Impact of Chlorinated Water Exposure on Contaminant Transport and Surface and Bulk Properties of High-Density Polyethylene and Cross-Linked Polyethylene Potable Water Pipes

The aim of this work was to determine if the aging of polyethylene (HDPE, PEX-A and PEX-B) water pipes by exposure to chlorinated water altered polar and nonpolar contaminant diffusivity and solubility by analyzing new, laboratory-aged, and exhumed water-distribution system polyethylene (PE) pipes. After 141?days of aging in pH 6.5 water with 45??mg/L free chlorine, the surface chemistry and bulk properties of PEX-A pipe were unaffected. Carbonyl bonds (σ = 1,713??cm-1) were detected on the surfaces of HDPE and PEX-B pipe, and these oxygenated surfaces became more hydrophilic, resulting in statistically significant increases in diffusion rates. All 10 contaminant and four pipe material combinations had diffusivity increases on average of 50% for polar contaminants and 5% for nonpolar contaminants. Contaminant solubility was slightly increased for aged PEX-A and slightly decreased for PEX-B pipes. Toluene and trichloromethane diffusivity and solubility values for 7- to 25-year-old buried water utility pipes were similar to values for new and laboratory-aged HDPE-based materials. Because chlorinated water exposure alters how polar contaminants interact with aged PE pipes, results of this work should be considered in future health risk assessments, water quality modeling, pipe performance, and service-life considerations.     

Full-Scale Field Tests on Flexible Pipes under Live Load Application

This paper describes the procedure and results of the field tests on high-density polyethylene (HDPE), PVC, and metal large diameter pipes subjected to a highway design truck loading. Numerical simulations using finite element method are performed to determine pipe-soil system response under live load application. Comparisons of field test data with the predicted responses are made for soil pressures around and above the pipes, deformed cross-sectional pipe profiles, and pipe deflections. The field test results indicated that the buried flexible pipes, embedded with highly compacted graded sand with silt, demonstrated good performance without exhibiting any visible joint opening or structural distress. Under shallow burial conditions, the AASHTO specified deflection limit of 5% is found to be adequate for installation of the flexible pipes during the construction phase, and a vertical deflection limit of 2% is suggested for HDPE pipes based on the truck load response and repeated loading effect.     

Contaminant Diffusion, Solubility, and Material Property Differences between HDPE and PEX Potable Water Pipes

The objectives of this work were to identify differences between the composition, bulk properties, contaminant diffusivity and solubility for new high-density polyethylene (HDPE) pipe and crosslinked polyethylene (PEX) pipe, as well as determine which contaminant and polymer properties are useful for predicting contaminant fate in water pipe. Variations in PE pipe density (0.9371–0.9547?g/cm3), crystallinity (69–72%), crosslinking (60 and 76%), and oxidative induction time (33 to >295?min.) were detected. While numerically these differences seem minor, results show that slight material differences have a notable effect on contaminant diffusivity and solubility. Nonpolar contaminant diffusivity and solubility were best predicted by bulk density. Polar contaminants were more soluble and diffused faster through PEX than HDPE pipes because PEX pipes contained a greater amount of oxygen. For all materials, dipole moment and Log Kow were good predictors of contaminant fate and molecular volume was only useful for predicting diffusivity and solubility values for haloalkane and nonpolar aromatic contaminants.     

Analysis of PVC Pipe-Wall Viscoelasticity during Water Hammer

This research work focuses on the analysis of hydraulic transients in polyvinyl chloride (PVC) pipes, which are characterized by a viscoelastic rheological behavior. Transient pressure data were collected in a pipe rig consisting of a set of PVC pipes. The creep function of the PVC pipes was determined by using an inverse transient model based on collected transient pressure data and compared with that obtained by carrying out mechanical tensile tests of PVC pipe specimens. The numerical results obtained from the transient solver have shown that the attenuation, dispersion, and shape of transient pressures were well described. The incorporation of the viscoelastic mechanical behavior in the hydraulic transient model has provided an excellent fitting between numerical results and observed data. Calibrated creep function based on inverse analysis fit the one determined by mechanical tests well, which emphasized the importance of pipe-wall viscoelasticity in hydraulic transients in PVC pipes.     

