LABYRINTH SEALS - Design Concepts

The standard labyrinth ring assembly utilizes a carbon ring which is shrink fitted into a low expansion stainless steel alloy.  The assembly of these two parts is designed to match the thermal and centrifugal growth of the shaft that is to be sealed.  Consequently, at elevated temperatures the floating ring assembly grows at a rate similar to that of the shaft.

The linear pressure drop, which occurs between the lateral sealing faces, provides the closing force necessary to maintain contact between the carbon and the mating surface.  For low pressure or reverse pressure applications, a wave spring is used to maintain face contact.

To minimize leakage, a computer-aided analysis is used to determine the optimum clearance between the labyrinth ring assembly and the shaft.  Computer programs are also used to analyze thermal expansion of the labyrinth ring assembly and the shaft; stress in the labyrinth ring assembly; centrifugal growth of the shaft; labyrinth ring stability; and thermal gradients in the seal. Additionally, a finite element analysis program is available to evaluate the seal assembly and the shaft.

FINITE ELEMENT ANALYSIS  OF LABYRINTH SEAL  COMPONENTS