This paper presents the outcome of an industrial case study that involved condition monitoring of piping system that showed signs of excess fatigue due to flow induced vibration. Due to operational requirements a novel non-destructive assessment stratagem was adopted using different vibration analysis techniquessuch as Experimental Modal Analysis (EMA) and Operating Deflection Shapes (ODS) -and complemented by visual inspection. Modal analysis performed near a drain valve showed a dynamic weakness problem (several high frequency flow induced vibration frequency peaks) hence Condition Based Monitoring (CBM) was used.This could easily be linked to design problem associated with the dynamic incompatibility due to dissimilar stiffness between two 3 rd party supplied pipe and valve systems. It was concluded that this is the main cause for these problem types especially when systems are supplied by third parties, but assembled locally, a major cause of dynamic incompatibility. It is the local assembler's responsibility to develop skills and expertise needed to sustain the operation of these plants. This paper shows the technique used as result of one such initiative. Since high amplitude, low frequency displacement can cause low cycle fatigue, attention must be paid to ensure flow remains as steady-state as possible. The ability to assess the level of design incompatibility and the level of modification required using non-destructive testing is vital if these systems are to work continuously.

Flow in piping generates random excitation which is non-periodic and that means resonance will not be the key factor to pipe failure. One of the main causes of pipe failure is weak supports. Due to their dissimilar stiffness in the piping system, it leads to low frequency and high amplitude flow induced vibration that causes high cyclic stress resulting in high cycle fatigue failure of the joints. Other contributing factors in pipe failure are poor or inadequate design, poor workmanship during installations or maintenance and inadequate or weak and flexible support. These pipes are usually required to work non-stop for 24 hours a day 7 days a week for weeks, months or years at a time. Regular monitoring and in-service dynamic analysis should ensure continuous and safe operation. This paper presents a case study on monitoring, diagnosis, and maintenance of a piping system. High vibration was observed during routine maintenance, in a 30 m high, 24 inch diameter amine pipes at an oil and gas processing plant in southern Thailand. Amine liquid leakage due to high cycle fatigue crack was reported at the piping bearing and this remained a major concern for the personnel at the plant. A non-destructive testing approach which relies on a combined experimental techniques (i.e. Operating Deflection Shapes (ODS)) and computational mechanics (i.e. Finite Element (FE) modal analysis, Computational Fluid Dynamics (CFD) Analysis, Fluid-Structure Interaction (FSI) Analysis) was used to assess the structural integrity of the piping and in the effort of proposing a suitable recommendation in rectifying the high vibration issue. The analyses concluded that the root cause of high vibration was due to inadequate and weak piping support. As a result, additional supports were proposed to counter the deflection of the piping generated by the flow. The supports were found effective in reducing vibration in which the stress concentration at the new supports and the piping was considered relatively low.

In oil and gas industry, piping system provides transport for a wide range of substances such as petrochemicals and water. They are required to operate nonstop for a schedule of 24/7. Flow-induced vibration (FIV) of the piping system is the most common causes of high cycle fatigue. Besides, excessive load caused by unfavourable operating condition may increase the probability of failure occurrence. Duplex Stainless Steel (DSS) is commonly used for piping system in oil and gas industry due to its reasonable high endurance limit for dynamic stress intensity, high corrosion resistance and low cost.Failure of the DSS piping system can have disastrous effects, leading to injuries and fatalities as well as to substantial cost to industry and the environment. Therefore, there is a need to perform failure analysis of this kind of flow-induced vibration problem. In this study, novel method of failure analysis of DSS piping system due to flow-induced vibration, while in-service, is proposed. The proposed non-destructive technique is able shows that maximum operating conditions are 360mmscfd and 400mmscfd for fullyopened and partially-opened Flow Control Valves (FCVs) respectively. Beyond this limit, the piping system most likely will fail.

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

This paper is about predicting the noise and vibrations for railways project in Malaysia by using Finite Element Analysis method. In recent years, Malaysia is massively developing railways industry. This has created a great awareness in the public, regarding noise and vibration from railways trains during operations are generated from the rolling interaction of the wheels with the rails. Additional noise may be generated from brake squeals during braking at the stations and curved segments of the rail alignments. Over the years, it is relatively easy to measure the acoustic sound power of a train and to calculate noise levels. However, it would be advantageous to be able to reliably and efficiently predict the noise and vibration impact resulting from proposed railways projects. Comprehensive noise and vibration shall be predicted to determine noise and vibration levels along the entire track alignment to ensure that noise and vibration levels shall comply with Malaysia Department of Environment (DOE) approved limits. The result of analyses can be used to identify and to design noise and vibration mitigation measures for the entire railway project. Several methods have evolved to predict noise and vibration from various operational sources, but their suitability for prediction of noise and vibration from railways trains is not well known and has not yet been thoroughly tested. This study document finite element analysis undertaken for the noise and vibration aspects of the viaduct design of the railways track. Data and inputs for finite element model and analysis are including the aspect of “Geometry, atmospheric, ground effect, analysis type and boundary conditions”, as mentioned by Makarewicz (1998) and Lamancusa (2009). A comparison of finite element model and analysis will be conducted by adding the additional aspects of “Material properties and applied loads”, which to be determined as better accuracy of predicting noise and vibration from railways train.