable. Similar is the case with minute discontinuities such as micro-fissures and micro-porosity. Laminations cannot be detected at allude to their unfavourable orientation using radiography techniques. X-rays and gamma rays as well known to cause severe health problems like blindness, sterility, blood cells and skin damage and even disability or death. Thus the protection of the operating personnel as well as those in the vicinity becomes utmost important. Such high standard safety needs restrict the usage of radiographic testing.


Dual Post Graduate Diploma Program

Dual Post Graduate Diploma Program is an ideal course offered by FutureNDT for the engineering graduates and diploma pass outs who are seeking to build their career in core engineering sector. It is a combination of two programs – Post Graduate Diploma in Quality and Industrial Engineering and Post Graduate Diploma in Thermal Power Plant Operation. This program is specifically designed to aid engineering graduates and postgraduates to get associated with esteemed core sector companies.

Dual Post Graduate Diploma program

These modules were designed within association with industrial specialists and consultants from renowned firms and included several concepts, which incorporates advanced technologies such as QA/QC Welding, Power Plant Maintenance, Metallurgy Process, ConventionalNDT(non-destructive testing), Isometric Drawings,Aerospace, Oil& Gas Industries,Ship Building companies Maintenance,Fabrication, Codes & Standards and Application of NDT in these Industries. The prime objective of this course is to train the aspirants in accordance with the requirements of the client and support them in being placed in esteemed companies around the world.

This Program includes complete training content as per the rules for high capacity Thermal Power plants laid by Indian Electricity. The students who enroll to this program undergo both classroom training as well as field training. Apart from classroom training, the students will be provided with both audio and video modules on all critical topics, a set of twenty books covering all the curriculum aspects and E-library support. In addition, the candidates will also be offered frequent industrial visits, live projects on Industrial issues, Industrial case studies, report writings, practical on all NDT methods, simulator training of thermal power plant and Internship with a paid stipend, accommodation and food for three months. They can also avail the opportunity of getting an internship and placements with these firms. After the completion of the course, the students will acquire the needed eligibility and capability to work with renowned organizations in core sector.

Our institutes located at Nagpur and Vijayawada are equipped with full range real time Simulators for 120MW thermal power plant fired by fuel fossil. The simulator setup at Vijayawada is a direct replica of 120MW Thermal power plant unit. This enables the trainees to experience the full range operations and challenging situations of unit operations in integrated mode. This experience helps the freshers to refine their technical skills and improve their practical knowledge. On the successful completion of this course, the student will be awarded a certificate of completion, Future NDT certificate, a Performance certificate PG Diploma in Quality & Industrial Engineering apart from a certificate issued by Synergem for PG Diploma in Thermal Power plant Operation. In addition, the aspirants can also avail the of  QA/QC Certificate (Valuated by CSWIP / AWS-CWI Inspector), T, K, Y- Joints Certificate on Plates & Pipes (Valuated by TKY-UT Expert & Recognized by ASNT), NDT Certificates– 07 No’s (Recognized by ASNT), PAUT Certificate (Recognized by ASNT), AUTO CAD Certificate (For Isometric Drawings), Petrochemical / Refinery / Oil & Gas Maintenance Certificate (Valuated by Industry Expert), Radiation Safety officer Application through IIS NDT for topper (Recognized by BARC) and On-Site Training Experience Certificate from Prestigious Companies.


Phased Array Ultrasonic Testing(PAUT)

Ultrasonic testing instruments are widely in use in industrial applications for more than sixty years. However, the concept of these instruments appears relatively newer for any newbie to this technology. A number of techniques were being employed to detect hidden voids, cracks, discontinuities etc., since 1940 based on the laws of Physics, which govern the high frequency sound waves propagation through a variety of solid materials. Phased Array ultrasonic testing is an advancement of  Ultrasonic testing which is a conventional ndt technique.

phased array ultrasonic testing

Ultrasonic testing is an extensively employed testing process in various industrial applications owing to its safe and non-destructive approach. Earlier the growth of ultrasonic instruments mostly remained in par with the advancements made in electronics and computers. Prior to that, these instruments were exclusively confined to medical field as the applications in these field were relatively simpler than the industrial applications which involved a wide range of acoustic properties of ceramics, metals, fiber glass and other composites as such. In 1980s, the first industrial phased array systems found their application in inspecting in-service power generation. These systems were typically huge and needed the aid of computers for data processing which made relatively complex systems. Apart from these, they were employed in applications involving low pressure turbines and large forged shafts. The latest advent of power electronics, microprocessors and digital signal processing has enormously cut down the size and cost of these equipment and eventually extended their range of applications into various industrial sectors which led to the advent of next generation phased array equipment.

