1 April 11, 2023

ITT Flygt Mechanical Seals

• Introduction

• Basic seal technology

• ITT Flygt Sealing system

• Plug-In seal

• Seal material

• Qualification testing

• Service

2 April 11, 2023

Pump anatomy

Motor

Hydraulics

Heart

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Static and Dynamic seals

Static seals: No relative movement between sealed surfaces

Dynamic seals: Relative movement between sealed surfaces

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Shaft seals

Stuffing box Lip seal

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Mechanical face seal basics

Spring Seal rings

Sealing interface

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Seal rating

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Leakage

P1

P0

P1P0

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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

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Mechanical face seal

Spring Seal rings

Sealing interface

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Mechanical face Seal

Torque locks

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Leakage

h

Q~h3

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Leakage

Estimated daily leakage for a 50 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

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Flatness

0.00

06

max

Deviation from perfect flatness max 0.0006 mm =

2 light band of sodium light

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Flygt Sealing System

Inner sealBuffer fluid

Outer Seal

Impeller

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Sealing system in 3085

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Flygt Sealing System- New products

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Flygt Sealing System in 3153

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Positive closing force

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Buffer fluid

• Lubricates the seal faces

• Cools seal rings and other components

• Dilutes leakage to minimize risk of crystallization

• Doubles as coolant for new drive units.

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Spin-out

Wear caused by abrasive particles trapped by boundary current

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Spin-out

The spin out groove directs the abrasive particles out to the pump housing

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Plug-In seal

45 mm Plug-in seal

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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

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Plug-In seal series

Plug-in Seal

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Seal ring material

High Hardness

High Stiffness

Good Sliding Properties

High Thermal Conductivity

Low Thermal Expansion

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WCCR Corrosion resistant tungsten carbide. Standard material in Flygt seals

RSiC Silicon carbide. Optional material.

Al2O3

Aluminium Oxide.

CCarbon. Almost phased out. Only for inner seals in small products.

Seal ring material

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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

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Other materials

Metals

Stainless steel AISI 329

Plastic

Only PPS . High temperature limit, strong and stable. Excellent chemical resistance.

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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

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Approval of mechanical design properties

Lab 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

Qualification testing

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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

Qualification testing

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Performance

Seal life is dependent of

• Leakrate

• Temperature

• Presence of abrasives

• Clogging

• Pressure

• Vibrations

• Dry running

• rpm

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performance

SEAL FAILURE

•High leakage

•Overheating

•Abrasive wear

•Thermo cracking

•Solid film build up

•Corrosion

•Incorrect mounting

•Mechanical failure

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Service

Do not remount mechanical face seals.

The seal rings will wear matching grooves into each other. If the seal is re mounted after service, the grooves will not match.

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Service

Pay attention to where to apply oil and where to apply grease

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Service

Keep hands and tools clean.

Microscopic particles left on the seal faces can cause leakage.

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Service

Clean shaft and check for damage that can cause the o-ring to leak

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Service

Lubricate stationary o-ring. Use oil if the seal ring lacks mechanical torque lock. Otherwise, use oil or grease.

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Service

Grease the shaft

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Service

Apply some DROPS of oil on the seal surface to prevent sticking

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Service

Place the rotating ring in place

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Service

Apply just 20 Newton of power on the tool when mounting the grip ring.

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Service

Check the clearance

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Service

Check the seal housing and shaft for defects.

Grease the shaft.

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Service

Oil the stationary O-rings (works as a torque lock)

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Service

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

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Service

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

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Service

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Service

50 April 11, 2023

Service

Apply grease on the retaining ring to protect it from corrosion

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Run-out tolerances

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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.

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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 April 11, 2023

– No worries

Flygt mechanical seals