Isolation Valve Research Articles

Increasing energy efficiency and flow coefficient by determining fluid behaviours with computer aided design and CFD analysis in isolation valves

In this study, it was aimed to convey theoretical and practical development of the double eccentric butterfly valve, which would be the first in the sector, with highly efficient, saves energy, has a long life, and requires less maintenance. For this purpose, a prototype with lower weight and higher flow coefficient has been developed by the Computational Fluid Dynamics (CFD) method. Thanks to the use of computer aided design and simulation techniques, environmentally friendly and highly efficient valves have been produced, improving competitive conditions and an innovative product has been obtained in the sector. The design, CFD analysis, and casting simulation were carried out by Solidworks, ANSYS, and Anycasting computer programmes respectively. At the same time, as a result of this study, a design suitable for an innovative production technique that leads to less energy and less waste has been obtained. Innovative material selection and casting techniques were used by optimising the total material weight and valve cost.

Reliability Analysis of Subsea Riser System Based on Fuzzy Fault Tree Analysis Method

Abstract To deal with the complex structure of subsea riser system and the lack of failure statistics and insufficient information during operation, a fuzzy fault tree analysis (FFTA) method is applied to analyse the reliability of the subsea riser system, and a qualitative and quantitative analysis is carried out by establishing a fault tree model of the riser system to obtain the minimum set of cuts and the basic events. The fuzzy importance degree of each fundamental event is determined as well as the failure probability of the headline event of the fuzzy fault tree, “failure of subsea riser system,” using the triangular fuzzy number computation method. Finally, the “average value” method of comprehensive analysis of the fault tree model, the analysis results show that the bottom event riser check valve, riser buoyancy device, riser working medium isolation valve, riser line, riser gas lift device and other components of the failure of the subsea riser system is relatively the weak links, compared with the actual situation, the analysis results in line with the actual engineering situation, these five aspects should be regularly detected and focused on prevention. In conclusion, this research helps to comprehensively analyse the reliability of the riser system and take into account the uncertainty factors, and provides more accurate guidance on the reliability constraints for the localized design and production of subsea riser system.

Optimization of isolation valve placement to improve reliability and resilience of water distribution systems

Optimization of isolation valve layout is critical to improve post-failure response restoration of water distribution systems (WDSs) when pipes are damaged. Many studies have been done to optimize isolation valves to improve reliability of WDSs, but less attention has been given to improving the seismic resilience. This paper proposes a multi-objective optimization model for isolation valves placement considering reliability and seismic resilience simultaneously. The newly developed model employs topology-based reliability and resilience indicators to improve efficiency of optimization algorithm by identification of accidental segments and unintended isolation segments using graph theory without hydraulic simulation. The optimization model was applied to two networks with different loop structures. Subsequently, searching trajectory guided by constraints is investigated and performance of isolation valve placements under different valve densities are assessed including topological structure of isolation valves, criticality of segments and isolation valves, and seismic resilience. The results showed that optimal layout of isolation valves obtained through optimization can improve the reliability and resilience of the system. Our novel approach can benefit water utilities that frequently encounter optimal placement of isolation valves to improve the reliability and resilience of WDSs.

Improving the Understanding of Secondary Impacts of Isolation Valve Closures on the Performance of Water Distribution Systems

Improving the Understanding of Secondary Impacts of Isolation Valve Closures on the Performance of Water Distribution Systems

Use of magnetic fluids in process system for pipe isolations

This paper investigates the use of magnetic fluids known as ferrofluids to act as ad hoc valves within pipe systems to create isolation points for stemming pipe leakages and to halt leakages before they become largescale disasters. The sealing abilities of ferrofluids were proven for microvalves (ID ≤ 1 mm) in hydrostatic experiments and extended to the macroscale applications (ID ≥ 6 mm). Theoretical prediction and magnetic finite element analysis (FEA) were also undertaken to predict the burst pressure, and a comparison of both results against the experimental measurement was made. The up-scale results (10–18 mm ID) indicated that it is feasible to develop a ferrofluid that can be extended to approximate the applicable magnet strength to achieve higher burst pressure. It was concluded that the ferrofluid isolation valves hold potential in macroscale environments for process engineering in favour of a positive isolation.