A simple combination of a number of discrete elements in single casing forms an array transducer. The sequential order of pulsing those elements is termed as phasing. A specialized ultrasonic transducer constituting a number of such individual units forms a phased array ultrasonic system. A typical phased array system consists of a 16 to 256 such units which can be pulsed individually in a preset programmed pattern. These transducers may be used in either immersion-testing mode or in contact mode along with different types of wedges. They may be shaped round, squared or rectangular while their operational frequencies range from 1 to 10Mhz. Phased array systems both send and receive pulses from multiple elements in an array. These elements are set to be pulsed to generate multiple beam components, which combine to form a single wave front, which would travel in the direction desired. The receiver as well functions in the same pattern to produce a single wave from multiple elements. The possibility of shaping and steering the waveform in desired pattern enables the generation of vast variety of ultrasonic profiles of beam from single probe assembly, which indeed can be programmed to dynamically create electronic scans.

phased array ultrasonic system can potentially replace any traditional application that employs a conventional ultrasonic flaw detector. They are widely seen used in crack detection and weld inspection applications which are extensively found in a wide variety of industrial sectors such as aerospace, petrochemical, power generation, tubular goods suppliers, metal billet, structural metals, pipeline construction, maintenance and general manufacturing.

The ability to steer, scan and focus beams from multiple elements enable the phased array technology to offer superior benefits compared to conventional UT. Beam steering is technically referred as sectorial scanning and is used for mapping the components at opposite angles.

This eventually results in great simplification of complex geometrical components inspection. The smaller size of transducer footprint and the ability to modify the beam sweep without the probe movement enormously prove helpful in inspection of components with limited mechanical scanning. Sectorial scanning is also employed widely in weld inspection. The probability of anomalies detection is enormously increased due to the ability of multiple angle testing of welds with a single probe.

paut industrial applications

The support of electronics application enables the optimization of beam size and shape as well as the precise location of defects. It also offers the ability to probe through multiple depths which in turn aids in identifying the critical defects in volumetric inspections. Significant improvement in signal-to-noise ratio is noticed in challenging applications. Their shortcomings ofcost effectiveness and need for expertise supervision are overweighed by the considerable reduction of time required for inspection and flexibility they offer.

FutureNDT provides an excellent training of PAUT phased array ultra sonic testing to enable the participant to carry out tests according to the codes and standards under the supervision of level 3 personnel. The course is especially designed to provide a best theoretical classes as well as practical training.


Regardless of technological advancements in inspection techniques the primary and most important inspection / test technique is visual inspection.

visual inspection using glass

 

Visual testing (VT) is the most common widely used nondestructive testing (NDT) methods for the detection of discontinuities or flaws before they cause major problems. According to the NDT Training & Test Center visual inspection is the first step in the inspection of any variety of product form in various industries including manufacturing, structural steel, automotive, petrochemical, power generation, aerospace ect. Compared to other techniques, visual testing is low in cost and easy to apply, and often eliminates the need for further types of testing.

“Visual inspection is the process of examination and evaluation of systems and components by use of human sensory systems aided only by mechanical enhancements to sensory input such as magnifiers, dental picks, stethoscopes, and the like. The inspection process may be done using such behaviors as looking, listening, feeling, smelling, shaking, and twisting. It includes a cognitive component wherein observations are correlated with knowledge of structure and with descriptions and diagrams from service literature.”

Generally, almost any specimen can be visually examined to determine the accuracy of its fabrication.

For example, visual inspection can be used to determine whether the part was fabricated to the correct size, whether the part is complete, or whether all of the parts have been appropriately incorporated into the device.

