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NDT & Advanced NDT Services
Phased Array | TOFD | MFL | Eddy Current |UT | RT & More
NDT & Advanced NDT Services
Phased Array | TOFD | MFL | Eddy Current |UT | RT & More
Brochures
Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more. The Ultrasound energy is generated using Piezo Electric Principle and introduced in the part being inspected, which can propagates through the materials in the form of waves. When there is a discontinuity (such as a crack) in the wave path, part of the energy will be reflected back from the flaw surface which was received and analysed to know the nature and dimensions of the discontinuity.
Ultrasonic Inspection is a very useful and versatile NDT method. Some of the advantages of ultrasonic inspection that are often cited include:
Radiographic Testing (RT)), or industrial radiography, is a nondestructive testing (NDT) method of inspecting materials for hidden flaws by using the highly penetrating electromagnetic waves such as X rays or Gamma rays. These radiations are of short wavelength electromagnetic radiation (high energy photons) which can penetrate in to various materials.
Either an X-ray machine or a radioactive source (Ir-192, Co-60, or in rare cases Cs-137) can be used as a source of photons. Since the amount of radiation emerging from the opposite side of the material can be detected and measured, variations in this amount (or intensity) of radiation are used to determine thickness or composition of material. Conventional Radiography uses the Film as the source of recording media and advanced /Digital radiography uses advanced digital recording technology.
Ultrasonic Testing (UT)is a non-destructive testing method used for defect detection. Magnetic flux leakage is the Basic Principle used in this technique. MPI is fast and relatively easy to apply. Surface preparation is not as critical as it is for some other NDT methods.
MPI uses magnetic fields (Electromagnetic filed mostly) and small magnetic particles (i.e. iron filings) to detect flaws in components. The only requirement from an inspectability standpoint is that the component being inspected must be made of a ferromagnetic material such as iron, nickel, cobalt, or some of their alloys. Ferromagnetic materials are materials that can be magnetized to a level with an external magnetising force that will allow the inspection to be effective.
MPI uses magnetic fields (Electromagnetic filed mostly) and small magnetic particles (i.e. iron filings) to detect flaws in components. The only requirement from an inspectability standpoint is that the component being inspected must be made of a ferromagnetic material such as iron, nickel, cobalt, or some of their alloys. Ferromagnetic materials are materials that can be magnetized to a level with an external magnetising force that will allow the inspection to be effective.
Liquid Particle Testing or Dye Penetrant testing is a method that is used to reveal surface breaking flaws by bleed-out of a colored or fluorescent dye from the flaw. The technique is based on the ability of a liquid to be drawn into a "clean" surface breaking flaw by capillary action. After a period of time called the "dwell," excess surface penetrant is removed and a developer applied. This acts as a blotter. It draws the penetrant from the flaw to reveal its presence. Colored penetrants require good white light while fluorescent penetrants need to be used in darkened conditions with an ultraviolet "black light".
The advantage that a liquid penetrant inspection (LPI) is that it makes defects easier to see for the inspector. LPI produces a flaw indication that is much larger and easier for the eye to detect than the flaw itself. Many flaws are so small or narrow that they are undetectable by the unaided eye. Highly sensitive to Surface cracks and technique is applicable for all materials except Porous.
Ultrasonic thickness measurement (UTM) is a non-destructive measurement (gauging) of the local thickness of a solid element (typically made of metal, if using ultrasound testing for industrial purposes) basing on the time taken by the ultrasound wave to return to the surface. This type of measurement is typically performed with an ultrasonic thickness gauge.
UTM is frequently used to monitor metal thickness or weld quality in industrial settings. with portable UTM probes measurement can be made steel plating in sides, tanks, decks and the superstructure. They can read its thickness by simply touching the steel with the transducer.
Advantages :
Visual Inspection is a Basic NDT method to be used for each and every component before it is used for fabrication or installation or usage. It is the most common method of quality control, data acquisition, and data analysis. Visual Inspection, used in maintenance of facilities, mean inspection of equipment and structures using either or all of human senses such as vision with normal aids. Visual Inspection typically means inspection using raw human senses vision and/or any non-specialized inspection equipment.It constitutes an important aspect of practicable quality control for weldments with joints that require testing.