Analysis of particles containing alpha emitters in stagnant water in Fukushima Daiichi Nuclear Power Station’s Unit 3 reactor building

Particles containing alpha (α) nuclides were identified from sediment in stagnant water in the Unit 3 reactor building of the Fukushima Daiichi Nuclear Power Station (FDiNPS). We analyzed different concentrations of α-nuclide samples collected at two sampling sites, the torus room and the main steam isolation valve (MSIV) room. The solids in the stagnant water samples were classified, and the uranium (U) and total alpha concentrations of each fraction were measured by dissolution followed by inductively coupled plasma mass spectrometry and α-spectrometry. Most of the α-nuclides in the stagnant water samples from the torus and MSIV rooms were in particle fractions larger than 10 μm. We detected uranium-bearing particles ranging from sub-µm to 10 µm in size by scanning electron microscopy–energy-dispersive X-ray (SEM–EDX) observations. The chemical forms of U particles were determined in U–Zr oxides, oxidized UO2, and U3O8 with micro-Raman spectroscopy. Other short-lived α-nuclides (plutonium [Pu], americium [Am], and curium [Cm]) were detected by alpha track detection, and the particles with α-nuclides was characterized by SEM–EDX analysis. α-nuclide-containing particles with several tens to several 100 µm in size mainly comprised iron (Fe) oxyhydroxides. In addition, we detected adsorbed U onto Fe oxyhydroxide particles in the MSIV room sample, which indicated nuclear fuel dissolution and secondary U accumulation. This study clarifies the major characteristics of U and other α-nuclides in sediment in stagnant water in the FDiNPS Unit 3 reactor building, which significantly contribute to the consideration of removal methods for particles containing α-nuclides in the stagnant water.

On periodic maintenance for a protection system

This article presents a model for maintenance planning of protection systems, such as isolation valves, circuit breakers, and other safety barriers. These systems are designed to operate on demand and prevent environmental catastrophes. The proposed model is novel because: (i) inspections (functional tests) are fixed and periodic; and (ii) the replacement policy has three-phases, corrective, opportunistic-preventive, and scheduled-preventive. Thus, the system is replaced: at a positive test; at a test regardless of the outcome either if an opportunity arises or when the system reaches a critical age. The model is relevant because periodic inspections are largely the practical, engineering reality, and particularly useful for geographically distributed systems, for which there is limited time and resources for maintenance. The paper provides a web-based application as a demonstrator of the proposed model. The study extends and refines well-known policies from the literature, providing valuable insights about applicability across various parameter settings.

Analysis of transient characteristics and design improvement of the passive residual heat removal system of NHR-200-II

NHR-200-II is a small integrated pressurized water reactor with 200 MW core thermal power. The core heat is transferred to two independent intermediate circuits via fourteen in-vessel primary heat exchangers (PHE), and the heat in the intermediate circuits is transferred to feedwater by two steam generators (SG) in the two intermediate circuits respectively. A passive residual heat removal (PRHR) branch is connected to each intermediate circuit to remove core decay heat under postulated accidents. During normal operation, PRHR branches are isolated by valves while SG branches in intermediate circuits are open. The valves in PRHR branches will be opened and the isolation valves of SG branches will be closed during decay heat removal scenarios. The decay heat removal capacity of NHR-200-II PRHRS could be seriously deteriorated once the isolation valves for SG branches fail to close, which was confirmed in a scaled integral test loop previously. Current understanding of PRHRS’s thermal-hydraulic characteristics with possible isolation failure in SG branches is limited. In this paper, the NHR-200-II PRHRS is modeled with RELAP5 considering the case of success and fail to isolate SG branches. A series of numerical simulations are carried out to study the impact of various parameters, such as the initial temperature, the size of the intermediate circuits’ header, and the initial flow direction in the intermediate circuits. Oscillatory flow is found when SG branches fail to be isolated under certain parameters combinations. An improved PRHRS design is purposed to eliminate possible flow oscillations, and the purposed improved design are tested by numerical simulations.

An In-Vitro Comparison of Steady State Leakage Rates through Introducer Sheaths Used for Fenestrated Endovascular Aortic Aneurysm Repair

