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.