Non-destructive testing (NDT) is a method of testing the integrity of welds without having to destroy them. There are various types of testing that fall into the category of NDT, one common choice by manufacturers being ultrasonic testing:
What is it?
Ultrasonic testing is an NDT method for weld inspections. This type of NDT uses ultrasonic sound waves, at a much higher pitch than that at which a human can hear. The most common range for the frequency of ultrasonic testing is between 500 KHz and 20 MHz. The ultrasonic sound waves are sent through the material in order to check for cavities or weaknesses within the weld. This type of NDT is the method of choice when it comes to thick materials with low accessibility. It can be used to check non-ferrous and ferrous materials for discontinuities and is the best option for finding the smallest of discontinuities.
How does it work?
There are several components that make up the system for ultrasonic testing. These include the receiver, transducer and display. The receiver creates electric pulses, while the transducer creates the ultrasonic sound waves used to locate the discontinuities within the material. The display devices will show any discontinuities found by the ultrasonic energy. The pulses will be sent though the material, bouncing off any discontinuities. As the pulses bounce back and forth from the discontinuity, they will create and image on the display indicating that a discontinuity is present.