Those of you who have experienced accompanying your elders in your childhood to domestic market might have noticed that while purchasing coconuts or clay vessels, they used to tap with their fingers and observe the sound. We were wondering in those days how do they determine the tightness or soundness and ensure that they are defect free.
Later when we grew up and gathered much technical knowledge, we realised that what they did was nothing but Non Destructive Evaluation of coconuts or mud pots using a technique that is somewhat similar to acoustic emission testing. Hence the basics of various NDT & NDE techniques that are in use currently have all evolved from such ancient practices.
Inspection – the need
Inspection - as a part of equipment life assurance practice - was identified as a key factor way back in 1854, when a boiler exploded killing 21 lives and injuring more than 50 people at Connecticut in the USA. The government passed a rule to make inspection of boiler compulsory. Hence Inspection plays a vital role in any industry; to safeguard lives against failure of equipment.
This paved a way for developing techniques to check the soundness of the material so as to ensure the safety of the human - using or operating it.
Later, thanks to various kinds of innovations and developments that happened in Science and Technology, different techniques using variety of scientific principles were invented. Elaborate efforts were taken to streamline training methods and certifying people who practice NDT to standardise NDT practices and ensure reliability.
NDT – the revolution
Nondestructive testing or NDT is a wide group of analysis techniques used in industry to evaluate the properties of a material, component or system without causing damage. NDT does not permanently alter the article being inspected, it is a highly valuable technique that can save both money and time in product evaluation, troubleshooting, and research.
NDT methods may rely upon use of electromagnetic radiation, sound, and inherent properties of materials to examine samples. Common NDT methods include ultrasonic, magnetic-particle, liquid penetrant, radiographic, visual inspection, eddy-current testing, etc.,
Birth of NDT
History of NDT recognises the first ever NDT method developed to be the oil & whiting method, in the later part of 18th century, to check the railroads, which is in principle similar to the present day LPI method.
In today's scenario, when natural resource are fast depleting, we are forced to optimise the usage of available material and ensure that they are fit for the purpose. So precise identification and measurement of defects, characterisation of metals and non metals are becoming increasingly important. Hence newer and advance NDT methods are being evolved to ensure safety, reliability and soundness of materials.
NDT – the industry favourite
Apart from helping the inspection engineers in quick and accurate results, NDT is also much liked by the industry executives / management for the reasons of economy and investment friendly returns that it provides. It assures the sound state of the plant / work place / equipment and also enables swift QC processes that lead to quicker deliveries and revenue.
The advantages of NDT are:
- No damage to the material being inspected
- Access to interior/unapproachable areas of a component
- Safe to execute
- Based on physical principles and hence absolute recording of results possible. No need for 'opinion' based findings.
NDT supports various kinds of engineering activities like mechanical, automotive, civil, electronics and many others. Hence it is utilised by a gamut of industries that deal with manufacturing processes using any or all of the above mentioned engineering process and further beyond.