In water distribution systems,water leakage from cracked water pipes is a major concern for water providers.Generally,the relationship between the leakage rate and the water pressure can be modeled by a power function...In water distribution systems,water leakage from cracked water pipes is a major concern for water providers.Generally,the relationship between the leakage rate and the water pressure can be modeled by a power function developed from the orifice equation.This paper presents an approximate solution for the computation of the steady-state leakage rate through a longitudinal line crack of a water distribution pipe considering the surrounding soil properties.The derived solution agrees well with results of numerical simulations.Compared with the traditional models,the new solution allows assessment of all the parameters that related with leakage including the pressure head inside the pipe,hydraulic conductivity,crack size and its position,and pipe size and its depth.展开更多
Minimizing water loss in water supply networks is one of the objectives for protecting water resources. Currently, the large amount of water loss is mainly due to leakage of the pipeline network. The leaking of pipe c...Minimizing water loss in water supply networks is one of the objectives for protecting water resources. Currently, the large amount of water loss is mainly due to leakage of the pipeline network. The leaking of pipe can be caused by incorrect construction, impacted by external forces, or corroded pipe material and aging. Therefore, to control and predict the cracking area on pipe, it is necessary to collect data about pipe conditions, approve the solution of technology improvement and define the ability of pipe capacity from setting up to the first preparing time. This paper will demonstrate how to evaluate corrosion pipe under the age of pipe and the impact level of internal pressure pipe at different times, and will put forward solution of effective leaking management on water supply network.展开更多
In high sour gas reservoir drilling process, it happens occasionally that high-strength drill pipe suffers brittle fracture failure due to stress corrosion cracking, and poses serious hazard to drilling safety. To sol...In high sour gas reservoir drilling process, it happens occasionally that high-strength drill pipe suffers brittle fracture failure due to stress corrosion cracking, and poses serious hazard to drilling safety. To solve this problem, this paper studied the stress corrosion cracking mechanism and infl uencing factors of highstrength drill pipe in sour environment with hydrogen permeation experiments and tensile tests. We simulated practical conditions in laboratory and evaluated the stress corrosion cracking performance of the high-strength drill pipe under conditions of high stress level. For the problems occurring in use of high-strength drill pipe on site, the paper proposed a technical measure for slower stress corrosion cracking.展开更多
For different strength matching, the reliability index and failure probability of welded pressure pipe with circumferential surface crack were calculated using three dimensional stochastic finite element method. This ...For different strength matching, the reliability index and failure probability of welded pressure pipe with circumferential surface crack were calculated using three dimensional stochastic finite element method. This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method. The effects of external moment and the depth of the circumferential surface crack (a) on the reliability of pressure pipe were also calculated and discussed. The calculation results indicate that the strength matching has certain effect on the reliability of the welded pressure pipe with circumferential surface crack. The failure probability of welded pressure pipe with high strength matching is lower than that with low strength matching at the same conditions. The effects of strength matching on the failure probability and reliability index increased by adding external moment (M) and the depth of the circumferential surface crack (a).展开更多
The reliability of welded pressure pipe with circumferential surface crack was calculated by using 3D stochastic finite element method.This method has overcome the shortcomings of conservative results in safety assess...The reliability of welded pressure pipe with circumferential surface crack was calculated by using 3D stochastic finite element method.This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method.The calculation of reliability was based on 3D elasticplastic stochastic finite element program which was developed by ourselves.The effects of variables such as fracture toughness,bending moment and depth of the circumferential surface crack on the structure reliability were also discussed.The calculation results indicate that the crack opening angle has certain effect on the reliability of the welded pipe.When the mean value of bending moment is 10kN·m,with the crack opening angle increasing from 30°to 180°,the failure probability of the welded pipe changes from 3.8379×10-8to 3.6943×10-6.When the mean value of bending moment is 15kN·m,with the crack opening angle increasing from 30°to 180°,the failure probability of the welded pipe changes from 3.986 5×10-6to 1.936 7×10-3.The bending moment has great effect on the reliability of the welded pipe.When the mean value of moment is changed from 10 to 15 kN·m,the failure probability of the welded pipe increases dramatically for the same circumferential crack opening angle.Regardless of changing of moment,the pipe has higher reliability if the crack opening angle is less than 60°.The method has put forward a new way for safety assessment of welded pipe with circumferential surface crack.展开更多
