The investigation of guided wave propagation around a pipe bend using an analytical modeling approach

Guided wave inspection has the advantage of providing full volumetric coverage of tens of meters of pipe from a single test location. However, guided wave behavior is complex and there are many factors to consider such as the numerous possible vibrational modes and multiple reflections. The guided wave inspection technique is potentially valuable for pipelines that cannot be inspected with internal "pigs." However, in situations such as this, there are often bends in the pipe and the presence of the bend is known to distort the received signals. In order to address this issue, a study has been carried out that uses a combination of finite element analysis and experimentation to understand the behavior of guided waves in pipe bends. In addition to this, an analytical modeling methodology is put forward that uses basic information from finite element models of pipe bends to create a computationally fast solution to a potentially infinite number of scenarios. The analytical model can be used to both predict the effects of pipe bends on a range of signals and undo the distortion caused by pipe bends. Examples of this are given and compared to finite element results for flaws beyond pipe bends.