Paradigm, Apr-Jun 2022

2 Crack & scoring marks observed Turbine
between white metal & shell of
bearing no.3. 01 Logic modification that is 1X HH in
addition to 2X High (AND LOGIC).

3 Scoring marks on Babbitt metal 02 VSC in service to avoid
of bearing no.4 & 5. Higher oil condensation and improvement of
clearances. MOT oil condition.

4 Higher Run-out observed Deployment of Consultants and
towards HP-MOP side.
03 Experts from NTPC, BENTLY
Action Taken to avoid the high vibration NEVADA & DOOSAN for the
trips: study of vibration analysis for their
suggestions & opinions.
01 Study of different process
parameters for deviation findings. 04 Bearing#3,4,5 was replaced with
new bearings
02 Gland steam pressure reduction and
gland steam side drains flushing. After the mentioned findings & rectification work,
the M/C was synchronized on 27.01.2019. But,
03 LP side gland sealing system spray the trend of high shaft vibration continued. The
minimization and to maintain the total nos. of tripping of Turbine due to high shaft
steady gland sealing system. vibration mainly through 1x (325 micron; pk-pk)
reached to 25 from the month of January,2019 to
04 HP casing drain flushing to flash July,2019.
box during vibration rise. Remedial Action Plan as decided by Higher
Authority:
05 Maintaining steady load of the M/C Detailed checking of M/C for vibration
during rise of vibration. rectification Job:
• M/C was desynchronized and vibration
06 Increase and decrease of load
during rise of vibration. rectification job started from 01/08/2019 on
HPT and IPT side mainly.
Observations and action taken during the
vibration rectification Job:
Runout measured HP rotor & the readings are
as below:
• MOP shaft:0.24 mm, Journal 1:0.03 mm, Rear
gland box :0.17 mm, Stages 10 to11:0.18 mm,
Stages 7 to 8:0.11 mm, Stages 4 to 5:0.07 mm,
Stages 1:0.10 mm, Journal 2:0.01 mm.
• Balancing done for unbalance of the rotor due
to bend of the HP rotor.
• Before balancing unbalance of the HP rotor
was: HPR Side:906 gms. & HPF Side:273

45

• gms. After balancing final unbalance is HPR Turbine
Side:46 gms. & HPF Side:48 gms.
Action taken by the department to
• Before balancing unbalance was IPF Side: Reduce the vibration & final observation in
122 gms. & IPR Side: 107 gms. After balancing December,2020:
final unbalance is IPF Side: 38 gms. & IPR
Side: 13 gms. 1 Special type insulation
(MICROTHERM OVERSTITCHED
• Axial rubbing of HP rear gland seals was high temperature flexible
observed. All the seals were replaced by new microporous insulation panel)
seals. Clearance made as per design. Before was applied at HP &IP both sides
total bump was: 2.86 mm & now total bump to reduce the radiation heat
is 4.35 mm. dissipation.

Finally, M/C was synchronized on 30.9.2019 at 10:40 2 nos. industrial pedestal fans,
hrs. The shaft vibration values were found normal compressed air ring header and
for 3-4 days from the date of synchronization. 04 nos. compressed air line (1/2”)
But again, the shaft vibration 1X,1Y, 2X are 2Y are used for cooling the bearing
are reached at high peak value after 7 to 10 hours no2.pedestal area and 01 nos.
intervals irrespective of load during steady state industrial pedestal fan is used at
condition as well as during transient condition and bearing no1.pedestal area. After
process parameters. M/C tripped on 31.10.2019 cooling by this method following
through 2X high vibration. M/s.Bently Nevada parameters are observed:
had also visited at site and studied the vibration
pattern in details. i Cyclic vibration of all the bearings is
steady & did not reach alarm value
Observations during running condition of the (except one time reach) from Oct 2019.
Turbine:
ii The temperature gradient of both side
Vibration pattern for bearings is cyclic in on the brg. no.2 is reduced.
nature and has been continuing in steady state
condition after recent vibration rectification job iii This resulted decrease in bearing cover
done in Aug 2019. temperature to around 100 deg C and
resulting lower vibration.
• Increase of bearing-2 pedestal temperature
was found to be above 200 deg C and huge From October 2019 to December 2021
heat observed at IP casing front. There is also there is no tripping due to turbine bearing
gland steam leakage observed from IP inlet vibration.
side. The heat radiation from IP gland side
may be due to poor or improper insulation Why this type of approach came in mind to solve
at IP front side. The Babbitt temperature of the frequent tripping due to vibration by applying
bearing no.2 towards IP turbine & HP turbine compressed air as well as industrial pedestal Fans:
side are 88 °C and 77 °C respectively.
M/s.Doosan Skoda Power Ltd, OEM of the
• There is no probability of condensation as machine, has visited at site on Nov,2015 and
gland steam and other process parameters May,2019 & their recommendation was to open
remain steady. Also, VSC has been in service all bearing pedestal covers and HP casing to
since last synchronization and maintaining measure the deformation of HP rotor followed by
proper and steady vacuum. strengthening or replacement of HP rotor.

