B i Operation Basic O i Conventional “Wet” Mechanical Seals © 2003 John Crane EAA
85
Basic Mechanical Seal
Loose ring set screwed to the shaft 86
Basic Mechanical Seal Wear here will create leakage
O-ring prevents leakage through the bore 87
Basic Mechanical Seal Heat generated here
Leak path
Large component
Spring ensures automatic adjustment 88
Basic Mechanical Seal Gasket or OO-ring
Inserted stationary component
API Plan 2
Basic Mechanical Seal
API Plan 2
Basic Mechanical Seal
API Plan 2
Basic Mechanical Seal
API Plan 2
Heat control / removal
.
Heat control / removal API Plan 11
Product recirculation line.
94
Basic Mechanical Seal Recirculation for cooling
API Plan 11 95
API Seal Flush Plan
Seal Failure Analysis
.
Seal Failure Analysis
.
Basic Mechanical Seal
Secondary Seal
Primary Seal
Tertiary Seal 99
Basic Mechanical Seal Spring or Spring Force
Mating Ring or Seat
Primary Ring or Face 100
Spring Drive
Left hand or right hand spring?
Mechanical Seal Theory Primary Seal
© 2003 John Crane EAA
102
Primary Seal Primary Ring
Mating Ring
Springs
Higher pressure on outside diameter Higher pressure holds faces closed Fluid is forced between faces to lubricate Springs keep faces closed when no pressure
Primary Seal
Faces lapped flat to within 1 - 3 light bands 104
Film thickness = leakage
Leakage - Newtonian Fluids Diameter (mm) 100
Speed (rpm)
80 60
40 30
20
Pressure (bar g) 0
2
4
6
8
10 12 14 16 18 20 0.01 Balanced Seal
L e a k a g e ( m l/h ) 0.1
1 Unbalanced Seal
10
100
Primary Seal
Fluid film thickness is very important Ê Ê
too thin - wear, wear causing early seal failure too thick - visible leakage
Must be: b Ê Ê Ê Ê Ê Ê
present - beware dry running stable clean - beware abrasive wear symptoms reasonable viscosity temperature controlled acceptable pressure.
Abrasive Wear
.
Is this abrasive wear?
.
Abrasives or no lubrication?
.
Seal Failure Analysis
Primary Seal - Abrasives
How do we prevent damage and failure caused d by b abrasives? b i ?
112
Primary Seal - Abrasives
Primary Seal - Abrasives
Cyclone Separator
To mechanical seal From pump discharge To pump suction
Cyclone Separator
.
116
Abrasive Wear
Cyclone separator
API Plan 31
Filtered recirculation
API Plan 12
Clean flush
API Plan 32
Reverse circulation
API Plan 13
Pressurised double seal
API Plan 53 or 54
Up--Stream Pumping seal Up
Hard faces
Seals designed g for veryy heavyy abrasives
Seal for Heavy Abrasive Service
Type 5860
Viscosity VISCOSITY (cSt) Seal Type
Up to 500
500 to 750
750 to 1000
1000 1500 2000 2500 3000 to to to to to 1500 2000 2500 3000 3500
Pusher Seals with Positive Drive
Standard Seal & Mating Ring
Standard Seal & Pinned or Clamped Mating Ring
Refer to John Crane
Elastomer Bellows Non-Pusher Seals
Standard Seal & Mating Ring
Standard Seal & Pinned or Clamped Mating Ring
Standard Seal with Hard Faces Pinned or Clamped Mating Ring Limited Velocity - See Below
Standard Seal & Clamped p Mating g Ring g
Refer to John Crane
Standard Seal & Pinned or Clamped Mating Ring
Standard Seal with Hard Faces Pinned or Clamped Mating Ring Limited Velocity - See Below
PTFE Bellows Non Pusher Non-Pusher Metal Bellows Non-Pusher Recommended R d d Minimum Radial Seal Clearance Heating at Start-Up Maximum Shaft Velocity (m/s)
Standard Seal & Mating Ring
Standard
5 mm
Refer to John Crane
Refer to John Crane
10 mm
Optional
Seal Design Maximum
3500 and Above
Recommended
10
8
6
4
3
Refer R f tto John Crane
Seal Failure Analysis
Seal Failure Analysis
Stable Fluid Film
Coning Out – Positive Rotation
Coning Out – Positive Rotation
Coning In – Negative Rotation
CStedy
Type 48 Refinery Seal CStedy simulation.
