MIL-STD-1894A, MILITARY STANDARD: RADIOGRAPHIC REFERENCE STANDARDS AND RADIOGRAPHIC PROCEDURES (17 OCT 1986)., This standard provides standard reference radiographs and recommended radiographic inspection procedures for partial-penetration weldments in steel plate, casting, or forging, 0.5 to 2 inches (in.) (12.70 to 50.80 millimeters (mm)) thick