• Individual bearing drain oil temperatures are The Observation of M/s.Bently on 10.01.2019
in the normal range (60-65 deg C) is bearing no.2 cover temperatures are running
high above 200°C due to radiation heat from IP
• All gland drain temperatures are found above gland side due to poor insulation. The gradual
200 deg C and flushed to flash box as per increase in 1X and hence direct vibration at HP
saturation temperature logic. both bearings may be due to temporary bow of

• Other TSI parameters like axial shift,
differentials etc. remain unchanged during
these vibration peaks.

the rotor. This temporary bow may be created Turbine
due to oil carbonization/oil coking symptom. This
oil carbonization/oil coking is formed may be due arrest the gland steam entering into the pedestal
to gland steam entering into the oil labyrinth/seal no.2 housing.The separate 04 compressed air lines
area and or due to radiation heat from IP gland also were erected and directed towards pedestal
side. When the close clearance area between oil no.2 for cooling purpose. After that tremendous
seal and rotor gets reduced due to build-up of success came & vibration interval of two peak
oil cooking, soft rub occurs and a local thermal was increased (07 to 08 days from earlier 10 to 14
gradient is created on the rotor which results hrs.) & shaft vibration amplitude also not reached
in temporary bow of the rotor resulting in high tripping value even alarm limit.
vibration 1X and direct vibrations at bearing
no.2.As the coking material is removed, thermal Conclusion:
gradient gradually reduces, the temporary bow is
removed and the vibrations comes back to normal. Hence thermal stress is developed in the bearing
no.2 pedestal as well as shell of bearing no.2 which
To see the vibration trends, all observations by is combined journal & thrust bearing housing. This
M/s.Doosan Skoda Power Ltd. & M/s.Bently are thermal stress effects the stable hydrodynamic
not fully correct. If rotor is bend, then vibration force of bearing no.2 lubricant, causes high
exist all time but, in this case, cyclic vibration was vibration & cyclical in nature. Now after applying
coming after 06 to 07 hours interval. In the month of compressed air lines & industrial pedestal fans,
Decmber,2020 all bearing pedestal covers opened thermal stress developed into the pedestal no,2
& checked and found there is very less amount is reduced which causes reduction in cyclic high
oil coking which may not be the cause of cyclic vibration. Now during overhauling of unit 5 in
vibration. Special type insulation (MICROTHERM December,2021, IP Front gland seals will be
OVERSTITCHED high temperature flexible checked for further improvement of the machine
microporous insulation panel) was applied at HP vibrations.
&IP both sides to arrest radiation heat coming out,
but still high temperature of bearing no.2 pedestal Now Vibration Readings at 215 MW load: -
area persisted.
Bearing (Shaft) Vibration:1X: 88 microns; 1Y: 44
Then only area we were focused which was high microns; 2X: 107 microns; 2Y:106 micron; 3X:
temperature of bearing no.2 pedestal. At first , we 79 microns; 3Y: 44 microns; 4X: 78 microns; 4Y:
placed 02 nos. industrial pedestal fan for supply 58 microns; 5X: 40 microns; 5Y: 36 microns; 6X:
air (act as a forced draft fan) on the surface on 34 microns; 6Y: 38 microns; 7X: 37 microns; 7Y:
pedestal no.2 and placed another side 02 nos. 57 microns; (Alarm value:206 micron & Tripping
industrial pedestal fan to extract the hot air ( act value:325 micron).
as a induced draft fan).After that we observed that
interval of two peak of the vibration was increased Axial Shift values (AS1/AS2/AS3): 0.59/0.58/0.56
(10 to 14 hours from earlier 06 to 07 hours ).Then a
ring header with small holes of different positions Eccentricity: 499 microns; HPDE/IPDE/LPDE:
were erected to cool the pedestal no.2 & also to 1.69/1.14/5.82

Bearing (Absolute) vibration (mm/sec): 1V/1H
:1.9/2.6; 2V/2H:3.1/3.5; 3V/3H: 2.5/2.6; 4V/4H:
3.6/2.4; 5V/5H :4.3/1.4; 6V/6H: 2.0/1.6; 7V/7H:
1.4/1.5

47

C&I

METSO DNA DCS : arduous road
travelled by SgTPP.

