Nondestructive Testing

Nondestructive testing (NDT) includes an extensive range of analysis techniques that are used to assess the physical attributes of a component or a system. Some of the most popular Nondestructive testing (NDT) methods include ultrasonic, radiographic, magnetic particle, liquid penetrant, eddy current, visual, leak testing, mechanical, welder/welding procedure qualification, Positive Material Identification, Hydrostatic, Ground Penetrating Radar, and Digital Imaging.

With the success rate of Nondestructive testing (NDT) methods, they have become an integral part of the forensic engineering, mechanical engineering, electrical engineering, civil engineering, systems engineering, medicine, and art. The three main things that play major role during Nondestructive testing are (1) Electromagnetic Radiation, (2) Sound, and (3) Inherent Properties of Materials to be tested.

The application areas where Nondestructive testing (NDT) is used include automotive, aviation, construction, power plants, manufacturing, railways, military, and naval industry. NDT has been proved extremely beneficial for product evaluation, troubleshooting, and research as it does not affect the object that being tested in any way. Some of the applied examples of Nondestructive testing are given below:

Weld Verification

The NTD or Nondestructive testing techniques used in welds testing include as industrial radiography using X-rays or gamma rays, ultrasonic testing, liquid penetrant testing or via eddy current and flux leakage. All these tests help to identify cracks in the surface area which are not visible to the naked eye. Welding technique is basically for joining metals, usually the metal joints or connection is prone to extra wear and tear during the product life therefore it is very important to ensure that welding is properly done and all the testing procedures are carefully conducted.

Radiography in Medicine

Radiography has been widely used to image parts or functions of the body. Some elements of human body act in response to radiographic inputs like x-rays or magnetic resonance which help the medical professionals to study the functionality of the human body. It is used to detect bone fractures and diseases and also examine the interior of mechanical systems. Radiography is majorly used in many types of medical treatments and due to its accurate and efficient results has become an integral part of the medical science.

Abcndt.com use reliable non-destructive and destructive testing methods to increase customer satisfaction and lower manufacturing costs. They cater to industries, such as automotive, aviation, construction, power plants, manufacturing, railways, military, and naval industry. ABC Testing Inc. have Certified Welding Inspectors (CWI) doing welding inspections for steel, aluminum, specialized metals like Inconel, Monel and NiAlBrz, and many other alloys. Browse through www.abcndt.com for more information.

Points To Remember For Home Improvement

After many years of living in the same house, there may be a time when the house will need a facelift. Some parts of the house may need some renovation, while other parts may need some remodeling. All this work is collectively called home improvement of the house.

A home improvement project has to be thought of clearly to be successful without any confusion. Consider what part of the work you think you can do by yourself, without the help of the constructor, like perhaps the painting of the newly added room. You can also lower home improvement costs by considering less expensive alternatives when additions are being designed. For example, choose between a prefabricated fireplace unit and a traditional masonry. Plan all the work that you can do, before giving the contract to the constructor as additional changes made after the contract only leads to additional charges. It is always better to schedule your home improvement schedule to be completed in an off time period of the year. Like it is cheaper installing central air conditioning in winter and not in summer!

If you intend to take on the home improvement project on your own, you have to make sure you have the essential tools for the respective jobs. It is also necessary to be experienced in using the tools, lest you end up with injuries if the equipment is not used correctly. You may find a few home improvement tips on the Internet; but these tips are only feasible for minor repairs. However, it is very important that you have the skills to do the home improvement job. You should undertake any intricate work or a job that needs a high degree of craftsmanship only if you possess the necessary competence. However, it is always better to hire a professional as they will supervise the job from start to finish, and do it at a much better time than you would have taken to do it on your own!

The first thing that has to be done to get a good contractor is, to look around for a good contractor! Good contractors have a fine reputation, and do not mind entering into a contract. It is always better to have an idea of what home improvement you want to be done, before looking for a contractor. Then get recommendations for contractors through friends, neighbors and co-workers. It is always better to approach not one, but 3 to 4 contractors to get estimates of the job to be done. On meeting them, get written estimates for the same work from all of them, to make comparisons. If you want, you can also get references from them, to be contacted. You can then approach the references to find out how the contractors work is.

Once you are satisfied with the contractor, you have to get a written and complete contract. Include the contractors name, address, the total cost of the job, the start and completion date and a description of the project, including the materials to be used, the changes in the order and a written statement giving you the right to cancel the contract within three business days. Add a broom clause in the contract that makes the contractor responsible for all cleanup work of the job, including spills and stains. If you feel that there is something wrong with the contract, it is better to contact an attorney before signing.

Once the contractor is chosen, you have to choose your finance options. If you have cash, then it is fine. Otherwise, you will have to get a home improvement loan that are available in many banks. Consider the interest rates and the benefits of various banks before actually settling down to a choice for your home improvement project. Once the loan is sanctioned, it is always better to avoid paying cash to the contractor. Instead, pay by check and try to limit the down payment. Then make payments during the length of the project contingent on the completion of a definite amount of work. Always keep the final payment and the signing of the affidavit till you are satisfied with the work done, and that you are sure that all the subcontractors and suppliers have been paid.

