'TP-800B' Overhauling of Steam Turbine
'TP-800B' Overhauling of Steam Turbine
'TP-800B' Overhauling of Steam Turbine
’TP-800B’ Overhauling of
Steam Turbine
Prepared by:
Reviewed by:
Khadim Hussain (Head-Mach)
2 INTRODUCTION 1
1.1 BACKGROUND 1
1.2 JOB SCOPE 1
1.3 MAINTENANCE DURATION 1
1.4 PRE-TURNAROUND OBSERVATION 1
2 MAINTENANCE 1
2.1 TURBINE ‘TK-201’(Dismantling, Findings, Work done) 2-4
2.2 GOV. END BEARING PEDESTAL INSTALLATION 5
2.3 FINAL ADJUSTMENT OF BEARINGS. BOX-UP 7
2.3.1-2.3.5 CARBON SEALS, NOZZLE GAP & FLOAT, TRIP SETTINGS, PRE-STRETCH, BOX-UP 7-9
2.4 GEARBOX 9
2.4.1-2.4.2 FINDINGS, WORKDONE 9-10
2.5 ID FAN MAINTENANCE 10
2.5.1-2.5.3 FINDINGS, FANTHRUST SETTINGS, WORKDONE 10-11
2.6 INSPECTION OF FAN DUCT & DAMPER BEARING GREASING 11
2.6.1-2.6.2 FINDINGS, WORKDONE 11
2.7 ALIGNMENT 12
2.8 OIL REPLACEMENT/ GREASING 14
2.9 OVERSPEED TEST 15
3 STARTUP 15
4 PAINTING 16
5 CLEARANCES 16
6 SPARES CONSUMED 16
7 POST OVERHAULING NOTE 16
8 RECOMMENDATIONS 16
9 MAINTENANCE TEAM 17
10 VIBRATION DATA 18-21
11 Turbine, FAN & GEARBOX CLEARANCE SHEETS 22-24
12 TURBINE ROTOR DIMENSION SHEET 25
13 DUCT REINFORCEMNT DRAWING ‘MM-1D-02127’ 26
14 BAR CHART 27
1
1. EXCUTIVE SUMMARU:
Recently, in March 2020, moisture level in TP-800 D console oil increased to unacceptable levels. After
thorough checking of associated circuit for any moisture ingress point, it was decided to inspect the carbon
seals of turbine.
The turbine was completely overhauled. Its seal clearances were found increased. HP side last ring was
found damaged and garter spring of LP side last ring was found loose.
Blades of rotors were found thinned and bent at Curtis stages. However, overall condition of rotor was
satisfactory. Blades of diaphragms were found thinned & bent from edges. Some blades of diaphragms were
also found cracked from edges. Condition of 4th stage diaphragm was deteriorated and blades were welded
at some points.
1st, 2nd & 3rd stage diaphragms have been reverse engineered from M/s Ethos Energy (other than OEM) due
to cost saving. Owing to unavailability of 4th stage diaphragm as a spare, TP-601 reclaimed diaphragm was
installed so that 4th stage diaphragm of TP-800 can be reverse engineered & subsequently manufactured
from M/s Othose Energy. In this regard, special Sub Soc (M & P) was convened. Owing to DPT of
Diaphragms were carried out and Thinning & bending was observed at rotor blades. Blades of rotor were
thinned and bent New blade carriers which were reverse engineered from OEM supplied carriers were
installed in turbine and checked. They were found satisfactory.
New Carbon Seals & coupling end oil baffles were replaced with new ones against excessive clearance.
Additionally, Low Lube Oil Security & Emergency Trip & Throttle Valve was inspected to ensure the reliability of
the machine.
After assembly, machine was aligned, tested for Over-speed Tripping successfully in single attempt (7585
RPM) and turbine was taken in service with all parameters normal.
4
1.1. JOB SCOPE:
Job scope for TP-800B was as follows:
2. MAINTENANCE:
2.1 DISASSEMBLY:
Following activities and measurements were carried out during disassembly of TP-800B:
1. The coupling between turbine & gearbox (shim pack type) was removed after removal of coupling cover
to check the alignment. Distance between Shaft Ends (DBSE) was also measured (Mentioned on Annex-
I).
