Non-Destructive Testing Quiz | People

Quiz Answer Key and Fun Facts

1. Probably the most basic inspection technique is visual testing. Which of these items would a visual inspector most likely not use to carry out his duties?

Answer: Rubber mallet

Visual inspection is simply the act of using your eyes to check over an item to ensure it is manufactured properly. There are several items that may need to be used in visual inspection to enhance the visibility of the item under test. Bright lights may need to be used in dark locations, such as the inside of a storage tank or the bottom of a sewage pit. Magnifying glasses may need to be used to identify small defects that may be difficult to see with the naked eye. Measuring devices may have to be used to quantify the length, depth or width of a defect to compare to acceptance standards. Visual inspections rarely require the use of other tools in order to carry out the inspection. Sometimes, tools such as buffing wheels, grinders or scrapers may need to be used to clean the item of foreign materials before visual inspection takes place.

Other times, the inspector may not be able to access an item, so he may need to use other equipment to inspect things. Examples of this would include using a remote camera to see inside a storage tank that may hold a toxic atmosphere or using a borescope to see inside components of a jet engine.

2. Radiography, or x-ray testing, is similar to what a doctor would use to diagnose an illness in a person. The trained industrial radiographer places a slide of film behind an item under test and exposes the specimen to strong x-rays to see inside the item. Very commonly, welds used to fuse metal objects together are subjected to x-ray inspection. Which of the following isotopes are most commonly used in industrial radiography?

Answer: Iridium 192

Iridium 192 and Cobalt 60 are two common radioactive isotopes which can be used to perform industrial radiography. As described in the question, industrial x-ray testing is principally the same as medical or dental x-ray testing. An item is placed in front of a piece of film which is then bombarded with gamma rays from iridium or cobalt.

The film is exposed and an image of the internals of the test specimen is revealed on the film. The technician can then interpret the results of the film to determine if there are any defects such as cracks or voids which would limit the usefulness of the item. There are many reasons why x-ray testing is only performed by trained and experienced technicians. Exposing personnel to radioactive materials is dangerous and can cause physical burns or lead to cancer.

When performing x-ray testing, it is important that the area is barricaded with signs that clearly state that radioactive testing is in progress. The technician also has to be skilled to calculate the parameters of exposing the object to the x-rays and in how to set up the test. Radiography is a valuable tool to the industrial inspector, particularly in the inspection of welding of high-pressure items. X-ray testing can also be used to identify corrosion or erosion in pipelines, valves or other industrial components.

3. Penetrant testing, or PT, is an inspection technique where a dye is applied to a welded item. If any defects, such as cracks or pinholes are in the weld, the dye will seep into the defect so the inspector can see them easier. Which term best describes why the dye seeps into a defect?

Answer: Capillary action

All items have surface tension, and when that surface tension is broken, liquid will flow into that break via a tendency called capillary action. If there is a defect in the weld, the dye will seep into the bottom of the defect. The inspector can spray a powdered medium onto the tested surface which will expose the dye, showing where the defects are. Penetrant Testing is a quick and economical technique to enhance the visual inspection of a welded component.

There are many benefits to Penetrant Testing.

The inspector doesn't require extensive training, the materials are cheap and the results are gathered rather quickly. The disadvantages are that the defect has to opened to the surface for the dye to penetrate into it, the item has to be easily accessible to the inspector and the defects can be masked by oil, dirt or paint. Surface preparation is very important in performing penetrant testing.

4. Magnetic particle testing, or MT, is another inspection technique that helps the examiner see defects in welds. The principle here is simple; magnetic fields are induced into a specimen and metallic flakes are applied to the weld. If there are any breaks in the magnetic field, the metal flakes will accumulate into the crack or defect. Which of these items might be inspected utilizing the MT inspection techniques?

Answer: Cast iron forgings

Because the most important part of magnetic particle testing is being able to induce the magnetic flux into the specimen, the piece has to ferrous. Non-ferrous materials are not magnetic, therefore this type testing would not apply. Magnetic particle testing has advantages over penetrant testing because the technique will pick up subsurface defects, where the defect has to be open to the surface in PT. MT is a fast test where many linear feet of welds or many items can be inspected in a short period of time. Like PT, MT requires a clean surface for best results.