连铸冷却水复合膜过滤器技术的研发

为了钢铁工业节能减排、降低水污染和吨钢耗水量,进行了转炉炼钢连铸冷却水过滤器技术的研发,成功开发了一种以多孔PVC陶瓷复合管为过滤元件的过滤器装置。对由多孔PVC陶瓷复合管过滤器过滤的污泥进行检测,可知多孔陶瓷复合过滤管具有很好的分离效果。检测过滤前后的水质,发现过滤后水的浊度和悬浮物含量显著降低,水质达到指标要求。通过工业试验研究和近3年的实际应用,确定了多孔PVC陶瓷复合过滤设备的最佳操作条件和反冲洗条件。     

Development of Experimental Test Setup to Evaluate Abrasion Characteristics of Drainage Pipes

The longevity of drainage pipes is dependent on the material properties of the pipe, the surrounding load, the abrasive characteristics of the effluent, and the frequency, velocity, and quantity of the effluent that flows through the pipe. Each of these parameters has impacts on the age-related abrasive decrease in the wall thickness of the drainage pipe. Traditionally, the rotating pipe test is used to assess the vulnerability of drainage pipes to abrasion. To simulate more realistically the natural environment of drainage pipes, we designed an abrasion test that keeps the drainage pipe at variable slope with respect to the horizontal and continuously pumps abrasive slurry through the pipe for 30?days. The time dependent change in wall thickness of a cellulose fiber reinforced cement pipe was simultaneously compared to the change in wall thickness of a steel-reinforced concrete pipe. The wall thickness of the fiber reinforced cement pipe decreased approximately 5 times faster than the thickness of the steel-reinforced cement pipe.     

Bubble Movement in Downward-Inclined Pipes

An experimental investigation with large-scale model tests of bubbles moving upward and downward in downward-inclined pipes is presented. The shape, velocity, and drag coefficient of single nonspherical air bubbles in continuous air-water flows are discussed. The bubble height depends mainly on the approach flow water velocity and the pipe slope. For stagnant bubbles, the bubble height is determined depending on these two parameters. Equilibrium of the drag and buoyancy forces is applied on single air bubbles in downward-inclined pipes. In pipes with pipe slope ranging from 0.052–0.087, the bubble drag coefficient is independent of the bubble Reynolds number. However, the bubble drag coefficient depends on the pipe slope and the approach flow water velocity. Using the approach of the equilibrium of the main forces the volume of stagnant bubbles can be predicted.     

Estimation of Diffusion Coefficients and Solubilities for Organic Solvents Permeation through High-Density Polyethylene Geomembrane

Experiments on the permeation of several chlorinated and aromatic hydrocarbons through high-density polyethylene (HDPE) geomembranes were conducted using the ASTM F-739 standard test method. The diffusion coefficients were estimated by a one-dimensional diffusion equation based on Fick’s second law, and the solubilities of the solvents in HDPE were determined by the steady state permeation rates. The one-dimensional transient model was able to simulate the permeation concentrations and implied that equilibrium partition between organic solvent and HDPE geomembrane was not achieved during the initial permeation. The solubilities of organic solvents in the HDPE geomembranes obtained by immersion tests or weight gain methods of permeation experiments were not an appropriate boundary condition for the model simulation of permeation. It was found that the diffusion coefficients and solubilities of organic solvents correlated well with their molecular weights and dipole moment, respectively. The present work provides information on the extent of organic compounds permeations through HDPE geomembranes as applied in hazardous waste landfills.     

宝钢1550酸洗PVC+FRP管道变形情况剖析与对策

针对宝钢1550酸轧机组酸洗循环管路选用的PVC+FRP管道多次出现的管道变形堵塞、爆裂喷酸现象,进行了实验及原因分析,结果表明:防止管道过热,避免在高流速、涡流状态下使用该类管道,优化施工规范可以有效地防止管道变形堵塞、爆裂喷酸.     

Modeling and Control of Vinyl Chloride in Drinking Water Distribution Systems

In water distribution systems containing PVC pipe manufactured in the “early era” (prior to 1977), vinyl chloride can leach into drinking water resulting in vinyl chloride concentrations exceeding the 2 μg?L?1 maximum contaminant level. Field testing of dead-end segments of water distribution systems consisting of early-era PVC pipe was conducted to examine their initial intrapipe vinyl chloride monomer (VCM) concentrations based on a Fickian-diffusion-based leaching model. The experiments showed a wide range of VCM concentrations within early-era PVC pipe ranging from less than 50 to more than 600 mg?kg?1. Based on the diffusion modeling approach, a protocol was designed that provides a means for utility managers to calibrate the model for specific dead-end lines. The paper delineates procedures to determine which dead ends require flushing to control vinyl chloride, examines the effects of system parameters such as temperature on vinyl chloride leaching, and provides a method to devise flush schedules and volumes. Through a properly designed, tested, and maintained flush protocol such as that developed in this research, public water systems with dead-end lines consisting of early-era PVC pipe can control vinyl chloride concentrations using either manual or automatic flush valves.     

