Preload spacers to achieve the initial sealing pressure is, with the use of the gasket material is closely related to the type of gasket material in the same amount of compression, the gasket stress is different, i.e. the request of the same seal can seal medium pressure are not the same, or in the same media pressure, the resulting sealing properties not the same connection.

When the initial gasket stress applied to the spacer, the design life of the device to maintain a sufficient working stress gasket to maintain the required sealing performance. Because the connection by fluid pressure, the sealing surfaces are forced separation occurs, which requires the spacer to release the elastic deformation of sufficient capacity to compensate for the amount of separation, and to leave sufficient to maintain the sealing gasket necessary working stress. Moreover, this elastic energy compensating means also may occur during long-term operation of the connection structure relaxation, such as gasket material in high temperature and long term under stress gasket stress induced decrease in connecting member and the fastening of different materials due to different thermal expansion, resulting in decreased or increased gasket stress, high temperature creep fasteners fall in the gasket stress.

High temperatures recommended metal spiral wound gasket, metal jacketed gaskets, graphite gaskets.