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 (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.


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.


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


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.

What is PG Diploma In Quality and Industrial Engineering ?

Post Graduate Diploma in Quality and Industrial Engineering is the most advanced training Program introducing first time in India is a predominant and career set program enriched with high technical concepts which are especially using in many prominent companies like Jindal, Reliance, L&T ect, for all M.Tech and B.Tech  pass out candidates to get a lucrative jobs and remarkable career  in core engineering sector. After successful completion of Training, candidates are eligible to get placed in various core field companies like Refinery, petrochemical, Oil & Gas Industries, Power Plant Maintenance and Operation, Aerospace, Fabrication, Ship Building companies, Marine Companies, Manufacturing Industries etc.

post graduate diploma in quality and industrial engineering

The curriculum was designed by  industrial experts and manager of companies and added many essential concepts  which includes advanced technologies like Metallurgy Process, QA/QC Welding, Isometric Drawings, Conventional NDT(non destructive testing), Advanced NDT, Power Plant Maintenance, Refinery, Petrochemical, Oil & Gas Industries, Aerospace, Fabrication, Ship Building companies Maintenance, Application of NDT in these Industries and Codes & Standards. The main aspiration of the program is to train the candidates as per our client’s requirement & place them in prestigious companies all over the globe.


  • Quality and Industrial Engineering program content is designed by Industrial Experts and covers all topics like Metallurgy Process, QA/QC Welding, Isometric Drawings, Conventional NDT, Advanced NDT, Power Plant Maintenance, Refinery, Petrochemical, Oil & Gas Industries, Aerospace, Fabrication, Ship Building companies Maintenance and Application of NDT in these Industries and Codes & Standards.
  • Practical Training on PAUT, ECT, TKY Joints, Conventional NDT & Welding Modules on various Industrial Applications.
  • Practicals as per ASNT, ASTM, ASME, BINDT and CEA Standards.
  • Simulator Training of 120 MW Thermal Power Plants.
  • Audio & Video modules covering critical course topics.
  • Set of 20 books covering all aspects of course curriculum.
  • Certification on completion of course recognized by CEA, ASNT.
  • E-Library covering additional topics.
  • Library Facility: A set of all industry books, NDT, Advanced NDT, API, CSWIP, AWS CWI, NACE, BINDT, NPTI, Industrial Procedure Books & Other Authors, and Publications will be available in Institute.
  • On-Site Training (Internships) in Petrochemical. Refinery, Oil & Gas Industries, Power Plants.


  • Certificate from FUTURE NDT (Corporate Partner of ASNT).
  • QA/QC Certificate (Valuated by CSWIP / AWS-CWI Inspector).
  • PG Diploma in Thermal Power Plant Certificate (Recognized by CEA).
  • T, K, Y- Joints Certificate on Plates & Pipes (Valuated by TKY- UT Expert & Recognized by ASNT).
  • PAUT Certificate (Recognized by ASNT).
  • Petrochemical / Refinery / Oil & Gas Maintenance Certificate (Valuated by Industry Expert).
  • AUTO CAD Certificate (For Isometric Drawings).
  • Course Designed & Delivered by Industrial Experts.
  • Practical Course with Onsite Training in Top Companies.
  • High Paid Salaries in India & Abroad.
  • Live projects under Guidance of Industrial Experts.
  • Digital Library with Books, Audio & Video Modules.
  • Pay Fees in Easy EMI’S.
  • Industrial Visits for every Method with Case Studies.

Why should you choose Future NDT ?

we Future NDT is a Leading career development center conducting personnel training and certification programs and is a platform wherein individual members & organizations can interact and share their services. This is the only company introducing this outstanding Post Graduate program in Quality and Industrial Engineering to fulfill the clients requirements.

FUTURE NDT is an ISO 9001:2015 certified & MSME Registered NDT institute for its education quality management. FUTURE NDT is also a corporate partner of ASNT (American Society of Non Destructive Testing). Our courses are industry specific and aim to provide skill sets that are immediately relevant to the participant. Classroom activities are supplemented by practice sessions and projects, aided by our World Class Course Material. Certificate of Course Completion along with Performance Certificate is provided to all participants from FUTURE NDT which was recognized by American Society of Non-Destructive Testing and along with PG Diploma certification in Thermal Power Plant issued by Synergem.

brochure launch

FUTURE NDT is also an NDT & THIRD PARTY INSPECTION SERVICES company running its projects allover India with association of IIS NDT and Allied Services Pvt Ltd which was established in the year 1994 in Mumbai. We are jointly doing NDT services for prestigious companies like SBC, L & T MHI Boilers, L & T Hydro Carbons, ONGC, Reliance Petroleum, Esaar Steels, BHEL, IOCL etc. We have worked for prestigious societies like American Bureau Of Shipping, Davy Power Gas, Det Norske Veritas, Engineers India Limited, Humphery & Glasgow, Indian Boiler Regulation Act, Indian Register Of Shipping, Lloyds Register Of Shipping, Nuclear Power Corporation, Sacardande Engineers, Societe Generale De Surveillance.

