T9074-AS-GIB-010/271 Rev 1
3.5.5 Number, Location, and Placement of Penetrameters.
3.5.5.1 Penetrameter Location. The penetrameter shall be placed on the source side of the section being examined (see figures 3-7, 3-8, 3-9, 3-10, and 3-11). In the inspection of irregular objects, the penetrameter shall be placed on the part of the object farthest from the film. When performing double-wall radiography, the penetrameter shall be placed on the surface of the wall or walls being evaluated nearest the source of radiation (see figure 3-12). Where this is not practicable, the film side technique specified in 3.5.5.1.1, 3.5.5.1.2, the separate block technique of 3.5.5.1.3, or the technique shot approach of 3.5.5.4, as appropriate, may be employed. 3.5.5.1.1 Film-Side Penetrameter Technique (Double-Wall Exposure). The film-side penetrameter placement technique shall be as shown on figure 3-13. The radiographic technique shall be demonstrated in a similar section with the applicable penetrameter placed on the source side of the wall for which radiography is desired, and a series of penetrameters, ranging in thickness from that of the penetrameter required on the source side to one-fourth that thickness, shall be placed on the film side. If the proper penetrameter on the source side indicates the required quality level, the image of the smallest hole in the thinnest penetrameter clearly visible on the film side shall be used to determine the penetrameter and the penetrameter hole to be applied in evaluating production radiographs. Technique radiographs shall be made available for review upon request by the Government inspector. Table 3-2 contains a list of film side penetrameters that may be used in lieu of performing technique radiography and selection of penetrameters as described above. 3.5.5.1.2 Film-Side Penetrameter Technique (Single-Wall Exposure). For large diameter pipe (8-inch and over) where the diameters are such that the source may be placed inside the pipe for simultaneous single-wall radiography of welds but source-side penetrameter placement is not feasible, a film-side penetrameter technique may be employed provided the requirements of 3.4.6 and the radiographic quality level of the source-side penetrameter being 2-2T as required by 3.7 are met. When using an Iridium-192 or Selenium-75 (only applicable to Group 1 and higher for Selenium) source, the required source-side penetrameter may be selected from table 3-3 for the applicable wall thickness for single-wall viewing technique, or 2-4T for welds less than ¾ inch thick, whichever is less restrictive, and the film-side penetrameter selected from table 3-2. For castings and forgings, see note 2 in table 3-4. 3.5.5.1.3 Separate Block Penetrameter Technique. The penetrameter may be positioned on a block of the same or a lower group number material placed as close as possible to the area being radiographed. The block shall be of thickness equal to or greater than the thickness of the item being radiographed and, in piping 1-inch nominal pipe size and larger, shall be positioned so that the penetrameter is at the same distance from the film as it would be if placed on the source side of the item being radiographed. 3.5.5.2 Requirements for Castings and Forgings. One penetrameter shall represent an area within which radiographic densities do not vary more than plus 30 percent to minus 15 percent from the density measured as specified in 3.5. Not less than one penetrameter per radiograph shall be used except as specified in 3.5.5.4. If a shim is used, it shall be of the same or lower group number as the item being radiographed. When the film density varies by more than minus 15 to plus 30 percent, two penetrameters used as follows will be satisfactory. If one penetrameter shows an acceptable sensitivity at the most dense portion of the radiograph, and the second penetrameter shows an acceptable sensitivity at the least dense portion of the radiograph, these two penetrameters shall serve to qualify the radiograph within the density limits. For components where there are changes in wall thickness and wall alignment, and the use of two penetrameters is not practicable, the use of one penetrameter is approved. The required penetrameter density tolerance need not be met; however, the density in areas of interest shall be between 1.5 and 4.0. Where only one penetrameter is used, the penetrameter size shall be based on the thinnest wall being radiographed and shall be placed on the thickest wall section. For castings and forgings, see note 2 of table 3-4.
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