Water Hammer Caused by Fast Closing Valves

2017 ◽  
Author(s):  
Shesh R. Koirala ◽  
Ilker T. Telci
Keyword(s):  
Permanent Deformation ◽  
Joint Damage ◽  
Initial Pressure ◽  
Cost Effective ◽  
Piping System ◽  
Valve Closure ◽  
Transient Pressure ◽  
Transient Conditions ◽  
Piping Systems ◽  
Pipe Size

Operation of fast closing valves in piping systems can create an overpressure condition, resulting in permanent deformation, joint damage, leakage, or rupture. Fast closing valves are used in many piping systems to protect personnel, equipment and the environment from the danger of overpressure. When there is a sudden closure of a piping system valve, the change in the flow velocity produces a transient increase in pipe pressure. This increased pressure is commonly known as transient, fluid hammer waterhammer, or surge pressure. In a very simplistic system, the excess pressure created by this sudden closure of valves can be computed using a simple hand calculation using Joukowsky method. The method is applicable only for the initial pressure wave generated. In complex systems, where there are dead legs (e.g. closed by-pass valves) or branches, there is more chance of the pressure waves being reflected, transmitted and superimposed. The overpressure problem is even more severe if a liquid column separation and re-joining occurs during the transient conditions. The magnitude of the pressure in the system due to these effects may be higher than that estimated by Joukowsky method. Hence a transient analysis needs to be performed to estimate the overpressure in the system. In this case study, the transient conditions initiated due to closure of buckling pin valves (BPVs) are modeled using a proprietary software CE099. The objectives are to calculate the maximum surge pressures, dynamic loads, and to recommend mitigations to reduce transient pressures and loads. The results showed that pressures could be reduced by increasing the pipe size of few segments or adding expansion loops. The most sensitive parameter for transient pressure was pipe size and that for dynamic load was valve closure time. It is recommended that this kind of study be performed in the early phase of engineering design, so that any identified overpressures can be mitigated with simple, cost effective options such as increasing pipe size, altering valve closure times, and adding expansion loops.

Estimation of Bending Stresses in Piping Systems Subjected to Transient Pressure

2020 ◽  
Author(s):  
Maral Taghva ◽  
Lars Damkilde
Keyword(s):  
Dynamic Analysis ◽  
Static Analysis ◽  
Structural Integrity ◽  
Oil And Gas ◽  
Real Life ◽  
Piping System ◽  
Transient Pressure ◽  
Operational Conditions ◽  
Piping Systems ◽  
Bending Stresses

Abstract Modifications in aged process plants may subject piping systems to fluid transient scenarios, which are not considered in the primary design calculations. Due to lack of strict requirements in ASME B31.3 the effect of this phenomenon is often excluded from piping structural integrity reassessments. Therefore, the consequences, such as severe pipe motion or even rupture failure, are discovered after modifications are completed and the system starts to function under new operational conditions. The motivation for this study emanated from several observations in offshore oil and gas piping systems, yet the results could be utilized in structural integrity assessments of any piping system subjected to pressure waves. This paper describes how to provide an approximate solution to determine maximum bending stresses in piping structures subjected to wave impulse loads without using rigorous approaches to calculate the dynamic response. This paper proposes to consider the effect of load duration in quasi-static analysis to achieve more credible results. The proposed method recommends application of lower dynamic load factors than commonly practiced values advised by design codes, for short duration loads such as shock waves. By presenting a real-life example, the results of improved and commonly practiced quasi-static analysis are compared with the site observations as well as dynamic analysis results. It is illustrated that modified quasi-static solution shows agreement with both dynamic analysis and physical behavior of the system. The contents of this study are particularly useful in structural strength re-assessments where the practicing engineer is interested in an approximated solution indicating if the design criteria is satisfied.

Risk-Based Inspection Applied to Main Steam and Hot Reheat Piping Systems

2007 ◽  
Author(s):  
Marvin J. Cohn
Keyword(s):  
Cost Effective ◽  
High Energy ◽  
Accurate Estimate ◽  
Terminal Point ◽  
Rational Approach ◽  
Piping System ◽  
Piping Systems ◽  
Risk Areas ◽  
Main Steam ◽  
Life Consumption

