Dissertations / Theses on the topic 'HDPE Pipe'

Butt fusion welding process is an extensively used method of joining for high density polyethylene (HDPE) pipe. With the increasing number of HDPE resin and pipe manufacturers and the diversity of industries utilising HDPE pipes, a wide range of different standards have evolved to specify the butt fusion welding parameters with inspection and testing methods, to maintain quality and structural integrity of welds. There is a lack of understanding and cohesion in these standards for the selection of welding parameters; effectiveness, accuracy, and selection of the test methods and; correlation of the mechanical properties to the micro and macro joint structure. The common standards (WIS 4-32-08, DVS 2207-1, ASTM F2620, and ISO 21307) for butt fusion welding were used to derive the six welding procedures. A total of 48 welds were produced using 180 mm outer diameter SDR 11 HDPE pipe manufactured from BorSafe™ HE3490-LS black bimodal PE100 resin. Three short term coupon mechanical tests were conducted. The waisted tensile test was able to differentiate the quality of welds using the energy to break parameter. The tensile impact test due to specimen geometry caused the failure to occur in the parent material. The guided side bend specimen geometry proved to be too ductile to be able to cause failures. A statistical t-test was used to analyse the results of the short term mechanical tests. The circumferential positon of the test specimen had no impact on their performance. Finite element analysis (FEA) study was conducted for the long term whole pipe tensile creep rupture (WPTCR) test to find the minimum length of pipe required for testing based on pipe geometry parameters of outer diameter and SDR. Macrographs of the weld beads supplemented with heat treatment were used to derive several weld bead parameters. The FEA modelling of the weld bead parameters identified the length to be a key parameter and provided insight into the relationship between the geometry of the weld beads and the stresses in the weld region. The realistic bead geometry digitised using the macrographs contributed a 30% increase in pipe wall stress due to the stress concentration effect of the notches formed between the weld beads and the pipe wall. The circumferential position of the weld bead had no impact on the pipe wall stresses in a similar manner to the results of the different mechanical tests. IV Nanoindentation (NI) and differential scanning calorimetry (DSC) techniques were used to study the weld microstructure and variation of mechanical properties across the weld at the resolutions of 100 and 50 microns, respectively. NI revealed signature 'twin-peaks and a valley' distribution of hardness and elastic modulus across the weld. The degrees of crystallinity obtained from DSC followed the NI pattern as crystallinity positively correlates with the material properties. Both techniques confirm annealing of the heat affected zone (HAZ) material towards the MZ from the parent material. The transmission light microscopy (TLM) was used to provide dimensions of the melt zone (MZ) which displays an hour glass figure widening to the size of the weld bead root length towards the pipe surfaces. Thermal FEA modelling was validated using both NI and TLM data to predict the HAZ size. The HAZ-parent boundary temperature was calculated to be 105 ⁰C. The 1st contribution of the study is to prove the existence of a positive correlation between the heat input calculated from FEA and the energy to break values obtained from the waisted tensile test. The 2nd contribution providing the minimum length of pipe for WPTCR based on the pipe dimensions. The 3rd contribution is the recommendation for the waisted tensile test with the test using the geometry designed to minimise deformation of the loading pin holes. The 4th contribution related the weld bead parameters to pipe wall stresses and the effect of notches as stress concentrators. The 5th contribution is a new method of visualising a welding procedure that can be used to not only compare the welding procedures but also predict the size of the MZ and the HAZ. The 6th contribution of the study is the proposal of new weld bead geometry that consist of the MZ bounded by the HAZ, for butt fusion welded joints of HDPE pipes.

A possible way to continuously monitor the whole water distribution system is to equip pipes with many microsensors. If these sensors are to be integrated within the pipe walls, it is important to assess their impact on the structural integrity of the pipes. In order to test a large number of samples, small polyethylene samples were produced using compression moulding and tested in different stress modes such as tension, bending, Charpy impact and flexural creep, with respect to different chip sizes (4 and 16mm\(^²\)), shapes (circle and square), numbers (one and two), orientations and position as well as sample dimensions and chip-polyethylene interface. It was discovered that the square chip contributes to the highest increase in the polymer stiffness, but significantly reduces its ductility. The 4mm\(^²\) circle causes the smallest disruption in the polymer integrity, especially when including multiple chips and when there is no adhesion. It significantly improves the impact resistance, while its effect in the short and long term bending stress modes is insignificant. The 16mm\(^²\) circle perpendicular to the load direction failed in bending at large strains. The optimal chip orientation for improving the impact strength and reducing the embrittlement effect in tension is parallel to the applied load.