So, have you made your decision yet? If you are looking for a bright career opportunity in core engineering sector , Post graduate Diploma in Quality and Industrial Engineering  is where your search ends.

In thermal cycle of Post Weld Heat Treatment, the weld parts are heated in furnace often at lower temperature range (where material is not liable to phase change), followed by cooling in furnace. Well it’s not that simple. In PWHT heating and cooling is carried out, in controlled mechanized way with specific heating and cooling rates. For this, a number of thermocouples are employed for the monitoring of cooling and heating process. There are four essential elements that must be fulfilled in order to carry out effective post weld heat treatment.

Heating Rate
Soak Temperature
Soak Time
Cooling Rate

1. Heating Rate
The weld material is allowed to heat with controlled heating rate because on the detrimental side if the heating rate is not monitored, the material will prone to stresses due to high temperature gradient. In order to prevent any high stress level and consequent cracking, it is a recommended practice to heat steel weld parts (for example Carbon Manganese Steels) with heating rate range from 60 – 200 degree Celsius per hour. Normally the monitoring of heating rate is started above three hundred (300) degree Celsius because below this temperature most steels have adequate strength to avoid distortion which can be caused by intensification of stresses. Moreover it is to be noted that heating rate is primarily adjusted according to the weld thickness.


2. Soak Temperature
It is a temperature range where the heated weld part is held for some time, to effectively reduce the stress level. Soak Temperature is set according to the type of material and normally ranges from six hundred (600) to seven hundred and sixty (760) degree Celsius.

3. Soak Time
It is a specific time during which the material is allowed to heat at sock temperature range, in order to provide uniform heat throughout the weld thickness. Most important question here is how to predict the time frame for soaking, to homogenize the heat throughout the material thickness. Well suitable soak time is essential for the reduction of undesirable stress levels and it is determined depending on the joint thickness. Normally the codes call for soak time, one hour 1h per 20-25mm thickness.

4. Cooling Rate
In like manner, cooling rate must also be monitored carefully, in order to avoid higher stress levels and consequent cracking due to large temperature gradients. After giving particular soak time and temperature the material is cooled down in furnace with the regulation of cooling rate by thermocouples. It gives a complete thermal cycle from heating to cooling. Again the monitoring is required from soak temperature to three hundred (300) degree Celsius. Below three hundred degree Celsius the thermally treated weld material has enough strength to countenance the temperature gradients.

PWHT is most common practice in steel fabrication industries and normally carried out using oil or gas burning furnaces. The fuel must be clean from contaminants that may harm the weld job. Type of steel and service applications are the major considerations for applying post weld heat treatment because there are some exceptional applications and grade of materials where PWHT may induce detrimental effects. However its intended use is, to relieve stresses in steel welding that is why it’s commonly referred to as Stress Relieving.

Non-destructive testing( NDT ) is defined as test which can be performed on a material, components and assembly without damaging them and without affecting its ultimate serviceability.Mining industry is one of the vital sector where NDT is extensively utilised right from the row material selection to the finish product to assure product reliability and further for service inspection for operational reliability. The prime objective of the NDT techniques is to ensure safety by detection of such cracks attributed to the manufacturing inefficiency or develop during mining operations.

NDT Applications in Mining Industry

There are four techniques in particular which are being used to evaluate cage suspension gear, haulage items, head gear pulley shafts etc. are as follows:

  1. Visual inspection.
  2. Magnetic particle testing.
  3. Fluorescent crack detection.
  4. Ultrasonic testing.

Visual Inspection:
This technique is conducted visually by naked eyes or with the help of magnifying glass for detecting any visible surface defects like material loss, scratches, indentation and wear due to fatigue or visible cracks developed due to poor manufacturing processes. Visual inspection are needed for every mining components before going for any other NDT techniques and subsequently putting it into service.

Magnetic Particle testing:
Magnetic particle testing is nondestructive method for detecting surface imperfections in ferromagnetic material.
The mining components are of ferrous material and ferromagnetic in nature and thus this method is best suited for revealing the fine surface and subsurface flaws. Magnetic detection in ferromagnetic materials depends on the distortion of the magnetic field in a magnetized mass of metal by the defect or the difference in the magnetic properties between the defect and the main body . This distortion of difference is revealed by sprinkling the components with dry magnetic powder or spraying with a liquid containing magnetic particles of Magnetic Iron Oxide in suspension.

Fluorescent Crack Detection:
Fluorescent crack detection technique has an added advantage over magnetic particle crack detection that there is no directional sensitivity to be considered. In this method components are tested in a fluid containing fluorescent substance and penetrates into the surface defects which are revealed by a short wave radiation ultraviolet lamp. The ultraviolet light is produced by a high intensity mercury arc or mercury vapour discharge lamp.

