Ideal process/piping design is based on consistent and steady operating parameters. Sometimes these parameters varies significantly due to capacity or performance enhancements during operation. These flow changes from an ideal design to actual operating conditions are often resulting in flow induced vibrations. Excessive Vibrations in piping systems pose potential threats to plant safety and integrity. This paper presents the challenges to mitigate flow induced piping vibration due to multi-phase flow in rich amine systems with successful measures. A comprehensive study was conducted to identify the root cause for piping vibration in rich amine piping system (20″ pipe) from plate type heat exchanger to amine regenerator. The vibration measurement was carried out where the vibrations are visually high. The vibration screening and likelihood calculations were carried out based on Energy Institute's guidelines and those were identified in concern/problem zones. The process study including the review of hydraulics and piping stress analysis was carried out with actual operating conditions. The multiphase density/forces was simulated to identify root cause and to propose suitable recommendations for mitigation of piping vibration. Process study reveals that the fluid flow type is multi-phase where the sudden pressure drop occurs at control valve. The flow regimes were reviewed along the section of pipe to identify the major flow turbulences. The alteration in the operational modes shall reduce the impact of load due to slug flow and shall minimize the vibration. But, since it results in loss of energy, it was suggested to provide adequate piping supports to mitigate the piping vibration. Static/dynamic piping stress analysis reveals that the piping system needs better supporting arrangement to cater slug loads conditions. The natural frequency of existing system was calculated and found to be low with existing supports. The design of existing supports was reviewed and accordingly suggested suitable additional supports such as holddown and axial stop to increase the natural frequency of piping vibration. Since the piping vibration source is control valve where there is sudden change in pressure, the guides and axial stop restraints were proposed to control lateral/axial movements by keeping the stresses in safe limits. The proposed modification were implemented while plant is in operation. The post implementation vibration survey was carried out and the readings were found to be within acceptable limits. The challenges such as balancing the stresses in piping system with appropriate minimum natural frequency levels to make system rigid enough and implementation of proposed modifications without shutdown were successfully achieved. The novel information from this study is, by identifying exact root cause of piping vibration, it is easy to mitigate the same from source level by application of best design/analysis practices with successful measures.
Piping systems having service temperatures lower than ambient present a challenge for the pipe support design. Pipe supports for these cold piping systems are different from normal type of supports on pipes with service temperatures above ambient. Normally hot insulated piping systems have shoe type of supports directly welded to the pipe. In this case there is no relative movement between pipe support i.e. shoe and pipe while the pipe displaces due to changes in fluid service temperature inside the pipe. As the pipe expands when temperatures rise inside pipe, it displaces from its mean position of structural support. The shoe having been welded to pipe moves along with the pipe. On the other hand, shoe type supports on cold service pipes are not directly and permanently connected to pipe. This is due to the fact that the pipe insulation on cold service piping is designed to be seal tight so that outside air cannot get inside the insulation and reach pipe surface where it starts condensation. The condensation in turn causes corrosion issues. To avoid this moist air ingress inside the insulation, the shoes are made of clamp types and are placed outside the insulation cladding. This causes problem of clamp type shoe slippage on cladding and total displacement of pipe shoe from its structural support. This paper presents an engineering study of a piping system with cold fluid service (propane) where multiple supports had fallen from the structural supports or had dislocated considerably. At few support locations, cladding was found to be damaged and ice formation was noticed. In addition, many clamped shoes had rotated as shown in figure 1. The solution as outcome of study was simple, economical and easy to implement. A comprehensive study was conducted to identify the root cause of piping supports dislocation, displacement and rotation. The static/dynamic stress analysis of the piping system was carried out. The results revealed that the displacements in the piping system were not so high to cause the supports dislocation or high displacements of shoes. In addition, the stresses on the piping system due to the contraction of pipe upon cooling were within allowable limits. Figure 1Rotated and dislocated Clamp support on Cold Service Pipes As a part of study process, operation was enquired if any upset had happened which might have caused the dislocation and abnormal movement of pipe and hence transferred to its supports. Operations informed that there was no such incident and the line had been operating normally without any trouble. The process study including review of hydraulics, verification of line size and surge was performed to identify the root cause of piping abnormal movement. The process study concluded that line size was adequate and no surge scenario was identified for the line's concerned portion. So following reasons which could cause abnormal pipe movements and dislocation of supports were ruled out based on above study: Operation upset in the piping system (such as sudden opening or closing of a valve or sudden starting/stopping of a pump),Line sizing or surge flow,Contraction of line due to cooling of piping system or piping configuration. The next step in the study was to review the support configuration in detail. Study found basic design problem with the support configuration that was the cause of supports dislocation, excessive movement and rotation of clamped supports.
