Piping System Components Research Articles

Innovative Approaches to Expansion Loop Design for Enhanced Piping System Durability

Expansion loops are critical components in piping systems, designed to manage stress caused by thermal expansion and contraction, thereby ensuring the system's durability and safety. This study investigates innovative approaches to optimizing expansion loop design, focusing on improving the performance and reliability of piping systems under various operational conditions. The research examines multiple configurations, including alterations in loop length, shape modifications, and the incorporation of additional loops, to assess their impact on stress distribution within the system. While the primary focus of this study is on static stress analysis, transient operational factors, such as water hammer, were also considered in the analysis to provide a more comprehensive understanding of the loop configurations' performance under various conditions. The findings demonstrate that while increasing the loop length can effectively reduce stress, alternative designs, such as double loops or modified shapes, offer superior stress management, particularly in space-constrained environments. The study concludes that optimal expansion loop design should accommodate thermal expansion and provide robustness against potential transient effects, contributing to a more reliable piping system. These insights provide valuable guidelines for the design and optimization of piping systems across various industrial applications.

A turbulent flow topology optimization method for diverging tee resistance reduction

The resistance of local components in piping and duct systems significantly affects the energy consumption of fans and pumps, accounting for 40–60 % of the total building energy consumption. In this paper, an improved topology optimization method for variable density turbulent flow is proposed to design a low-resistance diverging tee structure in piping and duct systems. The advantages of the improved optimization method over the traditional method are analyzed using finite element numerical simulation, and the applicability of the proposed method is verified in the Reynolds number range of 0.6 × 105–2.6 × 105. In order to ensure the resistance reduction effect of the topology diverging tee under multiple operating conditions, the local resistance coefficients under nine flow ratios were simulated and calculated using the finite volume method. The results show that the topology diverging tee can significantly reduce the resistance. Compared with the traditional tee, the maximum resistance reduction rates in the straight-through direction and branch direction reached 63 % and 59 %, respectively. In addition, the intensity of secondary flow in five downstream sections was analyzed based on the dimensionless parameter Se. Finally, the actual resistance reduction effect of the topology diverging tee was experimentally verified. The optimization method and analysis results proposed in this study can provide a reference for the optimal design of pipelines with low resistance in energy-saving operation of buildings and in engineering fields such as petroleum and chemical industries.

Safety and reliability analysis for butterfly valves in the offshore oil and gas industry

Valve systems are essential components in piping systems in a variety of industries, including oil and gas to stop and start the flow of fluid, regulate and control fluids, prevent backflows, and provide safety. The safety and reliability of industrial valves is an increasingly critical issue that has been addressed in previous studies. In case of valve failure due to mechanical failure, material corrosion, poor manufacturing and testing, there can be negative consequences including loss of assets, leakage into the environment, and other issues. The objective of this study is to develop a method for measuring the safety and reliability of safety critical butterfly valves by combining safety integrity level (SIL) and failure mode and effect analysis (FMEA). On the basis of operational data, butterfly valve failure rates are estimated. Safe failure fraction (SFF) are calculated at approximately 89% for the valves and converted into SIL2 that meets the end-user requirements.

Thermal Stress Analysis of Process Piping System Installed on LNG Vessel Subject to Hull Design Loads

In this paper, the procedure for the strength evaluation of the piping system installed on liquefied natural gas (LNG) carriers is discussed. A procedure that accounts for the ship’s wave load and hull motion acceleration (as well as the deformation due to the thermal expansion and contraction experienced by the hull during seafaring operations) is presented. The load due to the temperature and self-weight of the piping installed on the deck is also considered. Various operating and load conditions of the LNG piping system are analyzed. Stress analysis is performed by combining various conditions of sustained, occasional, and expansion loads. Stress is assessed using finite element analysis based on beam elements that represent the behavior of the piping. The attributes of the piping system components (such as valves, expansion joints, and supports) are represented in the finite element model while CAESAR-II, a commercial software is used for finite element analysis. Component modeling, load assignment, and load combinations are presented to evaluate pipe stresses under various load conditions. An evaluation model is selected for the piping arrangement of LNG and the evaluated stress is compared with the allowable stress defined by the American Society of Mechanical Engineers (ASME).

Scope of Energy Conservation in Pumping System

Pumps consume about 22% of the world’s total energy generated, out of which 16% is consumed by centrifugal pumps and 6% by rotodynamic pumps. According to the American Hydraulics Institute, 30% of the total electrical energy consumed by pumping systems can be conserved either by designing highly efficient systems or by using appropriate pumps. As a result, the primary focus of global energy policy makers is to enhance energy efficiency in pumping systems. This paper aims to highlight the areas that need to be address in order to increase the pumping system efficiency. It is evident from studies that about 30% to 50% of the energy consumed by pumping systems could be saved through piping system components or control changes.