Click here to run…
Type48.aas
126
Type 48 Primary Rings
MP Type 48 48LP HP
Hydropad Primary Ring
Latest Development © 2003 John Crane EAA
LaserFace Technology
LaserFace Technology
Principle of Operation
LaserFace P
Available
T
Required
T - Reduced
R E S
LaserFace Effect
S U
Vapour Pressure Curve A
C
Seal Operating Area
R E T E M P E R A T U R E (Tp)
B Gas
LaserFace
Friction reduced
Face temperatures are lower
Leakage remains negligible / acceptable
Seal S l life lif is i extended t d d
Operate closer to boiling point
Reduce/eliminate expensive cooling.
Primary Seal
Excessive start / stop operation Ê
will drastically reduce seal life (MTBF - Mean Time Between Failure)
Ê
wear occurs between faces at startstart-up
Ê
wear on drive mechanism
no lubricating fluid film present
can cause lockl k-up / b lock bayoneting
Is start / stop operation necessary?
.
134
Primary Seal
If faces are not flat flat, contact generates heat Excessive wear = short life 1 light band = 0.00001181 inch or 0.0003 mm
Lapping
.
136
Lapping
.
137
Lapping
Flatness Checking - Tools
Flatness Checking
.
140
Flatness Checking
Flatness Checking
Distance between dark bands only affected by angle of Optical Flat
Flatness Checking
Flatness Checking
.
144
Flatness Checking
Flatness Checking
Flatness Checking
Flatness Checking
Reconditioning Seals
Best to return to supplier Ê
Expert checking of ALL components
Ê
Components replaced or reconditioned
Ê
Latest design upup-dates
Ê
Full knowledge of materials
Ê
Check dimensions within correct tolerances
Ê
Pressure tested
Ê
As new.
Handling
Do not unpack seal until ready to fit
Avoid touching or handling faces
Place seal on bench with face uppermost
Ê
on tissue paper
Ê
do not place face down, nor on its side
Keep hands clean when fitting seal
150
Handling
Always y carefullyy wipe p lapped pp faces clean with tissue and approved solvent just before placing together Ê
John Crane recommend Kemet CO CO--42
Do not use lubricant on the faces. faces
Primary Seal
Primary Ring (Narrow - Softer) Materials Ê
Carbon--graphite Carbon resin impregnated antimony impregnated
Ê
Carbon converted to Silicon Carbide
resin impregnated
Primary Seal C b converted Carbon t d to t Silicon Carbide
…
Primary Seal
Carbon converted to Silicon Carbide (121) Ê
Oven at 1625 – 2225 °C
Ê
Silicon Monoxide vapour
Ê
Several hours to convert
e.g. 2 hours @ 1925 °C ≈ 0.5 mm SiC depth
Primary Seal
Primary Ring (Narrow - Softer) Materials Ê
Carbon--graphite Carbon resin impregnated antimony impregnated
Ê
Carbon converted to Silicon Carbide
Ê
Ê
resin impregnated
Solid Silicon Carbide pure sintered reaction bonded Tungsten Carbide nickel or cobalt bonded
Primary Seal
Mating Ring (Wide - Harder) Materials Ê
Ni--resist™ Ni i t™
Ê
high nickel cast iron; austenitic cast iron
Ceramic
99.5% aluminium oxide
Mating Rings: Ceramic
.
Mating Rings: Ceramic
.