Objectives– fEVAR involves deploying a covered stent into the aorta followed by multiple visceral stents through fenestrations in the main body of graft. The most commonly used large sheaths for cannulation of visceral vessels are the Gore DrySeal Flex, Cook Performer Check-Flo and Medtronic Sentrant. None of these sheaths were designed for the insertion of multiple sheaths, and so a slow but steady leakage of blood occurs during the procedure. The aim of this paper is to assess in an in vitro setting which large bore sheath has the best valve for use when multiple smaller sheaths are inserted through it. MethodsThree large bore introducer sheaths (LBIS) were used for this study, The Gore DrySeal Flex LBIS, Medtronic Sentrant LBIS and Cook Performer Check-Flo LBIS. A test rig was constructed, made of an 18-litre fluid reservoir mounted vertically and receiving a constant supply of water from a domestic water supply which flowed into the reservoir and out of an overflow. The reservoir was connected to the LBIS by a vertical plastic pipe with an internal diameter of 40mm and an isolation valve. The LBIS was connected to the isolation valve by inserting the LBIS up a flexible silicone tube connected to the isolation valve. The LBIS was subject to a constant column/pressure of water and fluid leakage from the LBIS was collected in a plastic pot/tray placed underneath the LBIS. The leakage rates through each LBIS were determined for the following smaller diameter sheath combinations inserted through the valve, one 6 French Sheath, two 6 French Sheaths, two 6 French Sheaths and one 7 French Sheath. This was done to closely mimic a fEVAR procedure in vitro. The procedure was to insert different sheath combinations through the non-return valves in the LBIS and measure the volume of fluid that leaked through the valves. The leaked fluid was weighed, and the weight was converted to volume using the density of water (1g/ml). ResultsThe average (mean) leakage rates for each LBIS and each sheath combination showed that leakage rates when only one sheath was inserted were very low. For all three LBIS’s tested, the leakage rates increased dramatically when multiple sheaths were inserted. The Medtronic LBIS leaked the most, followed by Cook, followed by Gore. For the Cook LBIS, the leakage rates exhibited with 2 x 6 French sheaths were approx. 106 times greater than those for the Gore LBIS and five times greater for the 2 x 6 French + 1 x 7 French sheath combination. A similar comparison for the Medtronic LBIS vs the Gore LBIS yields factors of 132 and 8. ConclusionsLeakage rates increase significantly when multiple sheaths are inserted and the Gore LBIS demonstrates significantly lower leakage than both the Cook and Medtronic during procedures that require simultaneous, multiple insertions of smaller sheaths. Although the Gore Dryseal has by far the lowest leakage rate when three small diameter sheaths are inserted (just under 1ml/s), depending on the duration of the procedure this could still result in significant blood loss.

A concurrent fault diagnosis method for electric isolation valves in nuclear power plants based on rule-based reasoning and data-driven methods

In order to improve the fault diagnosis ability of electric isolation valves in nuclear power plants, especially for the diagnosis of concurrent faults, a novel concurrent fault diagnosis method based on rule reasoning and data-driven methods is proposed in this study. The concurrent fault diagnosis method is divided into two layers: the rule-based reasoning layer and data-driven layer. In order to realize the diagnosis of most concurrent faults, the rule-based reasoning layer is established by a rule inference model according to the failure mode and effects analysis (FMEA) of the electric isolation valve. In order to diagnose concurrent faults with mutual interference of fault features that cannot be diagnosed by rule-based reasoning layer, the data-driven layer is established by variational mode decomposition (VMD) and fast independent component analysis (Fast-ICA) method to separate concurrent fault signals and gate recurrent unit (GRU) method to identify fault patterns. After testing on the electric valve test bench and simulation data, multiple concurrent faults of the electric isolation valve are diagnosed accurately by the proposed concurrent fault diagnosis framework, including complex concurrent faults such as internal leakage and external leakage, and the framework can also work in a single fault diagnosis scenario without changing models. Compared with the concurrent fault diagnosis based on multi-label support vector machine, the accuracy of concurrent fault diagnosis is improved by about 25.3%. The research can provide a new idea for the concurrent fault diagnosis of electric isolation valves and other equipment.

Shielding optimization to reduce the radiation field in the accelerator systems of IFMIF-DONES

In IFMIF-DONES, a deuteron beam will impinge on a flowing liquid lithium target, resulting in an intense neutron source. Other radiation sources will also arise due to the interactions between deuterons and the beam facing accelerator components. These radiation fields may cause some negative effects, such as damage to equipment or the generation of residual radiation sources. The characterization and mitigation of all the radiation sources are crucial for a safe operation and maintenance of the facility. In this study, the optimization and/or implementation of some radiation shields located in critical areas is considered to reduce the doses during operation and shutdown. Three scenarios are assessed: (i) shielding optimization of the High-Power Beam Dump for the accelerator commissioning, (ii) shielding optimization for the scraper of the High Energy Beam Transport line and the Fast Safety Isolation Valves, and (iii) shielding implementation to reduce the radiation transmission through Heating, Ventilation, and Air Conditioning wall penetrations. Radiation maps of the biological dose and the dose to silicon are computed, showing the impact of such shielding elements.