Estimation of high energy steam piping degradation using hybrid recurrent neural networks

The degradation of high energy piping systems is very complex to simulate due to the many variables that influence the useful lives of such systems. Estimation of the extent of degradation is however important in the maintenance planning process. In this research the use of data driven machine learning techniques to deal with this complex problem is investigated. A hybrid recurrent neural network is created that consists of a combined recurrent neural network and a feed forward neural network. The hybrid model is trained on historical data that has been captured over a six-year time period. The following variables related to piping system components are used as inputs to the machine learning model: operating temperature and pressure time history, distance to the closest anchor point, distances to neighbouring supports, elevation survey readings, as well as the last known creep damage measurements on the component. The model is created in Python using the Tensorflow library. A recurrent neural networks (RNN) is employed, namely the gated recurrent unit (GRU). The adaptive movement estimation optimization algorithm, called Adam, is used to optimize the machine learning model. The trained model is able to predict the degradation classification of a component with an accuracy of up to 92% on the training dataset and up to 55% on the validation data set. When using this model to predict components with high creep damage, more than 400 voids per mm2 a hit rate of 25% is achieved. The current system employed at operating power stations shows a historic hit rate of 14%. This is a significant increase in performance and could be used to compile more efficient inspection plans. The model is successful in recognising patterns within the data and offers an automated way to parse large data sets that consist of a temporal and static data mixture simultaneously. Conventional data driven models are only able to look at either temporal data or static data. This suggests a generic approach to make objective decisions on similar complex data driven problems and its application is not limited to this particular problem. The methods applied in this research are expected to perform even better on problems where the frequency of data collection is higher than what is used in this research.

Operando Sub-Second Neutron Imaging of Cationic Species Migration in a Proton Exchange Membrane Water Electrolyzer

In recent years, it became clear that implementing energy storage on a large scale is a necessary route for the power production sector to maintain a stable and sustainable grid with increasing share of intermittent renewable sources of energy. Proton exchange membrane water electrolyzers show promise especially because of their suitability to be coupled to renewables in remote areas decentralizing the energy grid. There are, however, some challenges, which have to be tackled before market penetration can occur. One of the most pressing issues is the susceptibility of the proton exchange membrane to feed water impurities in form of cations [1], [2]. Titanium porous transport layers, piping and other system components will introduce slight amounts of cations during normal operation (Fe, Na, Cu, Ca, Ti), which over a longer period will become the cause of significant overpotential [3]. It is therefore necessary to understand the contamination mechanism of proton exchange membranes and its impact on the electrochemical performance of the cell. Motivated by the fact that the reversible degradation is one of the key factors which dictate the operability of an electrolyzer, we carried out experiments which bring further insights into the influence and behavior of the cationic species in the proton exchange membrane water electrolyzer under operation and standby conditions. Neutron imaging techniques were employed to observe the model contaminant in form of Gd3+, which is a perfect fit due to its large neutron cross-section. We found that under the effect of the electric field the cations migrate and accumulate near cathode catalyst layer/porous transport layer interface. A sub-second imaging setup enabled us to correlate the position of cations within the membrane with electrochemical data. Subsequently we regenerated the cell by operating it with diluted sulfuric acid (below 1mMol/L) injected into cathode compartment during the neutron imaging. Influence of the accumulation of the cations near the cathode catalyst layer on the electrolyzer performance and optimal operando regeneration procedures will be discussed. [1] S. Sun, Z. Shao, H. Yu, G. Li, and B. Yi, “Investigations on degradation of the long-term proton exchange membrane water electrolysis stack,” J. Power Sources, vol. 267, pp. 515–520, 2014. [2] X. Wang, L. Zhang, G. Li, G. Zhang, Z. G. Shao, and B. Yi, “The influence of Ferric ion contamination on the solid polymer electrolyte water electrolysis performance,” Electrochim. Acta, vol. 158, pp. 253–257, 2015. [3] U. Babic, M. Suermann, F. N. Büchi, L. Gubler, and T. J. Schmidt, “Critical Review—Identifying Critical Gaps for Polymer Electrolyte Water Electrolysis Development,” J. Electrochem. Soc., vol. 164, no. 4, pp. F387–F399, 2017. Figure 1

Cost Reduction of Valve: Using Value Analysis for Sustainability

Value Engineering (VE) defines a process in which the value of the product can be increased by significantly decreasing its cost to achieve a long-term profitability plan of a company. In this study, Value engineering tools has been primarily used to improve the value of the product and services by reducing the cost of the valve to make it cost effective. Valves are integral components in piping systems and uses for the various purposes. The study revealed the poor value areas for which the alternatives were developed and evaluated. The modification in valve can be made through analysing functional requirement of valve for the purpose of achieving the essential function at lower cost. Finally, changes in design were proposed which led to cost saving and directly profits the bottom line of the organization.

