Investigation of the Fluid Flow in a Large Ball Valve Designed for Natural Gas Pipelines
Round 1
Reviewer 1 Report
The topic is very interesting, but it is necessary to cover the following aspects: -Include more details about the background in the introduction. It is necessary to add more references. -which properties of the fluid were upload in the software-It should be detailed the boundary conditions-85% is methane and the other 15% is...? You must indicate the chemical composition because of the hydrates or lights hydrocarbons. -Which metal is used for ball valves in natural gas pipelines? -Which standards are used for designing valves? -How do you validate your results? -Why do you choose these angles closure? -You must include a table where the results are summarized -The authors must add more discussion and comparison with other works -What about the failure pressure provoked by the overpressure? The material characteristics are typically studied using FEM -Usually, it is studied steel pipeline behavior with corrosion defects. How can be related this kind of studies with your research work? You should mention it. It is recommended to include in the references: "FAILURE PRESSURE ESTIMATION FOR AN AGED AND CORRODED OIL AND GAS PIPELINE: A FINITE ELEMENT STUDY"
Author Response
We would like to express our thanks for the comprehensive comments and we hope that we succeeded to improve the manuscript.
Point 1.Include more details about the background in the introduction.
Response 1. The following paragraph was added in section 1.Introduction.
Lines 37-47: To be in line with the objectives set out in the Repower EU Plan [4], companies specialized in the production of valves for gas and oil industry must identify best solutions for large valves, which have to be constructed to answer to the specific requirements on a case-by-case basis. The unicity of the design for large valves is the result of a combination of factors such as the underground or the on-ground location, the climate framework that can expose them to extreme weather, the composition of the natural gas, the physical-chemical composition of the soil, disaster conditions such as fire development in the pipeline or heavy floods. Additionally, high pressure and large diameters lead to higher stress for components and the risks of destructions can be significant during dynamic operation. The mechanical engineer has to propose a holistic solution to answer to all the challenges, including special requirements of beneficiaries.”
Point 2. It is necessary to add more references.
Response 2. Following references were added: 5,6,7,8,9,10,11,18,21,30.
Point 3-which properties of the fluid were upload in the software-It should be detailed the boundary conditions-85% is methane and the other 15% is...? You must indicate the chemical composition because of the hydrates or lights hydrocarbons.
Response 3: The following paragraph was added in the section 2. Methods
Lines 151-160: “According to the standard SR EN 3317:2015, the composition of the natural gas is minimum 85% methane (CH4) and the rest of 15% is composed from the major components ethane (C2H6), propane (C3H8), butane (C4H10), pentane (C5H12), hexane (C6H14), azote (N2), carbon dioxide (CO2) and the minor components hydrogen (H2), oxygen (O2), carbon monoxide (CO) and helium (He) [21]. In the studied case, the density of 0.717 kg/m3 was taken into consideration for simulation, a value calculated for the previous composition, which is the composition in accordance with the standard and with the Romanian Energy Regulatory Authority (ANRE) regulations [22].”
Point 4 -Which metal is used for ball valves in natural gas pipelines?
Response 4: The following sentence was added in section 1. Introduction.
Lines 47-51: “For instance, the standard recommends the steel type A350 LF2 to be used for the body of valves and for the metal sealing components (the ball and the seats) of ball valves implemented in natural gas pipelines [5], but when the soil surrounding the underground pipeline contains salty hydrocarbures, the beneficiaries prefer stainless steel as material.”
Point 5.-Which standards are used for designing valves?
Response 5: The following sentence was added in section 1. Introduction
Lines 112-117: “The investigated valve was designed according to the standard API 6D [19] and the corresponding European standard SR EN ISO 14313 [20], which are the standards that specify requirements and provides recommendations for the design, manufacturing, testing and documentation of ball, check, gate and plug valves for application in pipeline systems meeting the requirements for the petroleum and natural gas industries.”
Point 6.-How do you validate your results?
Response 6: The paper contents a new section 4. Hydrostatic tests (Lines 541-622) to validate the results.