Heat Pipe Augmented Passive Solar System for Heating of Buildings

A passive solar heating system was built using heat pipes bonded to the absorbing surface of a solar collector mounted on the south wall of a building. The heat pipes provided one-way heat transfer from the absorber through the insulated wall of the building to water tanks placed inside the space to be heated. The space was then heated by means of natural convection from the surfaces of the tank. The evaporator and condenser ends of the heat pipe were designed to be connected by means of a flexible hose so that the system could be retrofit to an existing building. Simulations were carried out to match the experimental and simulated results. The conductance values obtained as a result of matching showed good agreement with theoretically calculated values. Potential performance improvements were identified, including increased liquid fill fraction in the heat pipes and increasing the heat transfer surface area of the water tanks at the condenser end of the pipe.     

含V、N无缝钢管表面外折缺陷产生原因的分析

通过对鞍钢生产的部分批号V、N微合金强化无缝钢管及生产该钢管的原料连铸坯和连轧管坯的表面缺陷进行研究，分析了含V、N钢管表面外折缺陷的成因，提出了改善钢管表面质量的方法。采用改进后工艺生产的无缝管，其表面外折废品量大幅度降低。     

Field Studies of Discoloration in Water Distribution Systems: Model Verification and Practical Implications

Discoloration in water distribution systems has been studied in partnership with a number of U.K. water companies by measuring the turbidity response to changes in hydraulic conditions induced by systematic flushing. The resulting data was used to verify a predictive empirical model and hence the underlying assumptions made in its development. Model simulations, made using previously established parameters defined solely by pipe diameter and pipe material, are presented alongside measured data to demonstrate this verification. The primary cause of discoloration observed is the mobilization of material from cohesive layers bonded to pipe walls. These layers demonstrate a profile of increasing shear strength with increasing degree of discoloration. Differences are demonstrated in the layer and ultimate shear strength characteristics of the discoloration layers formed in iron and plastic pipes, with a modeled shear stress of 1.2?N/m2 shown to exhaust material layers in plastic pipes. Based on the observed data it is theorized that accumulation of material to the pipe walls is primarily dependent on two mechanisms; ubiquitous background concentrations in the bulk water, and if present corrosion by-products from iron pipes and fittings. A consequence of this is that all pipes within a water distribution system are susceptible to the development of material layers. In the formulation of operation and maintenance strategies it is suggested that iron and plastic pipes should be treated differently to obtain optimum operational effectiveness and minimize discoloration risk.     

Permeation of BTEX through Unaged and Aged HDPE Geomembranes

The effects of aging of high-density polyethylene (HDPE) geomembranes on the diffusion and partitioning of a group of volatile organic compounds (VOCs) are examined. Two different 1.5?mm thick HDPE geomembranes were aged in the laboratory at 85°C by immersing in a synthetic leachate for up to 32?months. The results of partitioning and diffusion tests performed at room temperature on both unaged and aged geomembranes using a dilute aqueous solution containing four VOCs commonly found in landfill leachates [benzene, toluene, ethylbenzene, and xylenes (BTEX)] are reported. The diffusion and partitioning coefficients decreased with increased aging. The calculated permeation coefficients decreased by 36–62% after aging the geomembrane for about 10–32?months. This decrease in diffusion, partitioning, and permeation coefficients is related to the increase in geomembrane crystallinity during aging. A relationship between partitioning, diffusion, and permeation coefficients with the geomembrane crystallinity is established and could potentially be used to evaluate the migration of VOCs through HDPE geomembranes. Aging of HDPE geomembrane did not increase diffusive transport of organic contaminants.     

