Journal articles: 'HDPE Pipe'

1

Li, Zheng, Hong Wu Zhu, Xiang Ling Kong, and Abdennour Seibi. "Combined Effect of Temperature and Soil Load on Buried HDPE Pipe." Advanced Materials Research 452-453 (January 2012): 1169–73. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1169.

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HDPE pipes，mostly buried underground, have been widely used in industry. Much research has been done on pipe property changing with time or temperature. But thermal expansion of pipe was neglected. This paper investigated the combined effect of soil load and temperature on HDPE pipe with introduction of thermal expansion. Stress and deflection variation with time of buried HDPE pipe were studied in ABAQUS. Result showed pipe temperature had great influence on buried HDPE pipe performance. Thermal stress was much larger than stress caused by soil load. And thermal expansion prevented pipe from deflecting due to soil load, which can protect HDPE pipe in applications.

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2

Rofooei, Fayaz Rahimzadeh, Himan Hojat Jalali, Nader Khajeh Ahmad Attari, Hadi Kenarangi, and Masoud Samadian. "Parametric study of buried steel and high density polyethylene gas pipelines due to oblique-reverse faulting." Canadian Journal of Civil Engineering 42, no. 3 (March 2015): 178–89. http://dx.doi.org/10.1139/cjce-2014-0047.

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A numerical study is carried out on buried steel and high density polyethylene (HDPE) pipelines subjected to oblique-reverse faulting. The components of the oblique-reverse offset along the horizontal and normal directions in the fault plane are determined using well-known empirical equations. The numerical model is validated using the experimental results and detailed finite element model of a 114.3 mm (4″) steel gas pipe subjected to a reverse fault offset up to 0.6 m along the faulting direction. Different parameters such as the pipe material, the burial depth to the pipe diameter ratio (H/D), the pipe diameter to wall thickness ratio (D/t), and the fault–pipe crossing angle are considered and their effects on the response parameters are discussed. The maximum and minimum compressive strains are observed at crossing angles of 30° and 90°, respectively. It is found that the dimensionless parameters alone are not sufficient for comparison purposes. Comparing steel and HDPE pipes, it is observed that HDPE pipes show larger compressive strains due to their lower strength and stiffness. For both steel and HDPE pipes, peak strains increase with increasing D/t and H/D ratio for a constant pipe diameter and fault offset. For a given H/D ratio, compressive strains increase with increasing D/t ratio in HDPE pipes, while in steel pipes considered in this study, this effect is negligible. Finally, the peak strains of the pipes are compared to those suggested by Canadian Standard Association for Oil and Gas Pipeline System, CSA Z662.

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3

Qi, Fang Juan, Li Xing Huo, You Feng Zhang, and Hong Yang Jing. "Study on Fracture Properties of High-Density Polyethylene (HDPE) Pipe." Key Engineering Materials 261-263 (April 2004): 153–58. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.153.

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Butt-fusion welding is the main technology to join high-density polyethylene (HDPE) plastic pipes, which are widely used in transport the water, gas and corrosive liquid. Investigation shows that one of the failure modes of HDPE pipe is the crack slowly grows across the thick direction and leads to failure at last, so that it is very important to study the resistance to crack initiation of HDPE pipe and its butt-fusion welded joint. In this study, the elastic-plastic fracture mechanics parameter, crack opening displacement (COD) is used to describe the fracture initiation behaviors for the HDPE materials and its butt-fusion welded joints. The resistance to initiation fracture of HDPE pipe materials and butt-fusion welded joints were investigated at different temperature by using multiple specimen resistance curve method and silicon-rubber replica method. The results show that saturation initial crack COD- δis of HDPE pipe materials and butt-fusion welded joints decreases with the decreasing temperature. The δis of butt-fusion welded joints is lower than that of HDPE pipe materials. Investigation also proved that the silicon-rubber replica method is more suitable for HDPE engineering material than the multiple specimen method. At the same time the statistic distribution of the δis of HDPE butt-fusion welded joint was conducted. The results show that the value of the δis has the statistic variance inherently. The optimum fitting distribution of COD is Weibull distribution with three parameters.

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4

Yang, Hong Wei, Shi Liang Yang, Chao Wu, Yi Wei Fei, and Xian Yong Wei. "The Applications of Direct Fluorinated HDPE in Oil & Gas Storage and Transportation." Advanced Materials Research 328-330 (September 2011): 2436–39. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.2436.

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Characteristics of elemental fluorine and carbon-fluorine bonds were analyzed. The barrier and oil-resistance properties of direct fluorination of HDOE were unveiled from molecule structure. The HDPE surface fluorination results in the increase of surface energy, cross link to some extent and shrinkage of polymer free volume.The application of direct fluorination of HDPE in oil in oil ＆ gas storage and transportation fields were reviewed, including oil and gas pipe,plastic petrol-tanks and HDPE impermeable membrane applied in oil tank foundation. After direct fluorination processing, the anti-corrosion and the permeability to hydrocarbons of HDPE pipes are strengthened. With the development of technology, it will be the trend that the multi-layer fuel tanks replace the single layer fuel tanks. The HDPE is applied as the outermost layer of multi-layer structure to ensure the processing property and the impact resistance in low temperature.

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5

Majid, F., and M. Elghorba. "Critical lifetime of HDPE pipes through damage and reliability models." Journal of Mechanical Engineering and Sciences 13, no. 3 (September 26, 2019): 5228–41. http://dx.doi.org/10.15282/jmes.13.3.2019.02.0428.

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Damage models are not directly applicable on high-density polyethylene (HDPE) pipes. In this paper, static and strain-unified theory damage models are adapted to fit the HDPE case by substituting the dynamic tests’ endurance limits by preloading simulation through notch and stiffness evaluation. Then, tensile and burst tests are following up to evaluate the specimens’ residual life. Compared to virgin specimens, the rupture limit of old HDPE pipes’ specimens had dropped significantly and their elongation decreased from 275 mm to about 26 mm. The degradation of the seven categories of specimens are different. Indeed, the degradation is too noticeable, disappearance of the plastic phase, for the categories 6 and 7, which are in the bottom of the pipe. Then, a reduced plastic phase on the lateral categories 4 and 5 showing an important impact of degradations. Finally, a larger plastic phase for the categories 1 and 2 taken from the top of the pipe, showing a medium impact of degradation. Thus, the use of the stiffness factor, reflecting the variability of degradation of the different categories of specimens, and the thickness reduction as life fractions for both aged and neat HDPE specimens was possible. The developed strains damage model compared to static burst pressures’ one confirmed the damage stages and the critical life fraction of HDPE pipes. By comparing these models, the drastic change of HDPE pipes’ behavior, from a ductile to a brittle one, have been proved. These findings allowed us to find out the critical life fraction of neat and old HDPE pipes, which has been confirmed by comparing the burst pressure curves of a notched and an old pipe. The presented approach is cost effective allowing a deep analysis of HDPE pipes failure and damage quantification through simply made models based on static tensile and burst test instead of tedious and very costly dynamic ones.

