Tuesday, June 23, 2009

Ultrasonic Testing

Ultrasonic Testing is a Nondestructive Testing (NDT) method but it is used in various application areas, such as aerospace, automotive and transportation sectors. It is used for the inspection of metals, components, assemblies and composite structures. The process of Ultrasonic Testing involves introducing ultrasonic pulse-waves into the testing object to identify internal defects or to distinguish materials.

The frequency range of the ultrasonic pulse-waves is somewhere between 0.1-15 MHz. Ultrasonic Testing helps to determine the thickness of the object and check things like pipework corrosion. When Ultrasonic testing is done on steel and other metals and alloys high frequency waves are penetrated into the object. In case of concrete, wood and composites less resolution frequency waves are launched into the object.

Ultrasonic Testing – Working Explained

An Ultrasonic Testing system is used for the inspection procedure. The system comprises of certain functional units like pulser/receiver, transducer, and display devices.

• Pulser/Receiver: It produce high voltage electrical pulses
• Transducer: It produce high frequency ultrasonic energy
• Display Devices: Reflects signal strength

The high voltage electrical pulses produced by pulser/receiver are driven to the transducer which in turn generates high frequency ultrasonic energy. This energy wave propagates through the test object in the form of waves. If there is some obstacle in the wave path like a crack then some part of the energy is reflected back. The reflected energy shows that there is a flaw in the surface of the test object. The transducer transforms the reflected wave signal into electrical signal and displays it on the screen of the display device. Imperfections or other conditions in the space between the transmitter and receiver reduces the time of transmission of the signal and reveal the presence of defects.

Advantages Ultrasonic Testing

• Ultrasonic testing makes detection of the deep rooted flaws easy due high frequency waves that penetrate into the testing object.
• Ultrasonic testing also allows to spot flaws that are extremely small and otherwise not visible due to the high sensitivity of ultrasonic pulse-waves.
• Ultrasonic testing requires access to only one surface to detect the flaws and transmit the results.
• Ultrasonic testing produces extremely accurate results in comparison to the other nondestructive methods.
• Ultrasonic testing helps to determine the in-depth internal flaws with easy and also identify thickness of parts with parallel surfaces.
• Ultrasonic testing helps to estimate the size, orientation, shape and nature of defects as well.
• Ultrasonic testing is a highly automated operation and is not affected by the surrounding equipment and materials in the area.

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Tuesday, May 19, 2009

Industrial Radiography

Radiography is a procedure that helps to see objects that cannot be seen with naked eye. The use of electromagnetic radiation helps to view these objects without any hindrance. The concept of Radiography came into existence in 1895 when X-rays were discovered. Radiography soon became widely applicable in various areas for testing and inspection. Today, Industrial Radiography has become an integral part of nondestructive testing (NDT). The electromagnetic radiations penetrate deep into the object and help to inspect it from inside. The technology allows identifying the hidden flaws, and rectifying them at early stage.

Use of Industrial Radiography for Inspection of materials

Industrial Radiography is being widely used for testing and grading of welds of equipments to ensure their quality. It is used to carry out welding inspection in various areas and check the welds on pressurized piping, pressure vessels, high-capacity storage containers, pipelines, and other structural welds. While conducting a welding Inspection with radiography, it is advisable to inspect the component for any external defects. It is very difficult to inspect an irregular welded surface and identify internal defects.

Industrial Radiography can be used to inspect any flat or solid material, such as walls and floorings. It allows testing concrete and locating rebar or conduit and also inspecting pipe walls against anomalies that are caused because of corrosion and mechanical damages. Industrial Radiography is one of the most essential methodologies to maintain high quality standards and carry out welding inspection efficiently and effectively.

Industrial Radiography Equipment

Radiography (X-ray) or high energy X-ray machines are used in Industrial Radiography. These machines generate a radiograph of the object and show internal and external defects. The radiography is generated in variations of black, white and gray. These state-of-the-art machines also help to check the thickness variations and assembly details of inspected object. They are widely used in welding inspections and carry out the welding operations successfully.

Industrial Radiography Safety Precautions

Industrial Radiography is a critical task and involves use of high energy radiations and gamma rays; therefore, it is very important to take safety precautions for the people using this technology. Some of the safety tools used in Industrial Radiography inspections are radiation survey meter an alarming dosimeter, a gas-charged dosimeter, and a film badge or thermo-luminescent dosimeter (TLD). Use of these safety devices help to protect the radiographer against the injuries that can be caused due to overexposure to radioactive rays.

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Friday, April 24, 2009

Need of Non-Destructive Testing

Non-Destructive testing methods is to increase customer satisfaction and lower manufacturing costs. Non-destructive tests use to detect variations in structure, minute changes in surface finish, the presence of cracks or other physical discontinuities, to measure the thickness of materials and coatings and to determine other characteristics of industrial products.

Non-destructive tests are performed:-
(1) Ensure product integrity, and reliability
(2) Prevent accidents and save human life
(3) Ensure customer satisfaction and maintain the manufacturer's reputation
(4) Control manufacturing processes
(5) Lower manufacturing costs
(6) Maintain uniform quality level

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Sunday, April 12, 2009

Visual examination

Visual examination is performed to check weld size and appearance. This test is perform to detect surface cracks, fusion between weld bead, gas hole, excessive undercut and more. It is used in conjunction with all other NDT methods. For visual examination required several CWI’s staff.

Visual Testing is a cost effective method used for quality control. A minimum of equipment is needed.

Many Non Destructive Testing (NDT) techniques used for the inspection of welding is surface crack detection. We shall briefly examine the two most common methods of surface crack detection, Liquid Penetrant Testing (PT), sometimes referred to as Magnetic Particle Testing (MT).

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Tuesday, April 7, 2009

non destructive testing application

NDT(non destructive testing) is used in a variety of settings that covers a wide range of industrial activity.

  • Automotive
    • Powerplants
  • Construction
    • Structures
    • Bridges
  • Maintenance
    • Bridges
  • Manufacturing
    • Machine parts
    • Castings and Forgings
  • Industrial plants such as Nuclear, Petrochemical, Power, Refineries, Fabrication shops, Mine processing and Risk Based Inspection programmes.
    • Pressure vessels
    • Storage tanks
    • Welds
    • Boilers
    • Heat exchangers
    • Turbine bores
    • In-plant Piping
    • Pipelines
      • Pipeline integrity
      • Leak Detection
    • Railways
      • Rail Inspection
      • Wheel Inspection

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Tuesday, March 31, 2009

Ultrasonic Testing

Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and make measurements. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more.

Advantages

  1. High penetrating power, so that detection of flaws deep in the part.
  2. High sensitivity, permitting the detection of extremely small flaws.
  3. Greater accuracy than other nondestructive methods in determining the depth of internal flaws and the thickness of parts with parallel surfaces.
  4. Some capability of estimating the size, orientation, shape and nature of defects.
  5. Nonhazardous to operations and has no effect on equipment and materials in the vicinity.
  6. Capable of portable or highly automated operation.

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Monday, March 23, 2009

Adavantages of GPR

Advantages of GPR(Ground Penetrating Radar) :-

GPR is Cost effective technique.
GPR is Hi resolution, vertically and laterally.
GPR is used in Numerous areas of application.

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