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mechanical seal
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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
3 April 11, 2023
Static and Dynamic seals
Static seals: No relative movement between sealed surfaces
Dynamic seals: Relative movement between sealed surfaces
4 April 11, 2023
Shaft seals
Stuffing box Lip seal
5 April 11, 2023
Mechanical face seal basics
Spring Seal rings
Sealing interface
6 April 11, 2023
Seal rating
7 April 11, 2023
Leakage
P1
P0
P1P0
8 April 11, 2023
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 April 11, 2023
Mechanical face seal
Spring Seal rings
Sealing interface
10 April 11, 2023
Mechanical face Seal
Torque locks
11 April 11, 2023
Leakage
h
Q~h3
12 April 11, 2023
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
13 April 11, 2023
Flatness
0.00
06
max
Deviation from perfect flatness max 0.0006 mm =
2 light band of sodium light
14 April 11, 2023
Flygt Sealing System
Inner sealBuffer fluid
Outer Seal
Impeller
15 April 11, 2023
Sealing system in 3085
16 April 11, 2023
Flygt Sealing System- New products
17 April 11, 2023
Flygt Sealing System in 3153
18 April 11, 2023
Positive closing force
19 April 11, 2023
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.
20 April 11, 2023
Spin-out
Wear caused by abrasive particles trapped by boundary current
21 April 11, 2023
Spin-out
The spin out groove directs the abrasive particles out to the pump housing
22 April 11, 2023
Plug-In seal
45 mm Plug-in seal
23 April 11, 2023
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 April 11, 2023
Plug-In seal series
Plug-in Seal
25 April 11, 2023
Seal ring material
High Hardness
High Stiffness
Good Sliding Properties
High Thermal Conductivity
Low Thermal Expansion
26 April 11, 2023
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
27 April 11, 2023
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 April 11, 2023
Other materials
Metals
Stainless steel AISI 329
Plastic
Only PPS . High temperature limit, strong and stable. Excellent chemical resistance.
29 April 11, 2023
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 April 11, 2023
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
31 April 11, 2023
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
32 April 11, 2023
Performance
Seal life is dependent of
• Leakrate
• Temperature
• Presence of abrasives
• Clogging
• Pressure
• Vibrations
• Dry running
• rpm
33 April 11, 2023
performance
SEAL FAILURE
•High leakage
•Overheating
•Abrasive wear
•Thermo cracking
•Solid film build up
•Corrosion
•Incorrect mounting
•Mechanical failure
34 April 11, 2023
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.
35 April 11, 2023
Service
Pay attention to where to apply oil and where to apply grease
36 April 11, 2023
Service
Keep hands and tools clean.
Microscopic particles left on the seal faces can cause leakage.
37 April 11, 2023
Service
Clean shaft and check for damage that can cause the o-ring to leak
38 April 11, 2023
Service
Lubricate stationary o-ring. Use oil if the seal ring lacks mechanical torque lock. Otherwise, use oil or grease.
39 April 11, 2023
Service
Grease the shaft
40 April 11, 2023
Service
Apply some DROPS of oil on the seal surface to prevent sticking
41 April 11, 2023
Service
Place the rotating ring in place
42 April 11, 2023
Service
Apply just 20 Newton of power on the tool when mounting the grip ring.
43 April 11, 2023
Service
Check the clearance
44 April 11, 2023
Service
Check the seal housing and shaft for defects.
Grease the shaft.
45 April 11, 2023
Service
Oil the stationary O-rings (works as a torque lock)
46 April 11, 2023
Service
Place the Plug in seal in place, be aware of the torque lock gets in right position
47 April 11, 2023
Service
Mount the Retaining ring, be sure that it gets in to the groove in the shaft
48 April 11, 2023
Service
49 April 11, 2023
Service
50 April 11, 2023
Service
Apply grease on the retaining ring to protect it from corrosion
51 April 11, 2023
Run-out tolerances
52 April 11, 2023
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 April 11, 2023
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
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