Primary Seal
Mating Ring (Wide - Harder) Materials Ê
Ni--resist™ Ni i t™
Ê
Ceramic
Ê
99.5% aluminium oxide
Silicon Carbide
Ê
high nickel cast iron; austenitic cast iron
pure sintered or reaction bonded
Tungsten Carbide
cobalt b l or nickel i k l bonded b d d
Materials JC Code
Vickers Hardness
Silicon Carbide Pure Alpha Sintered
277
2500
Silicon Carbide +10% Si. Reaction Bonded
088
Converted Silicon Carbide/Carbon
121
Tungsten Carbide +6% Cobalt
025
Tungsten Carbide +6% Nickel
Material
Thermal Expansion Thermal Density Conductivity Coefficient Shock 000’s kg/m3 -6 W/m°C@20°C X 10 //°C 000’s W/m / / 125
4.0
24
3.1
150
4.6
35
3.1
50
4.0
30
2.0
1500-1600
100
5.2
48
14.7
005
1300-1500
80
5.6
43
14.7
Aluminium Oxide 99.5% Alumina
059
1500+
26
6.9
6
3.9
Austenitic Cast Iron 13% Ni, 6% Cu
007
200
40
19.3
-
7.3
Carbon-Graphite Resin Impregnated
171
12
3.7
10
1.8
2500
+ softer Silicon
2500
+ softer carbon
90
(estimated)
Primary Seal - Summary
A mechanical seal is selfself-adjusting for wear
Has three main parts ::-
Ê
Primary ring (narrower running face) + Secondary seal
Ê
Mating ring (wider running face - harder) + Tertiary seal
Ê
Spring(s) / Spring Force
The liquid film between the primary ring & mating ring is only 0.5 3.0 microns thick.
There are three main sealing areas ::Ê
Primary Seal
- Primary ring & Mating ring
Ê
Secondary Seal
- Primary ring & Shaft
Ê
Tertiary Seal
- Mating ring & Housing.
S lf Assessment Self A Questions / Answers
© 2003 John Crane EAA
Question 1
What are the main components that are required in any mechanical seal?
Primary Ring with its Secondary Seal Mating Ring with its Tertiary Seal Spring(s) or Spring Force
Question 2
What is the purpose of the springs?
To keep the faces closed Ê
When pump is off
Ê
At low pressure
Ê
By assisting the hydraulic y p pressure
Question 3
What assists the hydraulic pressure on the Primary Ring to keep the faces closed?
The spring(s), or spring force (e.g., from metal bellows)
Question 4
In most seal designs, where h is i the th MAXIMUM pressure in relation to the seal faces? Where is the MINIMUM pressure in i relation l i to the seal faces?
On the outside diameter
On the inside diameter
Remember - RULE 1
Question 5
Does the liquid being sealed provide lubrication at the contact area between the Primary Ring and the Mating Ring?
Yes, in all conventional wet seals
Question 6
What is the ideal thickness of the fluid film between the Primary Ring and Mating Ring?
0.5 to 3.0 μm (microns)
Question 7
Name the seal formed at the contact area between the Primary Ring and the Mating Ring?
The Primary Seal
Question 8
What term do we use to describe the component that seals the Primary Ring to the shaft or housing, but allows axial movement?
The Secondary Seal Ê
O-ring
Ê
PTFE Sealing Ring
Ê
B ll Bellows
Question 9
What is the purpose of the Tertiary Seal?
To seal the Mating Ring into its housing On some designs, it is also required to prevent the Mating Ring from g rotating
Mechanical Seal Theory Secondary Seal
© 2003 John Crane EAA
Secondary Seal
Secondary Seal
Three basic forms Ê Ê
O-rings PTFE sealing rings
Ê
Wedges Chevrons ‘C’ rings Sleeved o o--rings g
Bellows
Elastomer Metal M t l formed edge welded PTFE
Two groups Ê
Pusher Sliding oo-rings PTFE sealing g rings g
Ê
Non--pusher Non
Bellows
Secondary Seal: Pusher
Primary ring moves forward to take up wear O-ring moves forward with the primary ring Pushed by the hydraulic and spring pressures
Secondary Seal: Pusher Compact multiple springs
Positive drive
Optimised cooling flow
Optimised primary ring design
Typical pusher seal - low emission duties
Pusher Seal: HangHang-up An external quench will prevent hang--up hang
Product leakage solidifies / crystallises / polymerises Prevents oo-ring pushing forward - leakage increases
Pusher Seal: HangHang-up
Or, ensure minimum clearance here
Excessive pressure and / or heat: permanent set or extrusion
Secondary Seal: OO-Ring
Secondary Seal: OO-Ring
Type 48LP Cartridge Seal
Type 8B1 OO-Ring Pusher Seal
Secondary Seal: OO-Rings Material
Typical Trade/ Minimum Maximum ISO/DIN/ temperature temperature Common names in seals in seals
Comments
NBR Buna N
-40°C
100°C
General purpose material. Up to 120°C in hydrocarbons
CR Neoprene
-40°C
100°C
Ideal for refrigeration duties duties. Some specialist applications.
