Face Pressure


The sum of all the loads on the seal face including the spring load, hydraulic load and shaft axial thrust, divided by the area of the seal face.

We want enough load on the lapped seal faces to keep them together, but not so much that it would cause excessive heat between the lapped faces. The total face load can be reduced by friction between the sliding elastomer and the shaft or sleeve, centrifugal force, viscosity of the sealed product, hysteresis, etc.

The “rule of thumb” for initial face loading is a spring pressure of 30 pounds/ square inch (2 kg/cm2). The hydraulic pressure in the stuffing box will create an additional closing force. The actual amount of closing force will be determined by:

  • The hydraulic pressure in the stuffing box.
  • The percentage of seal face balance.

For further information please seeĀ hydraulic balance.


  • On February 15, 2018