Three-way pipes, T and Y pipes, are very important connecting components in pipeline systems, their strength are related to the safety of pipelines. In the case that crack is not detected in the three-way pipe, ANSYS ...Three-way pipes, T and Y pipes, are very important connecting components in pipeline systems, their strength are related to the safety of pipelines. In the case that crack is not detected in the three-way pipe, ANSYS finite element program version 5.6 is applied to study the stress distribution of the three-way pipe and to obtain the optimum fillet radius in the crotch region of the two pipes. The reasonable intersection angle of the two pipes is also obtained. In the case that a surface crack is detected in the three-way pipe, the maximum stress intensity factor (SIF) near the front of the surface crack is studied.展开更多
A three-dimensional finite element program for thermal analysis of hydration heat in concrete structures with a plastic pipe cooling system is introduced in this paper. The program was applied to simulation of the tem...A three-dimensional finite element program for thermal analysis of hydration heat in concrete structures with a plastic pipe cooling system is introduced in this paper. The program was applied to simulation of the temperature and stress field of the Cao＇e Sluice during the construction period. From the calculated results, we can find that the temperaiure and stress of concrete cooled with plastic pipes are much lower than those of concrete without pipes. Moreover, plastic pipes could not be corroded by seawater. That is to say, a good effect of temperature control and cracking prevention can be achieved, which provides a useful reference for other similar nearshore concrete projects.展开更多
Low cycle fatigue tests and crack growth propagations tests on P91 pipe base metal and its weld joints were conducted at three different temperatures: room temperature, 550℃ and 575℃. The strain-life was analyzed, a...Low cycle fatigue tests and crack growth propagations tests on P91 pipe base metal and its weld joints were conducted at three different temperatures: room temperature, 550℃ and 575℃. The strain-life was analyzed, and the changes in fatigue life behavior and fatigue growth rates with increasing temperature were discussed. The different properties of the base metal and its weld joint have been analyzed.展开更多
The influence of temperature on the resistance to rapid crack propagation of a semi-crystalline bio-based polymer was studied. The experimental results described in this study allow to initiate a first discussion on t...The influence of temperature on the resistance to rapid crack propagation of a semi-crystalline bio-based polymer was studied. The experimental results described in this study allow to initiate a first discussion on the role of viscosity and its link with the fracture behaviour and a heterogeneous microstructure such as the semi-crysalline polymer. Dynamic fracture tests on pipes were carried out. It would appear that a temperature decrease of approximately 40℃ relative to ambient has no significant influence on the average crack propagation velocity (≈0.6<em>c<sub>R</sub></em><sub>)</sub>, fracture energy and surface roughness. On the contrary, crack propagation paths seem to vary with temperature. The difference in fracture behaviour between the amorphous and crystalline phase varies significantly as a function of temperature. The difference between the initiation resistance and the rapid propagation also varies. This difference seems to be significantly reduced by lowering the temperature. The mechanisms of cavitation damage and plastic flow are increasingly limited by the decrease in temperature (and therefore in macromolecular mobility). Crack propagation in the pipe is more extensive and therefore more critical. This is emphasised in particular by the probability of the material to be macro-branched as the temperature decreases.展开更多
Crack opening displacement(COD) was applied to characterize the fracture initiation of the tough high density polyethylene. Normal single side notched three point bend specimens and silica rubber replica techniques ...Crack opening displacement(COD) was applied to characterize the fracture initiation of the tough high density polyethylene. Normal single side notched three point bend specimens and silica rubber replica techniques were used to study the characteristic COD of high density polyethylene pipe and its butt fusion joints including the weld fusion zone and heat affected zone at different temperature from -78 ℃ to 20 ℃ . Testing results show that the characteristic COD appears to depend on the structural features that are determined by welding process and the testing temperature. As the temperature is lowered, the characteristic COD of all zones studied decreases. Because the welding process significantly changes some structural feature of the material, characteristic COD of the weld fusion zone is the smallest one among those of the three zones. The results can be used for the engineering design and failure analysis of HDPE pipe.展开更多
In order to study crack propagation-arresting characteristics of steel pipe construction, a new test installation was designed. The experiments of 20 steel pipes, pipes with longitudinally weld, pipes with circumferen...In order to study crack propagation-arresting characteristics of steel pipe construction, a new test installation was designed. The experiments of 20 steel pipes, pipes with longitudinally weld, pipes with circumferential weld and steel pipe with sleeve were conducted. The testing results indi- cated that circumferential weld in pipe with overrnatching weld had beneficial effect on crack prop- agation arrcsting propcrtics and the mechanical split sleeve can be used as crack arrester to prevent crack propagation.展开更多
Focused on the girth weld of a φ762 x 28.6 mm （X65） offshore UOE pipe, the fracture toughness properties at different weld joint positions were tested. Meanwhile,the largest size of different cracks under service c...Focused on the girth weld of a φ762 x 28.6 mm （X65） offshore UOE pipe, the fracture toughness properties at different weld joint positions were tested. Meanwhile,the largest size of different cracks under service condition was calculated by using CRACKWISE. The service life of the UOE pipe with postulated crack-like flaws was calculated by considering various fatigue factors, such as vibrations caused by ocean current and fluctuations of inner pressure. The assessment process and results can be used to direct the repair of weld flaws laid in pipes or to assess the reliability of in-serving pipes.展开更多