EP; EPR; EPDM Nordel™
-40°C
135°C
Ideal for water up to 150°C. Avoid oil/hydrocarbons.
FPM Viton A™
-30°C
200°C
Maximum 135°C 135 C in water. water Hardens in high temp steam.
Perfluoroelastomer* (Low temp. grades)
FFKM; Isolast™ Kalrez™
-20°C
215°C
Wide range of chemical compatibility.
Perfluoroelastomer Perfluoroelastomer* (High temp. grades)
Isolast HT™ HT Kalrez™
-20°C 20°C
315°C
Wide range of chemical compatibility.
Medium Nitrile Chloroprene Ethylene Propylene Fluorocarbon*
* Note Health and Safety warning
Secondary Seal: OO-rings Fluorocarbon * > 275° 275°C - Hydrogen Fluoride gas is a possibility > 316° 316°C - Hydrogen Fluoride gas is a certainty Open system - Hydrogen Fluoride vapour Closed system (e.g., oo-ring groove) condenses to form liquid Hydrofluoric Acid
Wear Neoprene or PVC gloves Protect eyes Wash parts in Calcium Hydroxide solution
Secondary Seal: OO-rings Perfluoroelastomer * > 400°C - Hydrogen Fluoride gas is likely p system y - Hydrogen y g Fluoride vapour p Open Closed system (e.g., o-ring groove) condenses to form liquid Hydrofluoric Acid
Wear Neoprene or PVC gloves Protect eyes Wash parts in Calcium Hydroxide solution
Stainless Steel Colour Chart
Straw yellow
370 – 425° 425°C
Brown
480 – 540° 540°C
Blue
600° 600°C
Black
650° 650°C
ALL of these are above the danger level for Fluorocarbon and Perfluoroelastomer materials
Technical Comparisons Compression Set after 70 hours at temperature 90 80 70
Compression set %
60 Kalrez 4079
50
Chemraz 505
40
Isolast 9503
30 20 10 0 204
218
232
246
260 °C
400
425
450
475
500 °F
Temperature
.
Chemical Resistance 350 300 250 Kalrez 4079 Kalrez 1050LF Kalrez 2035 Isolast 9503
200 150 100 50 0
General Chemical
Strong Amines, Steam, Ethylene Acids Ammonia Hot Water Oxide
Propylene Oxide
Linear Cha ange in Le ength (mm m/mm)
Thermal Expansion 0.06 0.05 0.04 Isolast Kalrez*
0.03 0.02 0.01 0 38
93
150
204
Temperature °C *DuPont registered trademark
240
260
Secondary Seal: Wedge
Secondary Seal: Wedge
PTFE Wedge Seal – Type 109
Type 109B Wedge Pusher Seal
Secondary Seal: Chevrons
Secondary Seal: Sleeved OO-Ring
Secondary Seal: CC-Ring
Secondary Seal: PTFE Minimum temperature in seals
Maximum temperature in seals
Pure PTFE
-40°C
230°C
Glass Filled PTFE
-100°C 100°C
280°C
Exfoliated Graphite
-40°C
500°C
PTFE Sleeved Fluorocarbon
-20°C 20 C
200°C 200 C
FEP Coated Fluorocarbon
-20°C
150°C
Spring Energised Pure PTFE Envelope
-20°C 20 C
200°C 200 C
Spring Energised Glass Filled PTFE Envelope (Higher pressures)
-20°C
200°C
Material
Secondary Seal: Pusher
Advantages Ê Ê
sudden failure very unlikely higher pressure capability – Primary Ring not subject to external stresses
Ê
wide choice of materials for all components
Ê
field repairable
Disadvantages Ê
hang--up (not likely where o hang o--ring is well isolated)
Ê
permanent set / pressure problems (cause hanghang-up)
Ê
excellent shaft surface finish required
Ê
maximum temperature ~260° ~260°C
Secondary Seal: NonNon-Pusher No contact here
Elastomer Bellows grips shaft tightly
Secondary Seal: NonNon-Pusher
Bellows flexes to take up wear, misalignment and axial play Fine machined shaft surface required Do not use “good” lubricant - never use silicon grease
Elastomer Bellows Seal
Elastomer Bellows Seals
Hands--on Exercise Hands Assemble a Type 2 Elastomer Bellows Seal
.