The EYE :

  • Human eye is the most valuable NDT Tool
  • Sensitivity of the human eye varies according to the light source
  • Human eye has an excellent visual perception

Tools Used in Visual Inspection:

  • Mirrors :  Used for the in depth inspection of minute things and surfaces.
  • Magnifying Glasses :able to see the  magnified image of the object so that it is easy to inspect any flaws on the surface.
  • Microscopes :  Microscope increases the efficiency and accuracy of the visual inspection to a great extent
  • Borescope : If the area is inaccessible for inspection or accessibility may requires destructive , time consuming and/or expensive activity, then Borescope will be used for inspection.
  • Endoscope : should be inspected visually for conditions that could affect the disinfection process such as cracks, corrosion, discoloration, retained debris, and poor fiber optic illumination.
  • Computer Enhanced Systems : One of the finest and updated methods of visual inspection.

Applications of Visual Inspection:

  • It is used to inspect whether there is a misalignment of parts in the equipment
  • It checks for corrosion, erosion, cracks and deformities of machine components
  • It inspect the plant components for any leakage or abnormal operation
  • It is used to identify the defects in welding

What is Ultrasonic Testing?

Ultrasonic testing is one of the most common nondestructive tests also know as UT used to characterize the thickness or internal structure of the test object and also to find any flaws or cracks that exist in the same material through high-frequency sound waves and then listening to see what reflect back. The frequencies used for UT are much higher than the range of human hearing. Because of high frequencies technician uses a variety of specialized equipment to get the results. Pitches used for ultrasonic testing are in the range from 500 KHz to 20 MHz

Ultrasonic test in NDT

Why UT?

Ultrasonic Testing Services are required in almost all the industries including oil and petroleum industries, aerospace, defense, and where welded pipes, tubes and tanks are often tested.  Even offshore and marine industries use UT to maintain flawless materials. Heavy equipment and machinery manufacturers also rely on Ultrasonic Testing to check the quality standards. paper and wood are the two industries that are not suitable to apply UT.

Unlike with radiography or dye testing, ultrasonic sound waves won’t affect the test subject, and it is clean and results are highly reliable. Flaw detection using UT must require a skilled technician to set up the test with appropriate reference standards and obtaining results. Particularly the inspection of irregularly shaped materials is always challenging. The equipment using for UT is highly expensive compared with other NDT tests, even though it’s still one of the best methods for testing corrosion of all thicknesses in tanks and pipes, molded plastics and turbine blades.

Equipment and Applications:

An ultrasonic transducer converts electrical energy into mechanical vibrations (sound waves), and sound waves into electrical energy. Typically, they are small, hand-held assemblies that come in a wide variety of frequencies and styles to accommodate specific test needs. An ultrasonic flaw detector is an instrument that generates and processes ultrasonic signals to create a waveform display to identify hidden flaws in a test piece can be used by a trained operator.

 

Ultrasonic imaging systems are used to generate highly detailed pictures similar to x-rays, mapping the internal structure of a part with sound waves. Phased array technology used in industrial situations is to create cross-sectional pictures. Large scanning systems are used by the aerospace industry and metalworking suppliers to check for hidden flaws in both raw materials and finished parts. Ultrasonic pulser/receivers and signal analyzers are used in a variety of materials research applications.

UT is widely used in many industries to check the quality of the product and safety involving Steel beams, structural welds, pipelines and tanks, all the parts that go into heavy machinery or car frames are tested, along with rails and engines, power turbines, boat hulls, casting and plastic parts associated with assembly lines and medical equipment. The applications are practically endless.


In the Modern world, need for proficient person to perform welding inspection is eminent in all industries. There is a vast requirement for certified welding engineers, welding inspectors and qualified welders. Inspectors save thousands of lives and crores of rupees, yet many companies do not know how to use their skills less than their potential. If you are planning to become a certified welding inspector or work with one, keep the following things in mind:

facts about welding inspection

1. Can’t Judge By Sight :
Many underestimate the complexity of welding inspection, assuming that inspectors can find flaws just by looking at the metals. In fact, more metal flaws are far too subtle for the human eye to detect. Inspectors must instead rely on:
Magnetic Particle Testing, or the use of magnetic fields to find discontinuities in the metal.
Ultrasonic Testing, which involves detecting flaws with acoustics.
Other Non-Destructive Methods, including testing with liquid penetrants, radiation, and infrared technology.
Failing to understand the complexity of welding inspection is as harmful to manufacturers as it is for prospective inspectors. Many companies underestimate the task, don’t vet their inspectors properly, and end up with sub-par inspections.