2. Turbine exhaust spool was removed (using Locatelli crane) after fixing the position of expansion bellow
by Equipment Maintenance team & shifted to gravel area.
3. Casing bolts were opened after application of WD-40. 03EA guide pins were installed & casing was crack
opened using jacking bolts. Casing top half was removed, shifted to ground & placed on wooden blocks
in inverted position as shown in fig.
4. Rotor axial movement was checked using dial indicator on wheel face (Annex-I)
5. Nozzle gap checked (Annex-I) from three points i.e. blades, shroud & wheel face.
6. Wheels – Diaphragms clearance & inter-stage labyrinth seals clearances were checked from both sides
using feeler gauge (Annex-I)
7. Carbon Seal along with garter springs were removed.
8. Steam End Bearing Cover – Upper Half:
Low lube oil security and Governor dismantled & shifted to Workshop for inspection.
Bearing cover-upper half removed.
Nut beneath the bearing housing lower half (Pos. No. 344) was in contact.
Oil baffle clearance measured and found normal (Annex-I)
In order to check the axial movement of bearing housing, two dial indicators installed, 1st on
bearing housing & 2nd on rotor wheel. There was no movement in bearing housing.
5
Adopter ring-upper half (Pos. No. 341) removed and no shim was there under the ring.
Bearing housing upper half removed and thrust bearing (active & in-active pads) along with journal
bearing upper half removed, inspected & found in good condition.
9. Exhaust End Bearing Cover – Upper Half:
Bearing cover-upper half removed and shim of 0.1 mm was found between the cover & bearing housing
as shown in fig.
Inner and outer oil baffle clearances were checked using feeler gauge and found ok. Inner oil baffle teeth
were found worn out.
Bearing housing-upper half removed and journal bearing inspected. Journal bearing has the sign of
porosity in Babbitt lining.
10. Rotor removed from the lower half of casing using Locatelli Crane & shifted to Mechanical workshop.
11. Upper nozzle ring shim (Pos. No. 152) found broken. Both 02 shims were removed. Lower shim was
found in satisfactory condition.
12. Nozzles of nozzle ring (Pos. No. 151) found steam eroded.
13. Guide ring was also removed.
14. Diaphragms in both lower & upper casing halves were removed. Shims were found under the
diaphragms in lower half of casing.
15. Inter-stage labyrinth seals were removed.
2.1. 2 FINDINGS:
Nozzle Ring:
Steam erosion of nozzles
Guide Ring:
Blades of guide ring were found bent.
6
HP side seals:
Last Carbon seal ring towards governor side was cracked.
The clearance was greater than recommended
Garter springs were found to be in good condition
All partition plates in between the carbon seal rings were stuck inside the groove.
Heavy carbon deposition at shaft area was observed.
LP side seals:
Garter spring of last carbon ring was found loose.
Clearance was found excessive in all LP side carbon seal rings
All partition plates in between the carbon seal rings were stuck inside the groove.
Heavy carbon deposition at shaft area was observed.
Oil baffles:
All the oil baffles were in satisfactory condition except inner oil baffle seal towards coupling end. Rubbing signs
were observed at teeth of oil baffles.
Clearance of all oil baffles were acceptable.
Rotor:
Blades of Rotor had thinning at the edges. Moreover, some blades were found bent at all stages.
Carbon seal area of rotor was heavily covered with carbon deposition.
Shaft area under thrust collar had deep pitting resulting in less contact area of thrust collar ID with shaft.
Thrust collar was observed loose on shaft. It was just axially locked with the help of sleeve and lock nut.
Scoring marks were observed at oil baffle area.
Thrust collar had scoring marks at face.
Casing:
Carbon seal area was steam eroded at upper and lower half of casing.
Work Done
8
2.1.3 WORK DONE:
2.1.3.1 OLD ROTOR (NOT INSTALLED):
Following work has done
Owing to heavy scratches on the carbon seal area, rotor was machined. Machining of the rotor
carbon seal area has carried till 0.2mm at both ends, but the scratches remains as such and
smooth surface has not achieved.
