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POWER ENGINEERING 2A2 TEST PAPER 2026
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โ What are the four methods of destructive testing? Answer: Tensile Tests Hardness Tests Impact Tests Proof Tests โ In a tensile test, how is the shape of the specimen determined? Answer: The shape is defined by the standards established by ASTM โ In a tensile test, why is the shape of the specimen important? Answer: So that the beak occurs in the "gauge length" section. โ What is the mechanism called that is used for performing tensile tests? Answer: An extensometer โ When performing tensile tests, what are the five stress points plotted? Answer: Proportional Limit Yield stress Proof Stress
Ultimate tensile Strength Final instability point โ What is the proportional limit as it pertains to tensile tests? Answer: The stress point at which slip (or glide) due to dislocation movement occurs. โ What is yield stress as it pertains to tensile tests? Answer: The stress at which yielding occurs across the whole specimen. At this point, deformation is purely plastic (non-reversible) โ What is proof stress as it pertains to tensile tests? Answer: The point at which a specimen has undergone a certain value of permanent strain. Usually 0.2% โ What is the ultimate tensile strength (UTS) as it pertains to tensile tests? Answer: It is the point at which plastic deformation becomes unstable and a narrow region (a neck) forms in the specimen. โ What is the final instability point as it pertains to tensile tests? Answer: It is the failure point, at which fracture occurs. โ What are the two main types of strain? Answer: Elastic strain
โ What is the hardness measurement? Answer: The resistance of a material to surface indentation. โ What are the four common hardness testing methods? Answer: Brinell Rockwell Vickers Knoop โ Describe the Brinell Hardness Test. Answer: Specimen placed on an anvil Load applied through a plunger and ball Held for 10 to 30 seconds Diameter measured twice offset by 90ยฐ to get mean diameter Hardness number calculated โ What is the most widely used hardness test? Why? Answer: The Rockwell hardness test Because it's simple to perform โ What do Rockwell hardness testers use as an indentor? Answer: Either a diamond cone or ball
โ What are the letters that follow the numerical value for a Rockwell hardness test? What do they mean? Answer: 1234 H R (B or C) H = Hardness R = Rockwell B or C = Ball or Cone โ Describe a Rockwell Hardness test. Answer: A ball or diamond cone is pressed into a specimen at two loads (light load and heavy load.) The difference in depth is given a numerical value as indicated on a dial depth gauge. โ What do Vickers Hardness testers use as an indentor? Answer: Diamond pyramid โ What are the letters that follow the numerical value for a Vickers hardness test? What do they mean? Answer: 1234 H V 50 H = Hardness V = Vickers 50 = Load. Could be 5, 10, 20, 30, 50, 100, 120 kg
โ What categories of hardness testing do the four different hardness testers fall into? Answer: Knoop - Microhardness Vickers - either low load microhardness or macro Rockwell and Brinnell - Macrohardness โ What hardness tests are used for testing the hardness of welds? Answer: Rockwell or Vickers โ What is impact testing? Answer: The ability of a metal to resist fracture when subjected to shock loading. โ What is the cross-sectional area of a specimen subject to impact toughness testing? Answer: 1 cm โ What are the two common test for impact toughness? Answer: Charpy & Izod โ What is the shape of a specimen for impact testing? Answer: A rectangular bar with a 45 degree V-shaped notch removed.
โ What's the difference between the Charpy and Izod tests with respect to placement of the specimen? Answer: In the Charpy test the specimen is held at each end and struck in the middle. In the Izod test the specimen is held on one side of the notch and is struck on the other side of the notch. โ How can the notch behavior of metals be estimated? Answer: From their common tensile properties. If they are brittle in tension they will be brittle when notched. If they are ductile in tension they will be ductile when notched. This is not true for ferritic steels โ How can the notch behavior in ferritic steels be estimated? Answer: The notch behavior in ferritic steels cannot be predicted from their properties. โ What is another term for Proof Test? Answer: Hydrostatic deformation โ When is proof testing used? Answer: When no rules for the design have been given in the ASME code book
The application of pressure to be stopped when intended pressure is reached or at the first sign of yielding โ During proof testing of a portable water heater, what pressure should the parts withstand? Answer: A minimum of 3 times the desired MAWP โ All water heaters are required to be hydrostatically tested to what pressure? Answer: 1.5 times the MAWP โ What are five causes of weld discontinuities? Answer: Departure from qualified procedures Departure from weld designs Metallurgical causes Substituting or using defective materials Substituting or using defective electrodes โ How can weld discontinuities be detected? Answer: Visual inspection can usually reveal 80%
Non-destructive techniques are required to view the rest. โ How does the inspector evaluate weld imperfections to judge if the discontinuity will become a defect that leads to a failure? Answer: Has experience and knowledge of the flaws associated with the welding process. Knows the metallurgy of the base metals and filler metals Knows the design of the weld joint Knows the specifications, standards, and codes โ What does the welding term "defect" mean? Answer: A discontinuity or flaw whose size, shape, type, location, or orientation creates a substantial chance of failure. โ What does the welding term "discontinuity" mean? Answer: Any local variation in material continuity; including changes in geometry, properties of composition or structure, holes, cavities, or cracks. โ What does the welding term "fault" mean? Answer: Is used to denote defect but can also mean imperfection or flaw.