2. Can’t Work Alone :
Apart from misconstruing the complexity of inspection, many companies should realize that inspectors cannot stand alone. Testing is only as accurate as the conditions allow it to be, and even the most skilled inspector cannot test properly if the company doesn’t take proper precautions. For example, Cleanliness is necessary for an accurate test; if the metal is greasy or oily, it will trap magnetic particles, undermining that form of testing. Thus Manufacturers must keep their metal products as clean as possible and obey all of their inspector’s other instructions.

3. Can’t Switch From Job To Job
Not only is welding inspection a highly skilled profession, but the specific skills needed vary from company to company. Many companies create their own tests to certify welders and welding inspectors, which often differ significantly from the standard American Welding Society(AWS) ones. This can often make it difficult for inspectors to move to other companies if they don’t like their current jobs. At the same time, it means that certified welding inspectors become invaluable to companies once they are hired, giving them substantial bargaining power. In any dispute, a company is far more likely to accommodate its current inspector than it is to undertake the cost of hiring and training a new one.

unknown facts about welding inspection

4. Communication Skills Equally Important :
Although welding inspection is a highly technical job, communication is every bit as important to an inspector’s work. Inspectors must explain to welders and the broader company what flaws they detect, how to fix them, and how to avoid similar problems in the future. This means breaking complex scientific and engineering terms down into language that the uninitiated can understand. It takes great rhetorical skill to do this effectively.

Future NDT provides the best training in all aspects for our students, and make sure everyone has the skills and practical knowledge as industries needed


Magnetic particle testing or Magnetic particle inspection developed by welders and metal manufacturers to increase the metal quality. MPT is mainly designed to detect cracks and flaws, and one of the most popular quality assurance methods in the metal industry. If you work or take an interest in metal manufacturing, you should know that MPI :

Interesting facts about MPT

 

  1. Save Lives: 

MPI is a fairly simple process involves sending a magnetic field metal structure. Any metal object that is magnetized will be surrounded by an invisible magnetic field. If there is a defect – such as a crack or a hole in or on the surface of the metal object – the defect will cause a disruption in the magnetic field. Welders can thus detect and fix the damage that is too small can’t see with eyes.  Such damage can quickly compromise the metal in high-stress situations, which can be life-threatening when it occurs on cars, planes, military equipment, and other devices. Thanks to MPI, however, manufacturers can fix or scrap weak metal before it goes into service. This likely saves thousands of lives all over the world.

  1. Lean On UV Rays:

Though we often hear about UV rays as an environmental and public health threat, UV light is a metal inspector’s best friend. Inspectors have to detect fluorescent particles during MPI, but such particles are not visible in white light. When exposed to UV rays, these particles begin to glow, allowing inspectors to identify them with ease. UV light is available in different intensities depending on the specific particles. Magnetic particle testing lights rely entirely on UV-A rays, which do not harm eyes and skin.

  1. Cleanliness Vital: 

When inspectors perform MPI, cleanliness really is close to godliness. For all the sophisticated equipment, metals and material inspections can be performed correctly only when the product being inspected in its original condition or clean and fresh. It is particularly important to remove paint, grease, and oil, as these substances trap ferrous particles and prevent them from moving to weak parts of the metal. This produces false positives, causing welders and manufacturers to use metals that are not safe. Magnetic particle testing experts are thus urging their colleagues to better clean the metal prior to inspection.

magnetic particle testing

  1. Is Effective:

MPI is currently the most common form of testing to detect surface and subsurface metal flaws in developed countries like the United States and Europe and has been so for more than half a century. The use of magnetic particle testing is growing in India, China, and other emerging economies, where it provides a convenient and inexpensive way to test metal. Those who specialize in MPI and companies that make the technology will thus have increasing opportunities in many countries.

FutureNDT provides NDT Inspection services and certification courses, and trains candidates as per industrial standards to fulfill the requirements of the companies.


A Brief Introduction to Non Destructive Testing

Although history doesn’t give a particular beginning date for non-destructive testing, it was started several years ago.