Owing to machining, chrome (hard) coating thickness has reduced and therefore, further
machining was not carried out. So, it was decided to use new rotor available in warehouse.
Note:
One reclaimed rotor was also available in the warehouse. Shaft journal at carbon seal area has
88.90 mm size. But the reclamation certificate do not reveals about the coating. Therefore, it
was decided not to use the same.
2.1.3.1 NEW ROTOR (INSTALLED):
New rotor was issued and following were done.
a. All dimensions were checked and verified in view of the removed rotor and found same.
b. The shaft sizes were measured and recorded in attached sheet at page no. 25.
c. Position of the oil baffle rings and slinger ring on coupling side were different than the removed
rotor. Therefore, slinger ring moved ‘10mm’ by slight heating with heating torch and oil baffle
rings were moved ‘6.6mm’ towards coupling hub side by slight hammering (plastic hammer).
After movement, position of slinger and oil ring were same as that of removed rotor.
d. Thrust bearing (6311) and OST box was already installed on the rotor.
e. Coupling hub was removed from old rotor and installed at new rotor with same coupling
overhung of 4.60 mm.
f. For reference, turbine wheel run out was measured by placing dial gauge knob on wheel face.
The wheel was rotated one complete revolution. The run out (dial gauge reading) was found as
0.04 mm.
Note: Installed (new) rotor trip device has left hand threads whereas old has right hand threads.
2.2 GOVERNOR-END BEARING PEDESTAL INSTALLATION:
Prior to dismantling, reference value (alignment and lengths) were
recorded.
1. Both, governor and coupling end bearing pedestal level
with respect to turbine was checked by placing straight
edge, master level and filler gauge as shown in the pic. The
values are:
2. Governor end bearing pedestal level with respect to casing was also checked with the help of
dial gauge. For old bearing pedestal, values are -0.08mm (east), +0.04mm (west) and for new
bearing pedestal, -0.08mm (east) and -0.03mm (west)
respectively.
Le 487.5 487.5
Lc 486.2 486.2
Lw 486.2 486.3
Note: All dimensions are in mm
4. Turbine level was checked with the help of dial indicator. Measurement are
Non-drive (governor) end; East (06 area) side = 0.00, West (02 area) side = +0.01mm
Drive (coupling) end ; East (06 area) side = -0.09mm, West (02 area) side = 0.00
b. Both sleeves bearing contact with rotor shaft and turbine housing was checked by persian blue.
First, persian blue was applied at turbine housing bearing area. Rotor was resting on other end
bearing, and bearing has rolled
from one end to other in housing
and contact found at bearing outer
surface as in pic-1. In order to find
rotor shaft contact with bearing ID,
persian blue was applied at rotor
shaft bearing area and placed in
casing (with carbon seal rings and
bearing lower halves). Bearing
rolled in the housing from one end
Pic-I Pic-2
to another and contact found at
the bearing ID as in pic-2.
Approximately 80% contact at ID and OD of the bearing was found. Both DE and NDE bearings
lifts were also checked and found 0.29mm at governor end.
2.3.1 CARBON SEALS:
Old rotor was heavily rubbed at carbon seal area. Despite of machining, smooth surface has not
achieved. The rubbing is seems to be due to less clearance at the carbon seal area or due to
measurement error. To avoid this, old values along with other similar machines clearance (as
reference) were checked. After deliberation, it was decided to increase the carbon seal clearance. New
seals clearance (03 no’s) were adjusted at mandrel and final installed values are:
New garter springs and carbon ring stoppers were also installed along with the carbon seals.
7
’TP-800B’ Overhauling of Steam Turbine
After
2.3.2 NOZZLE GAP & FLOAT: installation/tighte
ning of both
sleeve bearing
housings,
measurement
are:
(
0
.
1
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m
)
p
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o
v
i
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h
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8
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nts
were
taken.