Arup Mondal 2ND January 2022 is a day of celebration for us. One
of the PA Fan of U#3 got tripped but the unit survived
Assistant Manager (PS)- and landed up safely at the Run Back Load . At one
Instrumentation, SgTPP, WBPDCL time this was unthinkable for a BHEL 500 MW Boiler.
The logics & control loops are carefully modified in
Served in Jindal Power Limited the following way to make it possible:
(JPL) from July 2011 as a C&I DCS
maintenance Engineer. Later in Sep 1 Other running PA Fan 2ndlub
2015 joined Jindal Steel & Power Ltd. oil pump auto started to cater
(JSPL) as a specialist Instrumentation the increased requirement of
oil pressure.
Engineer. In Sep 2017, joined
SgTPP under WBPDCL as AM(PS)- 2 1.5 time command given
to blade pitch control of
Instrumentation. running PA Fan.

3 Mill preferential trip command
given to number of top Mills
above 4 in time gaps.

4 Instant HAD/CAD closing
command given to all
preferentially tripped Mills.

Abstract However since bottom Mill combination was
Valmet Metso DNA DCS was compact this time, the machine survived without
supplied in 2X500 MW SgTPP much disturbance in flame or furnace draft. We may
U#3 & 4 by BHEL for the 1st not be that lucky if gap Mill operation takes place.
time in India . Teething troubles For such cases CD elevation oil gun auto insertion &
solved by WBPDCL along with MDV closing of preferentially tripped Mills are under
BHEL are narrated in this article. consideration. However we are confident that atleast
loss of PA will not happen in case of one PA Fan trip.
500MW U#3 & U#4 of SgTPP were commercially
made available during end of 2016.But at that time
it was felt that the machine will never stabilise due
to the premature Valmet METSO DNA DCS of these
units as U# 3 & 4 of SgTPP under WBPDCL are the
First Units with Metso DNA. Following frequent
troubles kept us always busy and made the machine
operation very unreliable and vulnerable. But SGTPP-
C & I Stage-II team along with BHEL solved almost all
the major issues to improve the system performance
at its best.

SL PROBLEM DESCRIPTION ACTION TAKEN C&I

PRESENT STATUS

BHEL redesigned the rack

1 Repeated controller (ACN/ IBC power supply module Almost 90% modified
both) fault/failure & redundant (IPSP) and segregated the IPSP installed and
controller earth point from the problem almost
not taking over. UPS, CHARGER & PANEL resolved.

earth in all possible routes.

2 Rack toggling due to card Extra clamping arrangement Looseness is reduced
looseness. done to hold the modules in significantly.

place.

Extra fan installed in all

3 Excessive heat generation made analogue module racks. Trouble has been
backplane brittle. Almost all old backplanes solved.
are replaced. Control room

AC made more efficient.

DCS 24V DC control supply

4 is not UPS but a charger with We commissioned auto Trouble completely
manual changeover and only changeover scheme of the rectified.
chargers to make 24V DC
20 min battery backup. So
bump less transfer was not uninterrupted.
possible causing DCS power

interruptions.

5 Network fault propagation from U#3 , U#4 & COMMON Now the network is
one loop to other like U#3 to System (CW/ACW) networks much reliable.
U#4 etc.
are segregated using a
managed layer 3 switch.

All redundant IOs were

6 configured in adjacent racks All tripping related IOs are No further tripping
due to which in case of Rack segregated in different due to such incidence
Instability, the IOs became Racks (not adjacent).
unavailable and Units tripped occurred.

many times.

Signal validation logic

Spurious tripping due (considering rate of Number of such

7 to malfunction of single change) incorporated in spurious tripping is
almost nil.
temperature element. all temperature protection

circuit.

8 All Compressors’ only ON ON & OFF commands are No further such
command was present due configured in different tripping occurred.
to which during IBC toggling, Racks.

Compressor tripped.