Moreover, the following paragraph was added in section 1. Introduction.
Lines 131-135: “The validation of results presented in section 4, consist in experimental tests on a ball valve with a 500 mm diameter, metal-metal sealing with DPE design, similar to the digital twin model analyzed by simulation. The results of experimental tests confirm the high quality of sealing that was point out and explained by analyzing the fluid flow using SolidWorks software.”
Point 7-Why do you choose these angles closure?
Response 7: The following paragraph was added in the Introduction.
Lines 123-131: “Ball valves are shut-off valves, designed to work at 0° and 90° opening positions. A large diameter ball valve can suffer high forces developed as a consequence of the difference between the momentum before and after opening/closing. Moreover, the acting moment is high and the actuator needs time to perform the stroke and the opening time can be at least 40 seconds. Different phenomenon might occur during the process, therefore, to point out the changes of the fluid flow motion correlated with the change of the configuration of the solid walls that represent the boundaries of the fluid flow simulation domain, five case-studies representing different positions of the ball: 30°, 45°, 60°, 70° and fully closed (90°) are studied.”
Point 8 -You must include a table where the results are summarized
Response 8: In section 4. Hydrostatic tests, the Table 2 and the Table 3 summarize results of experimental tests (Lines 597-602).
Point 9-The authors must add more discussion and comparison with other works.
Response 9: The following paragraph was added in section 3. Results and discussion
Lines 513-520: “A comparation between the present work and other studies performed by CFD methods indicate some similar results, although the investigated ball valves had different designs. For instance, in the simulation performed by Tabrizi A. et al. regarding how cavitation conditions influence the performance of ball valves [6], some similarities with the flow patterns obtained for small opening angles may be noticed, such as the dimension of vortexes that are high at small opening, decrease when the angles of opening increase and almost disappear at full opening. The visualization of the phenomena is in accordance with the decrease of pressure drop when the valve is opening.”
Point 10 -What about the failure pressure provoked by the overpressure?
Response 10: In the present work, we were interested in finding explanations about why the ball valves should work only in fully open or fully closed position. For ball valves, in fully open position the pressure drop is very small, because the internal walls of the ball valve have a geometry almost similar to the geometry of the internal walls of the pipeline. If overpressure by 50% is applied, the pressure drop remains very small, because there no obstacles. The pressure drop during opening was not discussed, because it does not significantly influence energy losses during operation since the duration of the process is 40-60 seconds for a DN500 ball valve. To clarify the limits of the present work, the following paragraph was added in the Introduction.
Lines 123-131: “Ball valves are shut-off valves, designed to work at 0° and 90° opening positions. A large diameter ball valve can suffer high forces developed as a consequence of the difference between the momentum before and after opening/closing. Moreover, the acting moment is high and the actuator needs time to perform the stroke and the opening time can be at least 40 seconds. Different phenomenon might occur during the process, therefore, to point out the changes of the fluid flow motion correlated with the change of the configuration of the solid walls that represent the boundaries of the fluid flow simulation domain, five case-studies representing different positions of the ball: 30°, 45°, 60°, 70° and fully closed (90°) are studied.”
Point 11. The material characteristics are typically studied using FEM -Usually, it is studied steel pipeline behavior with corrosion defects. How can be related this kind of studies with your research work? You should mention it.
Response 11.A paragraph was added in the 1. Introduction.
Lines 100-104. “The works [12-17] focus on new valves. Some researchers were more interested in the phenomena that occur in the components of old pipelines. For instance, Velázquez J. et al. studied the failure pressure in aged pipelines, by using finite element method, considering the changes of mechanical characteristics following a long working period. Their results demonstrate that corrosion defects and aging have impact on the failure pressure [18].”
Point 12. It is recommended to include in the references: "FAILURE PRESSURE ESTIMATION FOR AN AGED AND CORRODED OIL AND GAS PIPELINE: A FINITE ELEMENT STUDY"
Response 12. The reference [18] was included in Lines 721-723.
