Research On The Corrosive Effect Of Chlorine Disinfectant On Leaked Water Supply Pipeline With Longiyudinal Crack

The accelerating process of integration of urban and rural development has put forward higher requirements for the utilization rate of water resources and the guarantee rate of water supply.Leakage rate is an important indicator to measure the operation of the urban water supply network,and high leakage rate has always been a key and difficult problem.This paper starts from the cause of leakage in the water supply network and analyzes the main body of the water supply network system: drinking water and pipeline system,studying the effects of three factors,namely method of chlorine disinfection,pipe leak size and material properties,and making these factors concrete.Then an improved FAVAD(Fixed Area and Variable Area Discharge)leakage flow analysis model is established based the influencing factors,to predict the leakage flow of the pipeline network and provide theoretical basis for the control of leakage of pipe network leakage.The paper selected galvanized steel pipe,ductile iron pipe,UPVC pipe and PE pipe four commonly used water supply pipe,the longitudinal crack of the pipe was as the study object,through the test analysis and established model to study the corrosive effect of chlorine disinfectant on the leaked pipe.In the study of the corrosion effect of the chlorine disinfectant,the four kinds of pipes were analyzed for the surface of pipe cracks and the properties of the pipe materials.Using SEM-EDS to analyze the surface corrosion of the pipe cracks,it concluded that chloride ion was involved in the corrosion process,the chlorine disinfectant concentration and the time of corrosion were the important factors causing the corrosion of the four pipes.And The surface corrosion degree of the four pipes was: ductile iron>galvanized steel,UPVC>PE.It can been seen by analyzing the changes in the properties of pipe material after corrosion,d uring the process of corrosive damage by chlorine disinfectant,the elastic modulus basically increased firstly and then decreased,and the yield strength showed a decreasing trend,indicating that the corrosion effect of the chlorine disinfectant ha d a destructive effect on the stiffness and strength of the pipe.The corrosion effect of chlorine disinfectant on leaking pipe was simulated by dynamic corrosion device.The change of leakage flow rate further validated that the corrosive effects of chlorine disinfectants was an important factor to cause the change of longitudinal crack's area.For four kinds of pipe longitudinal crack's area,the degree of corrosion of chlorine disinfectant influenced was: ductile iron>UPVC>galvanized steel>PE.Moreover,the length of the longitudinal crack also had an effect on the change of the leakage flow,the length increased,and the leakage flow changed significantly.Based on test analysis,the FAVAD model was used to establish the specific relationship between the leakage flow and pressure head,and the slope m value of the linear relationship between pressure and leakage area was obtained.The leakage pipe model with longitudinal crack was established using ANSYS finite element software to simulate the variation of longitudinal crack area under different pressures,and the linear relationship between pressure and leakage area was obtained.After the analysis of the individual impact of chlorine disinfectant,pipe material performance and longitudinal crack size on the m value,it can conclude the power function relationship with the value of m.1st Opt software was used to analyze the comprehensive effect of each factor on the m value,it can been seen that the degree of influence of each factors on leakage flow of longitudinal crack in pipelines was in order: yield strength>elastic modulus>chlorine disinfectant concentration>longitudinal crack length.And the FAVAD model was obtain,including the comprehensive effect of chlorine disinfectant,pipe material performance and longitudinal crack size.It had practical significance in guiding the dosage of chlorine disinfectant and the selection and replacement of water supply pipes with good corrosion resistance.