Elastomer Bellows Seal
Two--Ply Rolled Metal Bellows Two
Rolled Twin Ply Bellows
Twin p plyy tube formed into bellows
Additional benefits of Saflex
Higher pressures Ê
up to 30 bar g
Open p convolutions Ê
better on solids, food & pharmaceuticals
Higher torsional strength
Ideal d a for o specials sp a s Ê
minimal tooling
Any size up to 18” (or possibly more)
Technical details - GL1B
DIN 24960 L1K
ANSI
metric / inch
230 psi (16 bar)
up to 480° 480°F (250° (250°C)
5/8” to 4”
up to 4500 rpm
Edge Welded Metal Bellows
Bellows Design The inside 45° 45° Tilt Angle developed for the NASA space program. Drastically reduces the stresses t att th the weld ld and d heat affected zone
This has been proven on test with fatigue failures occurring away from weld ld
Bellows Design Why is the 45° 45° angle at the inside edge only?
The seals are a e designed for fo external e te nal pressure. p ess e The outside weld is not so critical - the pressure forces the plates together on the outside and apart on the inside
Edge Welded Metal Bellows Low Temperature Seals
Type 680 - Alloy 20 Bellows
Type 670 - Hastelloy CC-276 Bellows
Type 675 - Titanium Bellows
Type 676 - AM 350 Bellows
Edge Welded Metal Bellows Type 680: Alloy 20 - 8 convolutions
Size Range 3/4” to 3.5/8” 18 mm to 100 mm
Temperature:
-75ºC to 200ºC
Pressure:
vacuum to 20 bar g
Speed:
to 25 m/s
Edge Welded Metal Bellows Type 670: Alloy CC-276 - 12 convolutions
Size Range 3/4” to 7” 18 mm to 150 mm
Temperature:
-75ºC to 200ºC
Pressure:
vacuum to 20 bar g
Speed:
to 25 m/s
Type 670 Welded Bellows Seal
Edge Welded Metal Bellows High Temperature Seals
Type 609 - Rotating Narrow Cross Section
Type 606 - Rotating Seal with Drive Lugs
Type 604 – Stationary Seal
Edge Welded Metal Bellows Type 609
Size Range 1” to 4” 25 mm to 100 mm
Temperature:
-75ºC to 425ºC
Pressure:
vacuum to 20 bar g ((up p to 65 bar g with double double--p ply) y)
Speed:
to 25 m/s
Type 609 Edge Welded Bellows
Double--Ply Welded Bellows Double
Edge Welded Metal Bellows Type 606
Size Range 3/4” to 3.3/4” 19 mm to 95 mm
Temperature:
-75ºC to 425ºC
Pressure:
vacuum to 20 bar g ((up p to 65 bar g with double double--p ply) y)
Speed:
to 25 m/s
Type 606 Edge Welded Bellows
Rotating High Temperature Seal
Edge Welded Metal Bellows Type 604
Size Range 3/4” to 4.5/8” and 5.3/8 5 3/8”
Temperature:
-75ºC to 425ºC
Pressure:
vacuum to 20 bar g ((up p to 65 bar g with double double--p ply) y)
Speed:
to 50 m/s
Type 604 Seal Head
Edge Welded Metal Bellows
Steam quench first cleans bellows, then running faces, then back to drain
Type 604 Cartridge
Secondary Seal: NonNon-Pusher Summary
No movement here
No contact here Bellows expands to take up wear
Secondary Seal: Metal Bellows
Bellows Materials Ê Ê Ê Ê Ê
IInconell XX-750 and d 718 Alloy C C--276 (e.g., Hastelloy C) AM350 Stainless Steel Alloy 20 Titanium
Shaft Seal Materials Ê Ê
O-rings - full range, details as before Exfoliated Graphite
~500°°C ~500
Secondary Seal: Metal Bellows
Advantages Ê Ê Ê Ê Ê Ê
temperatures to 425° 425°C (or more) no hanghang-up non--clogging non hygienic fine machined shaft surface acceptable elastomer bellows are rugged yet low cost
Disadvantages Ê
sudden failure possible, though unlikely
Ê Ê
(“flashing” or mismis-alignment)
not field repairable maximum pressure 35 bar g (2 (2--ply to 65 bar g)
Secondary Seal: PTFE Bellows
Secondary Seal: PTFE Bellows
Secondary Seal: PTFE Bellows
Type 10T
Type 10R
Secondary Seal: LeadLead-in
Seal Type (Example Only)
Seal Size
Y mm
Unbalanced Pusher Seals
Up to 65 mm
2.5 mm
Unbalanced Pusher Seals
Above 65 mm
4.0 mm
Elastomer Bellows
Up to 26 mm
5.0 mm
Elastomer Bellows
26 mm — 60 mm
6.5 mm
Elastomer Bellows
Above 60 mm
8.0 mm
For “Y” dimension see individual seal fitting instructions
S lf Assessment Self A Questions / Answers
© 2003 John Crane EAA
Question 1
Name the devices used for Secondary Sealing
O-rings
PTFE Sealing Rings
Ê
Wedges
Ê
Chevrons
Ê
Others
Bellows Ê
Elastomer
Ê
Metal
Ê
PTFE
Packing g Rings g Ê
Exfoliated graphite
Question 2
O-rings are often used as Secondary Seals. What, if any, are their drawbacks?