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6

Zhang, Chuntao, and Ian D. Moore. "Nonlinear Finite Element Analysis for Thermoplastic Pipes." Transportation Research Record: Journal of the Transportation Research Board 1624, no. 1 (January 1998): 225–30. http://dx.doi.org/10.3141/1624-26.

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Thermoplastic pipes are being used increasingly for water supply lines, storm sewers, and leachate collection systems in landfills. To facilitate limit states design for buried polymer pipes, nonlinear constitutive models have recently been developed to characterize the highly nonlinear and time-dependent material behavior of high-density polyethylene (HDPE). These models have been implemented in a finite element program to permit structural analysis for buried HDPE pipes and to provide information regarding performance limits of the structures. Predictions of HDPE pipe response under parallel plate loading and hoop compression in a soil cell are reported and compared with pipe response measured in laboratory tests. Effects on the structural performance of pipe material nonlinearity, geometrical nonlinearity, and backfill soil properties were investigated. Good correlations were found between the finite element predictions and the experimental measurements. The models can be used to predict pipe response under many different load histories (not just relaxation or creep). Work is ongoing to develop nonlinear constitutive models for polyvinylchloride and polypropylene to extend the predictive capability of the finite element model to these materials.

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7

Lapos, B. M., R. W. I. Brachman, and I. D. Moore. "Response to overburden pressure of an HDPE pipe pulled in place by pipe bursting." Canadian Geotechnical Journal 44, no. 8 (August 2007): 957–65. http://dx.doi.org/10.1139/t07-036.

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Measurements of vertical and horizontal pipe deflections are reported for a high-density polyethylene (HDPE) pipe experiencing an increase in vertical pressure after being pulled in place using pipe bursting techniques. Three tests were conducted to measure the diameter change of a 165 mm outside diameter HDPE pipe after replacing an intact clay pipe with an external diameter of 184 mm backfilled with a poorly graded dense sand. A fourth test measured the response of the HDPE pipe after replacing an intact clay pipe with an external diameter of 128 mm. Variable pipe deflections were measured in each test, which depended on the interactions among the broken clay pipe fragments surrounding the HDPE pipe. The orientation of the clay fragments controls whether the increase in vertical pressure is transferred immediately to the HDPE pipe. In some cases, the fractured clay pipe produced a structural ring encasing the HDPE pipe, thus providing additional hoop strength. Two of the replacement tests did not record diameter changes until 100 kPa because of the interaction amongst the clay fragments. The upsize test and one replacement test recorded diameter changes from a vertical pressure of 20 kPa, because there were no interactions observed among the clay fragments.

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8

Li, Bai-jian, Liang-sheng Zhu, and Xin-sha Fu. "Investigation of the Load-Sharing Theory of the RC Pipes Rehabilitated with Slip Liners." Advances in Civil Engineering 2019 (April 10, 2019): 1–8. http://dx.doi.org/10.1155/2019/9594379.

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Slip-lining is a preferred rehabilitation approach in the departments of transportation in China. Although the method is the most common rehabilitation technique, few research studies have been conducted on the mechanical behavior of a rehabilitated reinforced concrete pipe (RCP). A series of experiments were conducted on RCPs rehabilitated with a corrugated steel pipe (CSP), a steel pipe, a high-density polyethylene (HDPE) pipe, and a shape steel bracket. The RCP rehabilitated with the CSP showed an increase in both the load-carrying capacity (3.46 times greater than the RCP) and the stiffness (5.35 times greater than the RCP). The RCP rehabilitated with the steel pipe, HDPE pipe, and steel bracket exhibited an increase in the load-carrying capacity (1.23, 1.50, and 1.31 times greater than the RCP, respectively), and the stiffness of these three pipes was not markedly changed. The slip-lined pipe acts as a “pipe within a pipe” system. A “load-sharing” theory was proposed in this study and provides estimates of the load-carrying capacity of the slip-lined pipes.

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9

Mao, Feng, Say Kee Ong, and James A. Gaunt. "Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes." Journal of Water and Health 13, no. 3 (March 13, 2015): 758–72. http://dx.doi.org/10.2166/wh.2015.183.

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Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0 × 10−9 to 2.8 × 10−9cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

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10

Li, Zheng, Hong Wu Zhu, Pin Xian Qiu, and Abdennour Seibi. "Analytical Method for Temperature Distribution in Buried HDPE Pipe." Advanced Materials Research 452-453 (January 2012): 1205–9. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1205.

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HDPE pipes have been widely used in industry, which were mostly buried underground. Because of special material properties, which were affected by temperature, it is necessary to get the temperature profile of buried HDPE pipe. Most past solutions for temperature distribution in buried pipe were numerical ones. The aim of this paper was to present a simple analytical model under steady-state heat transfer condition with a new special heat transfer coefficient introduced. FEM method was used to check this model. The influences of fluid temperature, soil surface temperature and soil depth on pipeline temperature were also analyzed. The results showed a good agreement between the analytical model and FEM method. And fluid temperature in pipe was proved to be the key factor that affected the pipe temperature .

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11

Makarov, T. V., R. I. Vasiliev, A. S. Ivushkina, A. A. Parshin, A. V. Sukhinina, and E. V. Kalugina. "The effect of 3M Dynamar FX5911processing additive on butt welding of pipes based on HDPE and the processability of extrusion." Plasticheskie massy, no. 7-8 (September 11, 2019): 67–68. http://dx.doi.org/10.35164/0554-2901-2019-7-8-67-68.

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The use of 3M Dynamar processing additives based on fluoropolymers in the production of pipe grades HDPE allows to signifi cantly reduce the load on the screw and the pressure on the die, providing increase the productivity of the extrusion line. Conducted studies have shown that the addition of Dynamar FX5911, even at high concentrations, does not affect significantly the physicomechanical properties of HDPE and does not impair the strength of the weld when butt welding HDPE pipes.

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12

Qi, Fang Juan, Jian Li, Zhi Juan Yang, and Min Fang. "Experimental Studies on J-Integral of Welded Buried High-Density Polyethylene Pipes." Advanced Materials Research 291-294 (July 2011): 1116–21. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.1116.

