T9074-AS-GIB-010/271 Rev 1
(2) Quality level 2-1T radiography: The 1T hole in a penetrameter whose thickness (T) is no greater than 2 percent ( 1 ⁄ 50 ) of the material thickness shall be visible. (3) Quality level 1-2T radiography: The 2T hole in a penetrameter whose thickness (T) is no greater than 1 percent ( 1 ⁄ 100 ) of the material thickness shall be visible. (4) Quality level 2-4T radiography: The 4T hole in a penetrameter whose thickness (T) is no greater than 2 percent ( 1 ⁄ 50 ) of the material thickness shall be visible. (5) Quality level 4-2T radiography: The 2T hole in a penetrameter whose thickness (T) is no greater than 4 percent ( 1 ⁄ 25 ) of the material thickness shall be visible. 3.7.1 X-ray Radiography. For welds under the following conditions, a 2-4T quality level is acceptable: a. For butt welds with permanent backing, where the material thickness T m is less than ½ inch. b. For penetration and connection welds (figures 3-14 and 3-15) where the T m1 thickness is less than 2 inches. 3.7.2 Radioisotope Radiography. When radioisotopes are used, the quality level and selection of penetrameter shall, as a minimum, be in accordance with table 3-3. For welds and components not specified in table 3-3 (e.g., structural welds), the 2-4T quality level is acceptable under the following conditions: a. Penetration and connection welds (figures 3-14 and 3-15) when the T m1 thickness is less than 2 inches (applicable to all isotopes). b. Components and welds, other than above, when the T m is not greater than ¾ inch (only applicable to Iridium-192 and Group 1 and higher for Selenium-75).
3.8 SINGLE-WALL AND DOUBLE-WALL RADIOGRAPHY.
3.8.1 Single-Wall Radiography. Radiographs shall be made through single wall whenever practical. Shims under the penetrameter shall be as specified in 3.6. For cylindrical welds in piping, double-wall radiography is permitted as specified below.
3.8.2 Double-Wall Radiography.
3.8.2.1 Double-Wall Exposure/Single-Wall Viewing. For welds in pipe greater than 3½ inches nominal pipe size, only the weld closest to the film shall be viewed for acceptance. The source shall be positioned in such a location that the source-side weld image does not obscure the image of the film-side weld. Shims under the penetrameter shall be provided in accordance with 3.6. The minimum source-to-film distance shall be calculated based on the T s value illustrated on figure 3-13 and 3.4.6. 3.8.2.2 Double-Wall Exposure/Double-Wall Viewing. Welds in pipe or tube 3½ inches or less nominal pipe size may be radiographed using a technique in which the radiation passes through two walls and the weld in both walls is viewed for acceptance on the same film. The radiation beam may be offset from the plane of the weld at an angle sufficient to separate the images of source-side and film-side portions of the weld. Shims under the penetrameter shall be provided in accordance with 3.6. The minimum source-to-film distance shall be calculated using the outside diameter of the pipe or section as the specimen thickness T s (see figure 3-12 and 3.4.6).
3-15
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