9 Slow navigation & HMI refresh All control & HMI loops are Problem reduced to a
rate. ‘Externally Checked’ by great extent.
correcting all errors.

49

C&I

10 Insufficient Historical data Priority wise signal scan Problems reduced but
storing capacity in Historian. time adjusted. still the performance is

not satisfactory.

11 Alarm/Event/SOE/Log Reconfigured as per system Service improved but
configuration was insufficient to requirement. still not complete.

analyse any failure.

ACNs are not having any inbuilt Redundancy achieved
in place of single BU
12 memory. In case of power Surrogate BU Servers are
failure, ACN loads all necessary configured for each network server but lack of
logics from Back Up (BU) server inbuilt memory is
loop (viz. HMI, SG/TG & design limitation.
which is time consuming & BOP)

prone to database corruption.

13 Single Engineering as well as Redundant Engineering as Hot redundancy is still
Historian Server. well as Historian Servers is not achieved as it is
system limitation.
configured.

All LVS were Client of OWS Each LVS are made Server. Overall System

14 due to which overall system Now all OWS & LVS are HMI performance is
enhanced.
operation was slow. Servers individually.

15 Background colour of HMI was In-house modification along Pages are modified on
white causing strain for Control with Black background is requirement basis.
done as per requirement.
Desk Engineers.

16 Ribbon Alarms are not properly Modified Alarm window is Ribbon alarm work is
configured. developed as per operation’s under progress.

requirement.

17 No inbuilt FSTOUT or RELEASE New Pop-up windows are Continuous
window for any Drive/Valve. developed for all major modification as per

Drives and Valves. requirement.

18 Unreliable Logic Blocks causing Necessary Logic Problem is minimised
spurious tripping of Drives. modifications are made but not completely
to overcome the flaws of eradicated.
available logic blocks.

ADVANTAGES OF MAX DNA DCS 2 Complete DCS is distributed in
Metso DNA has evolved a lot since its inception nature without any Server.
in SgTPP, but still many properties of Max
DNA (already installed in BkTPP& STPS under 4 Historian Servers are Hot
WBPDCL) are better as compared to Metso DNA: Redundant as a result Trend,
Alarm& SOE is more reliable
DPUs are having inbuilt memory
and there is no concept of Back-Up 5 Data backup of Historian server
Server. can be exported as well as restored
when required.
2 DPUs are rack mounted due to
which requirement of individual
network switches in each panel is
not required.

6 Colour specific FBD for easy 14 C&I
identification (e.g.- CYAN for FORCED
blocks & RED for BYPASSED blocks). HMI pages can be checked in test
mode.
7 Values of I/Os can be FORCED from
HMI. 15 Scripts behind each face plate/
symbols can be modified as per
8 Multi-level user authentication is requirement.
available for Operator as well as
Engineering Station. Above mentioned properties of Max DNA makes
it extremely user friendly as well as maintenance
9 DCS components are more Robust free keeping the reliability of DCS system at par.
with better mounting and cooling
arrangement as compared to Metso PROPERTIES OF MetsoDNA DCS WHICH
DNA Components. ARE INSTANT HIT

10 Each OWS can be made Alarm/HMI However there are few properties of Metso DNA
Page specific for easy operation. which are new and instant hit for us like:

11 Each of the HMI face plates are 1. Playback of parameters in HMI pages for easy
editable making it too convenient for trip analysis.
drive specific loop windows.
2. System is Channel redundant instead of Rack
12 All drives/valves are having inbuilt redundant.
RELEASE/FSTOUT faceplate.
3. HART values are integrated in DCS for all
13 All logics & their corresponding HART enable modules.
FBDs are tested and verified
making the overall performance of 4. Licenses are Server based in place of dongle
the DCS system much reliable and based.
maintenance free.
5. Combined network philosophy (teaming of
network IPs) is possible making its network
much more reliable as compared to other DCS
system.

6. Control cycle timing can be made from 20 ms
to 64 s.

Considering the fact that Metso DNA is still in
its infant stage and is developing each day due
to rigorous effort and dedication of Engineering
community, we hope that in near future it will
overcome all mentioned shortcomings and
emerge as the Best DCS worldwide.