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Investigation shows that one of the failure modes of HDPE pipe is the crack slowly grows across the thick direction and leads to failure at last. So that it is very important to study the resistance to crack initiation properties of HDPE pipe and its butt-fusion welded joint. The J-integral is applied to character the fracture initiation of a tough polymer for which the concept of linear elastic fracture mechanics (LEFM) are inapplicable for reasonably sized specimen due to extensive plasticity. In this paper, the multiple specimen resistance curve technique was employed for J-integral. The normal single side notched three-point bend (3PB) specimen was used to study the characteristic fracture parameter of high-density polyethylene pipe and its butt-fusion joints at different temperature. Testing results show that values of characteristic fracture parameter are affected by the welding process and experimental temperature respectively. The toughness value of HDPE butt-fusion joint is lowered than that of HDPE pipe. With the temperature decreasing, the toughness value of HDPE pipe and Butt-fusion welded joint decrease. And the same time testing results also show that J-integral can describe the fracture character of high-density polyethylene exactly. Testing results can be used for the engineering design and failure analysis of HDPE pipe.

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13

Liu, Jianping, Hong Zhang, Baodong Wang, Dong Zhang, Beilei Ji, Fan Fei, and Xiaoben Liu. "An Accurate and Efficient Fitness-For-Service Assessment Method of Pipes with Defects under Surface Load." Energies 14, no. 17 (September 3, 2021): 5521. http://dx.doi.org/10.3390/en14175521.

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With continued urbanization in China, the construction of urban gas pipelines is increasing, and the safety of gas pipelines are also increasingly affected by urban development and the increased scope of buildings and roads. Pipes with defects are more likely to fail under the surface loads. In this study, uniaxial tensile tests of high-density polyethylene (HDPE) pipes were carried out to obtain the real material parameters of pipe. A pipeline-soil interaction finite element model of HDPE pipeline with defects under surface load was established. The failure mechanism of the urban gas pipeline was studied and the influence of parameters such as internal pressure, defect position, defect depth on the mechanical behavior, and failure of pipelines were analyzed. A failure criterion for HDPE pipes with defects under surface load was proposed based on the limit-state curves obtained under different working conditions. Furthermore, an accurate and efficient fitness-for-service assessment procedure of pipes with defects under surface load was proposed. The results showed that maximum Mises stress of the pipeline gradually increased with increasing surface load and the position of maximum stress changed from the top and bottom of the pipe to the defect position and both sides of the pipe. Finally, when Mises stress of the HDPE pipe exceeds the yield limit, failure will occur. Internal pressure, defect location, and defect depth were found to influence the failure process and critical surface load of the pipeline. Safety evaluation curves of the gas pipeline with defects under surface load were obtained by calculating the critical failure load of the pipeline under various working conditions. Finally, a nonlinear fitting method was used to derive a formula for calculating the critical surface load under different defect parameters. The proposed method provides a useful reference for urban gas pipeline safety management.

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14

Fang, Hongyuan, Peiling Tan, Xueming Du, Bin Li, Kangjian Yang, and Yunhui Zhang. "Numerical and Experimental Investigation of the Effect of Traffic Load on the Mechanical Characteristics of HDPE Double-Wall Corrugated Pipe." Applied Sciences 10, no. 2 (January 15, 2020): 627. http://dx.doi.org/10.3390/app10020627.

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The high-density polyethylene (HDPE) double-wall corrugated pipe, which is a kind of flexible pipe, is widely used in municipal drainage networks. The characteristics of the surrounding soil and pipe bed, pipe cover depth, backfill compaction, type of pavement and pavement design, and traffic loads are some of the major factors that affect the stress and deformation of pipes. In this study, the ABAQUS 3D finite element model was used to analyze the influence of backfill compactness, traffic loads, diameter, and hoop stiffness on the mechanical characteristic of an HDPE pipe under traffic loads. A series of full-scale tests were carried out to verify the validity of the simulation results. For the conditions tested, the results showed the following: (1) the Von-Mises stress of the pipe was mainly determined by the earth pressure at the crown, and the stress caused by backfill compaction increased significantly but had a short duration and limited impact on the pipe; (2) traffic load alone had little influence on the mechanical behavior of the pipe: while under the action of the loose backfill in contact with the pipe, the pipes were more sensitive to the traffic load response; (3) the fluctuations in the Von-Mises stress of the pipe mainly depended on the magnitude and speed of the traffic load; (4) for pipes with a small diameter, non-compacted backfill easily caused stress concentration in the pipe, while the degree of backfill compaction had almost the same effect on the distribution of stress for pipes with different hoop stiffness.

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15

Regad, Abdelmalek, Djebara Benzerga, Habib Berrekia, Abdelkader Haddi, and Nourredine Chekhar. "Repair and rehabilitation of corroded HDPE100 pipe using a new hybrid composite." Frattura ed Integrità Strutturale 15, no. 56 (March 28, 2021): 115–22. http://dx.doi.org/10.3221/igf-esis.56.09.

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The good management of drinking water begins with a supply network, with a low rate of leakage. Currently, the pipes used in the water transport system are mainly made of polymeric materials, such as HDPE. The corrosion degradation of this type of pipe has received a lot of attention from the drinking water supply companies. It is therefore important to understand the effect of pressure on an HDPE pipe with a surface defect. To answer this problem, we will first study the mechanical behavior at failure of HDPE pipes in the presence of a surface defect using a finite element method. For the rehabilitation of pipe in presence of surface defect, we try to use a new composite. This new laminated composite is reinforced with a natural organic load. It is obtained from a laminated composite woven by incorporating a natural non-polluting organic load (granulates of date cores) which becomes hybrid composite. The new economical hybrid composite material is made of an organic matrix containing methyl methacrylate, a woven reinforcement including a reinforcing glass fiber and a fabric perlon having an absorbing role. The textile reinforcement made up of several folds reinforcing laid out according to the orientations (90, 452, and 0). A numerical simulation with the ANSYS Workbench software is carry out to study the behavior of the HDPE pipe with surface defect and with defect repaired by the new hybrid composite material in the form of rings to consolidate the cracked area of the tube. The numerical results will allow us to decide on a real practical use of the new hybrid composite.

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16

Vlase, Sorin, Marin Marin, Maria Luminița Scutaru, Dumitru Daniel Scărlătescu, and Carol Csatlos. "Study on the Mechanical Responses of Plastic Pipes Made of High Density Polyethylene (HDPE) in Water Supply Network." Applied Sciences 10, no. 5 (March 1, 2020): 1658. http://dx.doi.org/10.3390/app10051658.

