Practical Non Destructive Testing Pdf Free Download

[Giorgina Makara]

Testingis an integral part of equipment maintenance. It is essential to evaluate the materials, components, design, and structure of your products and assets. Based on the state of the tested component after the testing is done, the procedures can be classified under either destructive testing or non-destructive testing.

If the component gets damaged or destroyed during the testing process, the testing method employed is described as destructive testing. In contrast, non-destructive testing is carried out without causing damage to the tested piece of equipment.

Testing methods that do not compromise the structural integrity of the parts being tested are called non-destructive tests (NDT). NDT employs various inspection techniques to evaluate the components, individually or collectively. It uses different principles in scientific fields (physics, chemistry, and mathematics) to test the components.

Instead of cutting it open, the piston can be tested with radiography. We can use ionizing radiation (X-rays, gamma rays) to detect defects or material degradation in the component. If it passes the test, the component can still be used. This is a form of non-destructive testing.

NDT is used to test the quality of components and machine condition before or during their active use. Non-destructive testing is used for condition assessment and quality control in a wide range of industries, which include (but are not limited to):

The distinct advantage of NDT is the reusability of the tested components. On top of that, non-destructive testing can often be employed on components that are still in operation. Devices and testing equipment used to conduct most methods of NDT are compact and portable. This makes it easier to test components in a working machine.

Visual inspection is by far the simplest non-destructive testing method. It is often classified as a part of routine maintenance work. Maintenance professionals use it on a daily basis to check for common signs of wear and tear. Depending on its application, it may or may not be conducted while the machine is in operation.

In its most advanced application, visual testing is combined with machine learning algorithms. This is only economical for product quality testing where there is a large volume of standardized components that need to be inspected.

Ultrasonic testing is based on the principle of propagation and reflection of high-frequency sound waves. It can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more. Testing is performed with an ultrasonic receiver and transmitter.

Ultrasonic soundwaves are transmitted through the tested material. The sound propagates through the component and reflects off the rigid surface placed at the opposite end of the transmitter. The time required to transmit and receive the sound waves is measured. The variance in the time at different sections of the component can be used to identify the defects in the material.

Different types of ultrasonic testing modes can be used to identify different defects, cavities, material deterioration, etc. Mechanical components that operate with heavy workloads are regularly tested with ultrasonic testing. A good example of ultrasonic testing is testing to identify defects and deformation in the wheels and axles of railway carriages.

Vibration analysis is a commonly used method to monitor the condition of rotating components in operation. The underlying principle of vibration analysis is that different materials have different vibration signatures.

Aside from a vibration meter device, there are different types of sensors that can be installed to measure vibrations. They are designed to measure displacement, velocity and acceleration, misalignments, looseness, and similar faults that rotating equipment can experience.

Magnetic particle testing is used to detect near-surface defects in ferromagnetic materials. The test piece is kept between the two poles of an electromagnet and a suspension of magnetic particles is poured over the test piece. This testing method is based on the effect of a magnetic field on ferromagnetic materials.

Magnetic particle examination can be performed with a wet horizontal MPI machine or handheld devices like magnetic yokes. National Board Inspection Code (NBIC) specifies MT may be used for the inspection of items such as:

During a penetrant inspection, a liquid dye penetrant is sprayed over the area to be tested and left untouched in the open air. The time required to leave the penetrant to work (a.k.a. dwell time) on the surface could be anywhere from 10 minutes to an hour. It depends on the characteristics of the tested material.

The liquid penetrant is removed from the work surface with a dry lint-free cloth. A light application of developer liquid is sprayed over the tested work surface. If there are defects on the tested surface, the liquid dye will be brought to the surface after the developer liquid is applied.

When electric voltage is applied across a coil, it generates a strong magnetic field. When metal is introduced inside the coil, the magnetic field fluctuates and the current flowing through the circuit increases. This is due to the eddy current flow inside the metal.

This type of nondestructive examination is performed with eddy current testing equipment, which can include electromagnetic probes, current flaw detectors, ECT conductivity meters, and other accessories. These tools are used to perform different types of electromagnetic inspections, such as surface scanning, subsurface inspection, weld inspection, fastener hole inspection, tube inspection, heat treatment verification, and metal grade sorting.

X-rays and CT scans can be used in industrial radiography to see the detailed images of the tested material. X-rays are passed through the components and the image can be imprinted on film or viewed in real-time using a computer.

Computed tomography technology can also color-code the various objects according to the composite metals or the cavities present. X-rays can be sent from different angles on the test object to gain images with higher details. X-ray testing and computed tomography fall under the broader category of radiographic testing, where different types of ionizing radiation can be used.

The seven types of NDT described in the previous sections are commonly used across different industries. However, there are many more NDT techniques employed in scientific laboratories and industry operations like:

For instance, with a little bit of training and a good PM checklist, some visual inspections can be performed even by novice technicians. In contrast, industrial computed tomography requires technicians with specialized knowledge of radiology and equipment used in the testing process.

In most other scenarios, testing is performed by the maintenance team. In some instances, OEMs can be responsible for conducting NDT tests according to a predefined schedule. In both scenarios, organizations can use CMMS software to schedule testing intervals and record testing data. When testing is performed by retrofitting machines with sensors, CMMS can be used to analyze incoming real-time data and automatically trigger alerts when it spots any deterioration signs.

The American Society for Nondestructive Testing (ASNT) is the pioneer in providing accreditation to qualified technicians. They offer various NDT training courses, conduct exams, issue certificates, and accredit different organizations. The details are provided on the ASNT website.

As the adoption of predictive and prescriptive analytics continues to grow, so will the usage of NDT. Algorithms need a high volume of accurate machine condition data to predict failures and offer solutions. There are no better ways to do that than through condition-monitoring sensors and non-destructive testing.

Industrial computed tomography for advanced industrial non-destructive evaluation is a complex technological area, encompassing nuclear radiation detectors, mechanical engineering, computational mathematics and radiation physics. Additionally, the cost of applying this technology may be prohibitive. This guidebook provides an introduction to gamma computed tomography for non-destructive evaluation imaging in the simplest configuration. It is intended to be of use to the non-destructive testing community, currently practicing conventional radiography techniques. It provides clear information on the relevant practical issues and problems related to setting up computed tomography for industrial non-destructive testing and establishes a basis for understanding the intricacies of the technology.

Dazhu Yang, Deputy Director General and Head of the Department of Technical Cooperation, and Ezio Tuberosa, President of AIPnD, shake hands following the signing of the Practical Arrangements. (Photo: O. Yusuf/IAEA)

On 10 September, the IAEA and the Italian Society for Non-Destructive Testing Monitoring Diagnostics (AIPnD) signed Practical Arrangements, establishing a framework for future cooperation in the application of non-destructive testing (NDT) between the two organizations. The first such Arrangements developed between the Agency and the AIPnD, the document covers a period of three years, from 2019 to 2022.

The Practical Arrangements were signed on behalf of the IAEA by Dazhu Yang, Deputy Director General and Head of the Department of Technical Cooperation, and by Ezio Tuberosa, President of AIPnD, who was joined by the Resident Representative of Italy to the IAEA, HE Maria Assunta Accili Sabbatini, and by Daniele Bisi and Aldo Canova, Vice President and General Secretary of AIPnD, respectively.

Non-destructive inspection technicians work with engineers to define and implement tests that locate and characterize material conditions and flaws that might otherwise cause planes to crash, reactors to fail, trains to derail, pipelines to burst and a variety of less visible but equally troubling events.

3a8082e126