KNS Secondary Frictional Connection
The secondary frictional connection dissipates the applied force in case a defined value is exceeded so that the force flows past the seal and through its support. As a result of this, the seal is compressed with a defined force and the applied force exceeding the sealing force is exclusively used as joining force of metallic components. The advantages are several: narrow sealing faces for obtaining a high surface pressure, protection against excessive compression, safety against blow-out, minimalisation of setting phenomena and exclusion of abrasive wear caused by fluid flow.
A safe sealing connection must be based on thorough design of seal, bolts, use of suitable materials and proper assembly. The sealing system has been designed by means of the computer program WT-Expert. The torque for tightening and the arrangement of springdiscs are among those values from the great number of output data that are relevant for the user and the perfect sealing of the system.
Spring-loaded sealing systems in round or square type flange connections require compression by springs with a working range in both directions. Thus stresses which occur during start-up and shut-down can be compensated. Flanged connections with long bolts subjected to heavy temperature variations are most susceptible to leaks.
Spring-loaded sealing systems in cover joints like manhole covers or air-coolers are subjected to internal pressure and are preferentially used to maintain the minimum sealing pressure during start-up and shut-down processes at a low internal pressure (surface pressure of seal < 25 N/mm²).
Since the seals are commonly rather high, spring columns are needed for large travel distance. When the internal pressure reaches a definite value, the spring force as sealing force will now be substituted by the pressure load of the cover.