Investigation on Redesigning Strategies for Water-Hammer Control in Pressurized-Piping Systems

2019 ◽  
Vol 141 (2) ◽  
Author(s):  
Mohamed Fersi ◽  
Ali Triki
Keyword(s):  
Numerical Solution ◽  
Transient Flow ◽  
Pipe Wall ◽  
Pressure Head ◽  
Water Hammer ◽  
Piping System ◽  
Proposed Model ◽  
Piping Systems ◽  
Control Water ◽  
Short Section

This paper explored and compared the effectiveness of the inline and the branching redesign strategies used to control water-hammer surges initiated into existing steel piping systems. The piping system is handled, at its transient sensitive regions, by replacing an inline, or adding a branching, short-section made of high- or low-density polyethylene (HDPE or LDPE) pipe-wall materials. The Ramos model was used to describe the transient flow, along with the method of characteristics implemented for numerical computations. The comparison of the numerical solution with experimental data available from the literature and alternative numerical solution evidenced that the proposed model could reproduce satisfactorily the magnitude and the phase shift of pressure head evolution. Further, the robustness of the proposed protection procedures was tested with regard to water-hammer up- and down-surge mechanisms, taken separately. Results demonstrated that both utilized techniques provided a useful tool to soften both water-hammer up- and down-surges. Additionally, the amortization of pressure-head-rise and -drop was sensitive to the short-section material and size. Moreover, the branching strategy illustrated several enhancements to the inline one in terms of period spread-out limitation, while providing acceptable pressure-head damping.

Leak Testing

2021 ◽  
pp. 143-147
Author(s):  
Charles Becht
Keyword(s):  
Wall Thickness ◽  
Pipe Wall ◽  
Piping System ◽  
Pipe Wall Thickness ◽  
Pressure Testing ◽  
Leak Testing ◽  
Piping Systems ◽  
Design Pressure ◽  
Important Test

While the exercise of pressurizing a piping system and checking for leaks is sometimes called pressure testing, the Code refers to it as leak testing. The main purpose of the test is to demonstrate that the piping can confine fluid without leaking. When the piping is leak tested at pressures above the design pressure, the test also demonstrates that the piping is strong enough to withstand the pressure. For large bore piping where the pipe wall thickness is close to the minimum required by the Code, being strong enough to withstand the pressure is an important test. For small bore piping that typically has a significant amount of extra pipe wall thickness, being strong enough is not in question. Making sure that the piping is leak free is important for all piping systems.

Shortcut Method for Pipe Expansion Loop Sizing

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Nikola Jaćimović ◽  
Miloš Ivošević
Keyword(s):  
Distribution Systems ◽  
Worked Examples ◽  
Engineering Practice ◽  
Piping System ◽  
Comprehensive Overview ◽  
Approximate Methods ◽  
Proposed Model ◽  
Piping Systems ◽  
Early Phases ◽  
Shortcut Method

Abstract In the engineering practice, it is often necessary to define supporting scheme and expansion loop requirements for piping distribution systems in very early phases of a project. While placing pipe supports is a relatively easy and straightforward task, providing accurate loop locations and dimensions for hot piping systems can often be challenging. In the early phases of any project, it is impractical, costly and time consuming to perform detailed stress analysis of a piping system to provide expansion loop dimensions, and therefore approximate methods are often used. Comprehensive overview of these existing procedures most commonly used in the engineering practice is given in this article. However, the fact is that most of the existing methods are based on the inconvenient charts and tables with scarce background data. Procedure proposed in this article is based on over 150 expansion loop models and provides a simple and accurate analytical method to size and verify piping loops. Two fully worked examples show the simplicity and accuracy of the proposed model and its advantages over the methods typically used in the engineering practice.

Exploring the performances of the dual technique-based water hammer redesign strategy in water supply systems

2019 ◽  
Vol 69 (1) ◽  
pp. 6-17 ◽  
Author(s):  
Mounir Trabelsi ◽  
Ali Triki
Keyword(s):  
Pressure Wave ◽  
Oscillation Period ◽  
Conventional Technique ◽  
Water Hammer ◽  
Water Supply Systems ◽  
Piping System ◽  
Wave Oscillation ◽  
Pressure Surge ◽  
Short Section ◽  
Steel Piping

Abstract This paper explored and compared the effectiveness of the inline and branching redesign strategies-based dual technique, implemented to enhance the conventional technique skills in terms of attenuation of positive and negative pressure surge magnitudes and limitation of the spreading of pressure wave oscillation period. Basically, this technique is based on splitting the single inline or branched plastic short-section, used in the conventional technique, into a couple of two sub-short-sections made of two distinct plastic material types. Investigations addressed positive and negative surge initiated water hammer events. Additionally, high and low density polyethylene materials were utilized for sub-short-section material. Results illustrated the reliability of the dual technique in protecting hydraulic systems from excessive pressure rise and drop, and evidenced that the (HDPE/LDPE) sub-short-sections' combination (where the former sub-short-section is attached to the sensitive region of the steel piping system parts, while the latter is attached to the second extremity of the steel piping system) is the most prominent configuration providing the best trade-off between pressure surge attenuation, and pressure wave oscillation period spreading. Lastly, it was found that the pressure head peak (or crest) and the pressure wave oscillation period values were markedly sensitive to the (HDPE) sub-short-section length and diameter.