Study of Transient Vapor Cavitation in Series Pipe Systems

The phenomenon of vapor cavitation due to water hammer in steel and plastic pipes (polyethylene and PVC) is investigated experimentally using high frequency pressure transducers. A wave character with a gradually increasing frequency of pressure oscillations is found to be associated with vapor cavitation. The influence of wall elasticity, liquid evaporation duration, and steady-state losses on the maximum cavitation pressure is shown. A growing pressure reduction is accompanied by gas desorption from the liquid. The liberated air reduces the amplitude of the pressure increase and prolongs the period of oscillations. The maximum cavitation pressure increase, directly proportional to the pressure wave velocity, can be many times higher than the maximum water hammer pressure amplitude. For the short liquid evaporation duration (below 0.06 s) considered in the experiment, the first maximum increase is also distinctly higher than previously published. The frequency of the vapor cavitation pressure wave depends on the duration of the oscillations. For the test cases, the frequency increases during the cavitation from about 400 to 900 Hz for steel pipes and from about 300 to 600 Hz for plastic pipes.     

脉动热管的理论研究与应用新进展

作为一种工作机理独特的新型传热装置,脉动热管具有极高的传热效率、较高的抗烧干能力、良好的环境适应性,且结构简单、可变,成本较低,具有很高的实际应用价值,是目前传热技术领域的研究热点.本文在对脉动热管的优点、结构形式和工作原理进行总体介绍的基础上,首先从理论建模研究入手归纳了目前研究中通常采用的直管、单弯头管、部分单弯头管等结构模型和质量-弹簧-阻尼模型,质量、动量、能量方程模型以及其他数学模型,然后从实验可视化研究和计算可视化研究两方面综述了脉动热管的运行过程、工作机理以及近年来国内外在脉动热管方面的最新研究进展,从启动性能、传热性能和传热极限三方面系统介绍了管径、长度、截面形状、加热方式、充液率、倾斜角度、输入功率和工作流体种类等不同设计和使用参数对脉动热管性能的影响.进一步从设计与应用方面,对脉动热管在电子设备、太阳能集热、动力装置热管理和低温环境换热等方面的研究进行了综述,展示了脉动热管在实际应用中的效果和优势.最后对今后的研究方向与发展趋势进行了展望,指出可通过更详细的理论和仿真建模研究脉动热管的工作机理、工作性能、工作过程和优化设计方法.      

Bending Behavior of Steel Pipe Girders Filled with Ultralight Mortar

Bending behavior of steel pipes filled with ultralight mortar was studied by bending tests using a steel pipe, steel pipes filled with ultralight mortar, and steel pipes filled with light aggregate concrete and normal concrete. The steel pipe model filled with normal concrete had 1.8 times higher bending strength than the steel pipe model. The bending behavior of the steel pipe filled model with ultralight mortar was not improved when the compressive strength of the ultralight mortar was less than 1 MPa. However, ductility was much improved when the compressive strength was over 5 MPa, and the ultimate steel strain was more than double of the steel pipe model. The strains of steel and concrete in all the models were proportional to the distance from the neutral axis until the steel plate yielded. A simple analytical method was proposed to calculate the bending moments of the ultralight mortar filled steel pipes. The calculated values agreed very well with the test results.     

锅炉补给水系统的节能技术改造与经济分析

介绍了某公司厂内二、三锅炉房在蒸汽和热水锅炉补给水系统进行的节能技术改进情况，以及对节能效果进行的经济分析。     

管线探测仪对测量供水管道漏损的作用

供水管道在供水过程中出现渗漏和破损,如何及时发现漏损的水量以减少供水的损失,减少漏失率,全功能管线探测仪在供水管道测漏上起了至关重要的作用。     

电阻焊接钢管电磁加热过程隐性缺陷

随着中国钢铁行业以及电磁冶金技术的飞速发展,焊管工业发展迅速,焊接钢管质量不断提升。但电磁冶金技术难以避免固有的集肤、邻近效应导致的产品缺陷,限制了焊接钢管在深海、极地、高压等恶劣环境的广泛应用。为提高钢管的安全服役性,提出了一种依靠精密加热技术分析隐性缺陷问题的新方法。将钢管焊接和热处理两道工序作为一个整体进行对比分析,定量阐述了一种区别于常规加热缺陷的钢管内部隐性缺陷。给出了缺陷面积率作为评价隐性缺陷的量化指标,并分析了管坯生产速度对各类隐性缺陷的影响规律。当管坯运动速度为55～65mm/s时,面积缺陷率变化趋于平缓;速度过高时,面积缺陷率增加幅度变快;速度过低时,加热重复区导致不宜忽视的能量损耗。对提高焊管在恶劣环境服役的可靠性,促进钢铁制造绿色化发展具有一定的积极意义。