During Roman times flour and oil were used to examine cracks in marble slabs. for hundreds of years, blacksmiths used sonic NDT once paying attention to the ring of various metals as they were being beat into shape; a way conjointly utilized by early bell manufacturers.

The primary recorded use of NDT was in 1868, using magnetic characteristics of a compass once by a scientist Englishman S.H. Sax to find cracks in gun barrels.

NDT History and Methods

X-Ray Testing:

X-Ray testing was the first NDT method used in industrial application. German scientist Wilhelm Conrad Rontgen discovered X-rays in 1895 with cathode rays experiment. This invention brought him First Ever Noble Prize. He described various uses of X-rays including possible flaw detection in his first article.

Industry failed to utilize this invention at the time, however medicine did it, thus X-Rays were primarily used to develop medical equipment. In the year 1930 Scientist Richard Seifert developed higher energy medical equipment expanding its use with other application then the industrial applications came into existence

Magnetic Particle Testing (MPT):

History of Non destructive testing

Magnetic particle crack detection was implemented even earlier than X-ray testing by Englishman S. M. Saxby that we mentioned already. But in 1917, William Hoke, an American scientist also tied to detect cracks in gun barrels using magnetic inductions.Real industrial application came in 1929 by Alfred Victor de Forest and Foster Baird Doane, who formed the first manufacturing company namely “Magnaflux” to produce NDT products.

Liquid Penetrant Testing (LPT)

According to NDT History, Oil and Whiting technique is one of the first methods of NDT, came into use within the half of the nineteenth century. Now we are calling it as Liquid Penetrant Testing (LPT). Initially this method was used by Railroad industry to increase the visibility of the defect  not typically seen with naked eye.

Ultrasonic Testing (UT)

Ultrasonic testing is the present NDT technique to come into industrial use.  James Prescott discovered Ultrasound in the year 184, later in 1880 by Curie and his brother Paul Jacques.

The first “industrial” application was recommended following the tragic sinking of the Titanic. In France Chilowski and Langevin started their development to detect submarines by ultrasound during World War I. In 1929, a Russian named Sokolov proposed the use of ultrasound for testing castings.

History of Non destructive testing

NDT Following World War II:

NDT began to be recognized as an independent technology during WWII, partly through the founding of The American Industrial Radium and X-ray Society in 1941 – known today as ASNT.

The uses of visual aids like mirrors, telescopes, and rigid borescopes (at times stated as endoscopes), as well as other measuring devices enlarged into and different industrial fields.

Water-washable penetrants refined well after 1950’s and wet developers originated during World War 2.

The benefits of MPT were accomplished throughout the war, and within the years following, vital developments and refinements contributed to its enhanced use and distended applications.

Radiographic testing also saw much significant innovation after the war.

NDT has come a long way from the early years,  those involved with NDT today should appreciate the significant improvements to this technology made possible through the innovative equipment at our disposal.


Welding is extensively used in all industrial components. Despite the best care taken during design, fabrication and inspection, many of the welded components fail especially at the weld and heat affected zones, drastically influencing the performance reliability and component availability. Majority of the failures are attributed to improper design of weld joint, selection of base materials and filler materials, welding processes, residual stress, inspection procedures and operating parameters. Non destructive testing (NDT) is the best way to minimise the failures of welded components to ensure that no unacceptable defects are present. Variety of NDT techniques exits and nearly every form of energy is used in NDT field to device methods for detection and evaluation of nearly all kinds of defects, be they surface or internal. While a few basic NDT methods such as penetrant, ultrasonic, radiography, visual testing are sufficient and routinely employed for the inspection of welds, use of advanced NDT techniques is resorted to when high sensitivity detection and quantitative characterisation of harmful defects is envisaged. Often, signal and image processing methods are adopted to meet these objectives.