51

Turbine

Case Study : Unit 5, BkTPS Fire Hazard and
LP Turbine Outer Casing Deformation
Dated : 16th June 2011

Cause of incident:
During the coasting down of the Unit 5 turbine for
a planned outage and at the time of opening of the
Turning Oil Supply Valve, the local pressure gauge
on the turning oil supply line got uprooted. Then due
to nozzling action the oil got sprayed all over the
acoustic enclosure over Brg. No. 3 and caught fire.

Nirmalya Paul

Sr. Manager
Turbine Maintenance, BkTPS, WBPDCL

Joined WBPDCL on 1999 at KTPP. As
trainee posted at BkTPP and served
in different capacity there upto 2015.
Posted at SgTPP project department
for few years before returning BkTPP as

HOD of Turbine Maintenance.

Abstract OBSERVATION:
About 10 years back a massive
damage took place in BkTPP 1 After the turbine came at dead
stop condition during coasting
U#5 Turbine. The cause and down, initially it was impossible to
effect study is discussed here give hand turning to the turbine.
to make shure that no similar

event recur at any plant.

The insulations of the Cross Turbine
Over Pipe, the Cross Around
Pipe, some portions of the ACTIONS TAKEN REGARDING OPENING
LPT outer casing:
2 IP Turbine & Right IPSV and
IPCV body and majority of pecial fixtures, clamps and wedges were to be
the drain valves are found prepared for the disassembly of the LP Turbine
burnt and oil packed. The Outer Casing Bolts and Dowel Pins.
instrument cables in the
nearby portion had been
damaged fully.

3 Two LP diaphragms are
found to be in damaged
condition.

Hand turning was possible
to a very little extent

4 and finally when the
HP Casing temperature
came as low as 900C full
rotation was possible with
a slight rubbing sound at a
particular position.

Before turning gear could Bowed flange of the front portion of the casing
be given, Bearing No.3 was noted after LP Outer Casing Disassembly
along with high offset of the front side bolts and
5 was inspected and found dowel pins.
to be free from rubbing
or scrubbing. Bearing seal 53
clearances, gland seal
clearances found to be
normal.
Later on, when the turbine
was put on barring gear
an abnormal sound
was observed and upon

6 inspection from the front
side LP Casing inspection
hole, it was found that
the front guide corn was
rubbing with the front side
of LP Rotor. So, decision
was taken to open the LP
Outer Casing.

ACTIONS TAKEN REGARDING OPENING Turbine
LPT outer casing:
pecial fixtures, clamps and wedges were to be LP Outer Casing was lifted up – Guide Corn
prepared for the disassembly of the LP Turbine top portion disassembled – grinded and the
Outer Casing Bolts and Dowel Pins. again placed into position after making proper
Bowed flange of the front portion of the casing clearances.
was noted after LP Outer Casing Disassembly LP Outer Casing Lifted up – Centering Check & Roll
along with high offset of the front side bolts and Check Done – Adjustments done as required
dowel pins.

Radial keys machined and locked in position
since no other abnormalities found. 0.6 mm
shim withdrawn to adjust the top & bottom
clearances and radial keys thickness adjusted as
per requirement after ROLL CHECK

Again, LPT Outer Casing placed on position but it
was impossible to jack and put the dowel pins and
do further tightening of the bolts at the both left &
right front side.
At this condition hand turning was done and no
abnormal rubbing sound was further observed
So, decision was taken to cut the LP Outer Casing

with confirmation from OEM, M/s Fuji Electric. Turbine
LPT Outer Casing cut at the center in between the
ribs by cutting and grinding tools Outside Welding complete at position as per
WELDING SEQUENCE – DPT done. Then inside
welding done after removal of casing from position
with subsequent DPT
Bolt hole machining, flange matching done –
packings replaced. LP diaphragms replaced

After edge preparation, both the halves had been
placed in position
Gaps checked at full tight condition - bridge

welding done between them and welding done as
per Quality Plan

Again, LPT Outer Casing placed in position – gaps
checked at bolt tight condition

55

After confirmation of zero clearances at almost all Turbine
points both externally and internally, again bolts
were freed, LP Outer Casing lifted up, stag seal Side by side the DAMAGED insulations are
added between flanges and final box up done with removed and further new insulations were
additional fixtures, clamps and wedges. Rotor & done. The DAMAGED instrument cables were
guide corn clearance checked again & found ok. replaced along with calibration of all Turbovisory
parameters. There was no decoupling & rotor
disassembly required during this process, as the
barring was found free with hand & oil support.