Bimodal polyethylene resins are frequently used for pipe applications. In this work, blending was used to produce polyethylenes with comparable properties, particularly with respect to processing, stress crack resistance and tensile properties. Suitable blend components were identified, and their performance screened used ECHIP experimental design software. Blends were characterized using gel permeation chromatography (GPC), differential scanning calorimetry (DSC), tensile testing, stress crack resistance measurements, impact toughness testing, capillary rheometry and melt index measurements. GPC, DSC and melt index results reveal that the method of meltcompounding produced morphologically uniform blends, with different degrees of compatibility depending on the type and level of branching of blend components. Most of the blends produced showed higher crystallinity values compared to a reference bimodal resin. Binary high density polyethylene (HDPE) blends showed better stiffness and strength properties, whereas metallocene catalyzed linear low density polyethylene (mLLDPE) containing blends illustrated superior elongation and toughness properties compared to the reference polymer and other binary blends. The highest resistance to slow crack growth (SCG) was shown by low density polyethylene (LDPE) and mLLDPE containing blends due to their high branching content. The overall blend resistance to SCG or toughness can be enhanced with levels less than 20% by weight of LDPE or mLLDPE in the blend although the tensile properties are relatively unaffected at these low concentrations. The performance of blends was optimized by changing component polymers and their weight fractions, and a model to predict optimum blends was developed using the Maple code. Optimized blends showed higher branching content, comparable molecular weight, molecular weight distribution, tensile properties, viscosity and processing behaviour to the reference polymer. Optimized blend 3, in particular, encountered the same degree of shear thinning as the reference material. Better toughness and resistance to SCG were shown by the optimized blends when compared to the reference polymer.

CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
As tubulações de aço carbono são amplamente usadas em muitas redes de distribuição de transporte de derivados de petróleo. Estas apresentam dois inconvenientes (corrosão e perda da pressão devido à rugosidade interna elevada). Porem, diversas distribuidoras tentaram substituir as tubulações metálicas pelos tubos poliméricos. Entre o material não metálico, o polietileno de alta densidade (PEAD) parece ser uma alternativa mais viavél e econômico. Não obstante, sua aplicação industrial tem mostrado já alguns problemas, tais como inchamento e microfisuras, especialmente nas linhas de distribuição do álcool, óleo e combustível. Assim, nossa pesquisa foi dedicada ao estudo físico químico do envelhecimento do PEAD em contato com derivados do petróleo. Dois líquidos modelos (Diesel e Marcol) foram usados para analisar a influência da espécie aromática e parafínica no envelhecimento do polímero durante 150 dias a T=20°C e 50°C. Primeiramente, fizemos a caracterização do PEAD e dos líquidos modelos antes do envelhecimento, para entender as interações do polímero-líquido. No estudo de envelhecimento, as medidas gravimétricas com experiências TGA fazem possível avaliar a difusão do fluido dentro do PEAD. Os resultados mostraram que apesar da composição aromatica, o diesel, solubilizou as cadeias de baixo peso molecular do polímero. Foram realizados também testes de fluência para investigar os efeitos macroscópicos durante o envelhecimento do PEAD. Para períodos muito curtos de envelhecimento, a flexibilidade do PEAD foi devida à sorção do fluido, para tempos maiores de exposição no gasoil, a plastificação do PEAD é reduzida significativamente devido à extração de unidades poliméricas pequenas, mesmo na temperatura ambiente.
Carbon steel pipes are widely used for the transportation of petroleum derivates in many distribution networks. However, these pipes present two important drawbacks (corrosion, pressure loss due to high internal roughness...) For these reasons, several petroleum furnishers have examined the opportunity to substitute metallic pipes by polymeric tubes. Among the non-metallic material, high density polyethylene (HDPE) represent a good alternative from a technical and economic point of view. Nevertheless, its application at the industrial scale has already shown some problems such as sweeling and microcracks especially in lines assigned to the distribution of alcohol, oil and fuel. Our research work was devoted to the physicochemical study of the ageing of HDPE samples in contact with petroleum derivatives. Two model fluids (gasoil and Marcol) were used to analyse the influence of aromatic and paraffinic species on the polymer ageing during 150 days at different temperatures (T=20°C and 50° C). First, we made the characterization of the polymer and of the model fluids before ageing for understand the polymer-liquid interactions. In the ageing study, the gravimetric measurements with TGA experiments made it possible to evaluate the fluid diffusion inside the polymeric matrix. Important discrepancies were shown between gasoil and Marcol actions. In spite of its aromatic composition, the former was more powerful to solubilize low weight polymer chains. Creep tests were performed to investigate the macroscopic effects on the ageing on the HDPE. For very short periods of ageing time, the HDPE flexibilization was due to the fluid sorption. For higher exposure times in gasoil, the HDPE plasticization is significantly reduced because of the occurrence of the extraction of small polymeric units even at room temperature.

