| Abstract:Based on more than 3,400 tests on cast iron dryers in Hangzhou area, an ultrasonic testing technic with longitudinal wave double-crystal probe was established. With this technic the volume defects were identified through testing the air holes, shrinkage cavities and inclusions in the dryer cylinder and small R transition zone with longitudinal wave double crystal probe at a small angle (5°), and the plane defects of deep cracks were found through testing the dryer cylinder and small R transition zone with longitudinal wave double crystal probe at a large angle (42°). It provided the solution to the issues of how to use the thickness measurement in regular online testing cast iron dryers to calculate their strength or compare with the design value, how to adjudge the low hardness value, how to determine the key parts foe online testing, how to conduct safety assessment of the cast iron dryers with small cracks. |