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This paper studies the mechanical behavior of high-density polyethylene (HDPE), from which the pipes used for water transport in water supply networks are manufactured. The study was generated by the practical problem of replacing and modernizing a water network of a city with 300,000 inhabitants. Of the numerous problems that have arisen and been solved by the group of researchers, only those referring to the mechanical behavior of the materials used for pipes are presented. HDPE, which is a thermoplastic material, is suitable for manufacturing the pipes used in water supply networks, having many advantages. Data on the mechanical properties of the material of which the pipe and elbow are made is obtained experimentally. The work involved the main steps required to design a water network, but the subject is not exhausted. The stresses in the polyethylene pipe are determined in two cases: buried in the ground and supported in a concrete massif. Thus, by calculation, the advantage offered by the second solution is justified. The crack of the pipes manufactured from HDPE is studied, taking into account the classical model used in the cracking process. A simulation of pipes and elbows cracking was made. The results obtained via MEF are useful for the users of the networks.

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17

Djebli, A., A. Aid, M. Bendouba, A. Talha, N. Benseddiq, M. Benguediab, and S. Zengah. "Uniaxial Fatigue of HDPE-100 Pipe. Experimental Analysis." Engineering, Technology & Applied Science Research 4, no. 2 (April 17, 2014): 600–604. http://dx.doi.org/10.48084/etasr.422.

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In this paper, an experimental analysis for determining the fatigue strength of PE-100, one of the most used High Density Polyethylene (HDPE) materials for pipes, under cyclic axial loadings is presented. HDPE is a thermoplastic material used for piping systems, such as natural gas distribution systems, sewer systems and cold water systems, which provides a good alternative to metals such as cast iron or carbon steel. One of the causes for failures of HDPE pipes is fatigue which is the result of pipes being subjected to cyclic loading, such as internal pressure, weight loads or external loadings on buried pipes, which generate stress in different directions: circumferential, longitudinal and radial. HDPE pipes are fabricated using an extrusion process, which generates anisotropic properties. By testing in the Laboratory a series of identical specimens obtained directly from PE-100 HDPE pipes in longitudinal directions, the relationships between amplitude stress and number of cycles (S-N curve) test frequency 2 Hz and stress ratio R = 0.0 are established.

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18

Chudnovsky, A., K. Sehanobish, and S. Wu. "Methodology for Durability Analysis of HDPE Pipe." Journal of Pressure Vessel Technology 122, no. 2 (December 15, 1999): 152–55. http://dx.doi.org/10.1115/1.556165.

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Toughness evaluation and durability analysis are two of the critical steps to design a toughened HDPE resin for durability in pipe applications. Durability analysis involves defect characterization, crack initiation and propagation mechanism, and long-term performance prediction. The methodology for durability analysis of high-density polyethylene (HDPE) pipe will be discussed in this paper. Various analytical techniques, such as fractography, hot-stage microscopy, energy-dispersive X-ray (EDX), microtransmittance infrared spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), have been used to characterize the defect properties and size distribution. Crack initiation and propagation mechanisms in HDPE have been analyzed by some accelerated tests and compared with that observed in the long-term hydrostatic pressure test. A new procedure for lifetime prediction of HDPE under creep is discussed based on the crack layer theory (Chudnovsky, A., 1984, NASA Contractor Report 174634). [S0094-9930(00)00802-7]

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Colditz, W., T. Gertel, and T. Gertel. "Welding of HDPE moulded pipe sections." Welding International 2, no. 4 (January 1988): 377–78. http://dx.doi.org/10.1080/09507118809447481.

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Tang, Jie, and Ping Ping Xu. "Application of High Density Polyethylene Pipe (HDPE) in Same Floor Drainage System." Applied Mechanics and Materials 99-100 (September 2011): 885–90. http://dx.doi.org/10.4028/www.scientific.net/amm.99-100.885.

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This paper analyses the technology characteristics of HDPE pipes and UPVC pipes that used in drainage. Using a residential building project in Hangzhou as an example, it compares the economic benefits and comprehensive benefits of HDPE pipes with those of UPVC pipes. It concludes that it’s better to use HDPE pipes in same floor drainage system, and the using of HDPE pipes will bring benefits in the promoting of the same floor drainage system.

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Liamani, Samira, and Sahli Abderahmane. "Modeling the Repair of a Crack in an HDPE Pipe." Periodica Polytechnica Mechanical Engineering 65, no. 2 (February 24, 2021): 134–40. http://dx.doi.org/10.3311/ppme.16487.

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A pipe is a buried or aerial pipeline carrying goods, whether in liquid or gaseous form. Pipes are most often made from polymer tubes. These pipes prove to be subject to damage caused by a lack of material or crack thus calling for methods of repair or reinforcement.The objective of this study is to analyze by finite element analysis the presence of a horizontal crack in a high-density polyethylene pipe subjected to patch-corrected internal loading.Part of this study is devoted to analyzing the Von Misses stress distribution along a horizontal line, the applied loading type effect, the orientation of the fibers and the nature of the patch have been highlighted.The second part of our study is based on the calculation of the J-Integral where the same parameters of the first part were considered.The results clearly show that the mechanical characteristics of the composite must be optimized to provide an effective repair safely and allow relief of stress concentrations at the crack front.

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22

Shan, Yongti, Guijun Shi, Qunfang Hu, Yunhui Zhang, and Fu Wang. "Numerical Investigation of the Short-Term Mechanical Response of Buried Profiled Thermoplastic Pipes with Different Diameters to External Loads." Mathematical Problems in Engineering 2021 (May 24, 2021): 1–18. http://dx.doi.org/10.1155/2021/8853959.

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High-density polyethylene (HDPE) double-wall corrugated pipe is a flexible buried pipe widely used in municipal drainage, and its deformation is affected by the compactness of the surrounding soil. This paper uses the ABAQUS to establish a three-dimensional pipe-soil model of double-wall corrugated pipes, and the mechanical response behavior of corrugated pipes with different nominal diameters subject to external loads is studied. The results show that the strain distribution characteristics for pipes with different diameters are very similar, and the circumferential strain value at critical positions of the pipe is proportional to its nominal diameter. Under poor backfill conditions, small-diameter pipelines are more prone to damage caused by strain concentration, while large-diameter pipelines may be damaged due to local bending.

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23

Guo, Zhouchao, Rui Xu, and Ping Xue. "Study on Preparation of Ultra-High-Molecular-Weight Polyethylene Pipe of Good Thermal-Mechanical Properties Modified with Organo-Montmorillonite by Screw Extrusion." Materials 13, no. 15 (July 27, 2020): 3342. http://dx.doi.org/10.3390/ma13153342.