O polietileno surgiu em 1898 e logo já começou a ser utilizado como conduíte e isolante. Desde então este material vem ganhando muito espaço no mercado de tubulações, seja no saneamento, mineração, indústrias ou no segmento de petróleo e gás. Seu tipo mais usado é o Polietileno de Alta Densidade (PEAD), que apesar de já ser comumente encontrado em adutoras, emissários e ramais prediais, somente nos últimos anos passou a ser utilizado de maneira mais abrangente nas redes de distribuição de água, se tornando um aliado importante no combate aos altos índices de perdas reais. No Brasil, somente nos últimos anos que a presença de tubulações de PEAD em redes de distribuição de água potável se tornou mais comum. Contudo, é possível identificar cenários de aplicação do PEAD em sistemas de abastecimento de água já relativamente consolidados, como é o caso do Departamento Municipal de Água e Esgotos (DMAE) de Porto Alegre, que utiliza o material há 25 anos, a Companhia de Saneamento Básico do Estado de São Paulo (Sabesp), onde desde 2009 a Diretoria Metropolitana vem utilizando o PEAD em novas aplicações em redes e a Odebrecht Ambiental da cidade de Limeira, que utiliza tubos deste material desde 2007. Através de análises de custos de implantação, operação e manutenção, de amostragens da condição de tubulações em operação, da evolução de índice de perdas e de entrevistas com as equipes de operação e planejamento, é possível verificar que realmente as tubulações de PEAD auxiliam no combate às perdas reais e na otimização da operação e eficiência das prestadoras de serviços de distribuição de água potável, no sentido de diminuir o tempo de intervenção de redes, os custos de manutenção e a frequência de arrebentamento e vazamentos nas redes de abastecimento.
Polyethylene appeared in 1898 and soon started been used as conduit and insulating material. Since then, the material has been gaining a lot of space in the pipes market in sanitation, mining, industries and oil & gas production. The most used type is High Density Polyethylene (HDPE), which despite being commonly found in water mains, emissaries and communication pipes, only in recent years began to be used more widely in water distribution networks, becoming an important ally in the fight against high rates of real water losses. In Brazil, only in recent years the use of HDPE pipes has become more common in public water distribution networks. However, it is possible to identify HDPE application cases in relatively consolidated water supply distribution networks, such as the Departamento Municipal de Água e Esgotos (DMAE) of Porto Alegre, which have used the material for 25 years; the Companhia de Saneamento Básico do Estado de São Paulo (Sabesp), where since 2009 the Metropolitan Unit has been using HDPE in new applications in network pipes and Odebrecht Ambiental, in Limeira city, which uses this material in water pipelines since 2007. Through research of implementation, operation and maintenance costs, sampling the condition of pipes in operation, analysis the real losses indicators and interviews with the operations and planning teams, it is possible to conclude HDPE pipes contribute to reduction of real losses and optimization of the operation and efficiency of the providers of drinking water distribution services, decreasing maintenance time and costs.

Tubos flexíveis são estruturas complexas compostas de várias camadas metálicas e poliméricas empregados pela indústria offshore na exploração de hidrocarbonetos. O estudo do comportamento estrutural e das falhas que podem advir do lançamento e uso desses sistemas em campo é uma área vasta e fecunda da mecânica estrutural. Apesar dos progressos alcançados na análise e nos vários estudos conduzidos ao longo dos anos, no sentido de explicar o surgimento do fenômeno conhecido por birdcaging pesquisando o comportamento das camadas conhecidas como armadura de tração, pouca atenção foi direcionada ao comportamento estrutural da capa plástica externa. A presente tese contribui com os estudos do mecanismo deflagrador do birdcaging à luz do comportamento estrutural da capa plástica e apresenta um critério limite para a previsão do fenômeno. Estudos analíticos, numéricos e principalmente experimentais foram realizados em tubos de PEAD simulando a capa plástica com a finalidade de investigar a instabilidade axissimétrica desta quando sujeita a compressão axial e pressurização interna. Utilizando o modelo analítico adaptado, foi criado um diagrama de limite de instabilidade com o uso de força e pressão interna adimensionalizadas. Este diagrama, testado com simulações realizadas em elementos finitos, ensaios experimentais em tubos de PEAD, e com valores de ensaios experimentais em tubos flexíveis, oferece um critério de engenharia para a predição do fenômeno em questão.
Flexible pipes are complex structures composed of several metallic and polymeric layers employed by the offshore industry in oil and gas exploration. The study of the structural behavior and failures that may arise from the laying down operations and use of these systems in the field is a vast and fruitful field of structural mechanics. Despite the progress in the analysis and several studies conducted over the years in order to explain the appearing of the birdcaging phenomenon through the research of the behavior of layers known as tensile armors, not too much attention was directed to the structural behavior of outer plastic layer. This thesis contributes with the studies of the birdcaging mechanism regarding the structural behavior of the plastic cover and presents a simple criterion to triggering the phenomenon. Analytical, numerical and mainly experimental studies were conducted with HDPE pipes simulating the outer plastic cover in order to investigate the axisymmetric instability under compressive loading and internal pressure. Using an adapted analytical model, a limit instability chart was constructed using dimensionless axial compressive load and internal pressure. This chart, tested with finite element simulations, experimental tests on HDPE pipe, and with values of experimental tests on flexible pipes, may offer an engineering criterion to predict the phenomenon in question.