Structure- and fluid-borne acoustic power sources induced by turbulent flow in 90° piping elbows

Abstract The structure- and fluid-borne vibro-acoustic power spectra induced by turbulent fluid flow over the walls of a continuous 90° piping elbow are computed. Although the actual power input to the piping by the wall pressure fluctuations is distributed throughout the elbow, equivalent total power inputs to various structural wavetypes (bending, torsion, axial) and fluid (plane-waves) at the inlet and discharge of the elbow are computed. The powers at the elbow “ports” are suitable inputs to wave- and statistically-based models of larger piping systems that include the elbow. Calculations for several flow and structural parameters, including pipe wall thickness, flow speed, and flow Reynolds number are shown. The power spectra are scaled on flow and structural–acoustic parameters so that levels for conditions other than those considered in the paper may be estimated, subject to geometric similarity constraints (elbow radius/pipe diameter). The approach for computing the powers (called CHAMP – combined hydroacoustic modeling programs), which links computational fluid dynamics, finite element and boundary element modeling, and efficient random analysis techniques, is general, and may be applied to other piping system components excited by turbulent fluid flow, such as U-bends and T-sections.

Noise generation and propagation effects on piping system components

In power plants and petrochemical plants, the piping systems form a network that extends throughout the facility. Various components in a piping system can be major sources of in-plant and community noise, both the pipe and the contained fluid can be noise propagation paths, and noise radiation can occur from the external surface of the piping. Though the basics of these phenomena are often understood, the translation into workable predictive tools has been slow. Several possible piping system noise sources are described and the experimental test program being undertaken to generate the required non-dimensionalized spectral data is outlined. The accuracy of pressure fluctuation scaling for pressure and flow rate is also reviewed based on the equal tee test program.

Derivation of New Emission Factors for Quantification of Mass Emissions When Using Optical Gas Imaging for Detecting Leaks

This paper describes the development of new “leak/no-leak” emission factors that are suitable for estimating facilities’ fugitive emissions when using an alternative work practice (AWP) that is based on optical gas imaging technology for detecting leaking piping system components. These emission factors were derived for valves, pumps, and connectors/flanges for instrument leak detection thresholds ranging from 3 to 60 g/hr using a combination of field data and Monte Carlo statistical simulation techniques. These newly derived leak/no-leak emission factors are designed to replace the U.S. Environment Protection Agency (EPA) 1995 Protocol factors, which were based on Method 21 monitoring of leaks at “uncontrolled” facilities. The emission factors published in the 1995 Protocol have not been updated since the 1970s. This derivation is based on results where the authors document the use of a Monte Carlo simulation technique to quantify the required leak detection thresholds that provide equal—or better—environmental benefits for an AWP. The use of these newly derived emission factors is demonstrated for different methods of computing fugitive emissions from a hypothetical model refinery. The resulting facility emissions calculated by using these new emission factors is compared with the existing emission estimation methods provided in the EPA 1995 Protocol. The results demonstrate that the new emission factors provide an emission estimate that is the closest to that obtained from the direct determination of total emissions by Monte Carlo simulations.

Damping of tubes due to internal two-phase flow

Abstract Two-phase internal flow is present in many piping system components. Although two-phase damping is known to be a significant constituent of the total damping, the energy dissipation mechanisms that govern two-phase damping are not well understood. In this paper, damping of three different clamped–clamped tubes subjected to two-phase air–water internal axial flow is investigated. Experimental data are reported, showing a strong dependence of two-phase damping on void fraction, flow velocity and flow regime. Data-points plotted on two-phase flow pattern maps indicate that damping is greater in a bubbly flow regime. The two-phase damping ratio reaches a maximum value at the highest void fraction before the transition to a churn flow regime. An analytical model that relates the two-phase damping ratio to the interface surface area is proposed. The model is based on rigid spherical bubbles in cubic elementary flow volumes. The analytical results are well correlated with the experiments.