Marginal flexibility
Extrusion
Hang--up Hang
Permanent set
Temperature limits Ê
HF acid possible
Question 3
Using a Bellows type Secondary Seal, describe how the component adjusts and compensates for primary ring wear or movement.
The bellows expands or flexes There is no relative movement on the shaft/sleeve.
Question 4
With a Wedge Ring d i off seal, design l the th Primary Ring rocks on the nose of the wedge g to take up any misalignment. True / False
True
Mechanical Seal Theory Tertiary Seal / Mating Rings © 2003 John Crane EAA
Basic Mechanical Seal
Secondary Seal
Primary Seal
Tertiary Seal 238
Tertiary Seal
Four basic types Ê
O-rings
Ê
elastomers
Sealing g Rings g (square ( q / rectangular g section)) PTFE graphite
Ê
Cup Rings
Ê
elastomers
Gaskets or Flat Joints PTFE compressed d fibre. fib
Tertiary Seal
Prevents P t lleakage k round d mating ti ring i
Sometimes also prevents rotation
Tertiary Seal: OO-ring
Tertiary Seal: OO-ring
Tertiary Seal: OO-ring
Tertiary Seal: OO-ring
Tertiary Seal: OO-ring
Tertiary Seal: Rectangular Ring
Tertiary Seal: Rectangular Ring
Tertiary Seal: Rectangular Ring PTFE or Graphite
Tertiary Seal: Cup Rubber
Tertiary Seal: Gasket
Mating Rings
A / AG
P / PG / PP
Mating Rings
BO
BP / 248X
Mating Rings
N / NG
W / WG
WM
Mating Rings
V / VM
U / UM
Special Mating Rings CE
SC
BC
BD
S lf Assessment Self A Questions / Answers
© 2003 John Crane EAA
Question 1
Describe the basic purpose of the ‘Tertiary’ seal
To prevent leakage round the mating ring Also in some applications Ê
Ê
Prevent rotation of stationaryy mating g ring g Cushion mating ring from distortion
Question 2
Name the forms of ‘T ti ’ sealing ‘Tertiary’ li components?
O-rings Ê
Seat Rings
(square or rectangular g section)) Ê Ê
PTFE graphite
C Rings Cup Ri Ê
elastomers
elastomers
Gaskets or Flat Joints Ê Ê
PTFE compressed fibre.
Question 3
Explain why the oo-ring groove is sometimes machined into the mating ring housing rather than the mating ring itself.
If mating ring is made from hard materials such as tungsten carbide or silicon carbide. Easier to machine accurate groove into stainless steel.
Question 4
What item is essential i the in th mating ti ring i housing when using PTFE or exfoliated graphite tertiary seals?
Anti--rotation pin Anti
Question 5
To install a PTFE t ti tertiary seal, l should h ld you heat it up to soften it, or cool it down to shrink it?
