平板闸阀非对称密封结构的设计与分析

Asymmetric Design of Sealing Surfaces for API6D Through Conduit Gate Valve

API 6D平板闸阀的阀座在设计时往往设计为双O形圈及弹簧预紧的结构,密封圈采用RPTFE、NYLON等软密封材料,在密封面的设计上因为考虑阀门双向密封所以采用对称的密封设计,在工况使用中由于进口端密封面和出口端密封面所承受的比压不同,所以出口端可能存在软密封失效的问题,当软密封失效时依靠阀座金属面和闸板金属面形成第二道密封,但这样不仅存在金属面擦伤的风险,也会大大增加阀门的扭矩,考虑到阀门在管道中实际使用时往往为单向流向,通过对阀前和阀后密封面比压的计算,设计非对称的密封面,不再考虑金属对金属的密封。

Double O-rings and spring preloading structures are commonly used in the seat design of API 6D through conduit gate valve.RPTFE,NYLON and other soft sealing materials are used in sealing ring.Considering the bi-direction sealing requirement,symmetric sealing design is used.In the working service and in closed position,the pressures of the inlet sealing surface and outlet sealing surface are different.So,the sealing ring of the outlet side may fail.When this situation happens,the secondary sealing between the metal surface of seat and metal surface of gate will effect.But,there is a risk of scratching the metal surfaces and the torque will increase.Considering that the valve will be used in unidirectional pipeline actually,through calculating the pressures of inlet sealing surface and outlet sealing surface,we use asymmetric design without considering the metal to metal sealing.