This paper presents the analysis of potential thermal cracking of light feedstocks in the SMR. Two different feedstocks, natural gas and light hydrocarbon (HC) feedstock at two different mixed feed inlet temperatures,...This paper presents the analysis of potential thermal cracking of light feedstocks in the SMR. Two different feedstocks, natural gas and light hydrocarbon (HC) feedstock at two different mixed feed inlet temperatures, are selected to study the HC thermal cracking. Effect of Crossover Piping Volume on feed thermal cracking is also discussed.展开更多
基金Project (No. 2012AA062608) supported by the National High-Tech R&D Program (863) of China
文摘In water distribution systems,water leakage from cracked water pipes is a major concern for water providers.Generally,the relationship between the leakage rate and the water pressure can be modeled by a power function developed from the orifice equation.This paper presents an approximate solution for the computation of the steady-state leakage rate through a longitudinal line crack of a water distribution pipe considering the surrounding soil properties.The derived solution agrees well with results of numerical simulations.Compared with the traditional models,the new solution allows assessment of all the parameters that related with leakage including the pressure head inside the pipe,hydraulic conductivity,crack size and its position,and pipe size and its depth.
文摘Minimizing water loss in water supply networks is one of the objectives for protecting water resources. Currently, the large amount of water loss is mainly due to leakage of the pipeline network. The leaking of pipe can be caused by incorrect construction, impacted by external forces, or corroded pipe material and aging. Therefore, to control and predict the cracking area on pipe, it is necessary to collect data about pipe conditions, approve the solution of technology improvement and define the ability of pipe capacity from setting up to the first preparing time. This paper will demonstrate how to evaluate corrosion pipe under the age of pipe and the impact level of internal pressure pipe at different times, and will put forward solution of effective leaking management on water supply network.
基金Funded by the Program for National Science Fund for Distinguished Young Scholars of China(No.51125019)the National Natural Science Foundation of China(Nos.50904050,51244007)+2 种基金the Basic Projects of Sichuan Province(2011JY0106)the Department of Education Science and Technology Innovation Team Program of Sichuan Province(13TD0026)the Sichuan Distinguished Youth Fund(2013JQ0037)
文摘In high sour gas reservoir drilling process, it happens occasionally that high-strength drill pipe suffers brittle fracture failure due to stress corrosion cracking, and poses serious hazard to drilling safety. To solve this problem, this paper studied the stress corrosion cracking mechanism and infl uencing factors of highstrength drill pipe in sour environment with hydrogen permeation experiments and tensile tests. We simulated practical conditions in laboratory and evaluated the stress corrosion cracking performance of the high-strength drill pipe under conditions of high stress level. For the problems occurring in use of high-strength drill pipe on site, the paper proposed a technical measure for slower stress corrosion cracking.
文摘For different strength matching, the reliability index and failure probability of welded pressure pipe with circumferential surface crack were calculated using three dimensional stochastic finite element method. This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method. The effects of external moment and the depth of the circumferential surface crack (a) on the reliability of pressure pipe were also calculated and discussed. The calculation results indicate that the strength matching has certain effect on the reliability of the welded pressure pipe with circumferential surface crack. The failure probability of welded pressure pipe with high strength matching is lower than that with low strength matching at the same conditions. The effects of strength matching on the failure probability and reliability index increased by adding external moment (M) and the depth of the circumferential surface crack (a).
基金the National Natural Science Foundation of China(No.59675046 )
文摘The reliability of welded pressure pipe with circumferential surface crack was calculated by using 3D stochastic finite element method.This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method.The calculation of reliability was based on 3D elasticplastic stochastic finite element program which was developed by ourselves.The effects of variables such as fracture toughness,bending moment and depth of the circumferential surface crack on the structure reliability were also discussed.The calculation results indicate that the crack opening angle has certain effect on the reliability of the welded pipe.When the mean value of bending moment is 10kN·m,with the crack opening angle increasing from 30°to 180°,the failure probability of the welded pipe changes from 3.8379×10-8to 3.6943×10-6.When the mean value of bending moment is 15kN·m,with the crack opening angle increasing from 30°to 180°,the failure probability of the welded pipe changes from 3.986 5×10-6to 1.936 7×10-3.The bending moment has great effect on the reliability of the welded pipe.When the mean value of moment is changed from 10 to 15 kN·m,the failure probability of the welded pipe increases dramatically for the same circumferential crack opening angle.Regardless of changing of moment,the pipe has higher reliability if the crack opening angle is less than 60°.The method has put forward a new way for safety assessment of welded pipe with circumferential surface crack.
