Industry forms the backbone of any economy. Various industries are working on a global level in various fields of work. These include, but are not limited to:

• Marine
• Civil
• Pipelines
• Chemical

Different NDE Methods can be effectively used for inspection during the manufacturing, in-service and shut-down stages of work. These include:

Ultrasonic Testing (UT) involves volumetric testing of various metallic and non-metallic components, using Ultrasonic sound waves. UT is able to determine various surface and subsurface discontinuities. It is also able to detect certain defects that cannot be determined by RT, such as laminations. It involves sending ultrasonic waves through the specimen being tested, generating an echo, and determining the location, size and orientation of any discontinuity based on the time required for the detection of the echo. It is a portable means of detection. It may not, however, provide a permanent record of the test.

UT can be further divided into the following methods: conventional UT, Phased Array Ultrasonic Testing (PAUT), Time of Flight Diffraction (TOFD). It is also possible to carry out oxide layer measurement using UT. UT can also be divided into contact UT and immersion UT.

Thickness measurement and defect detection in metals, plastics, ceramics and composites. It can also be used for wood and paper products, but is not accurate.

Liquid Penetrant Testing (PT) involves detection of surface discontinuities only. It is the preferred method of testing for detection of surface discontinuities, as against RT or UT. PT involves cleaning the component to be examined thoroughly, applying the penetrant, letting the penetrant soak for an amount of time known as dwell time, cleaning the excess penetrant, applying the developer, and looking at any indications that may arise. PT works on the principle of capillary action, and can be done for all types of non-porous materials. PT cannot be done on porous materials such as ceramics.

PT can be further divided into different methods, depending upon the type of penetrant and cleaning agent used. Based on type of penetrant, they are: Fluorescent, colour contrast (visible). Based on cleaning agent, they are: Solvent Removable, Post-Emulsifiable Hydrophilic, Post-Emulsifiable Lipophilic, Water Washable.

Used on any non-porous materials for detection of surface-breaking discontinuities. Materials include glass, all metals, ceramics, plastic, rubber etc. as long as the material is not porous and has good surface finish.

Quite often, utility pipes and electric cables are buried underground for transfer of liquid or electricity over long distances, such as cross-country. Under such circumstances, it may be difficult to determine the exact location of the pipes or cables, especially if they are buried deep under the ground. Not knowing exact locations of such pipes and cables is an issue when there is a leak in the pipe or a break or current leak in the cable. Determination of pipe and cable location is also important in situations where excavations are carried out.

Detection of the location of buried pipes and cables makes use of a high-performance multi-frequency locating equipment. Various modes are available, such as Power Mode, Radio Mode, Transmitter Mode and All Scan Mode. Proper modes can be selected and the equipment scanned over the ground. It will detect any pipes or cables that are present underneath over a wide range of depths.

Detection of exact location of electric cables and utility pipes for maintenance and repair, such as pipe leaks, cable breaks, cable groundings etc. Also used for determination of exact location of pipes and cables prior to carrying out excavations.

Any metallic item has a tendency to corrode – go back to its original state. Such corrosion can proceed at a rapid rate once it starts. The best way to prevent this is to apply protective coatings of various types such as paint, epoxy, varnish etc. The effectiveness of the coating depends upon the type and thickness of the coating applied.

Coating thickness measurement involves determination of the thickness of non-metallic coatings on metallic substrates. The metallic substrates can be either ferromagnetic or electrically conductive. The measurement of coating thickness can then be analysed to determine whether the correct thickness has been applied, and whether any changes need to be made.

 Determination of thickness of any non-metallic coating on any metallic substrate.

Helium Leak Testing (LT), involves use of Helium Gas to check for any small leaks or porosities in components. Usually, LT is carried out for pressure vessels and other critical components that contain liquids or gases for storage or use. Helium, being the lightest inert gas, can easily be handled, and be detected in cases of leaks.

LT can be further divided into different methods. They are Vacuum Test (sniffer), Pressure Test (tracer), Bubble Test etc. The testing involves either placing the component inside a vacuum chamber, pressurizing it with helium gas and checking for gas leakage outside the component (inside the chamber). Conversely, it can also involve pressurizing the component, and measuring the pressure drop over time. A detector can be placed so as to detect any leakage of gas. Bubble tests are similar to those used for detecting punctures in vehicle tires, in the sense that they consist of pressurizing the components, applying soap solutions at the seams, and determining any bubbles that may be formed.

Production and manufacturing industries such as refrigeration and air conditioning, automotive parts, aerosols, packaging, valves, steam products, gas bottles,  pressure vessels, flange connections, welded seams, seals and heat exchangers.

Spark Optical Emission Spectroscopy (SOES) is a special type of PMI testing, whereby the carbon content of a sample can also be detected, along with the presence of other elements.