Many utilities select critical welds in their main steam (MS) and hot reheat (HRH) piping systems by considering some combination of design-based stresses, terminal point locations, and fitting weldments. The conventional methodology results in frequent inspections of many low risk areas and the neglect of some high risk areas. This paper discusses the use of a risk-based inspection (RBI) strategy to select the most critical inspection locations, determine appropriate reexamination intervals, and recommend the most important corrective actions for the piping systems. The high energy piping life consumption (HEPLC) strategy applies cost effective RBI principles to enhance inspection programs for MS and HRH piping systems. Using a top-down methodology, this strategy is customized to each piping system, considering applicable effects, such as expected damage mechanisms, previous inspection history, operating history, measured weldment wall thicknesses, observed support anomalies, and actual piping thermal displacements. This information can be used to provide more realistic estimates of actual time-dependent multiaxial stresses. Finally, the life consumption estimates are based on realistic weldment performance factors. Risk is defined as the product of probability and consequence. The HEPLC strategy considers a more quantitative probability assessment methodology as compared to most RBI approaches. Piping stress and life consumption evaluations, considering existing field conditions and inspection results, are enhanced to reduce the uncertainty in the quantitative probability of failure value for each particular location and to determine a more accurate estimate for future inspection intervals. Based on the results of many HEPLC projects, the author has determined that most of the risk (regarding failure of the pressure boundary) in MS and HRH piping systems is associated with a few high priority areas that should be examined at appropriate intervals. The author has performed many studies using RBI principles for MS and HRH piping systems over the past 15 years. This life management strategy for MS and HRH critical welds is a rational approach to determine critical weldment locations for examinations and to determine appropriate reexamination intervals as a risk-based evaluation technique. Both consequence of failure (COF) and likelihood of failure (LOF) are considered in this methodology. This paper also provides a few examples of the application of this methodology to MS and HRH piping systems.

scholarly journals Experimental Study on Vibration Control of Suspended Piping System by Single-Sided Pounding Tuned Mass Damper

2019 ◽  
Vol 9 (2) ◽  
pp. 285 ◽  
Author(s):  
Jie Tan ◽  
Siu Michael Ho ◽  
Peng Zhang ◽  
Jinwei Jiang
Keyword(s):  
Free Vibration ◽  
Forced Vibration ◽  
Cost Effective ◽  
Tuned Mass Damper ◽  
Spring Steel ◽  
Piping System ◽  
Mass Damper ◽  
Piping Systems ◽  
High Flexibility ◽  
The Impact

Suspended piping systems often suffer from severe damages when subjected to seismic excitation. Due to the high flexibility of the piping systems, reducing their displacement is important for the prevention of damage during times of disaster. A solution to protecting piping systems during heavy excitation is the use of the emerging pounding tuned mass damper (PTMD) technology. In particular, the single-sided PTMD combines the advantages of the tuned mass damper (TMD) and the impact damper, including the benefits of a simple design and rapid, efficient energy dissipation. In this paper, two single-sided PTMDs (spring steel-type PTMD and simple pendulum-type PTMD) were designed and fabricated. The dampers were tested and compared with the traditional TMD for mitigating free vibration and forced vibration. In the free vibration experiment, both PTMDs suppressed vibrations much faster than the TMD. For the forced vibration test, the frequency response of the piping system was obtained for three conditions: without control, with TMD control, and with PTMD control. These novel results demonstrate that the single-sided PTMD is a cost-effective method for efficiently and passively mitigating the vibration of suspended piping systems. Thus, the single-sided PTMD will be an important tool for increasing the resilience of structures as well as for improving the safety of their occupants.

On Vibration Properties of Piping Systems and Practical Measures for Preventing Vibration Damages

2014 ◽  
Author(s):  
Lennart G. Jansson ◽  
Lingfu Zeng
Keyword(s):  
Cost Effective ◽  
Piping System ◽  
Dynamic Susceptibility ◽  
Vibration Properties ◽  
Piping Systems ◽  
Theoretical Predictions ◽  
Key Issues ◽  
Vibration Damage ◽  
Critical Sections

This paper addresses several key issues relevant to piping vibration: (1) vibration properties and their identification; (2) the dynamic susceptibility of a piping system; (3) standard velocity criteria for vibration damage. Practical approaches for identifying vibration properties and practical measures for preventing vibration damages are overviewed. An approach is presented for conducting vibration design reducing measures prior to installation of a piping system, and for planning post-installation vibration recording activities. This approach is based on “theoretical predictions” of “critical” sections of a piping system, namely the sections most sensitive to vibration. The critical sections can be ranked from most vulnerable to least vulnerable. Combined with knowledge of typical vibration sources, this is a cost effective way for preventing vibration damages and for forming a base for controlling actual vibrations in operation of plant, especially for closed premises. Examples are given to exemplify vibration risk.