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The study of processing characteristic and property optimization of ultra-high-molecular-weight polyethylene (UHMWPE) pipe is increasingly performed, mainly focusing on difficulties in the melting process and poor thermal-mechanical properties after forming, which have limited the wider engineering application of UHMWPE pipe. In this study, organo-montmorillonite (OMMT)-modified UHMWPE pipe with good thermal-mechanical properties was prepared by screw extrusion molding. First, high-density polyethylene was subjected to fluidity modification so that the screw extrusion molding of UHMWPE pipe was feasible. Then, OMMT-modified UHMWPE pipes under different addition amounts of OMMT were innovatively prepared by extrusion. Furthermore, the effects of the addition amounts of the compatibilizer HDPE-g-MAH and the silane coupling agent γ-(2,3-epoxy propoxy) propyl trimethoxy silane (KH560) on the thermal properties of OMMT-modified UHMWPE pipe were investigated for the first time. Compared with those of pure UHMWPE pipe, the Vicat softening temperature (from 128 to 135.2 °C), thermal deformation temperature (from 84.4 to 133.1 °C), bending strength (from 27.3 to 39.8 MPa), and tensile strength (from 20.8 to 25.1 MPa) of OMMT-modified UHMWPE pipe were greatly increased. OMMT-modified UHMWPE pipe with good thermal-mechanical properties was able to be prepared by extrusion for the first time. The compatibilizer method of HDPE-g-MAH was slightly more effective than the coupling agent method of KH560.

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Pokharel, Pashupati, Yoonsang Kim, and Sunwoong Choi. "Microstructure and Mechanical Properties of the Butt Joint in High Density Polyethylene Pipe." International Journal of Polymer Science 2016 (2016): 1–13. http://dx.doi.org/10.1155/2016/6483295.

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The microstructure and mechanical properties of the butt joint in high density polyethylene (HDPE) pipes were evaluated by preparing the joints with increasing the cooling time from 10 s to 70 s before pressure created for fusion of the pipes. Here, cold fusion flaws in HDPE butt joint were created with increasing the cooling time around 70 s caused by the close molecular contact followed by insufficient interdiffusion of chain segments back and forth across the wetted interface. The tensile failure mechanism of the welded pipes at different fusion time was projected based on the tensile test of dog-bone shaped, fully notched bar type as well as round U-notched specimens. The mechanical properties of the joints at different fusion time were correlated with the corresponding fracture surface morphology. The weld seam as well as tensile fracture surfaces were etched using strong oxidizing agents. The crystallinity of surface etched weld zone by potassium permanganate based etchant was found higher than unetched sample due to the higher susceptibility of amorphous phase of polyethylene with oxidizing agent. The U-notched tensile test of butt welded HDPE pipe and surface etching of the weldments provided clear delineation about the joint quality.

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Kubrak, Michał, Agnieszka Malesińska, Apoloniusz Kodura, Kamil Urbanowicz, and Michał Stosiak. "Hydraulic Transients in Viscoelastic Pipeline System with Sudden Cross-Section Changes." Energies 14, no. 14 (July 6, 2021): 4071. http://dx.doi.org/10.3390/en14144071.

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It is well known that the water hammer phenomenon can lead to pipeline system failures. For this reason, there is an increased need for simulation of hydraulic transients. High-density polyethylene (HDPE) pipes are commonly used in various pressurised pipeline systems. Most studies have only focused on water hammer events in a single pipe. However, typical fluid distribution networks are composed of serially connected pipes with various inner diameters. The present paper aims to investigate the influence of sudden cross-section changes in an HDPE pipeline system on pressure oscillations during the water hammer phenomenon. Numerical and experimental studies have been conducted. In order to include the viscoelastic behaviour of the HDPE pipe wall, the generalised Kelvin–Voigt model was introduced into the continuity equation. Transient equations were numerically solved using the explicit MacCormack method. A numerical model that involves assigning two values of flow velocity to the connection node was used. The aim of the conducted experiments was to record pressure changes downstream of the pipeline system during valve-induced water hammer. In order to validate the numerical model, the simulation results were compared with experimental data. A satisfactory compliance between the results of the numerical calculations and laboratory data was obtained.

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Rathner, Raffael, Wolfgang Roland, Hanny Albrecht, Franz Ruemer, and Jürgen Miethlinger. "Applicability of the Cox-Merz Rule to High-Density Polyethylene Materials with Various Molecular Masses." Polymers 13, no. 8 (April 9, 2021): 1218. http://dx.doi.org/10.3390/polym13081218.

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The Cox-Merz rule is an empirical relationship that is commonly used in science and industry to determine shear viscosity on the basis of an oscillatory rheometry test. However, it does not apply to all polymer melts. Rheological data are of major importance in the design and dimensioning of polymer-processing equipment. In this work, we investigated whether the Cox-Merz rule is suitable for determining the shear-rate-dependent viscosity of several commercially available high-density polyethylene (HDPE) pipe grades with various molecular masses. We compared the results of parallel-plate oscillatory shear rheometry using the Cox-Merz empirical relation with those of high-pressure capillary and extrusion rheometry. To assess the validity of these techniques, we used the shear viscosities obtained by these methods to numerically simulate the pressure drop of a pipe head and compared the results to experimental measurements. We found that, for the HDPE grades tested, the viscosity data based on capillary pressure flow of the high molecular weight HDPE describes the pressure drop inside the pipe head significantly better than do data based on parallel-plate rheometry applying the Cox-Merz rule. For the lower molecular weight HDPE, both measurement techniques are in good accordance. Hence, we conclude that, while the Cox-Merz relationship is applicable to lower-molecular HDPE grades, it does not apply to certain HDPE grades with high molecular weight.

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TALESNICK, M. L., H. W. XIA, and I. D. MOORE. "Earth pressure measurements on buried HDPE pipe." Géotechnique 61, no. 9 (September 2011): 721–32. http://dx.doi.org/10.1680/geot.8.p.048.

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Dobrotă, Dan, Ionela Rotaru, and Ioan Bondrea. "Welded Construction Design of Transition Fittings from Metal Pipes to Plastic Pipes." Metals 10, no. 9 (September 13, 2020): 1231. http://dx.doi.org/10.3390/met10091231.

