| In order to study the sealing performance of flanged joint with PTFE gasket filled with glass microballoon and ensure its safety in engineering application, the finite element analysis(FEA) of this bolted flange joint has carried out based on gasket mechanical properties. The influence of the pre-load and internal pressure on flange joint tightness is researched and experiment of sealability is completed. The main contents and conclusions are as follows:(1) The mechanical properties of glass microballoon filled PTFE is investigated by compression rebound, tensile and creep relaxation test. The conclusions show that compressibility, tensile strength and elongation of modified PTFE are decreased, but the resilience and creep relaxation resistance improved which are beneficial for sealing.(2) A three-dimension flange model of DN80, CLASS150 with glass microballoon filled PTFE gasket was established for finite element analysis and gasket stress distribution was analyzed under different preload and internal pressure. The tightness of the joint was also evaluated based on PVRC new gasket parameters Gb, a and GS. The results show that the distribution of gasket stress is uneven and it's larger on outer edge area. With preload increased, the gasket stress is larger and sealing performance is higher, at the same time, the influence of internal pressure on the joint tightness reduces. A larger bolt load is recommended.(3) Combining engineering application, the relatively weak reasons of DN80 flange joint among CLASS150 series flanged joints were analyzed with modified PTFE gasket and improvement measures were proposed.(4) A flanged joint sealing performance test device was built and leakage rate was measured at a given preload and pressure, which was compared with finite element analysis result. It's found that the tightness of flanged joint with glass microballoon filled PTFE gasket meets the requirement of PVRC T3 level and the results are close. |
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