Performance of components of ice slurry systems: pumps, plate heat exchangers, and fittings

In recent years, a lot of important work has been carried out in order to gather knowledge of the fundamental behaviour of ice slurry in piping systems and heat exchangers. The scope of this work has been to bring ice slurry one step closer to practical application, i.e. to provide a basis for selecting distribution pumps and investigating flow in piping system components. The performance of different multiple-stage centrifugal pumps has been measured with ice concentrations in the range from 0 to 30 wt% of ice. It was found that the pump operation is reliable in the entire range of ice concentrations. The pump performance decreases with increasing ice concentration due to the increasing viscosity of the ice slurry. The viscosity model proposed by Hansen [Viscosity of ice slurry. Second IIR Workshop, Paris, France (2000)] has been applied to compare the manufacturer data on the viscosity dependency. From the results, it cannot be concluded whether the pump performance is entirely determined by the increasing viscosity or whether the solid particles have an additional effect. The flow behaviour of ice slurry has been investigated in a test rig with transparent pipes to allow visual observation of flow patterns in various single components such as fittings, valves and heat exchangers. Finally, pressure loss coefficients in selected fittings have been measured to reveal the dependency of ice concentration.

Characterisation of pipe welds and HAZ in primary heat transport system piping of pressurised heavy water reactors

Weld joints of SA 333 Gr. 6 steel pipe have been prepared using GTAW root pass and SMAW filling of V-groove according to welding procedure specifications (WPS) conforming to ASME Sec IX, a procedure commonly used to fabricate nuclear piping system components. The objective of the present study was to characterise the base metal, weld deposit and HAZ of the pipe weld in terms of their chemical composition and metallurgical, mechanical and fracture mechanics properties. The fracture toughness behaviour of the welds and HAZ has been characterised by J-integral parameters. The fatigue crack growth rate has been characterised by Paris Law. The stretched zone width (SZW) at the fracture surface has been measured with SEM to evaluate the initiation fracture toughness. The values of initiation fracture toughness estimated on the basis of SZW and blunting line from EGF recommendation have been compared. The fracture mechanics properties of the base metal, weld and HAZ have been compared and correlated. Fracture mechanics properties of the weld and HAZ have also been correlated with microstructure.

ICONE11-36545 Using the RELAP5-3D^[○!C]Advanced Systems Analysis Code with Commercial and Advanced CFD Software

Fluent and RELAP5-3D^[○!C]/ATHENA are coupled using a technique that permits implicit inter-actions between them using an Executive Program (Weaver, Tomlinson, & Aumiller, 2002). Hence, if necessary, the Executive will allow Fluent and RELAP5-3D^[○!C]/ATHENA to move forward in calculation space on a time-step-by-time step basis. In addition, the point to three-dimension neutronics/reactor kinetics subroutine in RELAP5-3D^[○!C]/ATHENA (based on NESTLE) can be used, by itself, together with Fluent so a three-dimensional fluids model can be coupled with a three-dimensional neutronics model while the balance of the RELAP5-3D^[○!C]/ATHENA subroutines are used to model the system piping and other system components. Fluent and RELAP5-3D[○!C]/ATHENA were linked using an Executive Program (see Figure 1) that (a) monitors the calculational progression in each code, (b) determines when each code has converged, (c) governs the information interchanges between the codes, and (d) issues permission to allow each code to progress to the next time step. The Executive Program was interfaced with Fluent and RELAP5-3D^[○!C]/ATHENA using user-defined functions. User-defined functions were also used to ensure the fluid properties used by Fluent and RELAP5-3D^[○!C]/ATHENA are equivalent. The Executive Program uses the Parallel Virtual Machine (PVM) as the control medium. The Executive Program interacts with Fluent and RELAP5-3D^[○!C]/ATHENA and governs the interactions between Fluent and RELAP5-3D^[○!C]/ATHENA since the two codes are each independent domains. As noted in Weaver, Tomlinson, and Aumiller, 2001^* : "..volume 1 is adjacent to and connected to volume I, and volume 2 is adjacent to and connected to volume II. The boundary volumes in one of the domains (i.e., 1 and 2) represent normal volumes in the interior of the other computational domain (i.e., I and II). Information about these volumes must be passed between the domains at the coupling boundary to achieve an integrated solution." Using the above approach, the domains can be coupled explicitly or semi-implicitly depending on the problem type.

