ASNT Level III- Visual & Optical Testing

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Pre-marking with a stick is not practical under certain circumstances- when a heating period is prolonged a highly polished surface does not readily accept a mark or the marked material gradually absorbs the liquid phase of the indicator. In such instances, the operator frequently marks the workpiece with the stick. The desired temperature is noted when one ceases to make dry marks and begins to leave a liquid smear. A similar procedure can be employed to indicate temperature during a cooling cycle. But a melted mark, on cooling, will not solidify at the exact same temperature at which it melted, so solidification of a melted indicator mark cannot be relied on for temperature indication. Temperature ratings are in increments as small as 3.4 °C (6 °F) but increments ranging from 14 to 28 °C (25 to 50 °F) are typically used for welding applications. For most applications, a jump of 28 to 56 °C (50 to 100 °F) and a range of sticks up to 650 °C (1,200 °F) are usually adequate. Charlie Chong/ Fion Zhang
Temperature indicating sticks were developed in America by a metallurgist working on submarine hulls in the 1930s. At the time, preheat was measured with so-called melting point standards, granules of substances with known melting points used to calibrate heat sensing instruments. The engineer used the granules directly, spreading them on the preheated metal and using their melt as a signal to proceed with welding. The melting point granules were next formed into sticks held together with organic hinders. Different temperature ratings were added and some refinements have been made but the principle of indicators has remained unchanged. The sticks make physical contact with the heated test object, reach thermal equilibrium rapidly and do not conduct heat away from the test surface. For temperature ratings less than 340 °C (650 °F), indicator marks can usually be removed with water or alcohol. For ratings above 340 °C (650 °F), water is preferred. If the mark has been heated well above the rated temperature and has become charred, abrasion may be needed for complete removal. Charlie Chong/ Fion Zhang
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ASNT Level III- Visual & Optical Te
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At works Charlie Chong/ Fion Zhang
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Charlie Chong/ Fion Zhang Fion Zhan
Page 7 and 8: SECTION 4: BASIC AIDS AND ACCESSORI
Page 9 and 10: PART 4: MACHINE VISION TECHNOLOGY 4
Page 11 and 12: PART 6: TEMPERATURE INDICATING MATE
Page 13 and 14: PART 4: MACHINE VISION TECHNOLOGY 1
Page 15 and 16: 5.1 Cellulose Acetate Replication A
Page 17 and 18: 5.1.2 Fracture Surface Analysis The
Page 19 and 20: Replicas, in the as-stripped condit
Page 21 and 22: Microstructural replication is done
Page 23 and 24: If analysis with the scanning elect
Page 25 and 26: Sputter deposition is a physical va
Page 27 and 28: Sputtering http://en.wikipedia.org/
Page 29 and 30: Sputtering http://clearmetalsinc.co
Page 31 and 32: Sputter Deposition Charlie Chong/ F
Page 33 and 34: 5.1.4 Strain Replication The replic
Page 35 and 36: FIGURE 56. Principles of acetate ta
Page 37 and 38: Fatigue striations Charlie Chong/ F
Page 39 and 40: FIGURE 59. Documentation of creep d
Page 41 and 42: FIGURE 60. Documentation of stress
Page 43 and 44: TABLE 14. Action required for creep
Page 45 and 46: Cellulose Acetate Replication http:
Page 47 and 48: Replication Microscopy Techniques f
Page 49 and 50: Replication Microscopy Techniques f
Page 51 and 52: 5.2.1 Use of Silicone Replicating M
Page 53 and 54: FIGURE 63. Silicon replicas used to
Page 55 and 56: Brittle Failure Chevron Marking Cha
Page 57: PART 6: TEMPERATURE INDICATING MATE
Page 61 and 62: Levels of Charlie Chong/ Fion Zhang
Page 63 and 64: 6.2 Certification of Temperature In
Page 65 and 66: 6.3 Applications for Temperature In
Page 67 and 68: 6.3.2 Verifying Oven Temperatures T
Page 69 and 70: 6.3.4 Process Control Applications
Page 71 and 72: 6.3.6 Precise Post forming Heat Con
Page 73 and 74: Another example of handforrning is
Page 75 and 76: 6.3.7 Pipeline Coatings Epoxy powde
Page 77 and 78: The most common use for temperature
Page 79 and 80: FIGURE 67. Temperature indicating s
Page 81 and 82: PART 7: CHEMICAL AIDS 7.0 General T
Page 83 and 84: 7.1 Test Object Selection Figure 68
Page 85 and 86: 7.2 Surface Preparation Preparation
Page 87 and 88: 7.2.2 Removing Rust and Scale Rust
Page 89 and 90: If the required finish cannot be ac
Page 91 and 92: FIGURE 70. Example of contrast reve
Page 93 and 94: 7.3.2 Safety Precautions Etchants a
Page 95 and 96: Etchant Safety Charlie Chong/ Fion
Page 97 and 98: Etchant Safety Charlie Chong/ Fion
Page 99 and 100: 7.3.3 Containers Containers used wi
Page 101 and 102: 1. add the acid or alkali to the wa
Page 103 and 104: 7.3.6 Disposal Before disposing of
Page 105 and 106: 7.4.2 Swabbing Etching may also be
Page 107 and 108: 7.4.4 Test Object Preservation Rins
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7.5 Conclusion Visual testing is pe
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Cellulose Replica Sheets Charlie Ch
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Charlie Chong/ Fion Zhang
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ASNT Level III- Visual & Optical Testing

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