Identification of optimal number and location of isolation valves in an urban water distribution network

Abstract Urban water distribution networks (UWDNs) are critical infrastructures that provide essential services in an urban setting. Such infrastructures are subject to frequent breakdowns, disrupting services to downstream users. Installation of isolation valves (IVs) at strategic locations can reduce such adverse impacts by isolating small segments of the network and expediting repairs, which in turn contribute to water conservation and leak control. However, determining the optimal number of IVs and their placement is a disturbing question for the researchers. This study proposes a methodology to assess the optimal number of IVs in a UWDN and identify their placement in the best of the worst possible scenarios. Based on the network topology and the associated IV costs, it identifies the optimal numbers and their places to minimize the maximum undeliverable demand. The methodology is illustrated with the help of a small water distribution network. Thereafter, the proposed methodology is applied to a real-type UWDN. The results indicate that the optimal number of IVs for the case study is 10, which should be placed at strategic locations to reduce the maximum undeliverable demand to 18% of the total demand.

Engineering design status of IFMIF-DONES High Energy Beam Transport line and Beam Dump system inside the TIR and RIZ

IFMIF-DONES (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is a fusion materials testing facility that is currently being designed under the framework of a work package of the EUROfusion Consortium. It will use a 125mA at 40MeV deuteron beam to generate a high neutron flux through Li(d,xn) stripping nuclear reactions in a liquid lithium target. The High Energy Beam Transport line (HEBT), the most upstream system of the IFMIF-DONES accelerator, is responsible for the guidance and shaping of the beam towards the target. Additionally, during commissioning periods, the HEBT is also responsible for diverting the beam, through the Beam Dump Transport Line, to the Beam Dump for testing purposes. The HEBT is spread along different rooms and zones: the Accelerator Vault, the Radiation Interface Zone (RIZ), and Target Interface Room (TIR). The engineering design of the HEBT components situated within the TIR and RIZ has been updated to satisfy new requirements, with a focus on ensuring the protecting of the Fast Isolation Valve (FIV) from the backscattered radiation from the target. These modifications include relocating the FIV from the TIR to the RIZ, adjusting the building layout to accommodate the new FIV module, configuring an enclosure cabinet for the RIZ, and adding local shielding to extend the lifetime of the FIV seal actuators. This work describes the current status of these TIR and RIZ engineering design, including radioprotection, commissioning and maintenance plan, beam diagnostics devices, beam dynamics and new remote handling approaches, as well as the layout and integration of the required components along the beamline. The TIR and RIZ are critical areas for IFMIF-DONES, and their design and operation must be compliant with functional, reliability and safety requirements. The updated design addresses potential issues and enhances the facility’s overall functionality.

Failure analysis on fracture causes of stainless-steel studs in seawater system of nuclear power plants

Nine of the twelve B8M stainless steel studs on the flange of a seawater pipeline isolation valve of a nuclear power plant were encountered with premature fracture during service. To find out the cause of the fracture failure, the fracture studs were comprehensively detected and analyzed by means of appearance morphology analysis, chemical composition analysis, mechanical properties testing, microstructure testing, and fracture micro-area analysis. The results show that the main reasons are as follows: (1) The solid solution temperature of the raw materials for processing bolts is low, so the carbides are not fully dissolved and distributed in a mesh along the grain boundary. Thus, the chromium-poor near the grain boundary forms, resulting in the mechanical properties of the bolts weakening. According to the experiment, it was found that the corrosion resistance of the bolts is weak due to the low nickel content. Carbon easily precipitates at the grain boundary and forms Cr23C6 with chrome, which weakens the bonding strength of the grain boundary and causes the bolt to break along the grain.

