Crack opening area of pressurized pipe for leak before break evaluation

The prediction method for analyzing the crack opening area for a pipe is essential for leak-before-break evaluation. Several theoretical approaches are proposed for predicting crack opening areas. One approach is the Tada and Paris formula developed based on linear elastic fracture mechanics. Another approach is the method proposed by German and Kumar who have developed an engineering approach. Round robin analyses for crack opening areas are performed using the above two methods. The pipe analyzed is 6-inch diameter Type 304 stainless steel with a circumferential through-wall crack. The applied load is a bending moment. The crack opening areas calculated by the Tada's method coincided among the four participants. However, the area using German's method were quite different. It is concluded that the Tada's method is suitable for predicting the crack opening area in the present situation. In addition, material properties used in the calculations of the area are discussed compared with the results of the pipebending experiment. (author)