Water Piping Systems Research Articles

Gas Metal Arc Welding Parameters Effect on Properties of Tailored Orbital Weld of SS304 and BS1387

Dissimilar material pipes in a power plant boiler water piping system are used to transmit water at various temperatures, either in extremely high temperature water or room temperature water. In this study, tailored orbital welding of dissimilar material of Stainless Steel (SS) 304 and British Steel (BS) 1387 were performed by Gas Metal Arc Welding (GMAW) with automated fixed nozzle-rotational jig. This study focused on GMAW parameters variation effects on mechanical properties of SS304 and BS1387 dissimilar material tailored orbital welding. The weldment quality was tested by performing non-destructive dye penetrant test. The tensile strength and microhardness were studied to verify the influence of welding parameters variations. Design of Experiment (DOE) was employed to generate process parameter using Response Surface Methodology (RSM) method. Welding parameters that were arc current, arc voltage and travel speed as input response, whilst, tensile strength and microhardness as output response. Results from non-destructive test showed no major defect occurred. The tensile strength and microhardness increased when arc current and voltage increased and travel speed decreased. Microhardness at weldment was higher than base material.

A-28 給湯配管システムにおける溶存気体の挙動と銅管の潰食に関する研究

A-28 給湯配管システムにおける溶存気体の挙動と銅管の潰食に関する研究

A-46 密閉式冷温水配管の耐久性に関する一考察 : 運転初期における白管の亜鉛消失と亜鉛の電位変化について

A-46 密閉式冷温水配管の耐久性に関する一考察 : 運転初期における白管の亜鉛消失と亜鉛の電位変化について

Influence of intermittent water supply operations on the vulnerability of water distribution networks

Abstract Water authorities in countries facing water shortage problems are implementing intermittent water supply (IWS) policies, as a measure to conserve and control their national water resources. Implementation of such measures affects the behaviour of the water pipe systems during the operation stage. The research work presented herein presents a model simulating the behaviour of urban water distribution networks (WDNs) under normal operating conditions, as well as during a period of IWS operations. The modelling and analysis, based on an eight-year dataset (2003–2010) from a local Water Board, takes into account information related to breakage incidents within the WDN as well as external factors to perform vulnerability assessment of the pipe network. The results of the performed survival and cluster analysis show that during the implementation period of IWS operations, and right after that period, there is a significant increase in the deterioration rate of the affected network. Further, there is a change in the comparative importance of the factors affecting the network condition and their contribution to the WDN vulnerability.

Thermal field in water pipe cooling concrete hydrostructures simulated with singular boundary method

The embedded water pipe system is often used as a standard cooling technique during the construction of large-scale mass concrete hydrostructures. The prediction of the temperature distribution considering the cooling effects of embedded pipes plays an essential role in the design of the structure and its cooling system. In this study, the singular boundary method, a semi-analytical meshless technique, was employed to analyze the temperature distribution. A numerical algorithm solved the transient temperature field with consideration of the effects of cooling pipe specification, isolation of heat of hydration, and ambient temperature. Numerical results are verified through comparison with those of the finite element method, demonstrating that the proposed approach is accurate in the simulation of the thermal field in concrete structures with a water cooling pipe.

SAF: Stochastic Adaptive Forwarding in Named Data Networking

Forwarding decisions in classical IP-based networks are predetermined by routing. This is necessary to avoid loops, inhibiting opportunities to implement an adaptive and intelligent forwarding plane. Consequently, content distribution efficiency is reduced due to a lack of inherent multi-path transmission. In Named Data Networking (NDN) instead, routing shall hold a supporting role to forwarding, providing sufficient potential to enhance content dissemination at the forwarding plane. In this paper, we design, implement, and evaluate a novel probability-based forwarding strategy, called Stochastic Adaptive Forwarding (SAF) for NDN. SAF imitates a self-adjusting water pipe system, intelligently guiding and distributing interests through network crossings circumventing link failures and bottlenecks. Just as real pipe systems, SAF employs overpressure valves enabling congested nodes to lower pressure autonomously. Through an implicit feedback mechanism, it is ensured that the fraction of the traffic forwarded via congested nodes decreases. By conducting simulations, we show that our approach outperforms existing forwarding strategies in terms of the interest satisfaction ratio in the majority of the evaluated scenarios. This is achieved by extensive utilization of NDN’s multipath and content-lookup capabilities without relying on the routing plane. SAF explores the local environment by redirecting requests that are likely to be dropped anyway. This enables SAF to identify new paths to the content origin or to cached replicas, circumventing link failures, and resource shortages without relying on routing updates.

