A novel investigation into the application of non-destructive evaluation for vibration assessment and analysis of in-service pipes

Autor: Abdul Ghaffar Abdul Rahman, Hoe Cheng Eng, Siamak Noroozi, Shin Yee Khoo, Mihai Dupac, Zhi Chao Ong, Keen Kuan Kong
Rok vydání: 2019
Předmět:
Zdroj: Nondestructive Testing and Evaluation. 34:413-428
ISSN: 1477-2671
1058-9759
Popis: Flow induced vibrations that are close to resonance frequencies are a major\ud problem in all oil and gas processing industries, so all piping systems require\ud regular condition monitoring and inspection to assess changes in their dynamic\ud characteristics and structural integrity in order to prevent catastrophic failures.\ud One of the main causes of pipe failure is weak support causing low frequency\ud high amplitude flow-induced vibration. This causes wear and tear, especially\ud near joints due to their dissimilar stiffness resulting in fatigue failure of joints\ud caused by vibration-induced high cyclic stress. Other contributing factors in pipe\ud failure are poor or inadequate design, poor workmanship during installation or\ud maintenance and inadequate or weak and flexible support. These pipes are\ud usually required to work non-stop for 24 hours a day 7 days a week for weeks,\ud months or years at a time. Regular monitoring and in-service dynamic analysis\ud should ensure continuous and safe operation. A novel method of non-destructive\ud testing and evaluation of these pipes, while in service, is proposed in this paper.\ud This technique will enable early detection and identification of the root causes of\ud any impending failure due to excess vibration as a result of cyclic force induced\ud by the flow. The method pinpoints the location of the impending failure prior to\ud condition-based maintenance procedures. The technique relies on the combined\ud application of Operating Deflection Shapes (ODS) analysis and computational\ud mechanics utilizing Finite Element Analysis (FEA), i.e. linear elastic stress\ud analysis. Any structural modification to the pipes and their supports can then be\ud applied virtually and their effects on the system can be analysed. The effect on\ud vibration levels is assessed and verified. The effect of any change in the forces\ud corresponding to changes in the Differential Pressure (DP) at constant flow rate\ud through the pipes can then be estimated. It was concluded that maintaining the\ud differential pressure above some “critical” threshold ensures the pipe operates\ud under the allowable dynamic stress for a theoretically “indefinite” life cycle.
Databáze: OpenAIRE
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