NDT Advancements in Field of Welds

NDT advancements in the field of Welds

ACOUSTIC EMISSION TECHNIQUE

Acoustic Emission Technique (AET) is an important NDT technique. Its origination lies in the phenomenon of rapid release of energy within a component in the form of a transient elastic wave resulting from dynamic changes like deformation, crack initiation and propagation, leakage etc. It is a real time technique which can detect initiation and growth of cracks, plastic deformation, fatigue failure, leaks etc. AET is used during hydro testing of as-fabricated welded vessels and also in service during their hydro testing. AET is also used for on-line inspection of welded vessels and pipe lines for monitoring their structural integrity. In addition to this, of late AET is being considered for on-line weld monitoring during fabrication for simultaneous detection of defects as the welding progresses. The defects that can be detected, located and quantitatively evaluated by AE monitoring during welding are:

(1) Weld cracking associated with phase transformation,

(2) Nucleation and growth of cracks during welding and subsequent cooling e.g., delayed cracking,

(3) Porosity and slag inclusions,

(4) Micro fissuring,

(5) Hot and cold cracking and

(6) Reheat cracks.

Once weld defects are located, they are further probed using other NDT techniques for in-depth analysis. Therefore, in-process AE monitoring can be used both as an examination method and also as a means for providing feedback control.

ALTERNATING CURRENT POTENTIAL DROP TECHNIQUES

Ultrasonic and alternating current potential drop (ACPD) methods are the only two established NDT techniques used for measuring crack depth in welds. Unlike ultrasonic inspection, which is used for both detection and sizing, ACPD is used almost exclusively for crack sizing. The ACPD method is only applicable to surface breaking cracks and requires electrical contact with the specimen. The surface current introduced into the specimen by the ACPD technique induces a magnetic field in free space above the specimen surface. Mapping of the perturbation of this magnetic field provides an alternative means of measuring crack depth and crack length without the requirement for a contacting probe. This technique is also termed as alternating magnetic field measurement (ACFM). ACFM offers the capability of both detection and sizing of surface breaking defects without the need for calibration and without the requirement for cleaning to the base metal. This technique is finding increasing application, particularly in weld inspection in offshore platforms.

INFRARED THERMOGRAPHY (IRT) TECHNIQUE :

Measurements for this NDE technique are derived from changes in thermal resistance that arises in the flow of heat through the components. These changes can be detected by inferred cameras that are sensitive to surface temperature differences of less than 0.1 degrees Celsius. Precisely, IRT let one “see” heat . It is non-contact and fairly simple and it offers speed and high resolution plus the advantage of full-field imaging. IRT is also capable of providing very detailed images of situations invisible to the naked eye. By taking a thermograph of site electrical panels, thermographers develop and read a “heat picture” which reveals components that are overloaded or may become faulty. Unlike normal component operating conditions, faulty components exhibit readily detectable temperature increases over the ambient temperature profile. IRT verifies that electrical connections are properly made and maintained. IRT also detects hot spots that might be overlooked by visual inspections. IRT can be used to characterize defects in welds and voids in materials such as gaps in adhesive layers or air bubbles as these they have a much higher thermal resistance than the surrounding material. IRT has been used for the on-line monitoring of weld pools as part of intelligent processing of materials.

ndt advancements in the field of welds

X-RAY DIFFRACTION (XRD) TECHNIQUE FOR RESIDUAL STRESSES :

Residual stresses are introduced in industrial components during welding process and also during the service life of the welded component due to loading conditions. For example, the stresses are introduced during welding process due to non uniform heat distribution taking place during the welding process. Several nondestructive techniques are presently available for the residual stress measurements.

Some of these techniques include:

(i) Ultrasonic Testing.

(ii) X-Ray Diffraction (XRD),

(iii) Acoustic Barkhausen Noise (ABN) and

(IV) Magnetic Barkhausen Noise (MBN).

Additionally, semi-destructive hole-drilling strain gauge technique is also employed for measurement of residual stresses.  MBN and ABN techniques are based on Barkhausen effect and applicable only to ferromagnetic metals and alloys. Barkhausen effect takes place when a magnetic field is swept in the material along a hysteresis loop. MBN is due to irreversible change in magnetic domain movements during hysteresis and ABN is due to elastic deformation associated with magnetic domain rotation during irreversible changes in magnetization. MBN signals can be acquired by sensor coil or by Hall type probe and ABN signals are acquired by piezoelectric transducers. Both MBN and ABN signals are strong functions of stress condition and hence stresses can be assessed by analysing the MBN and ABN signals.

