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| You are here: Testing - Non-Destructive Testing (NDT) | ||||||||||||||||
Matco Associates is pleased to offer Non-Destructive testing services through our team of highly qualified, certified, and experienced Level II / Level III NDT professionals. The demands of today’s complex industries requires the most reliable, efficient, and cost effective services available. We at Matco pride ourselves in providing just that… The most reliable Non-Destructive Testing Service in the industry. Non-Destructive Testing is extremely reliable during the design, production, and service life of a product. We can provide tailored NDT solutions for your unique problem at a moments notice, with the aid of our full range of NDT capabilities: Ultrasonic, Magnetic Particle, Eddy Current, Fluorecent Dye Penetrant, and X-ray or Gamma Radiography. Our services include on-site and laboratory inspections. Industries Served:
NDT Method Explanation: Non-Destructive testing allows parts and material to be inspected and measured without damaging them. NDT provides an excellent means of balancing quality control and cost effectiveness. Ultrasonic Testing (UT) In ultrasonic testing, high frequency sound waves are introduced into a material via a transducer coupling medium to detect imperfections. The most widely used technique is pulse echo, whereby sound is introduced into a test specimen and reflections (echoes) from the internal imperfection or the part’s geometrical surfaces are returned to a receiver. Magnetic Particle Testing (MT) This Non-Destructive method is accomplished by inducing a magnetic field in a ferromagnetic material and then applying either dry or wet iron particles to the surface of the test piece. When a surface or subsurface discontinuity interrupts the magnetic field induced in the part, part of the field is forced out in the air above the discontinuity, forming a leakage field. Iron particles will form an outline of the leakage field revealing its location, size and shape. Eddy Current Testing (ET) Electrical currents (Eddy Currents) are generated in a conductive material by a changing magnetic field. There are factors which contribute to the strength of eddy currents such as; frequency, applied voltage, permeability and lift-off. Relevant indications are noted by the inspector when the flow of eddy currents is interrupted by a defect. These electrical currents are also affected by the electrical and magnetic permeability of a material, which allows this method to be used to sort some materials based on these properties. Penetrant Testing (PT) The process of this widely used test method involves coating the test specimen with a visible or fluorescent dye. Then allowing the penetrant to dwell in the part for an specific amount of time, as to ensure that it seeps down into any surface crevice. After the dwell time, the excess penetrant solution is removed from the surface, and a developer is applied to draw out the penetrant left behind in surface defects. With fluorescent dyes, ultraviolet lights are used to make the bleedout fluoresce brightly, allowing the inspector to easily see the surface imperfections. Radiography (RT) This involves the use of high energy Gamma or X-Ray radiation to produce a latent image on a piece of photographic film. The materials thickness and density changes are indicated as lighter or darker areas on the film. This allows for the interpretation of the materials internal features and soundness. X-ray machines or radioactive isotopes are used as a source of radiation. Cracks on a weld sample are noted on a radiograph as a thin dark irregular line along the length of the weld bead. Case Histories A recent example of MATCO’s ability to solve particularly difficult NDT questions concerned a major site cooling system which evidently was undergoing serious corrosion problems, placing the entire system in jeopardy. Small leaks had already been detected, several pipe joints had been removed, and significant metal loss was seen. The entire system needed to be checked. Ultrasonic examination seemed the obvious choice… but it didn’t work at all. The problem was that the system, composed of carbon steel pipes from 24 to 10 inches in radius, had been constructed with Victaulic couplings. These consist of heavy steel bolted clamps tied into rolled-in grooves at the end of each piece of pipe, over a rubber gasket. The clamps prevented the ultra sonic probe from transmitting or receiving properly so that the sites of most serious damage could not be examined. A new high-tech alternative was computed radiography, a process which can take place in the field. The pipes have to be emptied of water, but the detector plates are placed entirely on the opposite side of the pipe from the x-ray source which exposes the plate through the two layers of clamp and the two layers of steel in the pipe. Digital processing allows the extraction of the relevant information from the signal and presentation of that information as an image. A further example of MATCO’s rapid-response-team approach to emergencies was at an accident site on a major highway bridge some 50 miles south of Pittsburgh. A tanker truck had overturned and burned on the bridge. All traffic was stopped. The question was: Is the bridge safe to open to traffic? The PA Department of Transportation’s safety and engineering consultant knew they needed help immediately and called MATCO. Within a couple of hours a team of qualified engineers and scientists was on its way, fully equipped to deal with site examination in the field. The fire had actually impinged on the load-bearing steel members of the bridge and conceivably could have weakened them. On-site hardness measurements showed that while the properties of the steel had been affected, the damage was not such as to require the bridge to remain closed. MATCO’s inspectors are ASNT Level 2 and AWS-CWI certified. Code inspection requirements include: AWS, ASNT, ASME, API, AASHTO, SSPC, ASTM, AISC, BOCA and various Department of Transportation codes. Dr. M. Zee(*) Dr. George Bayer Mr. Jose Borge Mr. Kevin Groll (*) Ms. Debra Riley (*) Dr. Huiping Xu Mr. Dan Gibson Mr. John McArdle
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