It has been proven in numerous situations that an effective programme of visual inspection will result in the discovery of the vast majority of those defects which would be found later using some other more expensive non-destructive test methods.
Remote visual inspection tools allow people to visually inspect areas they have no easy access to. It may be Casting or a tank or a pipe where no access to visualize the condition of the component. Videoscope imaging technology has advanced the use of video scopes. Rather than using a fiber optic bundle to convey images, the video scope uses a CCD (charge coupled device, similar to digital camera chips) to send the video signal to the controller and then to the viewer/monitor. Pix-elated image, 180,000-420,000 pixels in a video scope image. The more pixels, the smaller the gaps between the pixels and hence the higher resolution. Good clear image will be obtained for analysis.
Applications:
Positive Material Identification (PMI) is the analysis of a metallic alloy to establish composition by reading the quantities or composition by percentage of its constituent elements. Typical methods for PMI include X-ray fluorescence (XRF) and optical emission spectrometry. PMI has the ability to eliminate human error. The Technique is simple and accurate. It has been proven that Mill certifications and heat markings in isolation can be unreliable. Human error in the stainless steel and nickel alloy fabrication industries is a constant occurrence. Positive Material Identification (PMI) is used to validate raw materials before fabrication of the final product begins and then once more validate the finished product prior to installation. PMI is used to differentiate group of metal from scraps. Used to test the filler material composition even after welding.
Infrared Thermography is method of measuring the difference in temperature at different locations. Thermal NDT methods involve the measurement or mapping of surface temperatures as heat flows to, from and/or through an object. The simplest thermal measurements involve making point measurements with a thermocouple. This type of measurement might be useful in locating hot spots, such as a bearing that is wearing out and starting to heat up due to an increase in friction.
This is a non-contact method used the collect the thermal information over a wide area to find the abnormalities. Thermal imaging systems are instruments that create pictures of heat flow rather than of light. Thermal imaging is a fast, cost effective way to perform detailed thermal analysis. The basic premise of thermographic NDT is that the flow of heat from the surface of a solid is affected by internal flaws such as disbonds, voids or inclusions.
Ferrite Measurement is a non-destructive test method which assures the quality of the product without the need of expensive laboratory based destructive test methods.This is the major technique which is used to find the Proportion of ferrite content in the material. This is simple and very good for onsite measurement. Austenitic, Duplex, Super-duplex stainless steels require adequate proportion of ferrite in the product to obtain acceptable corrosion resistance and strength and especially resistance to Stress Corrosion Cracking (SCC). The laboratory based destructive method such as microstructural analysis on the test specimen or sample is very tedious and time taking.
In order to guarantee the acceptable ferrite content in the final product, ferrite measurements are performed on the actual product using ferritoscope.
Phased Array Ultrasonic testing (PAUT) enables the generation and receiving of an ultrasonic beam where parameters such as angle, focal distance, and focal point size are controlled through software. The ultrasonic beam can be multiplexed over a large array. The wide range of capabilities Provides greater feasibility to the user in using PAUT. For instance, it is possible to quickly vary the angle of the beam to scan a part without moving the probe itself. Phased array also allows replacing multiple probes and mechanical components. Inspecting a part with a variable-angle beam also maximizes detection regardless of the defect orientation, while optimizing signal-to-noise ratio. Semi-Automated inspection and Data recording provides additional support to replace PAUT in place of RT.
Major Applications :
Time Of Flight Diffraction (TOFD)works with the Principle of diffraction in contrast to Reflection of ultrasound as used in conventional UT. The deflection of a wave front as it passes an ultrasonically opaque object and expands into the region that is behind the object and hence not directly exposed to the incoming waves. When ultrasound is incident at linear discontinuity such as a crack, diffraction takes place at its extremities. The study of this phenomenon has led to the use of time of flight diffraction method of crack sizing. TOFD is very sensitive to detecting all kinds of defects, irrespective of its orientation. Using this advanced technique gas, binding defects, porosity, slag inclusions and cracks can be detected independent of defect orientation with very accurate sizing of the defects.
