NDT - German Jordan University Faulty of Engineering...

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Page 1 of 5 German - Jordan University Faulty of Engineering Non-Destructive Testing (NDT) Unit Experiment No. 7 “Introduction to NDT” Practice preformed by: Eng. Jehad T. Ali Objectives . - To be familiar with NDT terminology and methods. - To Conduct an NDT test and obtain results Introduction: A general definition of nondestructive testing (NDT) is an examination, test, or evaluation performed on any type of test object without changing or altering that object in any way, in order to determine the absence or presence of conditions or discontinuities that may have an effect on the usefulness or serviceability of that object. Nondestructive tests may also be conducted to measure other test object characteristics, such as size; dimension; configuration; or structure, including alloy content, hardness, grain size, etc. In industry, nondestructive testing can be effectively used for the: 1. Examination of raw materials prior to processing 2. Evaluation of materials during processing as a means of process control 3. Examination of finished products 4. Evaluation of products and structures once they have been put into service NDT is looking for discontinuities in materials that upon evaluation will be either accepted (pass) or rejected (fail), the process of evaluation of the results requires skilled personnel, special equipment and test materials, means of calibration, test procedures and evaluation standards (acceptance criteria). NDT depends on well-known physical principles applied in a manner that any material property-change will impose an effect in a media that can be observed. NDT methods are divided into two main groups depending on the examined section of the material: - Surface Test Methods, where only the part’s surface and sub-surface is tested (in this experiment we will use Magnetic Particles Testing Method, MT) - Volumetric Test Methods, where the entire volume of part is tested (in this experiment we will use Ultrasonic Testing Method, UT) It should be clarified that NDT methods have limitations, these limitations are due to the test itself, but such limitations can be easily overcome by using more than one test method Part 1: Surface Test Methods Magnetic Testing: when a magnetic filed is generated, invisible lines of equal magnetic forces are formed between the north and south poles of the magnet. These lines are continuous and close to each other, and if these lines are crossed; they tend to “Jump” over that obstacle creating what is called a Magnetic Flux Leakage . Magnetic filed requires a conductor, tested materials must be able to be magnetized (like iron and most of its alloys). Aluminum requires very high magnetic field to be
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NDT - German Jordan University Faulty of Engineering...

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