The Meaning Of Non Destructive Testing

By Author: Jo Alelsto
Total Articles: 405
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Non destructive testing (NDT) involves several methods of identifying damage and flaws and is an essential procedure in industrial plant inspection. NDT is an engineering process of testing materials without altering them. There is no need to cut open a piece or scratch its surface when a nondestructive test is done. As a matter of fact there are numerous ways to test materials without having to alter them in anyway. This is important in various situations wherein the aesthetic appearance of a material cannot be compromised by testing and when the material in concern is hazardous. This process is usually part of industrial maintenance which is done regularly to ensure that the plant is in fit working condition. The techniques used will be used to make decisions whether to suspend operations and do preventive overhaul.

The purpose of NDT is to find out the probability of an existence of damage and flaw, as well as pin it down depending on the outcome of measurement. The methods for testing material flaw do not measure parameters like temperature and pressure.

NDT is a measurement of a physical property ...
... or effect from which the presence of damage or irregularity can be inferred. It is not a measurement of a fixed parameter such as temperature or pressure. The tests are conducted without impairing the capability of the equipment, securing its usefulness in the future. An interesting fact is that it uses various methods that are commonly found in medical applications. Use of x-rays, endoscopes, and ultrasound scanning are all applied in the industrial scene to examine objects. It must be noted that back in the 1940s, medical x-rays were utilized to examine objects. There are also techniques used in other fields such as radar and sonar, commonly used to map river beds or ocean bottoms but can also be used to inspect dams.

The goal of NDT is to find out if there is something wrong with a material and is usually done even before defects are detected. NDT is also employed to check the performance of a component, to find out if it works according to specifications that dictate how it must work. However, unlike other tests, NDT is a collection of methods that will not subject an object under damaging elements (high temperature, high pressure, and strong electric currents).

So, how can one distinguish between nondestructive testing and destructive testing? The trouble lies in the theory that anything you do on an object will alter it in any way. Even exposure to radiation can cause changes in the atomic or molecular level, changes that aren't visible to the human eye. According to some experts, these seemingly negligible changes may or may not affect the material depending on different factors, such as frequency of testing. Some experts think that there is no method that is completely nondestructive. For instance, if a means to test a material is by taking a sample of it, will the loss of mass not affect the future usefulness of the object? Although removal of minute amounts of the material will not cause damage, the act of removal itself forfeits non-destructiveness.

Nonetheless, the general idea of NDT is to render the sample object or material for testing still useful after tests are made. If tests render the materials to be no good for any use afterwards, then tests are destructive. Also, tests become destructive when materials are discarded afterwards, regardless of whether the process does not harm the integrity of the material.

NDT methods are not only bound to check on cracks and structural anomalies but are also concerned with other irregularities that may affect lifespan of a material and its susceptibility to damage. For instance, material identification checks the elemental content of objects using radiation scanning technology. This kind of test determines the presence of impurities that will affect the functioning of a material.
Jo is a writer for 'Inspection Consultants (Incon)', an independently owned and managed Non Destructive Testing (NDT) establishment located in Cheshire that has been giving a complete NDT program to their clients for twenty five years. In case you are looking for fully equipped and qualified mobile technicians who can provide a full range of Non Destructive Testing services both onsite or at their base station then have a look at Inspection Consultants (http://www.incon.co.uk).