Reviewer 2 Report
A simulation was conducted while lack of some key information. So a major revision should be conducted.
1. The GCI and grid independence test should be done.
2. The details about fluid simulation should be added, e.g., boundary, solver, etc.
3. How to validate the simulation?
4. The authors just presented simulation results with absence of in-depth discussion, which should be added.
Author Response
We would like to express our thanks for the suggested recommendations. We hope we succeeded to improve the manuscript.
Point 1. The GCI and grid independence test should be done.
Response1: GCI and grid independence tests regarding the accuracy of the mesh and the validation of results, are outputs of ANSYS software. The simulation presented in this paper uses SolidWorks, which does not provide key performance indicators, as outputs. To discuss the suggested issue a paragraph was added.
Lines 192-197: “To provide more robust and accurate simulations, nested iterations are used by SolidWorks solver to allow treating mutual influence of flow parameters and boundary conditions. These iterations are run step by step and repeated until the solver convergence is obtained, or until a maximum number of nested iterations is reached, or when each conservation law convergence condition is satisfied. The convergence solver allows to identify the goals that converge, in contrast to those that do not converge or have no solution [26].”
Point 2. The details about fluid simulation should be added, e.g., boundary, solver, etc.
Response 2: Lines 187-281 from the section 2. Methods present details about this issue.
The new version contains supplementary paragraphs, lines 192-270, to answer to the recommendation. TThey are marked on the manuscript.
Point 3. How to validate the simulation?
Response 3: The paper contents a new section 4. Hydrostatic tests (Lines 541-623) to validate the results.
Moreover, the following paragraph was added in section 1. Introduction.
Lines: 131-135: “The validation of results presented in section 4, consist in experimental tests on a ball valve with a 500 mm diameter, metal-metal sealing with DPE design, similar to the digital twin model analyzed by simulation. The results of experimental tests confirm the high quality of sealing that was point out and explained by analyzing the fluid flow using SolidWorks software.”
Point 4. The authors just presented simulation results with absence of in-depth discussion, which should be added.
Response 4: Several paragraphs were added in section 3. Results and discussions, next to a subsection 3.6.Analysis of results. Following lines were added.
Lines 309-313: “In this situation the pressure drop is low, but the use of the valve in this position for an extended period can produce damages. The explanation is that the mix of the gas and impurities, marketed on Figure 4a by purple color, strike a small surface of the upstream sealing zone and the coated layer of tungsen carbide can be peel off, similar to sanding process.”
Lines 328-330: “The maximum velocity is low, not very different to the velocity in full opening position, because there is enough space for the movement of the fluid. “
Lines 513-540. Subsection 3.6 Analysis of results.
Reviewer 3 Report
The paper presents an interesting study on the fluid flow in a large ball valve designed for natural gas pipelines. The methodology is rational, and the results and conclusions are useful. I have some comments for the authors to consider as follows:
1. It is necessary to present the governing equations of fluid flows in the simulations using SolidWorks 2023.
2. Are the flows turbulent or laminar? Have the turbulent models been employed in the simulations?
Author Response
Thank you very much for the nice appreciation of our work and for the recommendations. We added several paragraphs and we hope we succeeded to improve the manuscript.
Point 1. It is necessary to present the governing equations of fluid flows in the simulations using SolidWorks 2023.
Response 1: In section 2, several paragraphs regarding the governing equations of fluid flows used by SolidWorks 2023 were added (Lines 198-270). They are highlighted in the manuscript.
Point 2. Are the flows turbulent or laminar? Have the turbulent models been employed in the simulations?
Response 2: The flows are turbulent. Thank you to help us clarify this aspect. A sentence was added.
Lines 189-191: “Flow Simulation employs transport equations for the turbulent kinetic energy and k-ϵ model as dissipation rate.”