文摘Three-way pipes, T and Y pipes, are very important connecting components in pipeline systems, their strength are related to the safety of pipelines. In the case that crack is not detected in the three-way pipe, ANSYS finite element program version 5.6 is applied to study the stress distribution of the three-way pipe and to obtain the optimum fillet radius in the crotch region of the two pipes. The reasonable intersection angle of the two pipes is also obtained. In the case that a surface crack is detected in the three-way pipe, the maximum stress intensity factor (SIF) near the front of the surface crack is studied.
基金supported by the National Natural Science Foundation of China (Grant No. 50779010)
文摘A three-dimensional finite element program for thermal analysis of hydration heat in concrete structures with a plastic pipe cooling system is introduced in this paper. The program was applied to simulation of the temperature and stress field of the Cao＇e Sluice during the construction period. From the calculated results, we can find that the temperaiure and stress of concrete cooled with plastic pipes are much lower than those of concrete without pipes. Moreover, plastic pipes could not be corroded by seawater. That is to say, a good effect of temperature control and cracking prevention can be achieved, which provides a useful reference for other similar nearshore concrete projects.
文摘Low cycle fatigue tests and crack growth propagations tests on P91 pipe base metal and its weld joints were conducted at three different temperatures: room temperature, 550℃ and 575℃. The strain-life was analyzed, and the changes in fatigue life behavior and fatigue growth rates with increasing temperature were discussed. The different properties of the base metal and its weld joint have been analyzed.
文摘The influence of temperature on the resistance to rapid crack propagation of a semi-crystalline bio-based polymer was studied. The experimental results described in this study allow to initiate a first discussion on the role of viscosity and its link with the fracture behaviour and a heterogeneous microstructure such as the semi-crysalline polymer. Dynamic fracture tests on pipes were carried out. It would appear that a temperature decrease of approximately 40℃ relative to ambient has no significant influence on the average crack propagation velocity (≈0.6<em>c<sub>R</sub></em><sub>)</sub>, fracture energy and surface roughness. On the contrary, crack propagation paths seem to vary with temperature. The difference in fracture behaviour between the amorphous and crystalline phase varies significantly as a function of temperature. The difference between the initiation resistance and the rapid propagation also varies. This difference seems to be significantly reduced by lowering the temperature. The mechanisms of cavitation damage and plastic flow are increasingly limited by the decrease in temperature (and therefore in macromolecular mobility). Crack propagation in the pipe is more extensive and therefore more critical. This is emphasised in particular by the probability of the material to be macro-branched as the temperature decreases.
文摘Crack opening displacement(COD) was applied to characterize the fracture initiation of the tough high density polyethylene. Normal single side notched three point bend specimens and silica rubber replica techniques were used to study the characteristic COD of high density polyethylene pipe and its butt fusion joints including the weld fusion zone and heat affected zone at different temperature from -78 ℃ to 20 ℃ . Testing results show that the characteristic COD appears to depend on the structural features that are determined by welding process and the testing temperature. As the temperature is lowered, the characteristic COD of all zones studied decreases. Because the welding process significantly changes some structural feature of the material, characteristic COD of the weld fusion zone is the smallest one among those of the three zones. The results can be used for the engineering design and failure analysis of HDPE pipe.
文摘In order to study crack propagation-arresting characteristics of steel pipe construction, a new test installation was designed. The experiments of 20 steel pipes, pipes with longitudinally weld, pipes with circumferential weld and steel pipe with sleeve were conducted. The testing results indi- cated that circumferential weld in pipe with overrnatching weld had beneficial effect on crack prop- agation arrcsting propcrtics and the mechanical split sleeve can be used as crack arrester to prevent crack propagation.
文摘Focused on the girth weld of a φ762 x 28.6 mm （X65） offshore UOE pipe, the fracture toughness properties at different weld joint positions were tested. Meanwhile,the largest size of different cracks under service condition was calculated by using CRACKWISE. The service life of the UOE pipe with postulated crack-like flaws was calculated by considering various fatigue factors, such as vibrations caused by ocean current and fluctuations of inner pressure. The assessment process and results can be used to direct the repair of weld flaws laid in pipes or to assess the reliability of in-serving pipes.
文摘This paper presents the analysis of potential thermal cracking of light feedstocks in the SMR. Two different feedstocks, natural gas and light hydrocarbon (HC) feedstock at two different mixed feed inlet temperatures, are selected to study the HC thermal cracking. Effect of Crossover Piping Volume on feed thermal cracking is also discussed.