Advantages & applications of TOFD :
Two strong permanent magnets coupled to a steel core, generate a magnetic field that saturates the tube wall. An absolute coil (ABC) is wound around the core to measure magnetic field variation caused by general wall loss A flaw between two magnets caused the magnetic field in tube wall disturbed results in a small amount of flux leakage in to the inner tube. The flux leakage is detected by a differential coil located between the magnets and a trail coil at the end of probe detects the residual magnetism from the internal pits.
Applications of MFL:
Eddy Current weld Inspection is a method for the inspection of metallic parts Particularly Conductive material. The probe (coil), excited with an alternating current, induces an eddy current in the part being inspected. Any discontinuities or material property variations that change the eddy current flow in the part are detected by the probe. The Probability of detection will be more when the Eddy current is Perpendicular to the discontinuity
The eddy current technique is now recognized to be fast, simple, and accurate. The technique is widely used in the aerospace, automotive, petrochemical, and power generation industries in the detection of surface or near surface defects in materials such as aluminium, stainless steel, copper, titanium, brass, Inconel, and even carbon steel (surface defect only). Very sensitive to cracks. Under coat or painted surface inspection are possible with Eddy current inspection
A Major advanced technique similar to UTG but for a wide area thickness measurement instead of localised spot. Ultrasonic corrosion mapping is a key method in most non-invasive inspection strategies. In ultrasonic wall thickness mapping systems, a probe is linked to a equipment / computer so that thickness data for each predetermined measurement position can be recorded. Each thickness level can be colour coded and wall thinning by corrosion or erosion is more readily recognised than by manual inspection. High reproducibility (typically with 0.3 mm wall loss) enables accurate monitoring and calculation of corrosion rates. Automatic scanning or semi-automatic scan is possible.
Wall thickness mapping can be applied in-service at temperatures up to 250°C using special high temperature probes and couplant. Wall thinning, pitting, corrosion, hydrogen induced corrosion and hot hydrogen attack can all be detected and imaged.
Guaranteed 100% coverage of the inspection area.
Visualisation of wall thickness patterns using B, C and D scan presentations
Recent developments
Works with same Basic ultrasonic principle. The impedance mismatch reflects the ultrasound. Analysis of signal data with different display produces the information about the discontinuities. IRIS technology is used extensively as approve up technique for RFT, ECT, MFL.
Applications of IRIS:
Tank Floor Scanner is widely used NDT technique for the inspection of tank walls. Magnetic flux leakage principle is applied here for the inspection of tank bottom plates. Unlike the basic conventional NDT- MPI, the tank floor equipment uses sensors to detect the leakage field due to corrosion, pitting, wall loss and will be recorded in the system connected to Sensors.
For in-service inspection of tank plates, pipeline corrosion monitoring MFL is widley used. It is faster than other corrosion mapping techniques and also give better results. Dimensions of the defects can be well determined with this technology as the system uses encoders, software’s to track and record data
In-service inspection for Heat exchangers, boiler tube, air coolers, feeder water heater requires a high level multi technology equipment. Specific technique is necessary for different materials.
Heat Treatment is a group of industrial and metalworking processes used to alter the physical, and sometimes chemical, stress relieving, and other properties of a material. The most common application is metallurgical. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve a desired result such as hardening or softening of a material. Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering and quenching. It is noteworthy that while the term heat treatment applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such as hot forming or welding.
Pre weld heat treatment and post weld heat treatment for stress relieving most commonly used during fabrication.
Hardness is the measure of how resistant solid matter is to various kinds of permanent shape change when a force is applied. However, the term hardness may also refer to resistance to bending, scratching, abrasion or cutting. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, there are different measurements of hardness: scratch hardness, indentation hardness, and rebound hardness.
Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity
The usual method to achieve a hardness value is to measure the depth or area of an indentation left by an indenter of a specific shape, with a specific force applied for a specific time. There are three principal standard test methods for expressing the relationship between hardness and the size of the impression, these being Brinell, Vickers, and Rockwell.
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