Non-metallic inclusions โ What are base metal discontinuities? Answer: Deficiencies in the chemical, physical, or mechanical properties of the base metals which may contribute to a defect in the weldment. โ What are some sights for weld failure? Answer: Highly restrained tee and corner joints. โ What are the five basic weld joints? Answer: Butt Tee Lap Edge Corner โ What welds can cause areas of high stress? Answer: Misaligned butt joints Steep transitions between thick and thin lapped material โ What does it mean when the book says... "The degree of weld quality possible is not the same as the degree of weld quality necessary." Answer: It means that the function imposed
on the weld determines the required degree of weld quality. For example, welds for the pressure industry must conform to higher standards because of the potential for danger. โ What are the 7 most common types of NDE? Answer: Visual Inspection Magnetic Particle Testing Liquid Penetrant Testing Ultrasonic Testing Radiographic Testing Acoustic Testing Leak Testing โ What does the NDE term "flaw" mean? Answer: An imperfection in the material that may or may not be harmful โ What does the NDE term "indication" mean? Answer: A noticeable response to an NDE test that requires interpretation to determine its significance. โ What does the NDE term "discontinuity" mean? (Hint: It has the same definition as the welding term discontinuity) Answer: Any local variation in material continuity including changes
โ What are the four broad benefits of NDE? Answer: Safety Cost savings Service reliability Material Verification โ Visual inspection is the most widely used technique for what 3 things? Answer: Surface inspection Alignment of mating surfaces Evidence of leaking โ What are some types/techniques of visual inspection? Answer: Using the naked eye Remote visual examination (video systems) โ What are some visual inspection aids? Answer: Mirrors Magnifying lenses Artificial illumination โ If a visual inspection is required by code, what must the manufacturer provide? Answer: A written procedure and a list of the examinations to be performed
โ What types of metals can magnetic particle inspection be used on? Answer: Can be used on ferromagnetic materials such as cast iron, carbon steel, and steel alloys. โ What type of defect is magnetic particle inspection best used for detection of? Answer: Cracks present at the surface and subsurface of the component. โ Generally, how does magnetic particle inspection work? Answer: A magnetic flux is established in a component. If there is a crack then the faces of the crack will tend to form north and south poles that will interrupt the flux lines. Iron power is applied to the surface and will attract to the poles of the crack which will give a visual indication. โ What is used to create the flux in a material? Answer: AC transformers for surface defects DC currents for subsurface defects โ What are the magnetic particles used in mag particle inspection? Answer: Dry iron power
Apply the dye penetrant Interim cleaning (removing residual dye) Drying Apply developer solution Visually inspect Final cleaning โ Why is pre-cleaning important when conducting liquid penetrant tests? Answer: So the specimen is free of all dirt, scales, oil, fingerprints and all surface residue so the penetrant medium can penetrate into surface defects. โ What is the "dwell time" with regards to liquid penetrant test? Answer: The amount of time that the dye penetrant is left on the specimen. Typically 5 to 30 minutes. โ What is interim cleaning when speaking of liquid penetrant tests? Answer: It's after the dwell time. It's when the residual dye penetrant is removed. Low pressure water spray is used for this so that the penetrant isn't washed out of the surface cracks. โ How is drying accomplished when conducting a liquid penetrant test? Answer: With low pressure air or drying in an oven at 50ยฐ C
โ Explain the developing procedure when conducting a liquid penetrant test. Answer: Wet or dry developers are sprayed onto the surface. The developer draws the penetrant from any cracks to the surface. โ How is the visual inspection of a liquid penetrant test done? Answer: The operator completes this by making sure the ambient light intensity and UV intensity are constant โ What are some indications (6) with a liquid penetrant test? Answer: Small dot Continuous line Intermittent line Rounded areas Diffuse Brilliance โ When conducting a liquid penetrant test, what is important when doing the final cleaning? How is it done? Answer: It is important that the surface is free of developer. The developer may be removed with water. โ What measurement is ultrasonic? Answer: Any vibration (sound) over a frequency of 20 kHz