SOES involves applying electrical energy in the form of a spark generated between an electrode and a metal sample. Vapourized atoms are brought into a high energy state within a discharge plasma. These atoms create a unique spectrum specific to each element. The light generated by the discharge is a collection of the spectral lines generated by the elements in the sample. This light is split to extract the emission spectrum of the target elements. The intensity of each spectrum depends upon the concentration of each element in the sample. Detectors measure the intensities of these spectrum to evaluate the composition of the sample.

Identification of materials used, alloy content, determining material conformity to requirements and standards. SOES has the added benefit of being able to determine Carbon content accurately.

Tank interiors, chemical vessels, buried structures and corrosive environments.

Internal Rotary Inspection System (IRIS) is a special type of Ultrasonic Testing technique used for inspection of pipes and tubes. Water is used as a couplant. The tube to be inspected is flooded with water. A transducer generates an electronic pulse parallel to the axis of the tube being tested. A rotating mirror directs the ultrasonic wave into the tube wall. The mirror is powered by a water-driven turbine, with the water being pumped into the tube for flooding.

Parts of the waves are reflected by the ID and OD. Knowing the velocity of ultrasonic waves in the material of the tubes, the wall thickness can be calculated by determining the time required for both waves to be reflected from the corresponding walls. As the probe is pulled, the rotating mirror develops a helical scan path. IRIS can be used for boiler, shell-and-tube and fin-fan heat exchangers.

Metal pipes and tubes in boilers, heat exchangers and fin-fan tubes. It can also be used as a backup for remote field examination.

Computerized (CR) and Digital (DR) are modern types of Radiographic Testing. CR makes the use of a Phosphor Imaging Plate to obtain a digital image. CR uses a cassette based system like conventional film radiography, and can be considered to be a bridge between conventional film radiography and digital radiography. Certain advantages include low initial investment and the availability of various sizes enabling flexibility.

DR uses a Digital X-ray detector to automatically acquire images and transfer them to a computer for viewing. It is capable of fixed or mobile use. Certain advantages include faster image capture, better quality images and high volume capacity.

Useful where digital images of components are required, especially to save storage space and ease of handling. Also useful where ease of processing and viewing is necessary.

Pre-welding heat treatment involves heating the joints to be welded to specified temperatures before welding can be carried out. Likewise, post-welding heat treatment involves heating the weldment to specified temperatures to allow for gradual cooling and minimization of stresses. Stress relieving is based on the same principle, to relieve any external and internal inherent stresses before a component is put into service

Heat treatment and stress relieving can be carried out in a variety of ways. Electrical Resistance Treatment makes use of the principle that as current is passed through a metal, the resistance of the metal to the current flow causes an increase in its temperature. This increase further causes an increase in resistance, thereby requiring more current for penetration. Various temperatures can be achieved by gradually increasing the currents and based on the material being treated. Electrical Resistance Treatment can be done by using 80V, which is safer but more expensive, or 220V, which is comparatively cheaper. It consists of electrical coils that are wound around the parts to be treated. Current is passed through the coils, which causes the corresponding increase in temperature.

Another type of treatment is the Induction Treatment. This is based upon mutual induction, where electric currents are induced in metals via induction coils. These induced currents cause an increase in temperature.

A third type of heat treatment makes use of high velocity, oil-fired burners. These burners can be placed on the outside or inside the components, and fired at high velocities. The flame and resultant exhaust gases cause heating of the component, thereby enabling heat treatment. Damper and flow control can be used to ensure even and proper heating of the entire components.

Pre- and post-welding treatment for control of properties, stresses and distortion. Also used for stress relieving after welding to reduce internal stresses.

Welding inspection involves inspection of various aspects of a weld. Inspection can be carried out before, during and after the completion of the weld. Such inspections include joint preparation, procedure verification, settings, methods used, inter-pass inspection, depth of penetration, inter-pass and base metal fusion and so on.

Welding inspection can be carried out visually, as well as using NDE techniques of RT and UT. Welding inspection is usually carried out based on procedures and methods as per the requirements of various standards such as ISO, ASME and AWS.

Examination of welds and weld quality to ensure welds conform to required standards. Inspection of weld before, during and after welding process is completed, so as to ensure properties and quality of weld is maintained throughout.

Fugitive Emissions are emissions of gases or vapours from pressurized equipment due to leaks, and other unintended or irregular leaks of gases, mostly from industrial activities. Along with the economic costs, fugitive emissions contribute to air pollution and also pose health and safety hazards.

Fugitive Emission testing is a special type of Helium Leak testing that is carried out for valves, flanges, gaskets and fittings. These components can be tested at different temperatures or over a range of temperatures, with helium or methane gas, using the sniffer or vacuum method. Any leaks present at different temperatures can be detected.

Valves and associated components such as gaskets, seats, fittings and flanges, especially those used in critical applications where any leaks may be detrimental.