| In order to ease the energy crises and environmatal pollution problems, the new energy is being developed vigorously in China. The construction of natural gas transmission pipelines is one of the most important projects in that field. The filter is the nessesary device on the pipelines with the significant component called the quick opening structure. With the successive constructions of the third line and the forth line for West-East natural gas transmission project, the demand for quick opening end closures which can be used in the condition of larger diameter and higher pressure is increasing rapidly in China. However, those kinds of products are almost imported from foreign countries in present, which price is expensive and manufacturing time is long. Therefore, the localized development of quick opening end closures for natural gas filters is proposed in China. Based on the project demands and the previrous studies for large-scaled quick opening end closure, the deeper analyses and structure improvements for the new locking band type quick opening end closure have been conducted in this paper. The details of the study are as follows:Firstly, based on the newly developed saddle-shaped sealing ring with the feature of floatability, a kind of improved saddle-shaped sealing ring with an outside metal ring was proposed. Under the presime of floatability, the new type sealing ring can effectively prevent the serious deformation and failure caused by the rubber material extrusion from the sealing surfaces gaps. The structure design for the new type sealing structure was completed. Meanwhile, the numerical simulation was conducted by using the FEA software ABAQUS to research the seal performance, the feature of floatability and the feature of preventing rubber extrusion. And then the reasonable structure design parameters were obtained.Secondly, according to the safety interlock mechanism standars and regulations of quick opening structure for pressure vessels in China, a kind of new combined type safety interlock mechanism was presented. The structure for new design is more compact. And the interlock function is more reasonable and reliable. The structure design of new type safety interlock mechanism was accomplished in this paper. And then the finite element analysis was carried out by using software ANSYS. Besides, the national patent authorization for this new type safety interlock mechanism has been obtained.Thirdly, the internal medium of large diameter quick opening end closure is natural gas, which is a kind of flammable and explosive medium. And the medium pressure is very high. Since those harsh working conditions, it is necessary to conduct a comprehensive safety analysis from the perspective of structure reliability. In consideration of the anti-brittle fracture design, a circumferential crack around the dangerous position was assumed for the locking band type quick opening end closure in this paper. And then the stress intensity factor for that crack and its influence factors were analysed and calculated by using of software ABAQUS, which provided references for futher structure optimization.At the same time, applying the above new type saddle-shaped sealing ring for preventing rubber material extrusion and the new type combined safety interlock mechanism to the locking band type quick opening structure for natural gas filters, the engineering case study was taken as an example in this paper, which will be developed for the West-East natural gas transmission project in China with the internal diameter of 62 inches and design pressure of 12.6 MPa. And then, the structure design and analysis and stress intensity calculation were carried out. Moreover, according to JB4732-1995, the structure intensity evaluation and fatigue evaluations intensity based on the stress classification method were accomplished by using FEA software ANSYS Workbench.Finally, for the purpose of serialization design, the parameterized design software was developed based on the Visual Basic.NET for the new locking band type quick opening structure. The secondary developments of ANSYS, Excel and AutoCAD for this parameterized design software were carried out. The final software has many functions, such as design by rules, finite element analysis, generating of calculation books and drawing, etc. The design efficiency can be improved greatly by using this software with practical engineering significance. |
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