Failures of piping in the hydrocarbon industry represent a potential for catastrophicaccidents in terms of both lost lives and dollars. It has been reported that more than 20%of the piping failures in the UK sector of the North Sea were due to piping vibration andfatigue failures. It is clear that AIV is a serious risk since a single failure will often shutdown a facility for hours or days resulting in lost production, at a minimum. In the 1980s,nine AIV failures were documented and used to develop criteria. One resulting criteriasystem plots the sound power level versus the diameter of the pipe; another plots the soundpower level versus the ratio of the nominal diameter to the wall thickness of the pipe. Safedesign curves are then drawn through the data. One of the simplified approaches seems tohave misinterpreted the original data and now has a safe design curve where a failure hasoccurred. Since the 1980s, there have been many more failures, but the documentation ofthese failures has not been shared with the engineering community. This paper discussesthe existing criteria, presents CSTI’s past approach to the challenge of designing to avoidpotential AIV problems, identifies a new failure curve as a function of the ratio of the meandiameter to the thickness squared, and proposes a new safe design curve.
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