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

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