Charts for water hammer in pipelines resulting from valve closure

1980 ◽  
Vol 7 (2) ◽  
pp. 243-255 ◽  
Author(s):  
Eugen Ruus ◽  
Farouk A. El-Fitiany
Keyword(s):  
Pipe Wall ◽  
Pressure Head ◽  
Water Hammer ◽  
Wall Friction ◽  
Maximum Pressure ◽  
Valve Closure ◽  
Closure Time ◽  
Basic Parameters

Maximum pressure head rises, which result from valve closure according to (a) uniform, (b) equal-percentage, and (c) optimum valve closure arrangements, are calculated and plotted for the valve end and for the midpoint of a simple pipeline. Basic parameters such as the pipeline constant, relative closure time, and pipe wall friction are considered for closures both from partial as well as from full valve openings. The results of this paper can be used to draw the maximum hydraulic grade line along the pipe for these closure arrangements. It is found that the equal-percentage closure arrangement yields consistently less pressure head rise than does the uniform closure arrangement. Further, the optimum closure arrangement yields consistently less head rise than the equal-percentage one. Closures from partial valve openings increase the pressure head rise considerably and must always be considered.

scholarly journals Assessment of inline technique-based water hammer control strategy in water supply systems

2019 ◽  
Vol 68 (7) ◽  
pp. 562-572 ◽  
Author(s):  
Ridha Ben Iffa ◽  
Ali Triki
Keyword(s):  
Water Supply ◽  
Plastic Material ◽  
Pressure Head ◽  
Oscillation Period ◽  
Water Hammer ◽  
Steel Pipe ◽  
Water Supply Systems ◽  
Wave Oscillation ◽  
Supply Systems ◽  
Short Section

Abstract This article discusses and compares the effectiveness of the compound and dual technique-based inline strategy used to upgrade existing steel pipe-based water supply systems. Basically, these techniques are based on splitting the single inline short section, used in the conventional technique, into a couple of two sub-short sections made of two distinct plastic material types: high- and low-density polyethylene (HDPE) and (LDPE). The 1D unconventional water hammer solver based on the method of characteristics was used for numerical computations. Results evidenced that the specific setup of the compound technique based on (HDPE-LDPE) sub-short sections (where the former sub-short section is attached to the hydraulic parts, while the latter is attached to the main steel pipe) is the most prominent configuration providing an acceptable trade-off between attenuation of pressure head surge, and limitation of excessive wave oscillation period spreading. Furthermore, this compound technique setup allowed more important pressure head peak (or crest) attenuation as compared with the dual technique based on (LDPE-LDPE) sub-short sections; while inducing about similar values of wave oscillation period spreading.

Unsteady Velocity Profiles in Laminar and Turbulent Water Hammer Flows

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Alireza Riasi ◽  
Ahmad Nourbakhsh ◽  
Mehrdad Raisee
Keyword(s):  
Transient Flow ◽  
Pipe Wall ◽  
Velocity Profiles ◽  
Water Hammer ◽  
Zero Velocity ◽  
Initial Location ◽  
Wave Cycle ◽  
Dimensional Boundary ◽  
Accelerating Flows ◽  
Turbulent Water

The behavior of unsteady velocity profiles in laminar and turbulent water hammer flows is numerically investigated. In this way, the governing equations for the quasitwo-dimensional equations of transient flow in pipe are solved by using the modified implicit characteristics method. A k-ω turbulence model which is accurate for two-dimensional boundary layers under adverse and favorable pressure gradients is applied. The numerical results for both steady and unsteady turbulent pipe flows are in good agreement with the experimental data. The results indicate that both decelerating and accelerating flows are produced in a wave cycle of water hammer. During deceleration of the flow, a region of reverse flows and also strong gradients is formed near to the pipe wall. In case of the turbulent water hammer, this region is very close to the pipe wall compared with the laminar water hammer. Moreover, point of inflection and also point of zero velocity are formed in the unsteady velocity profile due to the water hammer problem. The results show that the point of zero velocity does not move very far from its initial location, while the point of inflection moves rapidly from the wall.

Condensation Water Hammer Calculation as Basis for Better Design

2003 ◽  
Author(s):  
Werner Schnellhammer ◽  
Tilman Diesselhorst
Keyword(s):  
System Design ◽  
Initial Conditions ◽  
Fluid Structure Interaction ◽  
Water Hammer ◽  
Operating Conditions ◽  
Piping System ◽  
System Operation ◽  
Structure Interaction ◽  
Piping Systems ◽  
Pressure Surge

Condensation processes can generate relevant loading on piping systems when large bubbles ore separated vapor volumes are collapsing in a pipe. For prediction of such loads condensation effects in piping systems were modelled and integrated in a pressure surge code for branched systems taking into account fluid structure interaction. From these calculations we get realistic results of condensation water hammer in the piping system. The loads are strongly depending on the initial conditions and operating procedures. By carrying out calculations with the different possible operating conditions the results give the basis to decide which load cases are covered by the system design and where countermeasures have to be taken. These measures may consist of changing the modus of system operation or modifying the system design itself. A typical example is given.