First install it onto the mating ti ring, i th then cooll it down (cold running water tap p or place p refrigerator) to ease installation into the mating ring housing. housing
Hands--on Exercise Hands Fit a Type 2 Elastomer Bellows Seal
Fitting a John Crane Type 2 Elastomer Bellows Seal
Type 2 Elastomer Bellows Seal L3
'X' Gasket
2
3
L3 = Scribed datum lines
1
Fitting a Type 2 Elastomer Bellows Seal
(1)
1 Scribe first datum line (1) on shaft.
Fitting a Type 2 Elastomer Bellows Seal
(1)
2 Remove shaft from seal chamber.
Fitting a Type 2 Elastomer Bellows Seal
‘X’
Gasket
3 Measure dimension ‘X’
Fitting a Type 2 Elastomer Bellows Seal
‘X’
(2)
(1)
4 Scribe line (2) ‘X’ mm inboard of line (1)
Fitting a Type 2 Elastomer Bellows Seal
‘X’
(3)
(2)
(1)
L3
5 Scribe line (3) L3 mm inboard of line (2), L3 is the working length of the seal unit (See Fitting Instructions).
Fitting a Type 2 Elastomer Bellows Seal
(3)
(2)
(1)
6 Ensure E setscrews t are withdrawn ithd sufficiently ffi i tl tto clear l shaft h ft and d slide abutment ring into position abutting line (3).
Fitting a Type 2 Elastomer Bellows Seal
(3)
(2)
(1)
7 Ti Tighten ht setscrews t and, d using i soft ft soap as a llubricant, bi t slide lid seal unit along shaft until it touches abutment ring.
Fitting a Type 2 Elastomer Bellows Seal
(3)
(2)
(1)
8 Replace shaft / seal in seal chamber. Ensure Primary Ring and Mating Ring are perfectly clean and dry.
Fitting a Type 2 Elastomer Bellows Seal
(3)
(2)
9 Insert gland plate into seal chamber.
(1)
Fitting a Type 2 Elastomer Bellows Seal
(3)
(2)
(1)
L3
10 Insert and evenly tighten 4 bolts, gently compressing seal to its working length (L3).
Fitting a Type 2 Elastomer Bellows Seal
Fitting a Type 2 Elastomer Bellows Seal
(1)
1 Lightly scribe first datum line (1) on shaft.
Fitting a Type 2 Elastomer Bellows Seal
(1)
2 Dismantle pump – remove seal chamber.
Fitting a Type 2 Elastomer Bellows Seal
‘X’
Gasket
3
Fit Mating Ring into Gland Plate. Measure dimension ‘X’.
Fitting a Type 2 Elastomer Bellows Seal
‘X’
(1)
(2)
4 Scribe line (2) ‘X’ mm outboard of line (1).
Fitting a Type 2 Elastomer Bellows Seal Note this dimension from line (3) to end of shaft or a shaft step. ‘Z’
‘X’
(1)
(3)
(2)
L3
5 Scribe line (3) L3 mm inboard of line (2), L3 is the working length of the seal unit (See Fitting Instructions).
Fitting a Type 2 Elastomer Bellows Seal Lubricate shaft with suitable lubricant
On single-ended pumps, first slide gland plate onto shaft, taking care not to damage the mating ring
Suitable pushing sleeve
(3)
(1)
(2)
6 Pushing on the tail of the bellows, slide seal head into position, passed line (3). NB: Spring and Locating Ring removed.
Fitting a Type 2 Elastomer Bellows Seal
(3)
(1)
7 Replace spring and spring locating ring.
(2)
Fitting a Type 2 Elastomer Bellows Seal Check this dimension from line (3) to end of shaft or a shaft step. ‘Z’
(3)
(1)
(2)
8 Ensure setscrews are withdrawn sufficiently to clear shaft and slide abutment ring into position abutting line (3).
Fitting a Type 2 Elastomer Bellows Seal
(3)
(1)
(2)
9 Check ring is square. Tighten setscrews. Refit seal chamber. Ensure lapped faces are perfectly clean & dry.
Fitting a Type 2 Elastomer Bellows Seal
(3)
(1)
10 Insert gland plate into seal chamber.
(2)
Fitting a Type 2 Elastomer Bellows Seal
(1)
(3)
(2)
