Abstract: Based on the finite element method, the contact stresses of the plunger- seal pair of OPI - 1800AWS fracturing pump were discussed in detail. The paper presented distribution law of contacting stress between plunger and rubber seal ring, and also analyzed the relationships between contacting stress and working pressure. Under the action of working medium pressure, it indicates the“centripetal effect”in rubber seal ring exists. ie., along the contacting length of seal ring, the lip of seal ring is extended, the root of seal ring is compressed, and the main sealing region is near the lip. At the same time, the position of the main seal region does not vary with the medium pressure,
and the ratio of the maximum contacting pressure to the working medium pressure is 1.23. Finally it provides the theoretical support for the analysis of lubrication and seal mechanism.

Key words: fracturing pump, plunger, seal, finite element method, contacting stress