Dry Gas Seal Presentation

1. John Crane Gas Seals
Gas seals and their application for maximum
reliability

2. John Crane Turbomachinery
Products & Operation

3. DGS Application Range
John Crane DGS
Operating Range
Temp: -140 to +315°C
Pressure: to 450 Barg
Speed: to 200m/s
Shaft: to 330mm

4. Type 28AT Seal Design Features
Compliant stationary face design providing
• maximum flexibility
• Optimum slow roll capability
Logarithmic spiral or
bi-directional design.
Tungsten carbide or silicon carbide rotating seat

5. Type 28 AT for duties to 82 bar
Carbon seal faces
Elastomeric ‘O’ Ring
Secondary seal

6. Type 28 XP for duties to 200 bar
Keyed Balance dia.
polymer
Carbon seal faces

7. Type 28 EXP for duties to 350 bar
Cranite seal faces
ADC Balance dia.
polymer

8. John Crane T28
Gas Seal
Standard Application Envelope
0
50
100
150
200
250
300
350
50 100 150 200 250 300
Shaft Diameter (mm)
M
a
x

P
r
e
s
s
u
r
e

(
b
a
r
g
)

-

S
t
a
t
i
c

o
r

D
y
n
a
m
i
c
John Crane
Range of Standard gas seals
High Speed
Re-injection Duties
LNG type Duties
Type 28 XPType 28 XP
Type 28 EXPType 28 EXP
John Crane dominate High Technology Market sectorsJohn Crane dominate High Technology Market sectors
Type 28 AT Type 28 AT
Core business

9. Type 82 Barrier seal
Benefits
Proven / reliable design
>15 years field experience on
a wide range of applications
Excellent protection against
Oil ingress into DGS
limited N2 Consumption
No explosive mixture risk
No process gas to bearing
housing
Environmentally Friendly

10. Control Panels & SEPro Systems
Complex Gas Seal control panel
& booster for BP Horn Mountain
SEPro system for BP

11. 0
50
100
150
200
250
300
350
400
450
1985 1990 1995 2000 2005
P
r
e
s
s
u
r
e
(
B
a
r
)
Gas seal performance progress
AT Triple
AT Triple
XP Tandem
XP Tandem
XP Triple
XP Triple
XP Q
uad
XP Q
uad
E
X
P
T
a n
d
e m
E
X
P
T
a n
d
e m
( C
r a
n
i t e &

( C
r a
n
i t e &

A
D
C
)
A
D
C
)
A
T
T
a n
d
e m
A
T
T
a n
d
e m

12. John Crane Turbomachinery
Seal design for maximum
reliability

13. John Crane Turbomachinery
System design for maximum
reliability
80% of seals fail prematurely because of
contamination

14. Ensure the gas is clean and dry
Process Gas
FI FI
FILTER
MODULE
PROCESS
GAS
EXTERNAL
GAS
Filtered Process Gas
For extended reliability
clean / dry seal gas is the
MOST important
•Gas should be filtered
to around 1 micron
•Coalescing filters can
be used to dry the gas
•Heaters can be used to
provide superheat
•Heat tracing should be
used to prevent heat
loss
•SEPro type systems
can be used to provide
static gas flow

15. AF 15256 Gas Composition
0
20
40
60
80
100
120
140
160
180
-180-160-140-120-100-80 -60 -40 -20 0 20 40 60
Temperature (C)
P
r
e
s
s
u
r
e

(
b
a
r
)
dew line bubble line Adiabatic Expansion Hydrate Curve (1% H2O)
Phase Diagrams
Check adiabatic expansion
Check hydrate formation

17. Using a thermocouple to measure seal
temp
•End User in Alaska
•5.687” Seal on Suction End
•6.929” seal On Discharge
•Reinjection duty with H
2
S
•325 bar working pressure
•350 bar max pressure
•11753 rpm
•Operating since August 2000
Specify a Thermocouple to
monitor seal temp
OEM will need to provide
exit gland

18. AF 15254
-59°C Dew Point
0
20
40
60
80
100
120
140
160
180
-200 -150 -100 -50 0 50 100 150
Temperature (C)
P
r
e
s
s
u
r
e
(
b
a
r
)
dew line bubble line Adiabatic Expansion Hydrate Curve
Gas from Skid Seal Gas DE Seal Gas NDE
Field Gas Analysis
- Plot operating conditions

19. AF 15254
-59°C Dew Point
0
20
40
60
80
100
120
140
160
180
-200 -150 -100 -50 0 50 100 150
Temperature (C)
P
r
e
s
s
u
r
e
(
b
a
r
)
dew line bubble line Adiabatic Expansion Hydrate Curve
Gas from Skid Seal Gas DE Seal Gas NDE
Field Gas Analysis
- Plot operating conditions
Measured operating
points from Data capture
system
Predicted worst case
expansion line
Actual worst case
expansion line passing
through liquid region

20. Review gas properties
White deposits found across IB seal faces
Caused seat and face to stick together
Clear evidence of liquid contamination
Area analysed
Element Wt%
C K 09.62
O K 09.40
AlK 00.11
SiK 00.32
S K 80.55
White deposits identified as deposition of elemental sulphur

21. John Crane Turbomachinery
- Create a clean environment for the
seal under all conditions

22. Clean seal gas injection
– Normal operation
Process Gas
FI FI
FILTER
MODULE
PROCESS
GAS
EXTERNAL
GAS
Filtered Process Gas
Flow path of
seal gas under
normal dynamic
operating
conditions