L3
11 Insert and evenly tighten 4 bolts, gently compressing seal to its working length (L3).
Pump Assembly Checks Tolerances to give extended seal life © 2003 John Crane EAA
Pump Assembly Checks Shaft/Sleeve Diametral Tolerance
Maximum Ovality
Shaft/Sleeve Surface Finish
PTFE Pusher Seals
±0.05 mm
0.025 mm
0.1-0.25 µm Ra
Ground and polished free from any machining marks
Elastomer O-Ring Pusher Seals
±0.05 mm
0.05 mm
0.3-0.6 µm Ra
Polished free from any machining marks
Elastomer Bellows
±0.05 mm
0.10 mm
0.8-1.2 µm Ra
Fine machined. High quality finish is undesirable
PTFE Bellows
±0.05 mm
0.05 mm
0.8-1.2 µm Ra
Fine machined. High quality finish is undesirable
Metal Bellows
±0.05 mm
0.05 mm
1.2 µm Ra or better
Fine machined or better
Cartridge Seals
±0.05 mm
0.05 mm
1.2 µm Ra or better
Fine machined or better
Secondary Seal
Description
Pump Assembly Checks
Rotating assembly correctly balanced VDI 2060 and ISO 1940
Pump Assembly Checks
Shaft should be straight Maximum TIR 0.05 0 05 mm
Pump Assembly Checks
Shaft run out 1450 rpm 0.08 0 08 mm TIR; TIR 2900 rpm 0.05 0 05 mm TIR
Pump Assembly Checks
Axial and radial bearing clearances 1450 rpm 0.08 0 08 mm TIR; TIR 2900 rpm 0.05 0 05 mm TIR
Pump Assembly Checks
Pump Assembly Checks
As square as possible 1450 rpm 0.08 0 08 mm TIR; 2900 rpm 0.05 0 05 mm TIR > 8,000,000 times a day
Pump Assembly Checks
Clearance in bore of stationary face = 0.4 to 0.5 mm Stuffing St ffi B Box concentric t i within ithi 0 0.15 15 mm TIR
Pump Assembly Checks
Check seal area and coupling shaft end 1450 rpm pm 0.08 0 08 mm TIR; TIR 2900 rpm pm 0.05 0 05 mm TIR
Pump Assembly Checks
Check coupling alignment accurately Which method do you use?
Pump Assembly Checks
Accurately align pipe work Pipe strain will cause premature seal and bearing failure 1 hour spent p aligning pipe work = 1 year extra seal life. lif
Pump Assembly Checks
Attach piping to the correct connections
Pump Assembly Checks
Shaft surface must be in g good condition: Ê
no pits, scratches or grubscrew marks
Ê
fine machined or better for nonnon-pusher seals
Ê
ground d and d polished li h d with ith no machining hi i marks for pusher seals
No pipe strain.
Hands--on Exercise Hands A Assemble bl and d Fit a T Type 109 PTFE W Wedge d Seal S l
Fitting a Type 109 PTFE Wedge Seal
Fitting a Type 109 Wedge Seal
(1)
1 Scribe first datum line (1) on shaft.
Fitting a Type 109 Wedge Seal
(1)
2 Remove shaft from seal chamber.
Fitting a Type 109 Wedge Seal
‘X’
Gasket
3 Measure dimension ‘X’.
Fitting a Type 109 Wedge Seal
‘X’
(2)
(1)
4 Scribe line (2) ‘X’ mm inboard of line (1).
Fitting a Type 109 Wedge Seal
‘X’
(3)
(2)
(1)
L3
5 Scribe line (3) L3 mm inboard of line (2), L3 is the working length of the seal unit (see Fitting Instructions).
Fitting a Type 109 Wedge Seal
(3)
(2)
(1)
6 Ensure setscrews are withdrawn sufficiently to clear shaft and slide seal into position abutting line (3).
Fitting a Type 109 Wedge Seal
(3)
(2)
(1)
7 Tighten setscrews and replace shaft / seal in seal chamber. Ensure running faces are perfectly clean and dry.
Fitting a Type 109 Wedge Seal ‘A’
(3)
(2)
(1)
8 Insert gland plate into seal chamber. Check gap ‘A’.
Fitting a Type 109 Wedge Seal
(3)
(2)
(1)
L3
9 Insert and evenly tighten 4 bolts, gently compressing seal to its working length (L3).
Holding Clips - Wedge Seals
Holding Clips - Wedge Seals