5. Just like the obstetrician, the industrial inspector also uses ultrasound in performing his duties. Similar in theory to the medical application, industrial ultrasound can be used as an imaging solution to see inside an item. Many pregnant women have learned the health or sex of their babies using ultrasound, and many an inspector has identified defects in welds using the same technique. What is the name of the device that the inspector, or the doctor for that matter, uses to scan across a surface to see what's inside?

Answer: Transducer

A transducer is simply a device that converts one form of energy into another form. In the case of ultrasonic inspection, electrical energy is converted to ultrasonic energy, which is injected into a specimen under test. Ultrasound can be used to measure the thickness of a piece of metal, characterize a flaw in a weld or see if a bolt has broken without having to remove it.

There are many ways that ultrasound can be useful to the inspector, but weld inspection is probably the most common.

6. Becoming a non-destructive testing technician requires a firm understanding of physics, chemistry, metallurgy and mathematics. Because clients are paying you to inspect their critical items, which would be another prime characteristic of the NDT inspector?

Answer: Ethics

Certainly, if you can understand formulas, remember number patterns or can manipulate a vehicle, you might be able to become a good inspector. However, it is the ethical standards of the NDT technician that has allowed personnel in the nuclear, chemical, petroleum, pharmaceutical and many other industries to rely on the NDT technician to inspect items and offer a diagnosis of the ability to perform in the function as desired. Most companies will have the NDT technician sign an ethical agreement not to commit fraud, perjury or negligent acts which may cause unsafe conditions, or allow damaged equipment from entering the market place.

7. In addition to needing technical abilities, the NDT technician should have excellent verbal and written skills. What is the major reason why an inspector should be able to write well?

Answer: Inspection results have to be transcribed to the client.

Sure, all of these items may be encountered as a member of the non-destructive community, but the overall most important job of the technician is to relay the results of an inspection to the client in clear, complete and detailed reports. The inspection report is the only tangible thing the client has after the inspection has been performed, so it must be as thorough and precise as possible.

8. The NDT technician has to rely on codes and specifications to outline the expectations of an item to perform satisfactorily. These specifications are used to assign acceptance criteria to objects as varied as bridges, pumps, automobiles, airplanes and hypodermic needles. If it is produced, there is a standard that governs its safety or quality. Of the following, which is a recognized agency that may specify the standards for the manufacturing of an item?

Answer: American Welding Society

There are many agencies which exist to provide the guidelines necessary for fabrication, manufacture or development of objects. The American Welding Society is a group based out of Miami, Florida who deals in the research and development of codes and standards used to fabricate materials by welding.

There are several other bodies in which the NDT technician will become knowledgeable including the American Society of Non-Destructive Testing, the American Society of Mechanical Engineers, the American Petroleum Institute and several other counterparts located in other countries.

9. Working in industrial facilities, the NDT technician has to adhere to safety regulations as directed by the client's safety programs. Which of these items would not constitute personal protective equipment to be worn during a typical day in an industrial facility?

Answer: Respirator

Obviously, a respirator would be considered personal protective equipment: however, in the day to day operations of a NDT technician, work boots, hard hats and eye protection are the uniform of the day. Respirators can certainly be included in the necessary safety equipment, but it should be the goal of the facility to remove the hazardous environment before the technician arrives instead of wearing breathing apparatus for safety. With this being said, all NDT technicians should be qualified and fitted for respirator devices in case all other engineering controls cannot eliminate the atmospheric hazards in a work setting.

10. Who would be the ideal candidate for a position in the field of non-destructive testing?

Answer: Any of these would be a good candidate.

The awesome thing about non-destructive testing is that anyone can become a skilled inspector if they have the desire to do so. A strong background in science, welding, manufacturing or quality control would certainly be beneficial, but there is no regimented requirement for the path to becoming a good inspector. Successful inspectors have backgrounds as varied as any other profession, but it is the utmost attention to detail that sets apart the best inspectors.

Source: Author ralzzz

This quiz was reviewed by FunTrivia editor Snowman before going online.
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Non-Destructive Testing Trivia Quiz

Non-destructive testing (NDT) is an industrial inspection technique to verify the usability of an item without having to take apart, destroy or otherwise damage an item. This quiz will explore different techniques of performing NDT inspections.

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