Ultrasonic testing:
This technique is used to reveal the internal flaw up to the depth of more than 1 mm from the outer surface. The flaw detector is based on the principle that a beam of ultrasonic frequency transmitted into a solid is reflected by discontinuities such as cracks or cavities. The reflectogram is picked up by a receiver placed on the same face as the transmitter. A second echo from the far face of the solid will also be received after an interval of time . This pulse echo techniques allows the detection of minute defect in ferrous and non-ferrous metallic object. All cage suspension gears attachments like Friction Wedge Type Rope Cappel, Safety Hook, Distribution plate , cage shackles etc. & Haulage Rope Cappel and also Head Gear Pulley Shaft are evaluated with this technique.

applications of ndt in mining indusrty

Electromagnetic Inspection:
Evaluation and assessment of structural integrity of steel wire ropes plays an important role in mining industry. In mine hoisting system wire ropes are subjected to different degradations by virtue of its service and environmental conditions. Premature failure of wire ropes results loss in personnel as well as heavy damage to the hoisting installation causing down time. Rope condition is evaluated by nondestructive technique after one month of this installation allowing a constructional stretch and this mother data is kept as a base for assessment of this condition on subsequent NDT investigations conducted on periodic interval.The two types of flaws i.e. localised flaws due to broken wires and distributed flaws due to corrosion and corrosion pitting are evaluated by Permanent Magnet dual function wire rope tester.
Non-Destructive testing of wire rope enables early detection of wear or corrosion and development of broken wires.

Non-destructive testing is the only suitable techniques to ensure safety of mine personnel during haulage transport and mine hoisting.Accident could have been avoided by knowing the flaws and its severity in mining components detected by NDTCareful maintenance and inspection of all winding components must be followed rigorously.

Non-Destructive Testing occupied very important role in recent times in industrial applications like Aerospace, aircraft overhaul, automotive, petrochemical and gas, railway, mining, agriculture, power generation, iron, shipbuilding, steel, pipe and tube manufacturing industries etc as a powerful quality tool. Mainly in Aerospace industry in view of high quality requirements safety and stringent Airworthiness requirements. All components are inspected before they are assembled into the aircraft and then they are periodically inspected throughout their useful life.

Most of the inspections done to an aircraft are visual inspections. During heavy maintenance work, much of the interior of the aircraft is stripped out so inspectors can look for damage on the inside surface of the fuselage. Aircraft suffer many types of structural deterioration including corrosion, fatigue, fabrication defects, operation and maintenance, and unforeseen loading. In aircraft maintenance, it is critical to inspect surfaces for any damage that may exist in order to determine the extent of repair work needed, whether that occurs as the result of manufacturing or while the aircraft is in service.

Non Destructive Testing Applications in Aerospace


Non-destructive testing (NDT) is one of the quick and most economical ways to perform inspections in Scheduled maintenance and the only way to discover defects that are not visible to the naked eye.

NDT Methods Used in the Aerospace Industry

Several types of non destructive testing methods like liquid penetrant testing, ultrasonic testing, magnetic particle testing and eddy current testing are used to test airplanes.

Liquid Penetrant Testing (LPT)

To reveal the cracks on the surface of airplane, Liquid penetrant testing is one of the most commonly used method in NDT in aerospace industry.

  • “The fundamental purpose of penetrant testing is to increase the visible contrast between a discontinuity and its background,” said a report on NDT techniques used in the aerospace industry.
  • Structural damages or surface defects of aircraft materials were observed with LPT. Fluorescent penetrants are used in critical areas for more sensitive evaluation.

Ultrasonic Testing (UT)

The most common sub-surface inspection technique, ultrasonic NDT uses high-frequency sound waves to locate defects under the surface.UT has many uses in the aerospace industry including detection of:

  • Surface and subsurface defects in welds;
  • Main structural fittings of landing gear legs and engine attachments;
  • Aircraft structure joints and pylons;
  • Bolts located in critical areas;
  • Adhesive bond quality of lap joints and composite structure;
  • Thickness measurement after damage or corrosion removal


Magnetic Particle Testing (MPT)

  • In magnetic particle testing, fine particles are applied to the surface to monitor magnetic flux. If damage exists, flux “leaks” from the item’s surface, attracting particles to the area.
  • In the aircraft, MPT is conducted on engines, pumps, landing gear, gearboxes, shafts, and shock struts. It is also widely used for bolt inspection.
  • Obviously, this task requires trained professionals who are capable of performing a variety of different NDT techniques to get a complete and accurate status of the airplane.

Eddy current Testing (ECT)

In any aerospace maintenance and repair organization Eddy current testing plays an important role.

  • Eddy current testing is used in Surface Crack Detection on Aluminum alloys
  • Intersect the inner surface of holes in the component to be inspected.
  • Automated Inspection of Aircraft Wheels / Wheel Hub / Rotor Disc
  • Subsurface Corrosion Detection

There is no question that the success of the airplane industry is dependent on NDT. Without NDT, the cost of maintaining and flying in airplanes would increase dramatically, while the safety of flying would decrease. When people step into an airplane they trust that it will get them to their destination with as little turbulence as possible. NDT plays a vital role in keeping air travel one of the safest modes of transportation.