Analyze and Comparison of Steady State and Transient Pressure for DCI and HDPE Pipelines Using the Finite Element Method and Bentley Water Hammer Software
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Date
2024-12
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Addis Ababa University
Abstract
Water hammer is a common issue in water pipelines; and cause significant damage and disruption. This study focuses on the Dire Dawa city water supply project, analyzing three transmission lines between booster pump station and service reservoirs. These lines are particularly vulnerable to water hammer, as their operation is influenced by the water levels in the two reservoirs at either end.
Most existing research focuses on either DCI or HDPE pipelines individually, lacking a comprehensive comparative analysis of their performance under steady-state and transient conditions. This gap limits the understanding of how these materials respond to different operational scenarios. The novelty of this study lies in the combined use of advanced simulation techniques (FEM and Bentley Water Hammer) to directly compare DCI and HDPE pipeline behaviours under both steady-state and transient pressure conditions, as well as hydrostatic pressure resistance, by considering detailed material properties. This integrated approach provides a more reliable understanding than previous isolated studies.
This study aims to analyze and compares the transient and steady-state pressure and structural responses of DCI and HDPE pipes. A quantitative research approach examines cause-and-effect interactions among variables. Bentley Water Hammer and FEM (Abaqus) software are used to simulate transient pressure and hydrostatic forces, respectively. Abaqus was chosen for its detailed stress analysis, crucial for safety; while Bentley Water Hammer was selected for its accuracy and user-friendly interface. Input data for the simulations are sourced from the Dire Dawa City Water and Sewerage Authority.
The study results indicate that transient pressure higher than steady-state pressure up to 127.63%. Both DCI and HDPE pipes showed the same steady-state pressure across all lines. However, HDPE pipes demonstrate advantages over DCI pipes by reducing the effects of transient pressure by up to 118.3%. Additionally, surge tanks reduce the transient pressure by 128.9% for DCI pipe and 11.7 % for HDPE pipe. When both pipes have the same nominal pressure and size, HDPE pipes experience stress levels that are 64.7% higher than those of DCI pipes.
The study finds that transient pressure exceeds steady-state pressure and is a key factor in pipe network design for setting nominal pressure. HDPE pipes demonstrate superior resistance to transient pressure compared to DCI pipes. Incorporating appropriate water hammer protection devices significantly enhances pipe performance. For the Dire Dawa city pipeline, HDPE can replace existing DCI pipes of the same nominal pressure. Further research, including laboratory models, is needed to fully understand steady-state and transient pressures in DCI and HDPE pipes.
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Keywords
Water Hammer, Steady State, Transient, HDPE, DCI, Bentley Water Hammer, FEM