Integrity of piping systems is critical for the safe and reliable Plant operations. Shaking or Vibration of piping systems pose potential threats to plant safety and integrity. In GASCO plants, vibrations were observed in some systems such as piping carrying two-phase flow, high pressure lines, piping associated with compressors / pumps, etc. Minimizing the pipe shaking to maximize the process safety through a systematic approach will result in economical, efficient, safe and time bound advantages. This paper presents GASCO's approach in resolving piping vibrations and mitigating the risks to plant operations. Studies were carried out to investigate the root cause and recommend required remedial measures. Walkthrough along the piping system was carried out to identify locations of high vibrations and to detect any mechanical abnormalities as first step. Process conditions were also verified for any upsets. This was followed by measurement of vibration parameters such as amplitudes, frequencies and accelerations. The data collected was analyzed and level of vibrations were classified as critical and non-critical based on recommended limits as per relevant industry standards. For the critical systems, detailed process studies / piping stress analysis were carried out by simulating actual piping vibration taking various excitation sources and as-built conditions into consideration. Theoretical results were compared with field data and were found to be consistent. In order to limit the vibrations within permissible values, necessary measures were recommended. Based on recommended modifications, revised piping stress analysis was carried out to ensure vibrations are within design limits. Implementation packages were prepared to execute the suggested remedial measures. Post-implementation vibration measurements were taken and observed to be comparable to design values and within permissible limits, thereby ensuring plant safety and integrity. Less attention paid to piping vibration during initial design phase, probably due to lack of clear and precise codes and standards, was found to be the main reason for piping vibrations. GASCO recognized the need for documenting the above best practices to address piping vibrations. The Guidelines are developed to identify/classify the severity of vibrations and the way forward to tackle the piping vibration issues which can be used by site personnel.
Piping systems under multi-phase flow are subjected to unbalanced forces during plant operation and they experience vibration. Usually, the piping vibrations can be minimized by either modifying piping configuration/supports or alteration of operational modes. This paper presents an engineering study of a challenging piping vibration problem, which was resolved by an inventive and cost optimizing solution, as there are limitations in modification of existing pipe support/configuration. The inventive resolution reduced implementation cost to the Company without impacting the operations. A comprehensive study was conducted to identify the root cause of piping vibration in rich amine piping system (36" pipe) from heat exchanger to amine regenerator, a tall column. The vibration screening and likelihood-of-failure calculations were carried out based on Energy Institute's guidelines and observed that the piping system is in concern/problem zones. The process study including review of hydraulics, verification of line size and control valve design was performed to identify the root cause of piping vibration. The piping stress analysis (static/dynamic) was carried out with actual operating conditions, which is under multiphase flow with varying density/forces. The process study revealed that the flow velocity and momentum are within process design requirements. However the flow in the piping system is multi-phase type, which generates unbalanced forces due to slug loads at each elbow of the piping system. Based on piping stress analysis results, it was identified that the natural frequency of piping systems is variable as the whole weight of the vertical piping system is resting on spring type supports, which in turn, are supported from vertical vessel cleats. These supports are provided to take care of relative displacements between vessel and vertical piping systems. Piping configuration cannot be modified considering large bore piping and requirement of huge structural supports. The existing supports also cannot be modified as they are connected to pressure vessel and will impact its design. In this scenario of multiple limitations, the indispensable flow induced vibrations of piping can only be minimized by damping the effect of flow-induced excitation with dampers. The dampers have elastic-viscous material in its main restraining body which can absorb the piping vibrations. The damper vendor performed the stress analysis, considering the effect of the damper in the whole piping system, and ensured the integrity of piping system. The challenge of maintaining existing spring supports and achieving required damping of piping vibration was successfully accomplished. Considering large sized piping and requirement of major structural supports in case of modifications, proposed solutions could be treated as cost effective and innovative. Though it was not possible to eliminate the root cause, this alternate innovative solution helped to not only to minimize vibration, but also optimize implementation/shutdown costs. Vibration damper in piping systems is unique to piping installations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.