Flame propagation in industrial scale piping

AbstractThe use of pipelines to connect vessels and transport material is a common practice in the processing industry. Often, these pipelines carry potentially hazardous materials, such as flammable gases. The potential of fires and explosions in the process industry has been well recognized and is addressed in consensus guidelines such as N F PA 68 – Guide for Venting of Deflagrations and N F PA 69 – Explosion Prevention Systems. Both of these guides differentiate between vessels and piping systems by providing diff e rent rules to address the differences in explosion propagation behavior. Both NFPA 68 and NFPA 69 are based on an understanding of explosion propagation behavior developed from empirical or experimental evidence.The purposes of this paper are to present experimental evidence and to further develop a detailed understanding of combustion propagation in industrial scale piping, primarily deflagration propagation in pipes. However, it is also the intent to understand the transition points between fires and deflagrations, and between deflagrations and detonations as related to piping systems. In order to study combustion propagation in industrial scale piping, three pipe diameters and three fuels were selected. Although, gaseous fuel mixtures are often transported in waste streams, only pure fuels were used in this study. The effect of bends was evaluated but other piping system components were not evaluated.

Pipe failure probability—the Thomas paper revisited

Almost twenty years ago, in Volume 2 of Reliability Engineering (the predecessor of Reliability Engineering and System Safety), a paper by H. M. Thomas of Rolls Royce & Associates Ltd. presented a generalized approach to the estimation of piping and vessel failure probability. The ‘Thomas-approach’ used insights from actual failure statistics to calculate the probability of leakage and conditional probability of rupture given leakage. It was intended for practitioners without access to data on the service experience with piping and piping system components. This article revisits the Thomas paper by drawing on insights from development of a new database on piping failures in commercial nuclear power plants worldwide (SKI-PIPE). Partially sponsored by the Swedish Nuclear Power Inspectorate (SKI), the R&D leading up to this note was performed during 1994–1999. Motivated by data requirements of reliability analysis and probabilistic safety assessment (PSA), the new database supports statistical analysis of piping failure data. Against the background of this database development program, the article reviews the applicability of the ‘Thomas approach’ in applied risk and reliability analysis. It addresses the question whether a new and expanded database on the service experience with piping systems would alter the original piping reliability correlation as suggested by H. M. Thomas.

Surmounting design problems in a complex piping system for groundwater remediation

AbstractThis paper describes the design of a fiberglass reinforced plastic (FRP) piping system which transports groundwater extracted from 43 wells at the site of a former chemical manufacturing plant in Toms River, New Jersey. This system conveys an average flow of 2.7 million gallons per day of groundwater contaminated with aromatics, chlorinated hydrocarbons and metals through seven miles of pipeline to a biological and physical treatment plant. The piping system, shown in Figure 1 exceeds the scale typically seen in most groundwater remediation projects, with respect to length, number of wells and volume of water treated.The groundwater extraction system is a manifold piping network that consists of the 43 wells and associated pumps, piping and controls and is capable of conveying 150% of the average flow. All piping within plant boundaries is above ground. Offsite piping is installed below ground and is double walled. Leak detection devices are installed below ground in manways along the buried pipe route. Discharge piping from well pumps is tied into manifolds which go to the groundwater treatment plant.This paper describes design choices significantly affecting the system construction, piping system components, design procedures and significant lessons learned in the construction of the system. System design commenced in 1993, was completed in 1995 and system construction was finished in 1996.

The basic concept to ensure the integrity of components during operation

The integrity of components which are relevant to safety is one of the most important prerequisites for the safe operation of a power plant. A systematic way of proceeding can be achieved by the basic safety concept. In doing so attention has to be paid to the balanced application of the so-called ‘redundant measures’. Using the pressuriser spray system of a nuclear power plant as an example, the relevant factors of influence and the way of proceeding are demonstrated for piping system components which are important to safety.

Excitation of finite and infinite length cylindrical shells by internal sound fields

Cylindrical shells, such as industrial piping system components, are efficiently excited by broadband internal noise at discrete frequencies below the ring frequency. Two types of excitation are recognized: finite length pipe resonances that are visible in short pipes, and coincident excitation that has been studied for long or anechoically terminated pipes. Both mechanisms occur to varying degrees in pipes of any length, and both require that the acoustic and structural wavenumbers be closely (or exactly) matched. Because ducts possess an infinite number of potential coincidence frequencies, coincidence transmission (i.e., precisely matched wavenumbers) is dominant in pipes. In the limit for long shells, both mechanisms are damping controlled and approach the same levels. Experimental data for short and intermediate shells show that coincidence transmission (“infinite shell”) can be the sole cause of vibration over wide frequency bands where the density of resonant modes is low. A simple theory is used to predict the frequency and amplitude of response peaks caused by both mechanisms. [Work supported by NSF.]