XRD technique measures the change in the inter planar spacing of the lattice in the presence of stresses in a material. It is well known that peak intensity of diffracted X-ray beam occurs when Bragg’s law is satisfied. In the presence of elastic macro-stresses, there is shift in the diffraction peakpositions. The magnitude of the shift gives a measure of the stress and the direction of the shift depends on the nature of the stresses i.e. whether they are tensile or compressive.XRD technique has been used to measure the residual stresses before and after post weld heat treatment (PWHT).

Advances in NDT techniques for inspection of welds for detection and quantitative Characterisation of defects, residual stresses and micro structural variations are highlighted. Since the probing medium and the interactions are different, capabilities and limitations of various NDT techniques for defect detection and evaluation differ. Hence, selection of NDT technique for a specific inspection application is very important. Today NDT is matured enough to take up nearly all kinds of challenging jobs in welded structures as regards to quick detection and sizing of harmful defects, almost as and when they form or before they grow to critical sizes causing Catastrophic  failure of components.


In the modern world need for proficient person to perform NDT(Non Destructive Testing) is eminent in all industries.  NDT personnel who have the proper training, have passed written and practical examinations, and have enough experience to properly perform NDT tasks using the applicable test method or technique are eligible to determine the competency of any system. If anyone is said to be “Qualified” must satisfy all these three requirements. Then that person can be “Certified”.

NDT Certification And Levels of Qualification

LEvel of Qualification ASNT

Most NDT certification programs have three levels of qualification: Level I, Level II and Level III

Level I:

An NDT Level I individual should be qualified to properly perform specific calibrations, specific NDT and specific evaluations for acceptance or rejection determinations according to written instructions and to record results. The NDT Level I should receive the necessary instruction and supervision from a certified NDT Level II or III individual.

Level II:

An NDT Level II individual should be qualified to set up and calibrate equipment and to interpret and evaluate results with respect to applicable codes, standards and specifications. The NDT Level II should be thoroughly familiar with the scope and limitations of the methods for which he is qualified and should exercise assigned responsibility for on-the-job training and guidance of trainees and NDT Level I personnel. The NDT Level II should be able to organize and report the results of NDT tests.

Level III:

An NDT Level III individual should be capable of developing, qualifying and approving procedures, establishing and approving techniques, interpreting codes, standards, specifications and procedures, as well as designating the particular NDT methods, techniques and procedures to be used. The NDT Level III should be responsible for the NDT operations for which he is qualified and assigned and should be capable of interpreting and evaluating results in terms of existing codes, standards and specifications. The NDT Level III should have sufficient practical background in applicable materials, fabrication and product technology to establish techniques and to assist in establishing acceptance criteria when none are otherwise available. The NDT Level III should have general familiarity with other appropriate NDT methods, as demonstrated by an ASNT Level III Basic examination or other means. The NDT Level III, in the methods in which he is certified, should be capable of training and examining NDT Level I and II personnel for certification in those methods.

NDT Instructor: The term “NDT Instructor” is used in ASNT Standard for Qualification and Certification of Nondestructive Testing Personnel, to describe an individual with the skills and knowledge to plan, organize and present classroom, laboratory, demonstration or on-the-job NDT instruction, training or education programs.

NDT Certification Systems:

There are multiple NDT certification systems worldwide, but they can generally be divided into two main types: “employer-based” and “central” certification systems.

NDT certification

Employer-based certification systems are systems in which the employers are responsible for the administration of the training and the qualification examinations of their own employees, as well as the documentation of the required training, examinations and experience in accordance with an employer-based standard or recommended practice. Most employer-based systems do allow the employer to accept training and examination services provided by outside agencies provided it is properly documented and the employer has determined that the content of those services meet their own company requirements as described in the employer’s Written Practice.

Central certification systems are systems in which the qualification examinations are administered by an independent third-party certification body based on a central certification standard. To be eligible to sit for these examinations, prospective candidates must provide acceptable documentation of their training and experience to the certification body. Upon successful completion of the third-party examinations, the certification body will issue a certificate attesting to the fact that the named certificate holder has met the requirements and passed the examinations described in the third-party certification system. The employer can then choose to accept the third-party certificate(s) as proof of qualification. As with employer-based systems, the employer has the ultimate responsibility to certify (authorize) the certificate holder to perform NDT tasks.