scholarly journals Pipe size sensitivity in pressure relief networks using genetic algorithms

2020 ◽  
pp. 32-32
Author(s):  
Sabla Alnouri ◽  
Mirjana Kijevcanin ◽  
Mirko Stijepovic
Keyword(s):  
Genetic Algorithms ◽  
High Performance ◽  
Network Performance ◽  
Cost Effective ◽  
Piping System ◽  
Network System ◽  
Optimization Approach ◽  
Pressure Relief ◽  
Overall Design ◽  
Pipe Size

This paper utilizes a stochastic optimization approach using genetic algorithms, for conducting rigorous pipe size sensitivity assessments onto the design of pressure relief networks. By sampling high performance candidates, only the finest options can survive. The pressure relief network system that was investigated in this work was previously reported in literature. The problem is constrained and involves minimizing a cost objective function that evaluates the overall network performance, in which the best pipe size combination should be selected for each segment within the network. The overall goal of this paper was to seek cost-effective designs for the pressure relief piping system by exploring different ranges of pipe diameters that are available for each segment in the network and comparing how the overall design of the system is affected, when the number of pipe size options to select from is varied.

scholarly journals Response of Piping Tees to Propagating Detonations

2013 ◽  
Author(s):  
Thomas C. Ligon ◽  
David J. Gross ◽  
Joseph E. Shepherd
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Structural Response ◽  
Initial Pressure ◽  
Finite Element Simulations ◽  
Steel Plates ◽  
Digital Data ◽  
304 Stainless Steel ◽  
Piping System ◽  
Piping Systems

This paper reports the results of experiments and finite element simulations on the structural response of piping systems to internal detonation loading. Specifically, the work described in this paper focuses on the forces that are produced at tee-junctions that lead to axial and bending structural responses of the piping system. Detonation experiments were conducted in a 2-in. (50 mm) diameter schedule 40 piping system that was fabricated using 304 stainless steel and welded to ASME B31.3 standards. The 4.1 m (162-in.) long piping system included one tee and was supported using custom brackets and cantilever beams fastened to steel plates that were bolted to the laboratory walls. Nearly-ideal detonations were used in a 30/70 H2-N2O mixture at 1 atm initial pressure and 300 K. Pressure and hoop, axial, and support strains were measured using a high-speed (1 MHz) digital data acquisition system and calibrated signal conditioners. It was concluded that detonations propagate through the run of a 90° tee with relatively little disturbance in either direction. The detonation load increases by approximately a factor of 2 when the detonation enters through the branch. The deflections of the cantilever beam supports and the hoop and axial pipe strains could be adequately predicted by finite element simulations. The support loads are adequately predicted as long as the supports are constrained to the piping. This paper shows that with relatively simple models, quantitative predictions of tee forces can be made for the purposes of design or safety analysis of piping systems subject to internal detonations.

Effect of Steam Hammer Pressure Wave Steepening on Pipe Supports

2018 ◽  
Author(s):  
Alex Mayes ◽  
Kshitij P. Gawande
Keyword(s):  
Pressure Wave ◽  
Safety Valve ◽  
Cfd Modeling ◽  
Piping System ◽  
Valve Closure ◽  
Pipe System ◽  
Piping Systems ◽  
Computational Fluid Dynamics Cfd ◽  
Thermal Fluid Flow ◽  
Flow Valve

Safety valve closure is employed within power plant piping systems to protect sensitive components from damage due to irregular events causing abrupt pressure variations of the thermal fluid flow. The valve closure creates a sudden obstruction to the flow, generating a pressure wave within the fluid which travels upstream and impacts at the pipe elbows. Such an event is known as steam hammer. This steam hammer pressure wave is capable of producing significant loads and stresses which can disrupt the piping supports as the wave travels throughout the pipe system. Previous studies have shown that the magnitude of these transient loads depend upon the characteristics of the flow, valve closure time, elbow-to-elbow pipe section lengths, the piping system flexibility, and the ‘steepness’ of the pressure transient. The latter effect has been ignored in most steam hammer studies; however, wave steepening has been shown to have a significant effect in cases where the pressure wave travels long distances from the safety valve. This study focuses on Computational Fluid Dynamics (CFD) modeling of rapid valve closure to produce this wave steepening effect and to investigate the significance in terms of transient pipe support loads.

