Mechanical Seals.ppt

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1 5 June 2013

ITT Flygt Mechanical Seals

• Introduction

• Basic seal technology

• ITT Flygt Sealing system

• Plug-In seal

• Seal material

• Qualification testing

• Service



2 5 June 2013

Pump anatomy

Motor

Hydraulics

Heart



3 5 June 2013

Static and Dynamic seals

Static seals: No relative movement between sealed surfaces

Dynamic seals: Relative movement between sealed surfaces



4 5 June 2013

Shaft seals

Stuffing box Lip seal



5 5 June 2013

Mechanical face seal basics

Spring Seal rings

Sealing

interface



6 5 June 2013

Seal rating



7 5 June 2013

Leakage

P1

P0

P1

P0



8 5 June 2013

Lubrication modes

Mixed film lubrication

Boundary lubrication

Seal ring

Lubrication

film

No wear

High leakage

Low wear

Low leakage

High wear

No leakage

Full film lubrication



9 5 June 2013

Mechanical face seal

Spring Seal rings

Sealing

interface



10 5 June 2013

Mechanical face Seal

Torque locks



11 5 June 2013

Leakage

h

Q~h3



12 5 June 2013

Leakage

Estimated daily leakage for a50 mm seal with different

lubrication film thickness

• 0.5 μm A couple of drops

• 1 μm Two table spoons

• 2 μm One glass

• 5 μm Half a bucket



13 5 June 2013

Flatness

0 . 0

0 0 6 m

a x

Deviation from

perfect flatnessmax 0.0006 mm =

2 light band of sodium

light



14 5 June 2013

Flygt Sealing System

Inner seal

Buffer fluid

Outer Seal

Impeller



15 5 June 2013

Sealing system in 3085



16 5 June 2013

Flygt Sealing System- New products



17 5 June 2013

Flygt Sealing System in 3153



18 5 June 2013

Positive closing force



19 5 June 2013

Buffer fluid

• Lubricates the seal faces

• Cools seal rings and other

components

• Dilutes leakage to minimizerisk of crystallization

• Doubles as coolant for new

drive units.



20 5 June 2013

Spin-out

Wear caused by abrasive particlestrapped by boundary current



21 5 June 2013

Spin-out

The spin out groove directs the abrasiveparticles out to the pump housing



22 5 June 2013

Plug-In seal

45 mm Plug-in seal



23 5 June 2013

Plug-in Seal

– Only one part to fit

– Fast service

– Protected seal faces

– Correct mounting guaranteed

– Same procedure for all seals

– Correct and precise spring load

– Pre tested

– Cooling pump incorporated



24 5 June 2013

Plug-In seal series

Plug-in Seal



25 5 June 2013

Seal ring material

High Hardness

High Stiffness

Good Sliding Properties

High Thermal Conductivity

Low Thermal Expansion



26 5 June 2013

WCCR

Corrosion resistant tungsten carbide.

Standard material in Flygt seals

RSiC

Silicon carbide. Optional material.Al2O3

Aluminium Oxide.

C

Carbon. Almost phased out. Only for

inner seals in small products.

Seal ring material



27 5 June 2013

Rubber Material

Flourinated rubber (Viton) (FPM)

High temperature limit and good

chemical resistance.

Standard in most face seals due to

high temperature limit.

Nitrile (NBR)

Good for most applications. Cost

effective



28 5 June 2013

Other materials

Metals

Stainless steel AISI 329

Plastic

Only PPS . High temperature

limit, strong and stable.

Excellent chemical resistance.



29 5 June 2013

Qualification testing

Seal face materials and Seal designs are approved

separately.

Materials are tested for tribological properties.

Seal designs are tested for mechanical performance and

operational performance



30 5 June 2013

Approval of mechanical design propertiesLab rig tests

•Leakage

•Pressure limit

•Negative pressure opening level

•Duration and wear of seal components

•Power loss

•

Dry running capability•Media temperature limit

•Torque lock and torque transmission capability




31 5 June 2013

Approval of operational performance

Field test in products

•Leakage

•Wear from abrasive pump media

•Clogging and wind-up of fibrous media

•“Snoring operation” capability

•Compatibility with product




32 5 June 2013

Performance

Seal life is dependent of

• Leakrate

• Temperature

• Presence of abrasives

• Clogging

• Pressure

• Vibrations

• Dry running

• rpm



33 5 June 2013

performance

SEAL FAILURE

•High leakage

•Overheating

• Abrasive wear

•Thermo cracking

•Solid film build up

•Corrosion

•Incorrect mounting

•Mechanical failure



34 5 June 2013

Service

Do not remount mechanical face seals.

The seal rings will

wear matching

grooves into each

other. If the seal isre mounted after

service, the

grooves will not

match.



35 5 June 2013

Service

Pay attention

to where to

apply oil andwhere to

apply grease



36 5 June 2013

Service

Keep hands and tools

clean.

Microscopic particlesleft on the seal faces

can cause leakage.



37 5 June 2013

Service

Clean shaft and check for damage that

can cause the o-ring to leak



38 5 June 2013

Service

Lubricate stationary o-ring. Use oil if the

seal ring lacks mechanical torque lock.

Otherwise, use oil or grease.



39 5 June 2013

Service

Grease the shaft



40 5 June 2013

Service

Apply some DROPS of oil on the sealsurface to prevent sticking



41 5 June 2013

Service

Place the rotating ring in place



42 5 June 2013

Service

Apply just 20 Newton of power on the tool

when mounting the grip ring.



43 5 June 2013

Service

Check the clearance



44 5 June 2013

Service

Check the seal housing and shaft for defects.

Grease the shaft.



45 5 June 2013

Service

Oil the stationary O-rings (works as a torque

lock)



46 5 June 2013

Service

Place the Plug in seal in place, be aware of the torque lockgets in right position



47 5 June 2013

Service

Mount the Retaining ring, be sure that it gets in to thegroove in the shaft



48 5 June 2013

Service



49 5 June 2013

Service



50 5 June 2013

Service

Apply grease on the retaining ring to protect it from

corrosion



51 5 June 2013

Run-out tolerances



52 5 June 2013

Service

Seals can run dry if the pump or mixer is filled

with correct amount of buffer fluid.

Seals for 80mm shafts or larger should be limited

to a few minutes of dry running to avoid

overheating.



53 5 June 2013

Tightness check

ΔPmax=0,017*Po*t/V [bar]

ΔPmax=Pressure drop

Po=pressure in test object [bar]

t =test time [min]

V =volume of the test object [l]



54 5 June 2013

– No worries

Flygt mechanical seals

Documents

Mechanical Seals.ppt