The performance of joints in buried gravity flow pipelines are important since failure of these elements can affect the structural capacity of soil-pipe systems and reduce their longevity. Currently, there are no clear guidelines to design joints for gravity flow pipelines and therefore their design is based on semi-empirical methods. It is necessary to identify and quantify the demands that act across joints when subjected to service loading conditions to establish adequate design guidelines. Such demands will vary depending on the type of joint, type of pipe, burial and loading conditions. Therefore work is needed to investigate the influence of these conditions on the performance of joints. Full-scale laboratory tests have been performed on rigid (reinforced concrete) and flexible (corrugated steel and thermoplastic) pipelines to investigate the response of their joints when buried and subjected to surface loading. The joints investigated are either ‘moment-release’ joints (those that accommodate rotation and reduce the longitudinal bending moments close to zero), or ‘moment-transfer’ joints (those that limit rotation and transfer longitudinal bending moments from one pipe to the next). These experiments evaluate the influence of different cover depths, loading locations, and installation conditions on the response of the joints. Additionally, the performance of each joint when the pipeline was buried with shallow cover and subjected to surface loads up to and beyond fully factored loads were also investigated. Furthermore, three-dimensional finite element analyses of a gasketed bell and spigot joint in a buried reinforced concrete pipeline subjected to surface loading have been developed employing material properties and joint rotational characteristics experimentally obtained. The data obtained from the experimental and computational studies are used to evaluate joint performance and to identify key demands (shear force and rotation or moment) acting across them. In addition, the different patterns of vertical displacement along rigid and flexible pipes were established. It was found that the stiffness of the pipeline, the geometry of the joint, the loading and burial conditions influence the response (and therefore the demands) of the joints examined. Finally, recommendations are provided regarding development of structural design methods for these pipeline and joint systems.
Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-12-29 12:47:31.826

碩士
國立屏東科技大學
土木工程系碩士班
90
High density Polyethylene (HDPE) pipes are mainly used in industry and public works. Since HDPE pipes introduced into market place is later than the other plastic pipes, the market of these pipes is still limited. However, the chemical resistance and durability of HDPE are better than other pipe materials. It is expected that HDPE pipes have a good potential to increase its sales in the near future. The objective of this thesis study is to investigate the feasibility to use HDPE pipes in drinking water and sewer lines. The construction procedure, cost analysis, and materials specifications for HDPE, PVC, and ABS pipes are discussed. The advantages and disadvantages of these pipes are compared. Two case studies are used for cost comparison analysis. The results of the study indicated that HDPE pipe is lighter than other plastic pipes and has better chemical resistibility. However, the material and construction costs are more than other systems.

碩士
國立臺灣海洋大學
輪機工程系
101
The deep ocean cold HDPE pipes segments deployed on the sea bed periodically encountered the impact of fluid induced vibration. The effects of the static hydraulic forces, the pipe segment displacement are not negligible. The analysis package ANSYS will be used. Four supports(ballast weight) and three pipe line segments will analysied. The results will include the parameter condition, ocean velocity, segment length and the net space between pipe and sea bed. It will be compared with the allowable stress for the future reference. From the study results, The main factors which influence the deep ocean cold water pipe are the segment length between ballast weights the ocean current. The space between pipe and sea bed is negligible. In this analysis, the 180mm outside diameter and the16.5mm thickness of HDPE pipe are used. The longest 7m segment length is suggested to be used in the future deep ocean cold water pipes. The results of the analysis is for the future piping design.