On the role of vibro-acoustics in leak detection for plastic water distribution pipes

Leaks have been detected and localized in water distribution in many countries for years, by using the cross-correlation of pipe vibration measured either side of a suspected leak and/or by using listening sticks. However, in modern plastic pipes this is problematic because of the strong coupling between the water and the pipe which results in significant attenuation of the coupled fluid-pipe wave, which in turn is responsible for the propagation of leak noise. Hence leak noise does not propagate as far as it did in older metallic pipes. This paper discusses how the vibro-acoustic behavior of the water-pipe-soil system influences leak noise propagation. To investigate this, a numerical model is developed, and the results are compared with those from an analytical model for two water pipe systems, one in the UK and one in Brazil. Experimental results are also presented. It is shown that the important difference between the two systems is the shear stiffness of the surrounding soil, which has a profound effect on both the speed of leak noise propagation and the attenuation of the noise along the pipe.

Burst behavior of CPVC compared to HDPE thermoplastic polymer under a controlled internal pressure

Abstract: The HDPE (High Density Polyethylene) and CPVC (Chlorinated Polyvinyl Chloride) are extremely used in water piping systems. The CPVC have the particularity to support high temperatures of water. Those two materials are known for their different characteristics toward the internal pressure. To quantify their behavior we exposed pipe specimens, prepared according to ASTM 1599, to an increasing internal pressure and we registered the burst and the time of each specimen. To push further our analysis, we created groove notches over the same category of specimens and we exposed them to the same conditions. Then, we have noticed a drop of the internal pressure in function of the time and the life fraction which is the ratio of thickness and its fluctuation (Δe/e). Indeed, the burst pressure, and the time of failure are drastically dropping according to the notch depth. Besides, one important consequence is noticeable over the mechanical behavior which shift from a ductile one, for neat pipes, to a brittle one for the other HDPE pipes. Meanwhile, The CPVC pipes have a brittle behavior for both of the specimen's categories. The discrepancies can be explained by the nature of the two materials, the first one is an original polymer while the second is a Chlorinated PVC material. Furthermore, the comparison of the failure mode of the two polymers are slightly different compared to the linear damage of Miner. For HDPE pipes, the static damage is evaluating nearby the Miner one until getting to the critical life fraction (βc) of 52% and then get over it. However, the CPVC damage has a very weak evolution bellow the βc of 60% from which we notice a drastic increasing and an acceleration of the damage. The CPVC show good performances toward the supported internal pressure, support up to 160 bars, and a brittle behavior. Meanwhile, the HDPE pipe can support up to 70 bars and show a ductile behavior. Finally, this paper can be considered as a window to understand the difference between HDPE and CPVC polymers under burst pressure and the severity of the groove defects for researchers and industrials.

