26.1 When the acceptance criterion of any impact test is specified to be a minimum average value at a given temperature, the test result shall be the average (arithmetic mean) of the individual test values of three specimens from one test location.
26.1.1 When a minimum average test result is specified:
26.1.1.1 The test result is acceptable when all of the below are met:
(1) The test result equals or exceeds the specified minimum average (given in the specification),
(2) The individual test value for not more than one specimen measures less than the specified minimum average, and
(3) The individual test value for any specimen measures not less than two-thirds of the specified minimum average.
26.1.1.2 If the acceptance requirements of 26.1.1.1 are not met, perform one retest of three additional specimens from the same test location. Each individual test value of the retested specimens shall be equal to or greater than the specified minimum average value.
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26.2 Test Specifying a Minimum Transition Temperature:
26.2.1 Definition of Transition Temperature: For specification purposes, the transition temperature is the temperature at which the designated material test value equals or exceeds a specified minimum test value.
26.2.2 Determination of Transition Temperature:
26.2.2.1 Break one specimen at each of a series of temperatures above and below the anticipated transition temperature using the procedures in Section 25. Record each test temperature to the nearest 1°F (0.5°C).
26.2.2.2 Plot the individual test results (ft.lbf or percent shear) as the ordinate versus the corresponding test temperature as the abscissa and construct a best-fit curve through the plotted data points.
26.2.2.3 If transition temperature is specified as the temperature at which a test value is achieved, determine the temperature at which the plotted curve intersects the specified test value by graphical interpolation (extrapolation is not permitted).
Record this transition temperature to the nearest 5°F (3°C). If the tabulated test results clearly indicate a transition temperature lower than specified, it is not necessary to plot the data. Report the lowest test temperature for which test value exceeds the specified value.
26.2.2.4 Accept the test result if the determined transition temperature is equal to or lower than the specified value.
26.2.2.5 If the determined transition temperature is higher than the specified value, but not more than 20°F (12°C) higher than the specified value, test sufficient samples in accordance with Section 25 to plot two additional curves. Accept the test results if the temperatures determined from both additional tests are equal to or lower than the specified value.
26.3 When subsize specimens are permitted or necessary, or both, modify the specified test requirement according to Table 9 or test temperature according to ASME Boiler and Pressure Vessel Code, Table UG-84.2, or both. Greater energies or lower test temperatures may be agreed upon by purchaser and supplier.
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5.2 Acceptance. QW-171.2
The acceptance criteria shall be in accordance with that Section specifying impact requirement.
5.3 Location and Orientation of Test Specimen. QW-171.3
The impact test specimen and notch location and orientation shall be as given in the Section requiring such tests.
When qualifying pipe in the 5G or 6G position, the notch toughness specimens shall be removed from the shaded portion of Figure QW-463.1(f).
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6. Radiographic Examination QW-191.1 6.1 Method QW-191.1.1
The radiographic examination in QW-142 for welders and in QW-143 for welding operators shall meet the requirements of Section V, Article 2, except as follows:
(a) A written radiographic examination procedure is not required. Demonstration of density and image quality requirements on production or technique radiographs shall be considered satisfactory evidence of compliance with Section V, Article 2.
(b) Final acceptance of radiographs shall be based on the ability to see the prescribed image and the specified hole of a hole type image quality indicator (IQI) or the designated wire of a wire type IQI.
6.2 Acceptance Criteria. QW-191.1.2
6.2.1 Terminology. QW-191.1.2.1
(a) Linear Indications. Cracks, incomplete fusion, inadequate penetration, and slag are represented on the radiograph as linear indications in which the length is more than three times the width.
(b) Rounded Indications. Porosity and inclusions such as slag or tungsten are represented on the radiograph as rounded indications with a length three times the width or less. These indications may be circular, elliptical, or irregular in shape; may have tails; and may vary in density.
6.2.2 Qualification Test Welds. QW-191.1.2.2
Welder and welding operator performance tests by radiography of welds in test assemblies shall be judged unacceptable when the radiograph exhibits any imperfections in excess of the limits specified below
(a) Linear Indications
(1) Any type of crack or zone of incomplete fusion or penetration (2) Any elongated slag inclusion which has a length greater than
(a) 1/8 in. (3 mm) for t up to 3/8 in. (10 mm), inclusive
(b) 1/3t for t over 3/8 in. (10 mm) to 21/4 in. (57 mm), inclusive (c) 3/4 in. (19 mm) for t over 21/4 in. (57 mm)
(3) Any group of slag inclusions in line that have an aggregate length greater than t in a length of 12t, except when the distance between the successive imperfections exceeds 6L where L is the length of the longest imperfection in the group.
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(b) Rounded Indications
(1) The maximum permissible dimension for rounded indications shall be 20% of t or 1/8 in. (3 mm), whichever is smaller.
(2) For welds in material less than 1/8 in. (3 mm) in thickness, the maximum number of acceptable rounded indications shall not exceed 12 in a 6 in. (150 mm) length of weld. A proportionately fewer number of rounded indications shall be permitted in welds less than 6 in. (150 mm) in length.
(3) For welds in material 1/8 in. (3 mm) or greater in thickness, the charts in Figure QW-191.1.2.2(b)(4) represent the maximum acceptable types of rounded indications illustrated in typically clustered, assorted, and randomly dispersed configurations.
Rounded indications less than 1/32 in. (0.8 mm) in maximum diameter shall not be considered in the radiographic acceptance tests of welders and welding operators in these ranges of material thicknesses.
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7. VISUAL EXAMINATION — PERFORMANCE QW-194
Performance test coupons shall show no cracks and complete joint penetration with complete fusion of weld metal and base metal.
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