So what exactly is Non-Destructive Testing?

Non-Destructive Testing is a blanket term used to describe various methods used to examine metal components such as shafts, mills, gears, bearings, steel plates and pipes for defects and cracks without destroying or damaging the item that is being inspected. 

These methods include: 

* Ultrasonic testing (UT)

* Wall thickness testing

* Phased Array testing

* Radiographic testing (RT)

* Magnetic particle testing (MPI)

* Dye Penetrant Testing (DPI)

* Hardness testing (HT)

* Visual Inspection

* Spark testing


This is a quick, reasonably affordable way of testing components for surface defects.  It is used with a color penetrant that is applied to the specimen; then it is cleaned off and dried.  A developer is then applied, which draws the colour penetrant out of the defect or crack.  This can then be visually interpreted to International standards.



This is done with relatively expensive equipment, but it is a very effective method to obtain quick results.

The equipment is small, thus it can be used anywhere and carried by hand.  With Ultrasounds, a sound beam is sent into the component; defect indications are displayed on the cathode ray tube and this is interpreted for its position, size and evaluated to International standards.  This method can also be used for thickness gauging.


This method is expensive and a safety hazard as X-rays and Gamma rays are used.  It is used by means of an X-ray tube or Gamma Isotope, which exposes an X-ray film of the specimen.  The film is developed in a dark room and interpreted to International standards. Radiographic testing can be successfully used anywhere, and on any component, but with a safety hazard to be precautious of.  A permanent image is recorded on a film and can be stored for a long time.


This is a method used with an electromagnet and is mainly used to detect surface defects such as cracks, etc.  The electromagnet is used to generate a magnetic field on the specimen and fluids containing fine steel particles, are applied.  These particles will be concentrated on a crack or defect, which can be visually evaluated to international standards. You can also do flourescent MPI to detect a defect.


This is done with a hardness machine and the hardness can be read in various methods i.e. Rockwell C/Brinell/Vickers or Shore.


This is done with an electric field fastened over a rubber liner to ensure there are no pinholes in the rubber liner.