Rapid repair of thermal aging embrittlement in 17-4PH martensitic stainless steel using pulsed electric current

The 17-4PH stainless steel serves as the main steam isolation valve in a light water reactor due to excellent comprehensive mechanical properties and corrosion resistance. Nonetheless, the thermal aging resulting from prolonged service poses a threat to the safe operation of nuclear power plants. The mechanism of thermal-aging embrittlement of 17-4PH stainless steel and its repairing behavior under the action of the pulsed electric current were studied using transmission electron microscopy and 3D atom probe tomography. The ductile to brittle transition occurred following the spinodal decomposition and G phase formation during the thermal aging of 5000 h at 673 K, resulting in a 100 HV increase in hardness of the 17-4PH stainless steel, of which 94.4 HV was attributed to the spinodal decomposition. Under the action of a pulsed electric current at 733 K, the hardness and impact energy can be restored to its original state, whereas heat treatment at the same temperature is unable to restore these properties. This is because the pulsed electric current treatment decreased the thermodynamic barrier to dissolution for the spinodal decomposition and G phases. The Kolmogorov-Johnson-Mehl-Avrami model was used to calculate the kinetics of spinodal decomposition dissolution. The results suggest that the pulsed electric current could increase the diffusion pre-exponential factor of Cr element and accelerate the elimination of spinodal decomposition. This process ultimately facilitates the quick regeneration of the 17-4PH stainless steel's performance.

Designing Isolation Valve System to Prevent Unexpected Water Quality Incident

Designing an effective isolation valve system (IVS) is vital to enhance resilience against unforeseen failures in water systems. During isolation, the system’s hydraulics undergo changes, potentially causing alterations in flow direction and velocity, leading to the dislodgement of accumulated materials and triggering unexpected water quality incidents. This study presents a novel IVS design approach by integrating the consideration of flow direction change (FDC) as an additional constraint within conventional reliability-based models. Two optimization models, Optimization I and Optimization II, prioritize reliability, with the latter also factoring in valve installation cost as a multi-objective function. Performance evaluation metrics, such as the Hydraulic Geodesic Index (HGI), Modified Resilience Index (MRI), and robustness index, were employed for a comprehensive analysis. The results indicated more than 40 instances of FDC in the traditional design, challenging the conventional notion that a higher number of valves inherently reduces risk. The superiority of the proposed model persisted for the single reservoir network in Optimization II. However, for networks with multiple reservoirs, the traditional design outperformed the proposed model, particularly in terms of cost. Nevertheless, when comparing designs with similar reliability, the proposed model showcased a superior performance, despite its higher associated cost. Notably, the proposed approach exhibits potential cost-effectiveness, considering the potential economic losses attributable to water quality incidents. In summary, the implementation of this methodology can effectively manage both water quality and quantity, enabling the identification of vulnerable pipes within the network for sustainable management.

Building resilience for an uncertain drinking water future

AbstractEnhancing drinking water resilience has become increasingly important. However, a comprehensive analysis of drinking water emergency countermeasures is lacking. This study evaluated eight countermeasures including monitoring, local alternatives, reclaimed water, interconnection, bulk water, pre‐packaged water, emergency treatment, and isolation valves from resilience and sustainability (i.e., life cycle cost) perspectives. While countermeasures such as interconnections perform relatively well from both perspectives, there is a clear trade‐off between resilience and cost. Local alternatives and emergency treatment respond quickly and provide sustained supply during emergencies but may incur higher costs. Bulk water and pre‐packaged water are typically inexpensive but have limited supply capacity and take time to distribute. As future threats are likely to become more frequent and prolonged, it is prudent for service providers to invest in countermeasures that perform well in both resilience and cost and use an integrated approach that combines high capital projects with bulk/pre‐packaged water contracts.

Developing a Simplified Practical Approach for Analyzing the Criticality of Isolation Valves

Developing a Simplified Practical Approach for Analyzing the Criticality of Isolation Valves

Isolation Valve Placement Strategy for Resilience Improvement of Water Distribution Systems

Isolation Valve Placement Strategy for Resilience Improvement of Water Distribution Systems

Extending the Application of Connectivity Metrics for Characterizing the Dynamic Behavior of Water Distribution Networks

AbstractWater distribution networks (WDNs) are complex combinations of nodes and links, and the current tendency is to modify their topological structure through the closure of isolation valves for monitoring and water quality reasons. For their analysis, several approaches based on graph theory have recently been proposed, mainly considering steady‐state flow conditions. However, in their real functioning, WDNs are continuously subjected to pressure transients generated by maneuvers on regulation devices or by users' activity. This study investigates the application of some metrics from graph theory, already used in the context of steady‐state analysis, for assessing the effects of changes in the topological structure of a network—due for example, to sectorization or branching operations—on its transient response when subjected to maneuvers on devices such as hydrants, pumps, etc. or users' activity. The analysis shows that some connectivity metrics can effectively reflect the dynamic pressure behavior of the network and, thus, provide useful indications for design and management operations taking into account unsteady flow features.