HDPE pipes failure analysis and damage modeling

Thermoplastic pipes are used in all the industrial fields such as water, sewage and gas piping systems and other industrial applications, like the transport of minerals and slurries. The choice of the right piping system's material depends on many criteria. First of all, it depends on the conditions of use of each kind of material. Secondly, it depends on the cost of the chosen material and finally the mastering of the material's scenarios of failure. The last criteria are possible through the mastering of the material characteristics and the capability to detect the failure, burst or crack, before its occurrence. The adopted approach must be proactive to facilitate the prediction of the failure and help the maintenance staff to apprehend the piping system's damage at the right time. In this paper, we chose HDPE pipes as material for our study. Then, we leaded a new approach of failure analysis and prediction using new models. These models are obtained through a modified version of the stress controlled unified theory, a static damage model using burst pressures and a static damage model using the time to failure. For that reason, we used burst pressures of undamaged HDPE pipe instead of ultimate stresses. Then, we created groove notches with different levels of depth. The obtained burst pressures from these pipes have been considered as the residual burst pressures used in our damage models. The representation of the obtained data according to the life fraction gave us an idea about the critical life fraction and then the critical groove depth which can be allowed. This information has been confirmed by three damage models. Then, we determined the different stages of damage to help the predictive maintenance to define the safe intervals of the HDPE pipes' service. Moreover, the three developed models, presented in this paper, represent a simplified approach to assess the damage based on static tests only, without doing any dynamic tests. The developed cost-effective approach can be a tool that can help the industrials to have an anticipative maintenance strategy and respect the safety requirements. Also, it can help them to do quick checks or launch audit mission to the manufacturers' factories for HDPE pipes' quality control and conformity check regarding the codes.

The spatial distribution of pollutants in pipe-scale of large-diameter pipelines in a drinking water distribution system

In large-diameter drinking water pipelines, spatial differences in hydraulic and physiochemical conditions may also result in spatial variations in pipe corrosion, biofilm growth and pollutant accumulation. In this article, the spatial distributions of various metals and organic contaminants in two 19-year-old grey cast iron pipes which had an internal diameter of 600mm (DN600), were investigated and analyzed by Atomic Absorption Spectrometry, Gas Chromatography–Mass Spectrometry, Energy Dispersive Spectrometer, X-ray Diffraction, etc. The spatial distribution of heavy metals varied significantly across the pipe section, and iron, manganese, lead, copper, and chromium were highest in concentration in the upper portion pipe-scales. However, the highest aluminum and zinc content was detected in the lower portion pipe-scales. Apart from some common types of hydrocarbons formed by microbial metabolites, there were also some microalgae metabolites and exogenous contaminants accumulated in pipe-scale, which also exhibited high diversity between different spatial locations. The spatial distributions of the physical and chemical properties of pipe-scale and contaminants were quite different in large-diameter pipes. The finding put forward higher requirements on the research method about drinking water distribution system chemical safety. And the scientific community need understand trend and dynamics of drinking water pipe systems better.

CFX study of flow accelerated corrosion via mass transfer coefficient calculation in a double elbow

Using CFX numerical simulation, this study aims at calculating Mass transfer coefficient (MTC) as a parameter that indicate the FAC rate on the wall of the double elbow. A double elbow in the feeder water piping system of a typical combined cycle power plant that had been damaged due to the FAC was considered and was studied. In this study the influence of several parameters such as the mean flow velocity and the dimensionless distance between the two elbows (L/D) on the MTC at the elbows was investigated. The geometrical factor and the close proximity of two elbows with respect to the mass transfer coefficient were studied.It is found that mass transfer coefficient increases by Reynolds number. The maximum MTC was occurred in the intrados of second elbow. It is found that there is a very good coincidence between the locus in which the maximum MTC was calculated and the locus in which minimum wall thickness was measured.It is observed that as the remoteness between the elbows (L/D) increases, the Close Proximity Effect (CPE) is decreasing for L/D < 7. As L/D gets amplified (L/D > 7) the CPE is increasing very slowly and became constant. This CPE value is lower in comparison with that of L/D < 7. This is due to the fact that, when L/D > 7, the second bend experiences less impact due to the first bend and, also, there is a fully developed flow between both the bends.