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Transition type fittings are components often used in facilities where fluids are transported that allow the passage from a high density polyethylene (HDPE) pipe to a steel pipe. In the presented studies, four types of transition fittings were analyzed in the first stage. The four types of transition fittings are distinguished by the shape of their welded steel construction. The performed analyses took into account testing the behavior upon exposure to fatigue, measuring the HDPE hardness and applying the finite element method (FEM). As a result of these studies it was demonstrated that the form of the welded steel construction has a very great influence on the operating behavior of the transition fitting. Thus, a new transition fitting with a welded steel construction was designed. In this new type of transition fitting, an approximately 50% increase in resistance to fatigue stress, an approximately 90% reduction in stress in the part material and a reduction in the hardness of the material in HDPE pipes was obtained. The studies allow not only an improvement of the characteristics for these types of parts, but also the optimization of other types of steel-plastic joints.

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Mangs, Sara, Morgan Fröling, Olle Ramnäs, and Ulf Jarfelt. "Transport of 1,1,1,3,3-Pentafluorobutane (HFC-365mfc) in Rigid Polyurethane Foam and Polyethylene." Cellular Polymers 21, no. 3 (May 2002): 155–64. http://dx.doi.org/10.1177/026248930202100301.

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This study focuses on the mass transfer properties of 1,1,1,3,3-pentafluorobutane (HFC-365mfc) in the insulating system used in most district heating pipes produced today, namely rigid polyurethane (PUR) foam with a protective layer of polyethylene (HDPE). The solubility, permeability and diffusion coefficients for HFC-365mfc in PUR foam and HDPE have been determined. The coefficients for HFC-365mfc in PUR foam are very similar to those of cyclopentane, currently the most common blowing agent in PUR foams used for district heating pipes in Europe. The polyethylene casing is a better diffusion barrier for HFC-365mfc than it is for cyclopentane. However, the main mass transfer resistance of HFC-365mfc in a district heating pipe is found in the PUR foam.

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Zhao, Linping, Nathaniel M. Beuse, and G. E. O. Widera. "External Pressure Testing of 4-in-Dia High-Density Polyethylene Pipe1." Journal of Pressure Vessel Technology 123, no. 3 (February 28, 2001): 398–403. http://dx.doi.org/10.1115/1.1376718.

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Many of the investigations dealing with the determination of the time-to-failure of high-density polyethylene (HDPE) pipes involve internal pressure tests. HDPE pipe, however, can also be subjected to external pressure such as from underwater laying, vacuum, or burial. For the particular case of uniform external pressure, only a small amount of data detailing the time-to-failure of such pipes is available, and no definitive testing procedure exists. Here, an experimental apparatus and corresponding testing procedure are developed to explore remedies for this situation. On the basis of the data thus obtained, a three-coefficient equation relating time, temperature, and pressure is generated. The failure predictions from this design basis equation are in good agreement with the available data existing in the literature.

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Lee, Jae-Hwan, and Chi-Ho Yoon. "Analysis of Structural Characteristics of HDPE Pipe for Manganese Lifting Test." Journal of Ocean Engineering and Technology 25, no. 6 (December 31, 2011): 86–90. http://dx.doi.org/10.5574/ksoe.2011.25.6.086.

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Zitouni, T. A., and Z. Labed. "Numerical Study on Dimensions and Orientation Effect of Semi-Elliptical Cracks in PE100 Pipelines." International Journal of Applied Mechanics and Engineering 26, no. 3 (August 26, 2021): 198–207. http://dx.doi.org/10.2478/ijame-2021-0045.

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Abstract The through-thickness crack or surface crack in PE100 pipes subjected to internal pressure represents a serious risk to the structural integrity of HDPE pipes, which has attracted wide attention in modern industry. Although experimental research offers reliable predictions of surface crack influence on pipes, the relatively high cost hinders its application. The numerical simulation, as a cost-effective alternative, has been widely applied to assess stress displacement and strain to the entire pipe structure. This is the initial approach adopted in recent decades. This article provides simulations tests of an uncracked pipe and cracked PE100 pipe under different internal pressure values, with varying each time the dimensions of the crack with 1 mm rate for minor and major radius and 0.5mm rates for the largest contour radius, using ANSYS MECHANICAL STRUCTURAL STATIC for simulation.

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Duvall, Donald E., and Dale B. Edwards. "Field Failure Mechanisms in HDPE Potable-Water Pipe." Plastics Engineering 68, no. 3 (March 2012): 12–19. http://dx.doi.org/10.1002/j.1941-9635.2012.tb00808.x.

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Nezbedova, E., A. Zahradnickova, and Z. Salajka. "BRITTLE FAILURE VERSUS STRUCTURE OF HDPE PIPE RESINS." Journal of Macromolecular Science, Part B 40, no. 3-4 (May 31, 2001): 507–15. http://dx.doi.org/10.1081/mb-100106173.

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35

Zhou, M., F. Wang, Y. J. Du, and M. D. Liu. "Performance of buried HDPE pipes – part II: total deflection of the pipe." Geosynthetics International 24, no. 4 (August 2017): 396–407. http://dx.doi.org/10.1680/jgein.17.00010.

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Imiełowski, Szymon, Apoloniusz Kodura, Aniela Glinicka, and Cezary Ajdukiewicz. "Experimental Study on Mechanical Properties of Polyethylene HDPE in Conditions of Hydraulic Impact Simulation." Solid State Phenomena 240 (August 2015): 149–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.240.149.

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Experimental research on mechanical properties of hardened polyethylene HDPE, is developed in the paper. The conditions of hydraulic impact simulation, caused by sudden opening or closing of the valve or by working pomp were adopted in the model. The created in such conditions shock wave moves at a high speed causing additional dangerous dynamic loadings, which lead to faster pipe wear process. The aim of this study is to determine Young's modulus of the pipe material in the cyclic load conditions. The assumed amplitude and frequency of the applied load relates to variation of the impact wave pressure also the speed of the disturbances propagation are taken from experimental measurement of the real water hammer. The measured Young's modulus is higher than that obtained from a static tensile test. The presented study arises from the need to verify the actual value of pipe material mechanical properties, i.e. longitudinal stiffness, for designing of hydraulic pipes under conditions of water hammer.

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Sargand, Shad M., and Teruhisa Masada. "Performance of large-diameter honeycomb-design HDPE pipe under a highway embankment." Canadian Geotechnical Journal 37, no. 5 (October 1, 2000): 1099–108. http://dx.doi.org/10.1139/t00-034.

