Copyright Goodheart-Willcox Co., Inc. Chapter 17 Welding Procedures, Defects, and Corrective Actions 149 inspection techniques will result in a safer, more thor- ough and precise inspection than any other method. Ultrasonic testing has certain advantages, including the following: • Superb penetration power, permitting testing of thick materials and a variety of welds. • Sensitivity suffi to locate very small defects ficient quickly. • Ability to be done from one surface. Radiographic Inspection Radiographic inspection is another nondestructive test that shows the presence and nature of discontinui- ties inside a weld. X-rays and gamma rays penetrate the weld, and fl aws are revealed on exposed radiographic fl fi lm or electronic display, fi Figure 17-12. Although radio- graphic inspection is expensive compared to other types of tests, the fi lm or printout of the display creates a fi permanent record of the weld quality. Goodheart-Willcox Publisher Figure 17-9. A magnetic particle test is being conducted on this butt weld. With the electromagnet activated, the gray test powder will be softly blown away until defect indications remain. Yoke Part Steps: 1. Apply magnetic field using electric current. 2. Apply magnetic particles while power is on. 3. Blow away excess particles. 4. Inspect. Magnetic lines of force Weld Goodheart-Willcox Publisher Figure 17-10. Magnetic particle test sequence. Goodheart-Willcox Publisher Figure 17-11. This inspector is preparing the weld and equipment for ultrasonic testing. During an ultrasonic test, the transducer is coupled (connected) to the test area by a thin layer of liquid. Gamma ray X-ray Film Lead Intensifying screen Film Source Source Goodheart-Willcox Publisher Figure 17-12. Radiographic test operation.