2.3.3 TRIP SYSTEM Gap
SETTINGS: betwe
F en
o trip
r lever
and
f over
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t weigh
u t is as
r follow
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o
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u
2. Old
9
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p gear
and
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Backla
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’TP-800B’ Overhauling of Steam Turbine
2.3.4 COUPLING PRE-STRETCH ADJUSTMENT:
After alignment, shim pack coupling (between turbine and gearbox) pre-stretch was measured. Both
coupling faces have varying gap of 0.4 - 0.8 mm. To adjust the
gap, complete turbine moved towards north (CCR side). To do
the same, 02 no’s dial indicator installed as in Pic and turbine
both foundation bolts were loosened. Turbine was moved
until pre-stretch of 1.5 mm achieved, the reading on dial
indicator was 1.32 mm. That is, complete turbine was moved
1.32 mm towards governor end.
2.4.1 Findings:
Following were the observations;
2.5.1 Findings:
1. Fan both ends bearing cover have water. Same is due to the cooling water leakage from the
threaded portion.
2. Axial float of fan rotor was found on higher side as 1.94mm (before bearing cover removal)/
1.72mm (after bearing cover removal) against TA-2011 value of 0.60 mm. This shows that the
fan rotor was moved towards the motor side.
3. Motor rotor float was also measured for reference and found as 0.75 mm.
4. The motor and fan side bearings were found in good condition.
5. Thrust collars were found in good condition.
2.5.2 Fan Thrust Setting: 0.3mm shim at 19mm spacer with 0.2mm
both thrust shim provided here
DBSE between motor and fan is 19.60 mm.
Both thrust rings were loosened. Now, 19 mm
spacer along with 0.2mm shim was placed
between motor and fan shafts with 0.3 mm
shims (filler gauge) were provided in front of
thrust collar (the collar were not tightened
yet) as shown in pic. After tightening of thrust
collars, the fan rotor float was found as 0.53
mm.
2.5.3 Work Done:
1. Fan rotor shaft diameter at bearing area was measured. Bearing clearance both by crow bar
and plastic gauge were also measured.
2. After cleaning, DPT of the bearings was carried out, found ok. Same journal and thrust bearings
were installed.
3. The cooling water lines were thoroughly cleaned. The bearing housing were leak tested by
opening the cooling water supply to the lines. They were found okay
4. The pre-load bolt of the bearings was torque at 170 N-m.
5. Fresh charge of SYN-FLIX GT-68 oil was filled into the bearing housings.
2.6.1 Findings:
Expansion bellow (adjacent to vent stack) was found cracked at many points (Equipment
Maintenance job) as shown in Pic.
All deflectors were found at their location and are in healthy condition as inspected visually.
Fan suction eye bolts nuts were loose/ missing. Also, welding at many bolts found cracked/
insufficient.
Already provided supports base plates welding were found cracked at area where welding has
terminated as in Pic. Also, crack reason was seems to be due to less area of the base plate.
Pic: Old Support Base Plate Crack Pic: Damaged Expansion Bellow
Loose/ missing nut/bolts ’(20 Ea)were provided and tightened followed by bolt head and nut
tack welding.
Duct cracked area were thoroughly grinded followed by weld repair.
Total 06 ea new supports (02 ea at upstream and 01 ea at downstream of fan were provided on
each side (drawing attached). After welding, DPT was carried out and found OK. New support
base plate area has increased to have better support
and to avoid cracking of the duct plate. New
supports work was carried out as per attached
drawing ‘MM-1D-02127’ at page no. 26. However,
old supports pad dia. has not increased as well as
only old flat bar repair work was carried out.
Whereas, drawing indicate the new base plate of old
supports and new flat bar.
The damper bearings were thoroughly cleaned with Pic: New Supports
2.7 ALIGNMENT:
Since, only work has been carried out at the turbine. Therefore, only alignment between turbine and
gearbox was carried out. Whereas, alignment between gearbox/fan and fan/motor remain as such as
found.