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This paper presents field performance data on a 1.07 m (42 in.) diameter, honeycomb (HC) design HDPE pipe which is buried under 15.85 m (52 ft) of fill at a highway construction site in Ohio. The pipe was instrumented with six biaxial strain gages to monitor strains during initial backfilling and earth-pressure cells for measuring load for about 1 year. A portable linear variable displacement transducer device was used to detect changes in vertical and horizontal diameters at mid-length sections. The pipe performance has been monitored for 386 days. The vertical and horizontal deflections of the test pipe stabilized at 10% and +3%, respectively. The pipe exhibited localized short-wave deformations and inner wall tearing at springline due to combined actions from bending and ring compression. Elastic solutions of Burns and Richard and a finite element computer code CANDE-89 were applied with long-term moduli specified for the pipe material to evaluate their analytical results in relation to the measured field pipe performance.Key words: field performance, plastic pipe, highway embankment, deep burial, finite element.

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Li, Min, Rui Zhao, Sude Ma, and Tianxue Yang. "Scale Deposition Inhibiting Composites by HDPE/Silicified Acrylate Polymer/Nano-Silica for Landfill Leachate Piping." Materials 13, no. 16 (August 7, 2020): 3497. http://dx.doi.org/10.3390/ma13163497.

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Scaling commonly occurs at pipe wall during landfill leachate collection and transportation, which may give rise to pipe rupture, thus posing harm to public health and environment. To prevent scaling, this study prepared a low surface energy nanocomposite by incorporating silicone-acrylate polymer and hydrophobically modified nano-SiO2 into the high-density polyethylene (HDPE) substrate. Through the characterization of contact angle, scanning electron microscopy and thermogravimetry, the results showed that the prepared composite has low wettability and surface free energy, excellent thermal stability and acid-base resistance. In addition, the prepared composite was compared with the commercial HDPE pipe material regarding their performance on anti-scaling by using an immersion test that places their samples into a simulated landfill leachate. It was apparent that the prepared composite shows better scaling resistance. The study further expects to provide insight into pipe materials design and manufacture, thus to improve landfill leachate collection and transportation.

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MP, Jenarthanan, Ramesh Kumar S., and Akhilendra Kumar Singh. "Fly ash-based green composite as pipe, gear and blade." World Journal of Engineering 15, no. 1 (February 12, 2018): 40–47. http://dx.doi.org/10.1108/wje-12-2016-0163.

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Purpose This paper aims to perform an experimental investigation on the impact strength, compressive strength, tensile strength and flexural strength of fly ash-based green composites and to compare with these polyvinyl chloride (PVC), high density polyethylene (HDPE) and low density polyethylene (LDPE). Design/methodology/approach Fly ash-based polymer matrix composites (FA-PMCs) were fabricated using hand layup method. Composites containing 100 g by weight fly ash particles, 100 g by weight brick dust particles and 50 g by weight chopped glass fiber particles were processed. Impact strength, compressive strength, tensile strength and flexural strength of composites have been measured and compared with PVC, HDPE and LDPE. Impact strength of the FA-PMC is higher than that of PVC, HDPE and LDPE. Structural analysis of pipes, gears and axial flow blade was verified using ANSYS. Barlou’s condition for pipes, Lewis–Buckingham approach for gears and case-based analysis for axial flow blades were carried out and verified. Findings Pipes, gears and axial flow blades made form fly ash-based composites were found to exhibit improved thermal resistance (i.e. better temperature independence for mechanical operations), higher impact strength and longer life compared to those made from PVC, HDPE and LDPE. Moreover, the eco-friendly nature of the raw materials used for fabricating the composite brings into its quiver a new dimension of appeal. Originality/value Experimental investigation on the impact strength, compressive strength, tensile strength and flexural strength of fly ash-based green composites has not been attempted yet.

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40

Fang, Hongyuan, Peiling Tan, Bin Li, Kangjian Yang, and Yunhui Zhang. "Influence of Backfill Compaction on Mechanical Characteristics of High-Density Polyethylene Double-Wall Corrugated Pipelines." Mathematical Problems in Engineering 2019 (October 31, 2019): 1–24. http://dx.doi.org/10.1155/2019/3960864.

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For flexible pipelines, the influence of backfill compaction on the deformation of the pipe has always been the focus of researchers. Through the finite element software, a three-dimensional soil model matching the exterior wall corrugation of the high-density polyethylene pipe was skillfully established, and the “real” finite element model of pipe-soil interaction verified the accuracy through field test. Based on the model, the strain distribution at any position of the buried HDPE pipe can be obtained. Changing the location and extent of the loose backfill, the strain and radial displacement distributions of the interior and exterior walls of the HDPE pipe under different backfill conditions when external load applied to the foundation were analyzed, and the dangerous parts of the pipe where local buckling and fracture may occur were identified. It is pointed out that when the backfill is loose, near the interface between the backfill loose region and the well-compacted region, the maximum circumferential strain occurs frequently, the exterior wall strain is more likely to increase greatly on the region near crown or invert, the interior wall strains increase in amplitude at springline, and the location of the loose region has a greater influence on the strain of the pipe than the size of the loose area.

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41

Phares, B. M., T. J. Wipf, F. W. Klaiber, and R. A. Lohnes. "Behavior of High-Density Polyethylene Pipe with Shallow Cover." Transportation Research Record: Journal of the Transportation Research Board 1624, no. 1 (January 1998): 214–24. http://dx.doi.org/10.3141/1624-25.

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In this investigation, a testing program was initiated to gain some understanding of the nature of high-density polyethylene (HDPE) as a structural material and as a buried structure. The testing program consisted of a series of parallel plate tests, a sequence of flexural tests, and field tests of buried pipes under varying backfill conditions. Parallel plate tests were conducted in accordance with ASTM D2412. The flexural testing consisted of applying two point loads to simply supported beam specimens. The field tests completed in this investigation were developed to study the response of large-diameter HDPE to concentrated loads under shallow cover. From the testing, it seems that in cases where high longitudinal stresses may be present (concentrated loads with shallow cover, uneven bedding, uplift, etc.) the pipeline designer should consider the longitudinal strength of HDPE pipes in addition to the circumferential and backfill properties. In addition, the designer must realize that when stresses exist in both directions, the Poisson’s ratio effect must be considered. This finding is supported by the longitudinal failure strains measured during the flexural tests and the field tests. In both types of tests, the pipes failed at approximately the same longitudinal strain level, approximately 1,300 microstrain. On the other hand, in the field tests, the pipes never reached the magnitude of strain associated with failure in the laboratory parallel plate tests.

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42

Li, Zheng, Hong Wu Zhu, Pin Xian Qiu, and Abdennour Seibi. "Analytical Method for Temperature Distribution in Buried HDPE Pipe." Advanced Materials Research 452-453 (January 2012): 1205–9. http://dx.doi.org/10.4028/scientific5/amr.452-453.1205.

