Advanced NDT Services
Eddy Current Testing
Eddy current Testing makes use of electromagnetic induction to detect and characterize surface and sub-surface flaws, crack, wall thickness layers or microstructure in conductive materials.
A coil of conductive wire is excited with an alternating electrical current. This produces an alternating magnetic field that oscillates at the same frequency as the current running through the coil. When the coil approaches a conductive material, currents opposed to the ones in the coil are induced in the materia.
Variations in the electrical conductivity and magnetic permeability of the test object, and the presence of defects causes a change in eddy current and a corresponding change in phase and amplitude that can be detected by measuring the impedance changes in the coil, which is a telltale sign of the presence of defects
RFT probes use one or several transmitter coils positioned two tube diameters apart from the receiver coil. The magnetic field created by the transmitter coil travels through and out of the tube wall, radially and axially, towards the receiver. The magnetic field must travel through the tube wall again to reach the receiver. This is called through-transmission and is what defines RFT. Through-transmission allows external and internal defects to be detected with equal sensitivity.
Two coupling paths exist between the transmitters and receivers. The direct path, inside the tube, is rapidly attenuated by circumferential eddy currents induced in the tube’s wall. The indirect coupling path originates in the transmitter’s magnetic field that diffuses radially outward through the wall. At the outer wall, the field spreads rapidly along the tube with little attenuation and rediffuse back through the pipe wall and are the dominant field inside the tube at the receiver.
Because IRIS is an ultrasonic technique, it requires a couplant. In this case, water. Tubes under test must therefore first be flooded to use this technique. IRIS relies on a transducer to generate an ultrasonic pulse parallel to the axis of the tube under test. It also relies on a rotating mirror that directs the ultrasonic wave into the tube wall. The mirror is driven by a small turbine powered by the pressure of water pumped into the tube.
Part of the ultrasonic wave is reflected by the inner-diameter (ID) wall, while the rest is reflected by the outer-diameter (OD) wall of the tube. Because the ultrasonic velocity of the tube’s material is known, it is possible to assess the thickness of the wall by calculating the difference in times of flight between the two diameters.
A critical aspect of IRIS is ensuring that the mirror is at the center of the tube. An off-center ultrasonic pulse yields a distorted scan image because of the different ID and OD wall sound paths. That’s why our IRIS kits are equipped with centering devices helping operators keep the system centered.
IRIS is commonly used in boilers, shell-and-tube heat exchangers, and fin-fan heat exchanger tubes.
Magnetic Flux Leakage
Vacuum Box testing is used to check for any leaks or fault in the welding of bottom & annular plates of the storage tank
The objective of the vacuum box technique of bubble leak testing is to locate leaks in a pressure boundary that cannot be directly pressurized. This is accomplished by applying a solution to a local area of the pressure boundary surface and creating a differential pressure across that local area of the boundary causing the formation of bubbles as leakage gas passes through the solution
PAUT & TOFD
Phased Array and ToFD applications usually require the use of powerful and complicated software for data analysis or to drive the UT acquisition units. Scope of the course is to train you to use advanced UT software efficiently by practical training on different software functions. Therefore, probability of detection could be maximized and time spent on data analysis minimized resulting in overall highly increased productivity and confidence.
This course is suitable for you as an advanced UT inspectors wanting an in-depth knowledge on the advanced UT software.
Different functions of software aiming at different applications (Corrosion mapping, Weld ToFD analysis, Weld PAUT inspection and analysis) will be demonstrated and practiced making the course suitable for inspectors involved in all industrial sectors using advanced UT inspection techniques.
Long Range UT
Hundreds of metres of pipe can be screened in one day from one single location and the technique can inspect 100% of the pipe wall. LRUT can be performed on piping that is in operation, insulated and buried, and in areas that are difficult to access such as those at high elevations. The method can therefore save time and money that would otherwise be spent on excavation, insulation removal and scaffolding.
A ring of transducers is fitted around the pipeline and the transducers generate and receive low frequency ultrasonic guided waves along the pipe. The returning echoes indicate defects such as corrosion and other abnormalities.
Helium Leak Test
A mass spectrometer or helium sniffer is used to detect helium although it is possible to use a residual gas analyser. Helium leak testing is many times more sensitive than using other leak detection techniques. Helium is in short supply globally and can be expensive and must be sourced locally and for this reason it is required that the client sources the helium gas to be used for the inspection.
Dacon uses the PHD-4 which is a portable compact leak detector which includes a battery for autonomous use in the field and uses helium as a tracer gas. The PHD-4 principle of operation is based on a Varian patented technology, Selective Ion Pump Detection (SIPD). The sensor incorporates a quartz capillary tube maintained under high vacuum by an ion pump. The quartz tube is heated with a platinum filament and becomes permeable to helium.
An industrial borescope camera is used to see in walls, inspect pipes and see inside engines. A borescope inspection is performed in automotive, HVAC, plumbing and machine maintenance and repair, because an industrial borescope camera allows for the nondestructive inspection of hard-to-reach places such as drains, sewer pipes, heating vents, air ducts, furnaces, motors, pistons, gears, valves, compressors, boilers and condenser tubes. Thanks to flexible cables and lightweight enclosures, borescope cameras are extremely agile and mobile.
An industrial borescope inspection camera helps you locate potential problems quickly and easily without the need to dismantle a system or machine, allowing corrective measures to be taken before costly downtime occurs.
Pulsed Eddy Current
A magnetic field is created by an electrical current in the coil of a probe. When the probe is placed on the insulation, fireproofing, or coating, the field penetrates through all the layers (including sheeting, if present) and stabilizes in the component thickness, and then the electrical current in the transmission coil is turned off, causing a sudden drop in the magnetic field. As a result of electromagnetic induction, eddy currents appear in the component wall. The eddy currents diffuse inward and decrease in strength. The decrease in eddy currents is monitored by the PEC probe and used to determine the wall thickness. The thicker the wall, the longer it takes for the eddy currents to decay to zero.
PEC is therefore the analysis of transient eddy currents in a conductive component following a sharp electromagnetic transition.
Unlike early thermal cameras that were large, very expensive, difficult to use, slow to acquire data, and offered poor image resolution, the technology has evolved to produce compact, ergonomic cameras that are easy and fast to use, are much more affordable and provide high resolution images. With the proper infrared camera and lens, you can scan details from targets as small as 25 microns to targets several hundred feet tall. The speed and convenience of today’s infrared cameras enable you to conduct inspections faster and find problems in areas that you might have otherwise overlooked.
The non-contact nature of infrared thermography makes it ideal for a wide range of applications where components are moving, very hot, dangerous to contact, difficult to reach, impossible to shut off, or could be contaminated or damaged through contact. Infrared cameras are also very helpful in detecting energy or moisture-related problems in a building envelope