THE NONDESTRUCTIVE TESTING (NDT)

THE NONDESTRUCTIVE TESTING Ultrasonic inspection (UT) Magnetic Particle Inspection (MT) Liquid Penetrant (LP) Radiographic Inspection (RT) Visual Inspection (VT) Hardness Testing (HD) Eddy Current Testing (ET)

THE NONDESTRUCTIVE TESTING ULTRASONIC INSPECTION (UT) It uses ultrasonic waveforms (high frequency > 20 kHz, i.e. Beyond heaing zone) to pass through a material to detect flaws and provide a complete volumetric inspection. It can detect small crack (size equals wavelength of the ultrasound wave) by scattering the ultrasonic vibration due to the defect in metal , which otherwise transmitted smoothly because of its elastic properties. The techniques available for ultrasonic testing include Pulse echo technique : A piezoelectric crystal is normally used to generate the ultrasonic waves. The basic technique applied in the case of pulse-echo, changes with the nature of flaws in the component. Transmission technique : Flaws reduce the amount of energy in form of continuous waves reaching the receiver, Resonance technique : resonance in the presence of flaws will keep the transmitted signal low Frequency modulation technique : Continuously changed frequencies generated from a signal transducer are echoed back with a changed frequency if the flaws are present. The phase difference between the transmitted and received frequencies provides the location of the flaws. Ultrasonic testing can also be used to measure thickness, detect corrosion and examine groove Welds. It is very portable for field inspection.

THE NONDESTRUCTIVE TESTING MAGNETIC PARTICLE INSPECTION (MT) MPI uses an electrical current (direct or indirect) to induce a magnetic field in the sample to detect discontinuities open to the surface or slightly subsurface using mediums such as visible dry or visible wet or fluorescent magnetic particles (Magnetic flaw-detection inks consisting of fine powder of black or red iron oxide suspended in liquid paraffin). When applied, while the part is being magnetized, the magnetic particles will accumulate anywhere there is a break in the part or a leak in the magnetic flux. This method allows for detection of indications that are too small to be visible to the eye to be further examined to the proper code and acceptance criteria. For ferromagnetic materials such as castings, weldments, forgings, machined or stamped parts. This is one of the fastest and most cost effective nondestructive examinations available.   Spray, pouring or immersion techniques are used depending upon the type of the component.

THE NONDESTRUCTIVE TESTING LIQUID PENETRANT (LP) Liquid Penetrant Inspection (LPI) has been used in various fields for years to identify discontinuities / defects open to the surface, too small for the eye to detect. Element technicians apply a dye, either visible or electrostatic fluorescent penetrants. After a short dwell time, the dye is removed following the proper removal process Then the developer is applied in accordance with established codes, specifications or procedures and indications of flaws can be identified, sized, and recorded. This method is one of the most portable of the surface inspection methods; LPI also has the advantage of being able to detect flaws in non metallic and non ferromagnetic materials like glazed ceramics, plastics.

THE NONDESTRUCTIVE TESTING RADIOGRAPHIC INSPECTION (RT) Radiographic inspection is performed using a radioactive isotope or an x-ray tube in order to create an image on a film or in a digital format. This method can be performed at our lab or in the field. This method is a volumetric inspection in which defects that are not open to the surface can be detected that may not otherwise be detectable. A vast array of material can be examined by this method which is an efficient and reliable way-ranging from tiny electronic components to large vessels. Element has the capabilities to perform conventional film radiography to Computed and Digital radiography. Computed and Digital radiography is a highly sensitive method of radiography that produces an image in a digital format that can be viewed on any laptop or computer.

THE NONDESTRUCTIVE TESTING VISUAL INSPECTION (VT) The visual inspection equipment includes mirrors, lenses, microscopes, enlarging projectors, comparators, photoelectric systems, fibre-optic scanners and closed-circuit televisions. A few instruments used for visual inspection are given below: Borescope : For inspecting narrow tubes, bores or chambers, the borescopes are used. Fibre-optic scanners : These are of two types Coherent devices (image carrying) used for medical and military purposes, and also for quality control inspection. Non-coherent devices (light piping) that are used for illumination purposes, and are available in the form of either glass or polymer materials. Cold light rigid probes : These instruments are particularly suitable for combustible and heat sensitive areas, as they work on the image transfer principle and transmit cold light.

THE NONDESTRUCTIVE TESTING VISUAL INSPECTION (VT) A few instruments used for visual inspection : Deep-probe endoscopes : Working on the principles of fibre optics, these are used for the inspection of the pipe work in boilers and heat exchangers. Pan-view fibrescope : Any defects in the wall of the tubes or in the internal parts of a machinery can be inspected by using this type of fibrescope. It can be inserted in the tube or internal part of a machinery providing forward viewing to check the defects. Electron fractography. This technique is used to find out the growth of fatigue cracks developing in a structure as each fracture has its Own fingerprints, which can be visualized by an electron microscope

VIBRATION MONITORING EQUIPMENT Transducers, vibration pick-ups or strain gauges detect the vibration signals, which pass through a machine component to the machine structure. In its simplest form, the vibration monitor may present a safe/unsafe indication of vibration severity, whereas an advanced vibration monitor may provide a spectrum or signature by means of which variations in the discrete frequency of the defective component can be used to identify the component which is likely to fail. In some cases, the data can be processed in detail to find out the type of defect within the component itself.

VIBRATION MONITORING EQUIPMENT Vibration analyzer : The vibration analyzer is used to pick up the signals from the working system in order to study the condition of a component/machine. With the help of a vibration analyzer, these complex waveforms can be analyzed by means of narrow band filters. The frequency range obtained enables the maintenance engineers to prepare routine check-ups on rotating machinery/ parts and to know that the vibration frequencies are within the specified limits. In a complex machine, the individual component vibration frequencies as well as the overall vibration level can be measured. The meters, provided in the vibration analyzer enable to measure acceleration, displacement, or velocity. Octave analyzer : The octave analyzer is used to measure the amplitude and frequency of components in a complex sound and vibration spectra. The analyzer consists of a high-impedance amplifier, a continuously tunable filter with narrow bandwidth. The centre frequency of the filter is continuously adjusted.

VIBRATION MONITORING EQUIPMENT Real-time analyzer An online real-time analyzer provides the analysis of the frequency spectra. Such analysis permits real-time processing without any loss of data. The use of programmable microcomputers have made it possible to develop these instruments incorporating a broad range of analysis techniques for the time series data. The other instruments used for the purpose of vibration analysis include a percentage bandwidth analyzer, a narrow bandwidth analyzer, a turbine vibration analyzer, and vibration limit detectors. These instruments indicate changes in vibration frequency and enable detection of shock pulses and plastic deformation.

OTHER EQUIPMENTS Balancing equipment, Gas cutting and welding, compressor, basic machine tools, chain pulley block, lubricators and lubricants, Tools different types of wrenches, torque wrench, pipe wrench, pliers, screw driver, dimension measuring instruments, feeler gauge, scraper, fitting shop tools, spirit level, hand grinder & drill, screw jack, etc.