3D numerical simulation of laminar water hammer considering pipe wall viscoelasticity and the arbitrary Lagrangian-Eulerian method

2018 ◽  
Vol 15 (2) ◽  
pp. 298-305
Author(s):  
Masoud Morvarid ◽  
Ali Rezghi ◽  
Alireza Riasi ◽  
Mojtaba Haghighi Yazdi
Keyword(s):  
Transient Flow ◽  
Stokes Equations ◽  
Pipe Wall ◽  
Water Hammer ◽  
3D Simulation ◽  
Transient Condition ◽  
Wall Region ◽  
Arbitrary Lagrangian Eulerian ◽  
Ale Method ◽  
Content Type

Purpose Analysis of fast transient flow in water pipe systems is an important issue for the prevention of unfavorable pressure oscillations and severe damage to the pipelines. This paper aims to present the performance of three-dimensional (3D) simulation of laminar water hammer caused by fast closure of valve. Design/methodology/approach The viscoelastic behavior of pipe wall is mathematically modeled by using the rheological model of Maxwell. The arbitrary Lagrangian–Eulerian (ALE) method is also used to simulate fluid–structure interaction. In this method, unlike the classical water hammer theory, the acoustic wave velocity is calculated during the numerical simulations and therefore it is not predetermined. Findings Investigating the velocity profiles and the shear stress diagrams for transient flow in elastic pipe showed that the strong effect of viscous forces on the near wall region in conjunction with the influence of inertial forces in the central region of the pipe leads to creation of reverse flow near the pipe wall. Comparing the numerical results obtained for elastic pipe with those of viscoelastic pipe revealed that during transient condition, the viscoelastic wall absorbs the energy of fluid and therefore pressure fluctuations of viscoelastic pipe are damped more quickly. Moreover, the 3D simulation of water hammer confirmed the plane wave hypothesis of water hammer. Originality/value The 3D Navier–Stokes equations are solved considering the viscoelasticity of the pipe and the ALE method using the software package of COMSOL Multiphysics.

Influence of Excitation on Junction Coupling at Water Hammer in Piping Systems

2014 ◽  
Author(s):  
Stefan Riedelmeier ◽  
Stefan Becker ◽  
Eberhard Schlücker
Keyword(s):  
Optical Measurement ◽  
Water Hammer ◽  
Piping System ◽  
System Configuration ◽  
Mean Flow ◽  
Structure Interaction ◽  
Piping Systems ◽  
Junction Coupling ◽  
System Configurations ◽  
Comprehensive Study

A comprehensive study on junction coupling in two piping system configurations in dependency of the excitation’s condition were performed. The source of the hydraulic excitation is characterized by water hammer produced at various initial mean flow velocities. The resulting forces on the piping system caused bend oscillations. For each system configuration and initial mean flow velocity the support position of the bend was varied. Thus the structural frequency was altered. The pressure inside the pipe, the displacement of the bend, the acceleration at the anchorage and the supports were recorded. Additionally, optical measurement equipment was utilized in order to characterize the structural oscillation more detailed. For both system configurations fluid-structure interaction effects were identified, but two-way effects at the base frequency of water hammer only occurred in one system. The amplitude of excitation had influence on the amplitudes of the pressure, displacement and acceleration and on the number of modes which built up. The results of the measurements pointed out that not only the bend oscillated but also the anchorage and pipe sections behind the bend. In both systems, an energy transfer from the fluid to the anchorage could be observed. Due to the bending of the anchorage, the bends oscillated in multiple directions.

Modelling solid transport in building drainage systems

1996 ◽  
Vol 33 (9) ◽  
pp. 9-16 ◽  
Author(s):  
John A. Swaffield ◽  
John A. McDougall
Keyword(s):  
Decision Making ◽  
Boundary Conditions ◽  
Numerical Solution ◽  
Water Conservation ◽  
Transient Flow ◽  
Drainage System ◽  
System Model ◽  
Flow Depth ◽  
Flow Conditions ◽  
Solid Transport

The transient flow conditions within a building drainage system may be simulated by the numerical solution of the defining equations of momentum and continuity, coupled to a knowledge of the boundary conditions representing either appliances discharging to the network or particular network terminations. While the fundamental mathematics has long been available, it is the availability of fast, affordable and accessible computing that has allowed the development of the simulations presented in this paper. A drainage system model for unsteady partially filled pipeflow will be presented in this paper. The model is capable of predicting flow depth and rate, and solid velocity, throughout a complex network. The ability of such models to assist in the decision making and design processes will be shown, particularly in such areas as appliance design and water conservation.

Sign in / Sign up

Export Citation Format

Share Document