Testing Services

Service Details:

Infrared Thermography (IR) involves temperature and gradient detection of components, mostly in the in-service condition. Temperatures of inaccessible and in-service components can be easily and conveniently checked. It also provides a colour-coded gradient indication of the temperatures of various locations of the components, thereby enabling detection of hot spots and high or low temperature areas.

IR involves the use of a temperature gun that sends out infrared rays. These rays are reflected back from the component at frequencies that depend upon the temperatures of the respective areas. These reflected waves are depicted in the form of areas of various colours depending on the temperatures, enabling temperature detection of the component remotely.

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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.

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Magnetic Particle Testing (MT) involves detection of surface and subsurface (upto 5 mm deep) defects in ferromagnetic materials. MT involves magnetization of ferromagnetic components. Once the component is magnetized, magnetic particles can be sprinkled on the component. They align themselves along any defects that may be present on the surface. An important thing to note is that, unless heat treatment is to be carried out after MT, or if any machining work is to be done, the parts must be thoroughly demagnetized. Also, note that testing has to be carried out in two (2) directions 90 o apart so as to have complete coverage of the specimen. MT can be further divided into the following methods: Visible and Fluorescent.

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Eddy Current (ET) testing involves use of Eddy Currents to determine flaws in electrically conductive materials. When a coil carrying a current is brought in proximity to a conductive material, eddy currents are set up in the material due to electromagnetic induction. As the coil approaches the component, the magnitude of eddy currents generated in the component increases. Similarly, as the coil moves away, the magnitude reduces. Moving the coil along the component being tested causes eddy currents to be induced along the component. Any defects that may be present, cause the magnitude of eddy currents generated to vary. This variation in magnitude can be checked in order to determine the type, size and orientation of the defects. Eddy currents are developed in a direction perpendicular to the direction of the coil.

Different types of probes can be used for different applications. These include straight probes or surface probes, which are used to detect flat surfaces, or components of geometrical shapes, encircling probes, which consist of coils that completely encircle the component, central conductors, which consists of probes that are inserted inside the tubes, and so on. Each of these probes can be used for a variety of applications, provided sufficient fill factors are achieved.

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Remote Field Eddy-Current Testing (RFET) is a special type of Eddy Current Testing that uses low-frequency Alternating Current to determine both internal and external defects on pipes and tubes with equal sensitivity. It is, however, unable to distinguish between the two.

An RFET probe consists of an exciter or transmitter coil that sends a signal to the detector or receiver coil. The exciter coil is pumped with an AC current and emits a magnetic field. The field travels outwards from the exciter coil, through the pipe wall, and along the pipe. The detector is placed inside the pipe two to three pipe diameters away from the exciter and detects the magnetic field that has travelled back in from the outside of the pipe wall (for a total of two through-wall transits). In areas of metal loss, the field arrives at the detector with a faster travel time (greater phase) and greater signal strength (amplitude) due to the reduced path through the steel. Hence the dominant mechanism of RFT is through-transmission.

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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.

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Hardness Testing involves measurement of surface hardness of a component. Surface hardness is the resistance to surface penetration. Hardness of a component depends upon the material composition, process it has undergone and heat treatment.

Hardness testing can be carried out to measure the Brinell and Rockwell hardness numbers. Brinell hardness testing is used for materials that are too coarse or too rough for other methods. A predetermined test load is applied to a carbide ball of a known diameter for a predetermined period of time. The size of the indentation is measured, which is compared with a Brinell chart to get the corresponding Brinell Hardness number (BHN). Rockwell hardness testing is used for almost all materials, except where too much variation may be introduced or size and shape of the component prevents the use. A pre-load is applied to the sample using a diamond or ball indenter. This breaks through any surface film that may be present. A baseline indentation depth is then measured. A main load is then applied, and held for a predetermined dwell time before being released. The pre-load is continued to be held for a further dwell time, and the depth of the indentation is measured again. The difference between the two depths is then converted to the Rockwell Hardness number (HR). The load and indenter are then removed.


Typical Applications

• To ensure surface hardness of given materials/components is as per requirements, so as to ensure required properties are achieved and that proper heat treatment is carried out. Can also be used to determine future heat treatment and processes that may need to be carried out.

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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.

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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.

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Holidays are areas or patches on coated pipelines and components where the coating has been removed due to some reason. Due to the lack of coating, anodic area are formed at those places. This leads to accelerated corrosion and can result in complete loss of material and formation of holes. These holidays may be microscopic in nature, thereby making them difficult and sometimes impossible to spot by the naked eyes. Holidays include discontinuities such as pinholes and voids.

Holiday test, also known as Continuity test, involves checking of an electric circuit to see if current flows to complete the circuit. If an electric flow is detected, the area is termed as conductive, indicating the presence of discontinuities. Holiday tests are performed by the use of holiday detectors, which is an electrical device. Testing can either be a low voltage holiday test, which is carried out for coating thicknesses less than 500 microns, or a high voltage holiday test, which is carried out for thicker coatings. Holiday testing is commonly used in offshore industries and other areas where piping and structures are coated with non-conductive coatings.

Ultrasonic Flow Measurement involves the use of ultrasonic transducers. The flow meter can measure the average velocity along the path of an emitted beam of ultrasound, by averaging the difference in measured transit time between the pulses of ultrasound propagating into and against the direction of the flow or by measuring the frequency shift from the Doppler effect. It is used to analyse the volume of liquid flow.