A descriptive term, Non-destructive Testing, is a range of inspection methods or techniques that are used to determine some specific characteristics of materials without even damaging those exact materials during the course of the testing process. In simpler terms, it is used for the examination or inspection of materials and its components in a matter that enables the materials to be examined without being altered or destroyed. A non-destructive testing equipment is used to find, identity, size, and locate the surface and the subsurface defects and errors.
Non-destructive testing plays an important role in the smooth functioning of our everyday life, as it ensures both safety and reliability. Some of the common examples that are inspected by NDT are refineries, motor vehicles, pipelines, aircraft, power stations, buildings, oil platforms, bridges, spacecraft, and trains.
It is a QA management tool which can help in providing impressive outcomes if and when it is used in an accurate manner. It requires a precise understanding of the numerous available methods, their limitations and capabilities, specifications needed for executing the tests, and the knowledge of the relevant standards.
Materials, equipment, or products which succumb under the failure of achieving the requisite designing requirements or the expected life owing to undetected defects might require some costly repair options or early replacement. These defects can also be because of unsafe conditions or disastrous failures or due to the loss of revenue because of the unplanned plant shutdown.
At each stage during an item’s construction, non-destructive testing can be applied. The materials and welds can either be rejected, approved, or repaired or can be inspected using non-destructive testing equipment. NDT techniques can be used following this to monitor the feasibility of the item all throughout its design life cycle.
Calibration of NDT
Like any other test and measurement equipment, the NDT equipment to needs to be calibrated in a periodic fashion in order to maintain its level of accuracy. For a piece of non-destructive testing equipment, calibrations are done using various precision test blocks that helps to stimulate the conditions and serve as reference standards. It is worth noting that different forms of test blocks can simulate different types of conditions. When selecting an NDT equipment here are the key pointers to keep in mind and consider:
- Understanding the parameters, such as flaw detection, thickness, etc., for which the material is being tested for.
- Understanding whether the equipment requires specialized training.
- The accessories which are required, like couplant, transducers, calibration blocks, etc.
- Understanding whether there are any professional standards which are needed to be adhered with.
The Value of NDT Equipment
Over the years, the plant examination industry has come to recognize the value of the NDT techniques in curbing down both time and money which are spent in research, product evaluation, and troubleshooting. The successful and continuous application of NDT firmly depends on personnel training, experience, as well as integrity.
The very first stage of NDT is a comprehensive visual examination, which is of great importance, however, some of the more in-depth techniques of NDT can let an experienced inspector know what needs to be repaired. These techniques include Magnetic Particle Testing, Ultrasonic Testing, and Liquid Penetration Testing. It is typically and preferably used for the following reasons:
- For preventing accidents and curbing down costs.
- To ameliorate product reliability.
- To determine approval of a given requirement.
- To provide information on the repair criteria.
Non-destructive testing equipment can even be used for the determination of an effective lifetime of plant and equipment by equating exactly how much deterioration has occurred in between each and every testing interval.