Mitigations to Flow Induced Vibration (FIV) in Control Valve Piping System using Visco-Elastic Dampers & Neoprene Pads ⬇️
The control valve piping is vibrating due to high flow rate and high velocity, also this line is running at different flow rate condition. The generic calculations based on Energy Institute Guidelines indicate that the flow is Turbulent and Likelihood of Failure is more than one. This number is alarming and detailed analysis considering change in flow, pipe route, supports etc. is recommended to be performed. This Paper aims to study the 12-inch Control Valve Piping Vibrations observed at site due high flow rates and high velocity. and also attempts to find probable cause of the vibration and the solution to minimize these vibrations.
Pipe will exhibit a series of natural frequencies which depends on the distribution of mass and stiffness throughout the system, and the distribution are influenced pipe diameter, material properties, wall thickness, location of lumped masses (such as valves), pipe supports and also fluid density. Each natural frequency will have unique deflection shape associated with it, which is called mode shapes, which has the locations of zero motion (node) and maximum motion (Antinodes). The response of the pipe work to an applied excitation is dependent upon the relationship between the frequency of excitation and the system’s natural frequencies. Vibration generated in the pipe work may lead to high cycle fatigue of components (such as Small bore connections) or the failure at welds in the main line itself.
Flow-induced vibration, or vortex shedding, is due to high flow velocities and High mass flow rates such as in a piping dead leg of a centrifugal compressor system. with certain flow conditions, piping systems will develop high levels of noise and vibration that can damage the pipes and related systems such as tube bundles, side cavities, and bluff or tapered bodies in flow streams. Pipe damage compromises plant safety, forces shutdowns, increases maintenance, and reduces efficiency and capacity.
1-Top Connection plate
2-Bottom connection plate
3-Serial Number plate
4-Position Indicator
5-Housing
6-Fluid
7-Piston
2-Bottom connection plate
3-Serial Number plate
4-Position Indicator
5-Housing
6-Fluid
7-Piston
System Description ⬇️
The system consists of 12-inch control valve piping which is observed to be vibrating at site. Also this line is running at different
flow rate condition. [5] The line serves between Potassium carbonate solutions to the rich solution flash tank. Points at which
Amplitude of Vibration is noted in the System were noted as A, B, C, D, E, F, G, H, & I as shown in below Figure.
The system consists of 12-inch control valve piping which is observed to be vibrating at site. Also this line is running at different
flow rate condition. [5] The line serves between Potassium carbonate solutions to the rich solution flash tank. Points at which
Amplitude of Vibration is noted in the System were noted as A, B, C, D, E, F, G, H, & I as shown in below Figure.
Approach towards Solution⬇️
Following approach has been applied to find most probable solution to Vibration problem in 12- inch control valve.
- A Qualitative Analysis has been carried out to identify the potential Excitation Mechanism that may exist. (LOW to HIGH).
- A Quantitative Analysis of an LOF score for each identified excitation mechanism from Qualitative Analysis and Periodic flow frequency calculation.
- Based on LOF score (0-1) Recommendation & corrective Actions have been recommended.
- Dynamic stress Analysis of the system using CAESAR-II to simulate analysis model with site observations.
- To propose corrective actions using results.
Following approach has been applied to find most probable solution to Vibration problem in 12- inch control valve.
- A Qualitative Analysis has been carried out to identify the potential Excitation Mechanism that may exist. (LOW to HIGH).
- A Quantitative Analysis of an LOF score for each identified excitation mechanism from Qualitative Analysis and Periodic flow frequency calculation.
- Based on LOF score (0-1) Recommendation & corrective Actions have been recommended.
- Dynamic stress Analysis of the system using CAESAR-II to simulate analysis model with site observations.
- To propose corrective actions using results.
Step 1: Determine ρv^2
For single phase flow ρv^2 = (actual density) x (actual velocity)
Kinetic Energy =1169×4.2782
Kinetic Energy =21934.201 kg/m-s^2
For single phase flow ρv^2 = (actual density) x (actual velocity)
Kinetic Energy =1169×4.2782
Kinetic Energy =21934.201 kg/m-s^2
Step 2: Determine Fluid Viscosity Factor
As the fluid in this example is gas the fluid viscosity factor (FVF) must be calculated; this requires the gas dynamic viscosity (μgas).
Fluid Viscosity Factor (FVF) = √μ / √1×10−3 (2)
Fluid Viscosity Factor (FVF) = √0.25 / √1×10−3
Fluid Viscosity Factor (FVF) = 15.82
As the fluid in this example is gas the fluid viscosity factor (FVF) must be calculated; this requires the gas dynamic viscosity (μgas).
Fluid Viscosity Factor (FVF) = √μ / √1×10−3 (2)
Fluid Viscosity Factor (FVF) = √0.25 / √1×10−3
Fluid Viscosity Factor (FVF) = 15.82