Instead of getting the contractor to buy all the material, you can supply the materials. In this way, you can shop for materials that are on sale. You are likeable to find building supply stores having various items like tile or wood flooring on sale at one time or the other, due to overstocks or any other factor. If you have the time you could also consider doing the light demolition, painting, garbage removal and landscaping work of the home improvement project. By doing so, you save the money you would have had to pay for labor. Keep all these home improvement tips in mind as it is greatly going to help you in your next major home improvement project!

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Basic Principles of Ultrasonic Testing

Ultrasonic Testing (UT) uses high frequency sound energy to conduct examinations and make measurements. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more. To illustrate the general inspection principle, a typical pulse/echo inspection configuration as illustrated below will be used.

A typical UT inspection system consists of several functional units, such as the pulser/receiver, transducer, and display devices. A pulser/receiver is an electronic device that can produce high voltage electrical pulses. Driven by the pulser, the transducer generates high frequency ultrasonic energy. The sound energy is introduced and propagates through the materials in the form of waves. When there is a discontinuity (such as a crack) in the wave path, part of the energy will be reflected back from the flaw surface. The reflected wave signal is transformed into an electrical signal by the transducer and is displayed on a screen. In the applet below, the reflected signal strength is displayed versus the time from signal generation to when a echo was received. Signal travel time can be directly related to the distance that the signal traveled. From the signal, information about the reflector location, size, orientation and other features can sometimes be gained.

Ultrasonic Inspection is a very useful and versatile NDT method. Some of the advantages of ultrasonic inspection that are often cited include:

• It is sensitive to both surface and subsurface discontinuities.
• The depth of penetration for flaw detection or measurement is superior to other NDT methods.
• Only single-sided access is needed when the pulse-echo technique is used.
• It is highly accurate in determining reflector position and estimating size and shape.
• Minimal part preparation is required.
• Electronic equipment provides instantaneous results.
• Detailed images can be produced with automated systems.
• It has other uses, such as thickness measurement, in addition to flaw detection.

As with all NDT methods, ultrasonic inspection also has its limitations, which include:

• Surface must be accessible to transmit ultrasound.
• Skill and training is more extensive than with some other methods.
• It normally requires a coupling medium to promote the transfer of sound energy into the test specimen.
• Materials that are rough, irregular in shape, very small, exceptionally thin or not homogeneous are difficult to inspect.
• Cast iron and other coarse grained materials are difficult to inspect due to low sound transmission and high signal noise.
• Linear defects oriented parallel to the sound beam may go undetected.
• Reference standards are required for both equipment calibration and the characterization of flaws.

The above introduction provides a simplified introduction to the NDT method of ultrasonic testing. However, to effectively perform an inspection using ultrasonics, much more about the method needs to be known. The following pages present information on the science involved in ultrasonic inspection, the equipment that is commonly used, some of the measurement techniques used, as well as other information.

Leak Testing

Leak testing equipment is used to measure the escape of liquids, vacuum or gases from sealed components or systems. Some configurations require a separate leak detector or sensor as an input. Such types of leak testing equipment are often equipped with various other components such as pumps, calibrators, gauges and cases. Output options include analog voltage, analog current, frequency or modulated frequency, and switch or alarm signal. Some leak testing equipment includes an analog front panel with potentiometers, dials, and switches. Other features a digital front panel that is set up with a keypad or menus. Leak testing equipment with a serial interface, a parallel interface, and/or integral application software is also available.

Leak test method is an important specification to consider when choosing leak testing equipment. Methods include bubble testing, colorimetric development, electronic gas detection, mass flow, mass spectrometry, and hydrogen leak detection. Bubble testing is used for applications which do not require high sensitivity. A pressurized test object is submerged in a water tank so that the emergence of bubbles indicates a leak. Colorimetric development uses a chemical developer which reacts with the leaking fluid, causing a visible color change to occur at the place of leakage. Leak testing equipment that uses electronic gas detection pressurizes the test object with a tracer gas so that a sniffer probe can be used to find the leak. Mass flow devices direct the leakage across a heating element. The temperature change produces an output voltage proportional to mass flow. Mass spectrometers are used with helium leak detection. Leak testing equipment that is designed to detect hydrogen leaks is also available.

Leak testing equipment may use test methods such as pressure differential (decay) and ultrasonic leak detection. A pressure decay test involves the initial inflation of the test object and the establishment of a reference pressure. After a designated amount of time, the pressure is measured again and the initial and final measurements are compared. The change in pressure can be used to calculate the leak rate given the internal volume of the device. Ultrasonic leak detection (sonic flow, choked flow) involves the turbulent flow of a fluid across a pressure boundary to create acoustic waves. These waves are transmitted through the medium of the fluid itself, through the containment structure, or through the air surrounding the containment structure. Leak testing equipment that uses other test methods is also available.