The Sealing of Fully Welded Forged Ball Valves for Natural Gas Pipelines (Part one)
Jan 10, 2023
The sealing of fully welded forged ball valves in long-distance natural gas pipelines will directly affect the reliability of pipelines, so its sealing effect should be strengthened. The advantages of fully welded forged ball valves for long-distance natural gas pipelines are analyzed, and the design points of the sealing structure of the all-welded forged ball valve are discussed from the aspects of the scientific calculation of the maximum bending load, reasonable design of key component parameters, appropriate selection of pipeline ball valve springs, and determination of the spherical sealing structure of the ball valve.
95% of China's natural gas needs to be transported by long-distance pipelines. To ensure its safety, it is necessary to do a good job in the design of the sealing of fully welded forged ball valves, take corresponding measures to enhance its sealing performance, to reduce the cost of transportation. Since natural gas is flammable and explosive, once the sealing performance of the ball valve structure is not good, it will lead to leakage of natural gas, which will affect the supply effect, so it is necessary to optimize the sealing structure of the ball valve.
1. Advantages of fully welded forged ball valves for long-distance natural gas pipelines
There are various types of ball valves on the market today, and all welded ball valves are widely used for long-distance natural gas pipelines. They are mainly composed of cast valve bodies and forged valve bodies. The ball pad used is also made of polytetrafluoroethylene and the valve stem has an explosion-proof function, which can adapt to high temperatures from -20°C to 150°C. They are used very often in long-distance pipelines such as natural gas and the chemical industry. In general, natural gas is a flammable and explosive gas, which will cause certain pressure on long-distance pipelines during transportation, especially in areas with complex terrain and great environmental temperature differences. Once the sealing of the fully welded ball valve used in the long-distance pipeline is not good, the operation will be affected. Therefore, higher requirements are put forward for the sealing structure. Fully welded forged ball valves have the advantages of faster opening and closing, good sealing, good hydraulic control, safer sealing parts, and they are also suitable for buried pipelines, which can meet the actual needs of long-distance natural gas pipelines, thereby ensuring the safe transportation of natural gas to bring the satisfactory quality of natural gas supply to the general public.
2. Main points of sealing structure design for fully welded ball valves for long-distance natural gas pipelines
1. Scientifically calculate the maximum bending load.
The scientific calculation of the maximum bending load helps the fully welded ball valve to have good sealing performance in complex working conditions such as foundation subsidence, thereby ensuring the safety of the natural gas transmission process. First, it is necessary to carry out a model bending deformation experiment. After the deformation, the upper and lower forces of the ball valve are different and the force is the greatest at the valve seat. According to the calculation results of the bending moment, it can be known that the radial force generated between the ball and the valve seat above the center plane will increase, and the upper end is the most dangerous position. Second, properly analyze the finite element of the fully welded ball valve. Taking continuous and isotropic valve bodies with Class 600 and DN800 as an example, the maximum stress of the ball valve should be calculated by means of numerical simulation experiments when studying finite elements. The requirement for the strength of the ball valve shows that the maximum bending load is 2360498.53N.m. Third, according to the maximum bending load to analyze the sealing performance of the ball valve, the following conclusions can be made: when the sealing ring and the ball contact each other, a sealing ring with good sealing performance will be formed, thereby prolonging the sealing.
95% of China's natural gas needs to be transported by long-distance pipelines. To ensure its safety, it is necessary to do a good job in the design of the sealing of fully welded forged ball valves, take corresponding measures to enhance its sealing performance, to reduce the cost of transportation. Since natural gas is flammable and explosive, once the sealing performance of the ball valve structure is not good, it will lead to leakage of natural gas, which will affect the supply effect, so it is necessary to optimize the sealing structure of the ball valve.
1. Advantages of fully welded forged ball valves for long-distance natural gas pipelines
There are various types of ball valves on the market today, and all welded ball valves are widely used for long-distance natural gas pipelines. They are mainly composed of cast valve bodies and forged valve bodies. The ball pad used is also made of polytetrafluoroethylene and the valve stem has an explosion-proof function, which can adapt to high temperatures from -20°C to 150°C. They are used very often in long-distance pipelines such as natural gas and the chemical industry. In general, natural gas is a flammable and explosive gas, which will cause certain pressure on long-distance pipelines during transportation, especially in areas with complex terrain and great environmental temperature differences. Once the sealing of the fully welded ball valve used in the long-distance pipeline is not good, the operation will be affected. Therefore, higher requirements are put forward for the sealing structure. Fully welded forged ball valves have the advantages of faster opening and closing, good sealing, good hydraulic control, safer sealing parts, and they are also suitable for buried pipelines, which can meet the actual needs of long-distance natural gas pipelines, thereby ensuring the safe transportation of natural gas to bring the satisfactory quality of natural gas supply to the general public.
2. Main points of sealing structure design for fully welded ball valves for long-distance natural gas pipelines
1. Scientifically calculate the maximum bending load.
The scientific calculation of the maximum bending load helps the fully welded ball valve to have good sealing performance in complex working conditions such as foundation subsidence, thereby ensuring the safety of the natural gas transmission process. First, it is necessary to carry out a model bending deformation experiment. After the deformation, the upper and lower forces of the ball valve are different and the force is the greatest at the valve seat. According to the calculation results of the bending moment, it can be known that the radial force generated between the ball and the valve seat above the center plane will increase, and the upper end is the most dangerous position. Second, properly analyze the finite element of the fully welded ball valve. Taking continuous and isotropic valve bodies with Class 600 and DN800 as an example, the maximum stress of the ball valve should be calculated by means of numerical simulation experiments when studying finite elements. The requirement for the strength of the ball valve shows that the maximum bending load is 2360498.53N.m. Third, according to the maximum bending load to analyze the sealing performance of the ball valve, the following conclusions can be made: when the sealing ring and the ball contact each other, a sealing ring with good sealing performance will be formed, thereby prolonging the sealing.
Next: The Sealing of Fully Welded Forged Ball Valves for Natural Gas Pipelines (Part two)
Previous: Design of Small-diameter Supercritical Fully Forged Gate Valves
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