Diagnosing of Pipeline Supports Instability using Acoustic Noise (Physical Modeling Data)

On the physical modeling results the possibility of determination of pipelines natural frequencies and mode shapes using acoustic noise records is demonstrated. It is shown that this information can be used for diagnosing instability of above-ground pipeline supports. Partial and especially total support instability expanding the length of pipe segment between stable supports leads to sharply change of flexural standing wave field structure. In the places of stable supports always the nodes of standing waves are observed, but decreasing of clamping rigidity leads to change of this regularity. In particular, for a pipeline with the same length of initial segments the antinodes will be observed in the place of unstable support for the odd modes.