23. FI FI
Filter No differential pressure
= no flow
Seal contaminated
by process gas
Can Lead to Seal
hang up on start-up
No seal gas flow at settle out conditions
Settle- out Conditions
(Pressurised standstill)

24. SEPro - Superior by design
• Application developed gas circulator
• Inbuilt safety and monitoring features
• Plug and play operating philosophy
• Auto start / stop functions
• Onboard logic and control
SEPro - Heated filtered seal gas on demand during
shutdown and periods of low differential pressure
ensure the seal is constantly maintained in optimum
condition and readiness for re-start.
Seal environment solutions Seal environment solutions fromfrom
When the unit is statically pressurised
there is no seal gas flow
JT expansion causes cooling
Any liquids or heavy ends are deposited in
the seal
This results in serious contamination and
premature seal failure
The SEPro system provides flow to keep
the seals clean and dry
Provides major increase in seal life

26. Seal environment solutions Seal environment solutions fromfrom
HEATER
MODULE
PI
FIT
N
2
PURGE
VENT
VENT
TE
PI
VENT
PI
GAS BOOSTER
CONTROL
MODULE
PI PI
MONITORING OUTPUTS
AIR
SUPPLY
STATUS
PANEL
S
FROM MAIN SEAL GAS FILTERS FEED TO DRY GAS SEALS
FILTER
NC
NC
NC
NC
SEPro Flow diagram

27. Seal environment solutions Seal environment solutions fromfrom
SEPro - More than just another filtered gas package
Maintain optimum seal condition
Increase compressor availability
Prevent liquid contamination at seal faces
Prevent process debris contamination
Increase dry gas seal MTBF
NACE material compatibility
ATEX and PED options
Experience has proven that process contamination is the
biggest single contributor to premature gas seal failure

28. John Crane Turbomachinery
Ensure the OB seal is
adequately alarmed

29. Ensure the OB seal is adequately alarmed
FI FI
N2 SECONDARY
FILTER MODULE
PCV
Filtered N
2
Secondary Gas
FLARE
FI
PI
FO
PI
FO
FI
Process Gas
FI FI
FILTER
MODULE
PROCESS
GAS
EXTERNAL
GAS
Filtered Process Gas
Process + N
2
Gas to Flare
Ensure OB seal is alarmed
•LP in PV = OB seal failure
•HP in PV = IB seal failure

30. John Crane Turbomachinery
Ensure adequate separation
from bearing oil

31. Type 82 Barrier Seal - Function

32. VENT
N
2
to Atmosphere
Ensure adequate Barrier Seal Supply
FI FI
N2 SECONDARY
FILTER MODULE
PCV
Filtered N
2
Secondary Gas
FLARE
FI
PI
FO
PI
FO
FI
Process Gas
FI FI
FILTER
MODULE
PROCESS
GAS
EXTERNAL
GAS
Filtered Process Gas
Process + N
2
Gas to Flare
Ensure Barrier gas
supply pressure is
adequately controlled
•Should be controlled
to 0.3 to 0.5 bar
•Barrier Seal leakage
changes with time
•Interlock with
bearing oil
PI PI
Barrier seal pressure
controlled with PCV’s

33. Type 82 Bushing Upgrade - the Type 83 Barrier Seal
Improved Product - Type 83 Barrier Seal
Carbon Segments
Garter Spring
Wave Spring

34. Type 83 Barrier Seal
New Development - Type 83 Barrier Seal
Oil
side
Dry
Gas
Seal
side

35. Type 83 Barrier Seal

36. John Crane Turbomachinery
Ensure The OEM’s test with
job seal system

37. Ensure the compressor is tested with
job panel
Complex Gas Seal control panel
& booster for BP Horn Mountain
The OEM’s often provide a
temporary seal system for the
compressor testing.
•Complex systems are left untested
•SD conditions left unchecked
•Lead to ‘prototype’ trials on site
If there is a problem with the seal it is
often not picked up
•Catastrophic failure
•Impossible to diagnose

38. Specification for maximum reliability
- Summary
Use polymer seals in place of O rings
•Even at low pressures XP seal show benefits
Ensure the gas is clean and dry
•Use coalescing filters to remove liquids
•Ensure adequate draining
•Heat trace lines + insulate
•Use SEPro system to provide seal gas under shutdown
•Protects the seal from process gas when the machine is shutdown
•Use heaters to increase margin over liquid formation
•Use a thermocouple within the seal to monitor temp

39. Ensure adequate OB seal failure sensing
Confirm test conditions reflect duty
•Axial movements
•Transient movement Vacuum testing
•Temperature transients
•Confirm seal vendor test conditions reflect duty
Leakage monitoring
•Ensure flowmetres are correctly sized
•Check shutdown flow rates
Barrier seal gas system
•Ensure adequate barrier seals are provided
•Adequate pressure control (0.3 to 0.5 bar)
•Confirm failure sensing
•Provide bearing oil interlock
•Consider explosive mixtures / including failure condition
Specification for maximum reliability
- Summary

40. John Crane Gas Seals Offer:-
Experience
•More experience than the other gas seal vendors put
together
Global service
•Local experience and support
•Local repair service
•All to a guaranteed global standard
Technology
•Proven high performance products specially selected for
specific requirements

41. John Crane – World leaders in Dry Gas Seal
Technology