Heat affect on pumps and seals

19-02 SOURCE AND AFFECT OF HEAT ON MECHANICAL SEALS AND PUMPS

HEAT SOURCE FROM THE SEAL LOCATION

  • Air trapped in the stuffing box ends up at the seal ID
  • Clogged discharge recirculation line filter.
  • Dead ended stuffing box.
  • Drained stuffing box jacket.
  • High friction face combination.
  • Face insulated.
  • Face load.
  • Impeller adjustment causing recirculation
  • No vent between dual seals
  • Poor conductivity of face materials
  • Rubbing of a rotating component
  • Seal faces running dry
  • Soak temperatures
  • Hydraulic unbalance design
  • Vertical pump stuffing box not vented. Faces running in an air pocket

HEAT SOURCE FROM THE PUMP

  • Bearing over load
  • Bearing over lubrication
  • Bearing oil level low
  • Discharge recirculation line covered with lagging
  • Internal recirculation
  • Operating off the bep.
  • No throttle bushing in jacketed stuffing box
  • Rubbing of a rotating component
  • High speed application
  • Stuffing box not vented
  • Throttled discharge, no recirculation

HEAT AFFECT ON SEAL

  • Changes product state. Product can vaporize, become viscious etc.
  • Dynamic elastomer squeeze can increase as metal tolerances change
  • Elastomer takes compression set/ failure
  • Face load
  • Increased corrosion
  • Lapped face can go out of flat
  • Plated face can crack
  • Shaft /sleeve tolerance can change causing interference with the seal dynamic elastomer
  • Vaporization of product causes ice formation outboard restricting movement

HEAT AFFECT ON PUMP

  • Alignment
  • Bearing oil deteriorates
  • Bearings lose 58rc hardness above 275 F
  • Cavitation probability increases
  • Centerline design needed to prevent pipe strain
  • Corrosion increases
  • Efficiency decreases
  • Impeller clearance changes
  • Pipe strain
  • Shaft size, axial/radial
  • Specific gravity of fluid changes
  • Stuffing box bushing contact
  • Wear ring clearance changes

Posted

  • On February 13, 2018