0.00 0.00
+0.20 +0.34
New, Installed:
1. Dial is on turbine.
2. After installation of new governor end bearing pedestal, rotor, bearings etc, the alignment
reading was
0.00 0.00
0.00 -0.41
3. The turbine was moved 1.32mm towards (north side) for adjustment of coupling pre-stretch.
0.1 mm shim was provided at coupling end and 1.0mm (0.8 mm + 0.2 mm) at governor end
were provided. The alignment reading at 1945 hrs was:
0.00 0.00
Hot Alignment:
Just after over speed test, alignment reading was as follows (dial is on turbine).
0.00
Owing to very little space between the coupling faces, axial alignment reading has not been taken. Gap b/w coupli
02 Area 06 Area
+0.22 -0.22
R
+0.00
Alignment b/w Gearbox and Fan:
Dial is on fan.
0.00 0.00
+0.01 +0.04
0.00 0.00
Note:
Alignment between ‘fan to motor’ and ‘fan to gearbox’ has not carried out. So readings are those which were
found.
Witnessed By:
Mechanical Team: Farhan Mahmood, Syed Asfandyar Gilani
Attempt:
Second Attempt:
Over speed weight tension was adjusted by turning nut half (counter clockwise).
Third Attempt:
Over speed weight tension was readjusted by loosening (turning) nut 1/8 of a turn (clockwise).
The turbine was now tripped @ 4640 RPM (1.10 % of rated speed, 4200 RPM).
At start-up of the turbine for over speed test, one spark was observed due to contact of
coupling faces. For over speed test, gaging bolts were installed at coupling flanges to avoid the
contact of coupling faces. Same were removed after over speed test.
After OST, coupling pre-stretch between turbine and gear box was found as 1.0 mm.
Hot alignment reading between turbine and gearbox was also measured. Reading has given in
alignment sheet.
During startup of ammonia front end no abnormalities were found on the ID fan train.
3. START-UP:
Lube oil circulation was for 03 hours.
Turbine has heated for 02 hours.
Slow rolling of turbine at 500 RPM for 04 hours.
Manual tripping of turbine was carried out.
Low lube oil tripping of turbine was checked and found at 0.8 Kg/cm 2.Tripping was reset and
turbine tripped at low lube oil pressure @ 0.65 Kg/cm 2. Low lube oil tripping lever gap was
found as 7.5mm.
Over speed test and vibration checked at 4000 RPM.
Fan was operated with the motor and found normal.
The turbine was coupled to the gearbox and fan was operated at a speed up to 980 RPM.
Vibrations were monitored during ramping up of the turbine speed. Vibrations were found in
acceptable limits. See attached vibrations reports for details.
4. PAINTING:
Turbine including gearbox, clutch and steam piping were cleaned with the help of emery paper and
wire brush followed by the painting.
5. CLEARANCES:
See attached clearance sheets (page no. 22-24) for turbine, gearbox or fan components.
6. SPARES CONSUMED:
Following spares were consumed during the Up-rating / overhauling activities;
8. RECOMMENDATIONS:
1. Carbon seal clearance has been increased (0.15 mm) due to rubbing of old rotor carbon seal
area. Effect of this increase in clearance to be critically evaluated in available opportunity for
future reference.
2. Two different types of carbon seal are available in warehouse. Two sets have been consumed.
Same type of carbon seals to be procured for future use.
3. Mandrel for new carbon seal ‘ID’ adjustment has not worked. Same to be manufactured for
future use.
4. Fan duct expansion bellow has cracked at many locations. Same to be replaced (by Equipment
Maintenance) in next available opportunity.
5. Fan bearing cooling water inlet/outlet lines dismantling and installation requires lot off time
due to welded unions/fittings. Same to be replaced with flexible pipe. It will not only improve
job quality but also save lot off time.
6. Replacement of damper bearings to be planned in the next turnaround.
7. Damper bearings pin welding to be modified with the bolted arrangement.
8. Clearance readings by plastic gauge to be taken in early morning or in evening hours. During the
day time, the readings have error due to the ambient temperature.
