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What is ultrasonic inspection? Part 1

Ultrasonic testing
A technician inspecting using phased array equipment to inspect a weld.

So what is Ultrasonic inspection?


UT Scan
Ultrasonic training using a Sonatest D-10


Well in the simplest terms it is the use of a sound wave echo to look inside of a material.

What!? How can we do that? I hear you ask.

Well here is the low down.

What is the primary goal of any non-destructive testing method?

It is to find any defects in a material without damaging it.

An expectant mother goes for an ultrasound to check the health of her baby.

A sound wave passes into the mother using a hand held thingmabob. These sound waves bounce off the baby and get picked up by the same hand held thingmabob that sent them in there.

Then by technical wizardry the returning sound wave is turned into a picture. A sonographer will then analyse this while it is cooed over by the expectant mother.

The same happens when a technician uses a sound wave to look inside a material. What are we looking for? Well various defects that can occur in manufacturing or when the material is in service.

When we fuse two pieces of metal together various things can go wrong.

Inclusions of slag in a weld can weaken it. The root of the weld might not fuse together in the correct fashion. If the weld cools too rapidly it can crack.. In this instance, ultrasonic sound waves analysis will detect these.

But what is ultrasound? Sounds sexy huh! It sounds like the best kind of sound out there.

“Hey man are you using sound over there?”

“No way, sound is so last year! We are using ULTRASOUND!!”

So, sound is usually made when something vibrates.

The faster is vibrates the higher the frequency of the sound.

The higher the frequency the higher the note sounds.

The human can hear sounds in what is know as the audible sound range.

This is between 16Hz and 20000Hz.

Unless you are a teenager.

If you are a teenager then the audible sound range appears to be zero.

Right back to the point.

When the frequency of sound increases above the level of human hearing we call it ultrasound.

So from 20000Hz up to 10Mhz.

Its sound in this frequency range that is used in non-destructive testing.

See? Simple!

In the next post we will have a look at the thingmabob that makes these mystically high sounds.

Ok, they are not mystical but they could be ok!? Don’t judge me. P.s. the thingmabob is not its real name.

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