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43

Pluimer, Michael, T. Walsh, and S. W. Dean. "A Service Life Assessment of Corrugated HDPE Drainage Pipe." Journal of ASTM International 8, no. 6 (2011): 102838. http://dx.doi.org/10.1520/jai102838.

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44

Novico, Franto, Indra Kurniawan, Andi Egon, and Davide Merli. "Application of Offshore HDPE Pipes Route Design in North Maluku Indonesia." ILMU KELAUTAN: Indonesian Journal of Marine Sciences 26, no. 1 (March 13, 2021): 45–56. http://dx.doi.org/10.14710/ik.ijms.26.1.45-56.

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The lack of fresh water for the inhabitants of Maitara island is a very urgent problem to be solved. Two main factors at least must be taken into account to deliberate the right of way of subsea High-density polyethylene (HDPE) pipes, namely the hydrodynamic conditions and of a block analysis. This paper presents the study to justify the best route of subsea HDPE pipes based on hydrodynamic model analysis and concrete block strategy. The method used to analyze the best route includes 2 aspects. Firstly, the investigation method consisting of a bathymetric survey conducted by a single beam echosounder, 15 days tidal observations and seabed sediment sampling. Secondly, the hydrodynamic modelling analysis using Mike 21 FMHD and concrete block analysis, all these studies have been completed in August 2018. In the morphological behaviour analysis, three alternative routes are considered for the subsea HDPE pipes from Tidore Island to Maitara Island. The outcome of the analysis shows that the second track line option has the smallest impact by the hydrodynamic conditions, with a current speed of less than 0,5m/sec and a significant wave height of fewer than 1.2 meters. Furthermore, the uniformity of the lithology along the route is the other reason to select the second route. Finally, the concrete block analysis generated a minimum dimension of 75cm x 60cm x 30cm, and a free span of 3 meters is safe to absorb the uplift and drag forces acting on the pipe.

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45

Zuo, Zheng, Yu Hu, Qingbin Li, and Liyuan Zhang. "Data Mining of the Thermal Performance of Cool-Pipes in Massive Concrete via In Situ Monitoring." Mathematical Problems in Engineering 2014 (2014): 1–15. http://dx.doi.org/10.1155/2014/985659.

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Embedded cool-pipes are very important for massive concrete because their cooling effect can effectively avoid thermal cracks. In this study, a data mining approach to analyzing the thermal performance of cool-pipes via in situ monitoring is proposed. Delicate monitoring program is applied in a high arch dam project that provides a good and mass data source. The factors and relations related to the thermal performance of cool-pipes are obtained in a built theory thermal model. The supporting vector machine (SVM) technology is applied to mine the data. The thermal performances of iron pipes and high-density polyethylene (HDPE) pipes are compared. The data mining result shows that iron pipe has a better heat removal performance when flow rate is lower than 50 L/min. It has revealed that a turning flow rate exists for iron pipe which is 80 L/min. The prediction and classification results obtained from the data mining model agree well with the monitored data, which illustrates the validness of the approach.

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Guo, Zhouchao, Xia Lan, and Ping Xue. "High-Precision Monitoring of Average Molecular Weight of Polyethylene Wax from Waste High-Density Polyethylene." Polymers 12, no. 1 (January 10, 2020): 188. http://dx.doi.org/10.3390/polym12010188.

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High-density polyethylene (HDPE) is a major component of polyethylene waste, yet only under 29.9% of waste HDPE is recycled. As an important additive, polyethylene wax (PEW) is increasingly used in many industries such as plastics, dyes, and paints. The preparation of PEW has received considerable interest because recycling and precisely controllable production can bring huge economic benefits. In this study, to recycle waste HDPE, a single screw extruder was innovatively combined with a connecting pipe to prepare PEW from the pyrolysis of waste HDPE. Using a test platform, PEWs were prepared under different pyrolysis temperatures and screw speeds, and corresponding number-average molecular weights (NAMWs) of PEWs were measured. To precisely monitor NAMW of PEW, a program was developed in MATLAB. First, the relationship between NAMW and pyrolysis ratio was obtained, and a measure-point-independence verification was conducted. Then, modified Arrhenius equations and time-dependent pyrolysis temperature were for the first time introduced into the HDPE pyrolysis model. Furthermore, the screw-speed-dependent inverse method was proposed and validated for high-precision monitoring of NAMW of PEW from the pyrolysis of waste HDPE by extrusion. PEW of desired molecular weight was able to be precisely obtained from waste HDPE.

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Xie, Xiaojian, Michael D. Symans, Michael J. O'Rourke, Tarek H. Abdoun, Thomas D. O'Rourke, Michael C. Palmer, and Harry E. Stewart. "Numerical Modeling of Buried HDPE Pipelines Subjected to Normal Faulting: A Case Study." Earthquake Spectra 29, no. 2 (May 2013): 609–32. http://dx.doi.org/10.1193/1.4000137.

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A systematic study is presented herein on the seismic response of buried pipelines subjected to ground fault rupture in the form of normal faulting. In this study, advanced computational simulations are conducted in parallel with physical testing using a geotechnical centrifuge. For the numerical simulations, the pipeline was modeled using isotropic 3-D shell elements and the soil was modeled using either 1-D spring elements or 3-D solid (continuum) elements. The results from continuum finite-element analyses are compared with those from a Winkler-type model (in which the pipe is supported by a series of discrete springs) and with results from centrifuge tests. In addition, via appropriate modeling of the soil-pipe interaction, the q-z relation of the soil medium is elucidated for normal faulting events. The numerical analysis results demonstrate the potential for continuum modeling of events that induce pipe-soil interaction and results in improved understanding of pipe-soil interaction under normal faulting.

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Alimi, L., K. Chaoui, W. Ghabeche, and W. Chaoui. "Short-term HDPE pipe degradation upon exposure to aggressive environments." Matériaux & Techniques 101, no. 7 (2013): 701. http://dx.doi.org/10.1051/mattech/2013083.

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Moore, Ian D., and Chuntao Zhang. "Nonlinear Predictions for HDPE Pipe Response under Parallel Plate Loading." Journal of Transportation Engineering 124, no. 3 (May 1998): 286–92. http://dx.doi.org/10.1061/(asce)0733-947x(1998)124:3(286).

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Song, Hyun-Bae, Do-Kyun Kim, Han-Suk Choi, and Kyu-Sik Park. "A Study of Structural Stability of HDPE Pipe during Installation." Journal of the Korean Society for Advanced Composite Structures 6, no. 1 (March 26, 2015): 59–66. http://dx.doi.org/10.11004/kosacs.2015.6.1.059.

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Journal articles on the topic 'HDPE Pipe'

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