Effects of calcium and ferric ions on struvite precipitation: A new assessment based on quantitative X-ray diffraction analysis

The precipitation of struvite (MgNH4PO4·6H2O) from waste streams has attracted considerable attention due to its potential for recovering phosphorus for fertilization. As struvite is primarily acquired by means of precipitation and crystallization from aqueous solutions, it is important to evaluate the roles of common metal ions, particularly those that are commonly found in wastewater, in the struvite crystallization process. This study was performed to quantitatively evaluate the effects of calcium and ferric ions on struvite crystallization using the Rietveld refinement method, which is based on the analysis of X-ray diffraction data. The results indicate that both calcium and ferric ions significantly inhibit the formation of struvite crystals, and the effects vary under different pH conditions. There was a negative linear correlation between the struvite weight content in the precipitates and the Ca/Mg molar ratio in the initial solution. However, ferric ions were confirmed to be a more efficient inhibitor of struvite crystallization. Ca2+ and Fe3+ further modified the needle-like struvite into irregular shapes. An unambiguous and quantitative understanding of the effects of foreign ions on struvite crystallization will help to reliably improve the quality of struvite products recovered from wastewater and the control of struvite deposits in water and sludge piping systems.

Biocorrosion in drinking water pipes

Copper is widely used in drinking water distribution systems due to its relatively low cost and favorable mechanical properties. However, copper corrosion may generate copper concentrations exceeding the thresholds prescribed by international drinking water standards. In-situ measurements performed in an actual system found that the copper mass released under flowing water conditions (pipe flushing) was greater than the copper mass release estimated considering only the mass of copper in the pipe's bulk water before the tap is opened. This work presents in-situ and laboratory results of copper release into the water and its dependence on biofilm structure, solid-liquid interface properties, and the pipe flow regime (laminar vs. transition flow). The results of this work highlight the necessity to incorporate the hydrodynamic effects in the analysis of corrosion and corrosion by-products release into drinking water piping systems. Initial modeling efforts are also presented.

Utilizing the building envelope for power generation and conservation

Heat loading of the building envelope is caused by strong solar radiation and incorrect material selection. As a result of the heat loading of the building envelope, the indoor air temperature is increased, resulting in high energy consumption by air conditioners to maintain a comfortable indoor thermal environment. This study explores the use of a hybrid wall integrated with heat collectors (water piping system) and solar thermal power generators, which absorbs solar radiation through water to reduce heat transmission thereby saving energy and generating power. Power generation is achieved by an OD (oscillator device) that installed between a water tank (hot side) and building interior (cold side). The device acts by temperature differences between hot air (expansion) and cold air (contraction). CFD (computational dynamic simulation) was used to assess the effects of the hybrid wall on the interior environment. The results show that exterior heat is absorbed by cool water thereby reducing the heat transmission into the building, resulting in less energy consumption by air conditioners and power generation by use of temperature differences.

Design criteria of Hazen-Williams C value of water pipe system

In this study, Hazen-Williams C value of pipes in wide waterworks system was estimated and statistically analyzed. Hazen-Williams C value of water pipe was predicted after 20 years of service period. From the results, it was found that C value of water pipe for treated water maintained higher value of 110 after 20 years of installation. Furthermore, it was found that velocity coefficients of steel pipe for less than and more than 20 years of installation were 117.7 and 109.3, respectively. C value of ductile iron pipe for less than and more than 20 years of installation were 118.1 and 114.2, respectively. In this study, it was also found that small value of C is used in the design of water pipe system. Therefore, excessively bigger size of pipe can be determined in the design of water pipe system. From the results of present study, optimum value of C can be used to avoid the oversized design of water pipe system.

Reduced order modelling of liquid-filled pipe systems

In the design of vibration-sensitive structures, large three-dimensional numerical models are frequently used, those occasionally being too large to be simulated in a practical manner. More specifically, the analyses of vibrating complex water-pipe systems require efficient model order reduction strategies. In the paper, a numerical procedure for model order reduction of a water-pipe system housed in a vibration-sensitive research facility is presented. The finite element model employed includes a water-pipe system where fluid–structure interaction effects are accounted for. The reduced model is developed using component mode synthesis and a reduction of the interface degrees of freedom, enabling time-efficient dynamic analyses. The model was proven to be time-efficient and to generate output of high accuracy.