Forces on Piping Bends due to Propagating Detonations

2011 ◽  
Author(s):  
Thomas C. Ligon ◽  
David J. Gross ◽  
Joseph E. Shepherd
Keyword(s):  
Finite Element ◽  
Structural Response ◽  
Initial Pressure ◽  
Finite Element Simulations ◽  
Digital Data ◽  
Analytical Models ◽  
304 Stainless Steel ◽  
Piping System ◽  
Detonation Cell ◽  
Piping Systems

This paper reports the results of experiments, analytical models, and finite element simulations on the structural response of piping systems to internal detonation loading. Of particular interest are the interaction of detonations with 90° bends and the creation of forces that lead to axial and bending structural response of the piping system. The piping systems were fabricated using 304 stainless steel, 2-in. (50 mm) diameter schedule 40 commercial pipe with a nominal wall thickness of 0.154-in. (3.8 mm) and welded construction to ASME B31.3 standards. The piping was supported using custom brackets or cantilever beams fastened to steel plates that were bolted to the laboratory walls. Nearly-ideal detonations were used in a 30/70 H2-N2O mixture at 1 atm initial pressure and 300 K. The detonation speeds were close (within 1%) to the Chapman-Jouguet velocity and detonation cell sizes much smaller than the tube diameter. Pressure, displacement, acceleration and hoop, longitudinal, and support strains were measured using a high-speed (1 MHz) digital data acquisition system and calibrated signal conditioners. Detonation propagation through a bend generates a longitudinal stress wave in the piping that can be observed on the strain gauges and is predicted by both analytical models and finite element simulations. The peak magnitude of the bend force is approximately twice that due to the pressure alone since the peak momentum flux of the flow behind the detonation front is comparable to the pressure in the front. With relatively simple models, quantitative predictions of the bend forces can be made for the purposes of design or safety analysis of piping systems with internal detonations.

Non-Linear Design Verification of Nuclear Power Piping According to ASME III NB/NC

2008 ◽  
Author(s):  
Lingfu Zeng ◽  
Lennart G. Jansson
Keyword(s):  
Nuclear Power ◽  
Design Evaluation ◽  
Piping System ◽  
Design Verification ◽  
Intensive Study ◽  
Non Linear ◽  
Piping Systems ◽  
Design Requirements

A nuclear piping system which is found to be disqualified, i.e. overstressed, in design evaluation in accordance with ASME III, can still be qualified if further non-linear design requirements can be satisfied in refined non-linear analyses in which material plasticity and other non-linear conditions are taken into account. This paper attempts first to categorize the design verification according to ASME III into the linear design and non-linear design verifications. Thereafter, the corresponding design requirements, in particular, those non-linear design requirements, are reviewed and examined in detail. The emphasis is placed on our view on several formulations and design requirements in ASME III when applied to nuclear power piping systems that are currently under intensive study in Sweden.

Comparison of Failure Modes of Piping Systems With Wall Thinning Subjected to In-Plane, Out-of-Plane, and Mixed Mode Bending Under Seismic Load: An Experimental Approach

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Shiratori
Keyword(s):  
Dynamic Behavior ◽  
Failure Modes ◽  
Seismic Load ◽  
Piping System ◽  
Shake Table ◽  
Shake Table Tests ◽  
Wall Thinning ◽  
Piping Systems ◽  
Out Of Plane ◽  
Plane Bending

Pressurized piping systems used for an extended period may develop degradations such as wall thinning or cracks due to aging. It is important to estimate the effects of degradation on the dynamic behavior and to ascertain the failure modes and remaining strength of the piping systems with degradation through experiments and analyses to ensure the seismic safety of degraded piping systems under destructive seismic events. In order to investigate the influence of degradation on the dynamic behavior and failure modes of piping systems with local wall thinning, shake table tests using 3D piping system models were conducted. About 50% full circumferential wall thinning at elbows was considered in the test. Three types of models were used in the shake table tests. The difference of the models was the applied bending direction to the thinned-wall elbow. The bending direction considered in the tests was either of the in-plane bending, out-of-plane bending, or mixed bending of the in-plane and out-of-plane. These models were excited under the same input acceleration until failure occurred. Through these tests, the vibration characteristic and failure modes of the piping models with wall thinning under seismic load were obtained. The test results showed that the out-of-plane bending is not significant for a sound elbow, but should be considered for a thinned-wall elbow, because the life of the piping models with wall thinning subjected to out-of-plane bending may reduce significantly.

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