Examination is carried out by using a pulse echo wave which is generarted electrically. The use of an A scan presentation enables an immediate response to a signal received from a discontinuity within the item being examined. The electrical pulses are transformed into mechanical waves which can travel meters in fine grain materials.

  Traditional Ultrasonic inspection uses high frequency sound energy to conduct examinations and perform measurements. Considerable information may be gathered during ultrasonic testing such as the presence of discontinuities, material or coating thickness. The detection and location of discontinuities is enabled by the interpretation of ultrasonic wave reflections generated by a transducer. These waves are introduced into a material and travel in a straight line and at a constant speed until they encounter a surface. The surface interface causes some of the wave energy to be reflected and the rest of it to be transmitted. The amount of reflected vs. transmitted energy is detected and provides information on the size of the reflector, & therefore the discontinuity encountered. Three basic ultrasonic techniques are commonly used:

  Typical equipment shall have calibrated attenuators with increments of 1 or 2 DB steps. The frequency ranges from 1 MHz to 5 MHz enabling us to examine various grain structured material. Automated ultrasonic techniques available

  The simplest form of ultrasonics is for the measurement of thickness usually utilising either a Kraut Kramer DMEDL or DMS or CYGNUS flaw detectors.

  The form of radiation either X-ray or Gamma rays from a radioactive source are utilised to test a component exposing a photographic film placed on the opposite side of the radiation source.

  The placing of the radioactive source will depend on the geometry of the piece being examined. After processing, the film obtained is a permanent record of the weld showing the majority of internal imperfections.

  As X-rays and Gamma rays are harmful full safety precautions are set down in the INSPEC site safety manual and the "Code of Practice for Site Radiography" issued by the Department of Transport in the United Kingdom and the specific Countries laws.

  Magnetization shall be carried out either utilising a permanent or electromagnet, inducing a magnetic field into the item being examined. The surface is coated with a background medium and iron partciles are applied to the test surface either as dry powder or suspended in a liquid.

  When the magnetic field is disturbed by surface or near-surface discontinuities the magnetic powder forms around an indication which can be seen quite clearly.

  This method of N.D.T is reliable only where the discontinuities are surface or near-surface and will not detect internal discontinuities.

   The particular penetrant liquid, usually a red dye or a flourescent dye when using a black light, is applied to generally non-ferrous materials. It is also advantageous to use a low sulphur and hallogen dye. The area to be tested must be clean.

  The dye is applied and left for approximately 1/2 hour or longer on the surface which enables the dye to be drawn by capillary action, into a surface breaking indication. The excess dye is removed by either water or solvent soaked cloth and developer is applied, a further waiting period of upto approximately 15 minutes or longer is required where the coloured dye will contrast with the white developer enabling the technician to identify any discontinuities.

  Penetrant testing - Based on the properties of capillary action, or the phenomenon of a liquid rising or climbing when confined to a small opening due to surface wetting properties of the liquid, Penetrant testing is used for finding surface breaking discontinuities on relatively smooth, nonporous surfaces. The types of defects that can be found with Penetrant inspection are: