Assessing Brittle Fracture in Pressurized Equipment Using a FAD Available to Purchase

While the probability of brittle fracture in pressurized equipment has typically been rare, the consequences are usually unacceptable from a risk standpoint. This article first briefly reviews the method used to prevent brittle fracture in new equipment used by most codes. The article then presents the approaches of increasing complexity to preventing brittle fracture in existing equipment with an emphasis on the fracture mechanics approach and the use of a Failure Assessment Diagram (FAD). Two examples are discussed, one of determining the maximum acceptable flaw size for a given operating scenario and the other of determining an acceptable operating envelope for a given flaw size.