Flow-induced vibrations in closed side branch pipes and their attenuation methods

Some problems due to flow-induced vibrations related to closed side branch pipes have been observed in thermal and nuclear power plants. Fluctuating pressure generated in the main pipes was unusually, acoustically excited in closed side branch pipes, and intense vibrations were caused at pipes and components. For example, flow-excited acoustic resonance in closed side branches of stub pipes of safety relief valves caused the failure of steam dryers in the United States Quad City Unit 2 nuclear power plant. Furthermore, there was a possibility that residual air or gas in a closed side branch pipe unexpectedly caused severe vibrations of low frequency in the feed water piping system. We have investigated the root cause and influence of air on severe vibrations. Intense fluctuating pressure was often caused by water hammer due to valve closure and it became larger in the closed side branch pipes. We showed that an additional side branch with an orifice was very effective to suppress the flow-induced acoustic resonance. Design methods of the orifice to attenuate fluctuating pressure generated by water hammer were presented considering Mach number, the pressure loss coefficient of orifice and the intensity of particle velocity. Moreover, suitability of the characteristic curve method was confirmed for evaluation of the attenuation effect of an orifice on fluctuating pressure generated by water hammer. Finally, we considered some flow-induced vibration problems related to closed side branch pipes and their attenuation methods.

Transient-Based Frequency Domain Method for Dead-End Side Branch Detection in Reservoir Pipeline-Valve Systems

AbstractUnexpected, unknown or unused side pipe branches, termed dead-end side branches in this study, commonly exist in water pipe systems because of incorrect device installations or illegal connections. These connections are detrimental to the water quality and the operation and management of pipe networks. This paper investigates a transient-based frequency domain method for detecting side branches in pipe systems. The frequency response function for a pipe system with a single dead-end side branch is first derived by the transfer matrix method and the side branch was found to cause shifts in the system resonant frequencies. The nature of the resonant frequency shifts can be used to inversely determine the location and size of the side branch. A two-step genetic algorithm based optimization is proposed in this study to efficiently solve the derived analytical expression for the resonant frequency shifts. The developed method is validated through numerical simulations, and the results demonstrate the f...

Importance of accounting for the piping system and boundary conditions in determining the maximum surge pressure following heat-exchanger tube-rupture

Shell-tube type heat exchangers are often used to exchange heat between a high-pressure fluid and a low-pressure fluid, and the pressure difference between the two fluids could be significantly high. If the difference in the design pressure between the low-pressure (LP) and high-pressure sides is greater than that covered by American Petroleum Institute (API 520 and 521) 10/13th rule, dynamic analysis is required to ascertain that the maximum surge pressure that could be reached does not compromise the integrity of the LP side of the exchanger. API guidelines also notes that attention should also be given not only to the shell-side of the heat exchanger under evaluation, but also to the “upstream and downstream systems” This paper offers further insight into the importance of including the surrounding piping systems around the subject heat-exchanger where a tube-rupture scenario is considered, and also directs attention to the importance of correctly specifying the appropriate boundary conditions (B.C.) at the far ends of both the upstream and downstream piping systems. It demonstrates the effects of specifying different B.C. on the maximum pressure surge via a case study of a hot separator vapour condenser in a bitumen hydrotreating unit, where the process fluid on the tube-side is a vapour–liquid mixture at 9660 kPa(g). The vapour mass fraction of the process fluid is approximately 0.5, and is mostly hydrogen. The fluid on the LP side is cooling water connected to the plant supply and return cooling systems as well as another adjacent low pressure condenser. The design pressure for the cooling water piping system and the adjacent condenser is 1380 kPa(g).

Non-Markovian model for the study of pitting corrosion in a water pipe system

The main studies on pitting consist in proposing Markovian stochastic models, based on the statistics of extreme values and focused on growing the depth of wells, especially the deepest one. We show that a non-Markovian model, described by a nonlinear Fokker–Planck (nFP) equation, properly depicts the time evolution of a distribution of depth values of pits that were experimentally obtained. The solution of this equation in a steady-state regime is a q-Gaussian distribution, i.e. a long-tail probability distribution that is the main characteristic of a nonextensive statistical mechanics. The proposed model, that is applied to data from four inspections conducted on a section of a line of regular water service in power water reactor (PWR) nuclear power plants, is in agreement with experimental results.