The need for NDT

          It is very difficult to weld mold a solid object that has the risk of breaking in service, so testing at manufacture and during use is often essential. During the process of casting a metal object, for example, the metal may shrink as it cools, and crack or introduce voids inside the structure. Even the best welders (and welding machines) do not make 100% perfect welds. Some typical weld defects that need to be found and repaired are lack of fusion of the weld to the metal and porous bubbles inside the weld, both of which could cause a structure to break or a pipeline to rupture.

During their service lives, many industrial components need regular nondestructive tests to detect damage that may be difficult or expensive to find by everyday methods. For example:

• aircraft skins need regular checking to detect cracks;

• underground pipelines are subject to corrosion and stress corrosion cracking;

• pipes in industrial plants may be subject to erosion and corrosion from the products they carry;

• concrete structures may be weakened if the inner reinforcing steel is corroded;

• pressure vessels may develop cracks in welds;

• the wire ropes in suspension bridges are subject to weather, vibration, and high loads, so testing for broken wires and other damage is important.

          Over the past centuries, sword smiths, blacksmiths, and bell-makers would listen to the ring of the objects they were creating to get an indication of the soundness of the material. The wheel-tapper would test the wheels of locomotives for the presence of cracks, often caused by fatigue — a function that is now carried out by instrumentation and referred to as the acoustic impact technique.

 

          Applications

          NDT is used in a variety of settings that covers a wide range of industrial activity: automotive, engine parts, frame, aviation/ aerospace, airframes, space frames, power plants, propellers, reciprocating engines, gas turbine engines, rocketry, construction, structures, bridges, manufacturing, machine parts, castings and forgings, industrial plants such as nuclear, petrochemical, power, refineries, pulp and paper, fabrication shops, mine processing and their risk based inspection programs, pressure vessels, storage tanks, welds, boilers, heat exchangers, turbine bores, in-plant piping, miscellaneous, pipelines, in-line inspection using "pigs" pipeline integrity, railways, rail inspection, wheel inspection, tubular NDT, for tubing material, corrosion under insulation (CUI), amusement park rides, submarines and other naval warships, medical imaging applications, etc.

 

          Methods and techniques used in our company
          NDT is divided into various methods of nondestructive testing, each based on a particular scientific principle. These methods may be further subdivided into various techniques. The various methods and techniques, due to their particular natures, may lend themselves especially well to certain applications and be of little or no value at all in other applications. Therefore choosing the right method and technique is an important part of the performance of NDT.

• Ultrasonic Testing

• Eddy Current

• Etch Inspection

• Penetrant Testing

• Resonance Inspection

• Digital Radiography

• Acoustography

• Guided-wave

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