Study on leak rate in LBB analysis of welded pipe

The leak-before-break (LBB) technology has been widely used in the design of welded pressure vessels and pipelines, and it is based on the theory that the penetration of fluid through cracks, which exist in the walls of the pipe and vessel, can be detected before the they reach a state of instability. In this paper, leak rates in different opening direction are calculated and analysed by finite element analysis software Fluent in the case of single phase fluid. It is concluded that there is no linear relationship between the leak rate and the CTOD value or the crack length, and that the influence of the CTOD increase on the leak rate is greater than that of the crack length.