9. Coupling between turbine/gearbox to be either adjusted on the basis of DBSE or coupling gap.
10. Coupling pre-stretch between turbine/gearbox (set as 1.50mm) to be slightly increased to avoid
the contact of coupling faces during OST.
9. MAINTENANCE TEAM:
Engineer:
Staff:
----------------------------------------------------------------------------
Vibration discoupled data.
----------------------------------------------------------------------------
10.2 COMPLETE TRAIN VIBRATION (ON LOAD):
Last Measurement Deviation Report
*********************************
Database: Fauji Fertilizer Company.rbm
Area: Ammonia
Report Date: 25-Sep-14 19:06
----------------------------------------------------------------------------
22 DBSE (between turbine shaft and pinion) Space was not available for measurement
Note:
During the measurement and from previous record, rotor float setting with respect to DBSE have lot of
confusion due to dimension variance. It was not clear from that the dimension given is hub to hub or
DBSE. Therefore, both values (DBSE and hub to hub) have recorded for future reference. Total DBSE
found was (31.46+21.92 = 53.38mm) and turbine was moved 1.32mm towards north (CCR) side. So, total
value 53.38+1.32 = 54.70mm.
Bearing clearances measured by plastic gauge.
Gear coupling torque was not available. So, first bolts were hand tightened followed by tightening @
53 NM. Hand tightening torque was almost same as that of 53 NM.
TK-201 Gear Box Clearance Sheet
# Description Design(mm) As Found Final
(mm) (mm)
2 Lube oil Pump End Pinion Bearing Clearance 0.10 - 0.15 0.13 0.13
3 Turbine End Bull Gear Bearing Clearance 0.15 - 0.25 0.18 0.18
4 Coupling End Bull Gear Bearing Clearance 0.15 - 0.25 0.21 0.21
5 Width of Axial Bearing / Bull Shaft Axial float 109.90/0.1-0.2 0.12 0.12
Note:
Only gearbox top cover (without bearing bridges) was removed for inspection. Therefore, all the measurements
have not taken as in TA-2011.
BILL OF MATERIAL
S.No DESCRIPTION MATERIAL QTY REMARKS
01 PLATE 10 Thk. 2000x1000 A516 Gr. 60 01 EA -
02 PIPE Ø2" -SCH. 40 API 5L Gr.B 06 MTR -
Drawing name: E:\IAE\AREA (02)\MM-1D-02127 K-201 REINFORCEMENT OF PLATES AT SUCTION SIDE OF FAN.dwg
NEW FLAT BAR 10 Thk
ON BOTH SIDES
(ALL BOLTS TO BE
REPLACED)
NEW SUPPORT
PIPE Ø2"
NEW SUPPORT
PAD Ø300
NOTES:
1- ALL DIMENSIONS ARE IN MILLIMETERS UNLESS OTHERWISE SPECIFIED.
2- ALL DIMENSIONS ARE TO BE VARIFIED IN FIELD.
2 - -
1 02-MA-A-32324 K201 ID FAN
S.No. DRAWING No. TITLE
REFERENCE
FAUJI FERTILIZER COMPANY LTD.
MIRPUR MATHELO (FFC-MM)
TITLE:-
K-201 ID FAN
SUCTION SIDE DUCT REINFORCEMENT
2
DESIGN CHECKED SCALE E.R. # REV.
1 - - -- MI NTS DRAWING No.
- -
- DRAWN APPROVED DATE MM-1D-02127
S.No. REVISION DATE BY CHKD. APR. IAE NIM 17-09-2014 SH. 01 0F 01
FAUJI FERTILIZER COMPANY LTD MM
TURNAROUND-2014 0909
A A P A
c c l 8 9 10 11 12 13
t 14 15 16 17 18
19 20 21 22 23
24 25 26 27 28
D 29 30
u
r
TURNAROUND-2014
Total
110
20SEP14 11:59
19SEP14 11:59
AMMONIA PLANT
Subtotal
110
20SEP14 11:59
19SEP14 11:59
MACHINERY MAINTENANCE
TK-201, COMPLETE OVERHAULING
Subtotal
110
20SEP14 11:59
19SEP14 11:59