What is NDT

Non destructive testing is a descriptive term used for the examination of materials and components in such a way that allows materials to be examined without changing or destroying their usefulness. NDT plays a crucial role in everyday life and is necessary to assure safety and reliability Typical examples are found in aircraft, motor vehicles, pipelines, bridges, trains, power stations, refineries and oil platforms which are all inspected using NDT NDT is a Quality Assurance management tool which can give impressive results when used correctly It requires an undersanding of the various methods available, their capabilities and limitations, knowledge of the relevant standards and specifications for performing the tests. Materials, products and equipment which fail to achieve their design requirements or projected life due to undetected defects may require expensive repair or early replacement Such defects may also be the cause of unsafe conditions or catastrophic failure, as well as loss of revenue due to unplanned plant shutdown. Non destructive testing can be applied to each stage of an item's construction. The materials and welds can be examined using NDT and either accepted, rejected or repaired. NDT techniques can then be used to monitor the integrity of the item or structure throughout it's design life.

Testing Methods:

The method that can be used for non-destructive testing depends on the physical properties of the material. A thorough knowledge of each NDT method is required to ensure the correct selection of the appropriate method for each application.

NDT is used typically for the following reasons:

  • Accident prevention 
  • To reduce costs 
  • To improve product reliability 
  • To determine acceptance to a given
  • To qive information on repair criteria.

In order to gain the information and obtain valid results, the following is required:

  • Trained and qualified personnel. 
  • A procedure for conducting the test. 
  • A system for reporting results. 
  • A standard to interpret the results.

NDT can be used to find, size and locate surface as well as subsurface flaws and defects

The commonly used NDT methods are:

  • Visual Inspection 
  • Liquid Penetration Inspection 
  • Acoustic Emission 
  • Magnetic Particle Inspection 
  • Eddy Current Inspection 
  • Ultrasonic Inspection 
  • Radiography
  • Phased array