2014 IR&D Annual Report

Testing and Analysis of Acoustically Induced Vibration Stresses in Piping
Systems, 18-R8478

Principal Investigators
Neal Evans
Tim Allison
Nathan Poerner

Inclusive Dates: 07/01/14 – Current

Background — Acoustically induced vibration (AIV) is the phenomenon of high-frequency piping vibration downstream of a high-amplitude noise source, which can potentially lead to fatigue failure of the piping at a branch or welded support. Although AIV has long been a concern in high-capacity gas piping systems, recent capacity increases to aging systems and debottlenecking operations, as well as the development of new higher-capacity systems have led to renewed interest in AIV mitigation strategies. Existing methods of AIV analysis used to predict if a weld failure is likely to occur are based on an incomplete historical dataset that does not properly address the fundamental physics of AIV, the high flow rates and pressure ratios encountered in modern blowdown systems, or the increasingly larger pipe sizes that are being implemented. In many cases, these methods are considered to be overly conservative and costly. Furthermore, AIV mitigation options are limited for existing systems that are predicted to fail.

Approach — Testing will be performed at SwRI’s gas blowdown facility to obtain dynamic pressure and stress measurements to validate models of the noise source, internal piping acoustics, and piping stress response for several representative configurations of gas blowdown piping. Several AIV remedies will also be tested for existing piping to characterize the stress reductions of these remedies. Application of associated stress reductions to existing analysis methods will enable SwRI to offer AIV analysis services with improved accuracy. Test data for various remedies will increase the pool of available design and retrofit options.

Accomplishments — The project began during the fourth quarter of 2014. Work completed to date has consisted of hardware procurement, test section assembly, and detailed experimental planning. Testing began in November 2014, and will continue through January 2015, with detailed data analysis to follow. Data analysis and reporting will conclude with an investigation of an updated AIV analysis procedure based on the program results and effectiveness of the AIV treatments.

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Southwest Research Institute® (SwRI®), headquartered in San Antonio, Texas, is a multidisciplinary, independent, nonprofit, applied engineering and physical sciences research and development organization with 9 technical divisions.
04/15/14