Mechanical Seals

Front 1

Seals

Back 1

Devices that prevent the passage of fluids along the rotating shaft.

Front 2

Main Purpose of Mechanical Seals

Back 2

To reduce the leakage of fluids to parts per million rather than drops per minute.

Front 3

Packing

Back 3

The sealing surrounds the shaft and closes down the clearances around it so that very little product can escape from the space between the packing and the shaft.

Front 4

Primary Sealing Element

Back 4

The primary ring is the rotating face of the mechanical seal that is fixed to the shaft but held closely against the casing by means of a spring and hydraulic pressure.

Front 5

Mating Ring

Back 5

Stationary face that is mounted in the gland which is mounted on the pump casting.

Front 6

Secondary Seal Element

O-Ring

Back 6

Used to prevent leakage along the shaft through the inner surface of the primary ring and the mating ring.

Front 7

Load Element

Coil Spring

Back 7

Used to provide mechanical tension for the sealing between the two sealing faces.

Front 8

Hardware Elements

Back 8

Collar, sleeve, and gland plate are the additional hardware elements of a Mechanical seal. Used to support the coil spring.

Front 9

Pusher Type Seal

Back 9

Move axially along the rotating shaft to maintain the contact between the two seal faces. They are designed to compensate for the wearing out of the seal faces or misalignment of seal faces with respect to the pump shaft.

Front 10

Non-Pusher Type Seal

Back 10

Pushes the rotating faces towards the stationary face by the combined force of bellows and liquid pressure.

Front 11

Cartridge Seal

Back 11

A complete seal assembly that can be installed in the field with minor disassembly to the pump.

Can be any type of mechanical seal arrangement

Front 12

Dry Gas Seal

Back 12

Non-contacting, dry-running mechanical seal that consists of a rotating seal face and a stationary seal face

Nitrogen or Gas supplied to the seal prior to starting the equipment.

Front 13

Signal Seal

Back 13

Used on products where a small leakage to the atmosphere is acceptable.

Front 14

Double Seal

Duel or Tandem Seal

Back 14

Used where the leakage of a product to the atmosphere cannot be tolerated, or where fluid pressure is dirty or unstable, or there is a danger of negative pressure being created.

back-to-back or face-to-face seals

Front 15

Seal Flush System

Back 15

Used to cool and lubricate the seal faces by introducing a small amount of fluid into the seal chamber close to the seal faces.

Hint 15

discharge side of process

Front 16

Quench

Back 16

Neutral fluid, such as steam or water, which is introduced on the atmosphere side if the seal to reduce the formation of a solid that may interfere with the seal movement.

Front 17

Quench Types

Back 17

Steam on Hydrocarbon

Water on Caustic

Front 18

Seal Cooler

Back 18

Heat exchanger that is used for cooling the flush

Front 19

Cooling Water Supply and Return Lines

Back 19

Connected to the seal cooler for supplying cooling water to the flush.

Front 20

Seal Reservoir (seal pot)

Back 20

Store the fluid that is passed through the seal faces

A non-pressurized system uses buffer fluid

Front 21

Instruments

Back 21

Used to indicate or alarm the operators when the process variables exceed the set limits.

Pressure gauges

Pressure Switches

Level Switches

Flow Meters

Front 22

Single Mechanical Seals

Back 22

Has the lowest leakage ratio if seals

Front 23

Coil Spring

Back 23

The component that is required to apply the mechanical tension to the primary and mating rings

Front 24

Tandem (double or duel)

Back 24

Two identical seals that are arranged one behind the other

Front 25

Quench

Back 25

Components of a seal support system used on the atmosphere side if the seal to reduce the formation of solids that may interfere with the seal movement.

(Coke and Crystalzation)

Front 26

Plugging of orifice

Back 26

Seal Problem- Differential temperature across the orifice

Front 27

Throttled isolation valve or restriction in the quench line

Back 27

Lack of quench flow

(steam or water)

Front 28

Cavitation

Back 28

The formation and subsequent imploding of gas pockets in a pump, causing damage to the internal parts of the pump.

Low Net Positive Suction Head aka Lack of Suction

Front 29

Gas Pockets

Back 29

Lack of lubrication to the seals, which cause the seals to overheat. Leads to seal failure.

Front 30

Flashing

Back 30

Heat builds up in the sealing faces due to friction, the process fluid on the sealing faces begins to vaporize or flash

Leaves Coke

Banging of the seal faces

Front 31

Improper Flushing

Back 31

Pump is running without proper flushing at the seal faces, ot causes excessive heat.

Common Factors

Plugged seal flush orifice

Plugged flush line

Flush not being cool enough

Front 32

Improper Venting/ De-gassing

Back 32

Gas pockets move into the seal cavity, becomes difficult for the seal flush to force the gas pockets out of the seal cavity and lubricate the seal faces.

Front 33

Plugging or Fouling in Seal Cooler

Back 33

Leads up to heating of the seal cavity

Front 34

Poor or Bad Steam Quench

Back 34

Formation of coke or solids between the dealing faces may open or damage the seal

Front 35

Poor or Bad Water Quench

Back 35

Formation of crystals on the atmosphere side of the seal faces

Stops the seal faces from moving forward.

Front 36

Improper Shaft Alignment

Back 36

Vibration of the pump, causes shorten of the seal life.