Chapter 5-STANDARDS and TESTING MATERIALS PDF

Significance of Testing Materials The testing of materials may be performed with one of the three points below: (1) to supply routine information on the quality of a product- commercial or control testing, (2) to develop new or better information on known materials or to develop n...

Significance of Testing Materials The testing of materials may be performed with one of the three points below: (1) to supply routine information on the quality of a product- commercial or control testing, (2) to develop new or better information on known materials or to develop new materials - materials research, (3) to obtain accurate measures of fundamental properties of materials - scientific measurement. 1  Commercial Testing Commercial testing is concerned with;  checking the acceptability of materials with respect to the specifications,  control of production. Generally, the type of the test has been specified, standard procedures are used, and the object is to determine whether the properties of a material fall within the required limits. 2  Materials research Materials research is done in order to; (1) obtain new understanding of known materials, (2) discover the properties of new materials, (3) develop meaningful standards of quality or test procedures. Scientific testing Scientific testing is the accumulation of orderly and reliable informations on the fundamental and useful properties of materials. 3  What is the difference between experiments and tests? Experimentation means that the outcome is uncertain, that new insights are to be gained. Testing is a more defined procedure, with the limits and results are clear. 4  Materials testing may be carried out on; 1. Full size structures, members, or parts, 2. Models of structures, members, or parts, 3. Specimens cut from finished parts, 4. Specimens of raw or processed materials. 5  Destructive testing & Non-destructive testing  Destructive testing is carried out until the specimen’s failure. These tests are generally much easier to carry out, yield more information and are easier to interpret than non-destructive testing.  Non-destructive testing is the type of testing that does not destroy the test object. It is vital when the material in question is still in service. 6 What is the Difference Between Destructive and Non-Destructive Testing? Destructive testing destroys or changes the part in some way such that even if it passes the test it is no longer fit for service. Examples might be tensile testing, 3 point bend test or macro sectioning. NDT does not destroy or change the part such that it is still fit for service if it passes the test. Nondestructive testing (NDT) retains a significant advantage over destructive testing because it covers more ground and saves on material costs. With NDT, analysts can avoid damaging assets and find more flaws in the process. Destructive testing is ultimately more expensive and wasteful, as inspectors must damage viable materials that could have been used during normal operations. Moreover, destructive-means testing is also less efficient than NDT in terms of inspection times, involving manual steps that take longer and require more effort than the streamlined processes NDT can offer. 7 Non-destructive testing (NDT) is a testing and analysis technique used by industry to evaluate the properties of a material, component, structure or system for characteristic differences or welding defects and discontinuities without causing damage to the original part. NDT also known as non-destructive examination (NDE), non-destructive inspection (NDI) and non-destructive evaluation (NDE). Current NDT test methods include: Acoustic Emission Testing (AE) Electromagnetic Testing (ET) Ground Penetrating Radar (GPR) Laser Testing Methods (LM) Leak Testing (LT) Microwave Testing Liquid Penetrant Testing (PT) Radiographic Testing (RT) Thermal/Infrared Testing (IRT) Ultrasonic Testing (UT) Visual Testing (VT) 8 What are the Advantages of using NDT? There are a number of distinct advantages; the most obvious of which is that the pieces being tested are left undamaged by the process, allowing for an item to be repaired rather than replaced should any problems be found. It is also a very safe testing method for operators, with most techniques being harmless to humans, although some types of test - such as radiographic testing - still need to be conducted under strict conditions. This testing technique can also help prevent injury or fatalities by ensuring structures, components and machinery is safe. Non-destructive testing is also a very accurate way of inspection since the tests are repeatable and a number of tests can be used together to correlate results. These testing methods are also economical. Unlike destructive testing, NDT is cost effective as it can prevent the need to replace an item before malfunction occurs without destroying the piece itself. https://www.twi-global.com/technical-knowledge/faqs/what-is-non-destructive- testing#WhatistheDifferenceBetweenDestructiveandNonDestructiveTesting 9 This testing technique also offers operators peace of mind, knowing that equipment is functioning as it should, preventing future accidents and determining any measures that can be taken for life extension. It is also useful for testing of welds and verification of welding procedures to ensure that a welding process has been completed to the correct specification within the bounds of quality control, for example to make sure that the base metal has reached the correct temperature, cooled at the specific rate and that compatible materials have been used to prevent welding defects. 10  Field Tests & Laboratory Tests  Field tests usually lack the precision of similar tests conducted in the laboratory,  However, some tests cannot be made in the laboratory and others cannot be made in the field. 11  Standard Specifications & Standardizing Agencies  Specification: A precise statement of a set of requirements, to be satisfied by a material, product, system or service. It is desirable that the requirements, together with their limits, should be expressed numerically in appropriate units.  A standard specification for a material is the result of agreement between those concerned in a particular field and involves acceptance for use by participating agencies. 12 The majority of testing methods for material properties are standardised. Each major country possesses its own standards institutions. The standards for a particular test procedure, for example the testing of metals in tension, will be similar from one country to another but may differ on some points of detail such as the specific dimensions of test pieces 13 It could be about making a product, managing a process, delivering a service or supplying materials – standards cover a huge range of activities. Standards are the distilled wisdom of people with expertise in their subject matter and who know the needs of the organizations they represent – people such as manufacturers, sellers, buyers, customers, trade associations, users or regulators. For instance, Quality management standards to help work more efficiently and reduce product failures. Environmental management standards to help reduce environmental impacts, reduce waste and be more sustainable. Health and safety standards to help reduce accidents in the workplace. Energy management standards to help cut energy consumption. Food safety standards to help prevent food from being contaminated. IT security standards to help keep sensitive information secure. 14 15 16