T9074-AS-GIB-010/271 Rev 1
3.5.1.1 Dissimilar Metal Welds.
3.5.1.1.1 Dissimilar Metal Welds of Same Group. For welds made between dissimilar metals in any one group, the penetrameters for that group or penetrameters of a lower group number shall be used, provided the quality level as applicable is maintained. 3.5.1.1.2 Dissimilar Metal Welds of Different Groups. For welds made between dissimilar metals not of the same materials group, two penetrameters shall be used, one on each side of the weld, of the material group (or lower group) corresponding to the base material upon which it is placed. The use of a single penetrameter is allowed, provided that the lower group number penetrameter is placed on the higher group number material, and the applicable quality level is obtained. 3.5.1.2 Other Metals. For radiography of materials not herein covered, penetrameters of the same material may be used, or penetrameters of any other material may be used if the following requirements are met. Two blocks of equal thickness, one of the material to be radiographed and one of the material of which the penetrameters are made, shall be radiographed on the same film by one exposure at the lowest energy level to be used for the production radiographs. Densitometer readings for both materials shall be read from the film and shall be between 2.0 and 4.0 density for both materials. If the film density for the material to be radiographed is within plus 15 percent or less than the film density for the penetrameter material, the penetrameter material may be used for radiography of the production material.
3.5.2 Penetrameter Dimensions. The dimensions of MIL-type penetrameters shall conform to those shown on figure 3-5.
3.5.3 Penetrameter Identification. MIL-type penetrameters shall be identified with lead numbers or engraved lead strips indicating the material thickness (T m or T s as applicable) to which the penetrameter applies as specified in table 3-1. Examples of corresponding identification numbers for ASTM-type penetrameters are also shown for reference. a. MIL-type rectangular penetrameters shall be identified with lead numbers attached to the penetrameters, as shown on figure 3-5. b. For MIL-type penetrameters, the lead numbers shall indicate the material thickness in hundredths of an inch up to l inch, and in inches to the nearest tenth of an inch over l inch. c. Each MIL-type penetrameter shall be further identified by permanently marking its metal or principal alloy composition into the surface of the penetrameter, and by notches in accordance with figure 3-6. 3.5.3.1 Lead Number Placement for Circular Penetrameters. Lead numbers shall be placed adjacent to the circular penetrameters to provide identification of the penetrameter on the film. 3.5.3.2 Identification for Special Quality Levels. For the special quality levels of 1-1T and 1-2T, the applicable penetrameter size shall be based on one-half of the material thickness. For the special quality level of 4-2T, the applicable penetrameter size shall be based on twice the material thickness.
3.5.4 Penetrameter Selection.
3.5.4.1 Welds. Penetrameter selection shall be based on material thickness (T m ) as defined in 3.2.1 for piping, machinery, and pressure vessel welds, and on T s as defined in 3.2.4 for structural welds. For double-wall viewing (see 3.8.2.2), the penetrameter shall be based on 2T m or 2T s as appropriate.
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