Reviewer 4 Report
The natural gas pipeline networks used for long-distance transportation are experiencing rapid expansion, with an increase in the construction of special valves having large diameters, particularly starting in 2022. Flow control equipment is designed and manufactured on a case-by-case basis, according to the requirements of the beneficiary. This study utilizes SolidWorks2023 software to simulate fluid flow for a 500mm diameter trunnion ball valve, providing significant insight into the development of fluid flow in both intermediate and fully closed positions. The simulation demonstrates that the shut on/off operation of large diameter ball valves is essential to prevent rapid destruction resulting from partial opening, as the large inner space of the ball allows for the development of high-amplitude vortexes. The study also highlights the effectiveness of metal-metal (MM) sealing with Double Piston Effect (DPE) seats in producing low leakage rates, even in the shut-off position. The pressure field analysis reveals that few gas particles succeed in crossing the upstream sealing zone and even fewer in the downstream sealing zone. Furthermore, the interpretation of results emphasizes the importance of using seats with DPE design to achieve fire safety, a requirement for natural gas pipeline applications.The study is interesting. In the introduction, I think the austhors should introduce other types of valves, like cantilver, flap and membrane types. some examples, like some papers, A micro vertically-allocated SU-8 check valve and its characteristics and Study on the fabrication of a SU-8 cantilever vertically-allocated in a closed fluidic microchannel. On the other hand, one important thing is that they should disscus the diodicity of the valves. finally, This paper has no data.
Author Response
We would like to express our thanks for the appreciation of our work and for the recommendations. We hope we succeeded to improve the manuscript.
Point 1. In the introduction, I think the authors should introduce other types of valves, like cantilver, flap and membrane types. some examples, like some papers, A micro vertically-allocated SU-8 check valve and its characteristics and Study on the fabrication of a SU-8 cantilever vertically-allocated in a closed fluidic microchannel.
Response 1: The following paragraph was added in the section 1. Introduction
Lines 52-54: “In the gas natural industry, a lot of categories of valves are used: ball valves [6], check valve [7], the plug valve [8], the float valve [9], the gate valve [10] and the butterfly valve [11].”
The suggested reference was added. It is reference [7] presented within lines 695-696.
Point 2. On the other hand, one important thing is that they should disscus the diodicity of the valves.
Response 2: We are sorry, we did not answer to this issue in this paper. Diodicity is a phenomen specific to other types of valves, such as the check valve that allows reversible flow and it is an interesting idea to discuss about it in further work. In the present work, we were more interested in finding explanations about why the ball valves should work only in fully open or fully closed position. The intermediary opening angles that we studied, were selected just to point the difference between the fluid motion when the valve is fully open and the internal walls of the ball valve have a geometry almost similar to the geometry of the internal walls of the pipeline, and other positions when the ball represent an obstacle that produce deviations from the expected trajectories. To clarify the limits of the present work, the following paragraph was added in the Introduction.
Lines 123-131: “Ball valves are shut-off valves, designed to work at 0° and 90° opening positions. A large diameter ball valve can suffer high forces developed as a consequence of the difference between the momentum before and after opening/closing. Moreover, the acting moment is high and the actuator needs time to perform the stroke and the opening time can be at least 40 seconds. Different phenomenon might occur during the process, therefore, to point out the changes of the fluid flow motion correlated with the change of the configuration of the solid walls that represent the boundaries of the fluid flow simulation domain, five case-studies representing different positions of the ball: 30°, 45°, 60°, 70° and fully closed (90°) are studied.”
Point 3. Finaly, this paper has no data.
Response 3: The section 4. Hydrostatic tests was added and experimental data are presented in Table 2 and 3 from this section (Lines 597-602).
Round 2
Reviewer 2 Report
The authors have answered all my questions. While, some format issues should be corrected.
Author Response
Thank you very much for the appreciation of our work. We modified the format issues that we noticed that were wrong, such as the size of the Figure 13, the contact details of the authors, or the visualization of pressure in figures.
Reviewer 4 Report
The authors carefully addressed my questions.
A small question, the authors should not use the streamline to express the value of pressure, which is difficult for other people to understand. The simple curve or tube might be better.
Author Response
Thank you very much for the appreciation of our work. We modified the visualization of pressure in figures.