Hood spray piping & Bellows again assembled
after replacement of the gaskets & Bearing 1,
jacking lift was adjusted for the fluctuating JO
pressure

Turbine put on Turning Gear after subsequent
hand turning operation
Vacuum Pulling done on 2nd July 2011 and over
704 mm Hg was witnessed and further rolling
& synchronization were done normally on 3rd
July2011, 05:50 am

**** As a remedial measure the isolation valve of
the pressure gauge of TURNING OIL SUPPLY LINE
is kept closed at all the Units when not in use .

Turbine

A brief report on 1st capital OH of
500MW KWU turbine of SgTPP #4

Arghya Kanti Kar INTRODUCTION:

Manager(T&A), SgTPP, WBPDCL As the steam turbine is the most important
9 years of experience in Operation component in the power generation system of
a thermal power plant, and the reliability of its
& Commissioning, 6 years of operation is a key factor to improve the operational
experience in Turbine maintenance. safety of the thermal power plant. Unit-4 (500MW)
of Sagardighi Thermal Power Project was suffering
Abstract: from high vibration problems since its inception to
The steam turbine is one of the grid.This article describe the entire journey to resolve
most critical equipment in the the long pending problem by carried out capital
overhauling of turbine within a stipulated period of
power generation system of time. It was the 1st Capital Overhauling carried out
thermal power plants, its timely during July-August 2021 by M/s BHEL.

overhaul will directly affect HISTORY:
whether the power generation
system can operate safely and It is a 500 MW unit with single flow HPT, double
stably. However, some faults flow IPT and LPT. The machine was declared for
commercial generation on 20.12.2016 but it was
unavoidably appear in the suffering high shaft vibration at different point. In
steam turbine in the long- order to rectify that issue several time rework done
term operation, if these faults time to time.
are not rectified in time may
causes the turbine to fail to During Oct-Nov. 2016 all bearing checking done
operate normally and affect the including UT, Generator-Exciter coupling checked
normal work of thermal power but no such improvement noticed.
plants. Sagardighi Thermal
Power Project of The West During Feb 2017, bearing no-4&5 checking done, but
Bengal Power Development no such improvement noticed.
Corporation Ltd.(A Govt. W.B
UT) is a major contributor to the During June-July2017 rework done to rectify high
grid with a present generation vibration problem including all bearing checking,
capacity of 1600MW in the decoupling & realignment of total TG shaft, all critical
manner of Stg-I of M/s DEC check done but still no such improvement observed.
make 2x300 MW units and Stg-II
of M/s BHEL make 2x500 MW During April-May-June 2018 again rework done for 64
units. The 5th Unit of 660 MW is days including all bearing and turbine critical checking
done. Shim added between HP-IP coupling to achieve
under construction desired swing check value. A little improvement
noticed but again started to deteriorate after few
months.

Trim balancing also done time to time. Total 5 times
trim balancing done with 27 nos. of rolling.

Ultimately we decided to go for capital overhauling
to resolve the issue and it was commenced from
04.07.2021.

CAPITAL OVERHAULING OF KWU 500MW
SET:

Capital OH commenced from 04.07.2021 after fast
cooling of turbine rotor which save almost 5 days.

57

Many abnormalities found and all were corrected. Turbine
HPT casing is connected to HPControlValve casing
by means of Breech Nut at both sides. To lift the Several attempts were made with CO2 gas, dry ice
HPT casing it is necessary to unscrew the Breech and external heating with pulling from EOT crane
Nuts. A major obstacle faced during dismantling but not succeed. Ultimately the Breech Nut was
of HP turbine was the unscrewing of Breech Nut. cut to lift HPT casing.
Left side Breech Nut got stuck after few threads. To fit new Breech Nut it was required to cut HP
Inlet Insert. A specialized agency was engaged to
cut 150 mm thick HP Inlet Insert with special type
of Pneumatic Orbital Cutting Machine.

Old HP inlet Insert fitted up with new Breech
Nut after edge preparation of both ends. After
HPT module placement , Inlet Insert alignment
done and the Breech Nut tightened fully with the
HPT casing and preparation for welding process
started.
Welding done in four stages of 30mm, 60mm, 90mm & 150mm thickness. Every step consist of

Preheating Welding up Controlled Natural
up to 350 to requisite Cooling up Cooling up
deg C thickness to 150 ° C to Ambient
Temp.

DPT and DPT and RT Grinding Of
UT Above up to 90mm Upper surface
90mm for NDT.

Turbine

Post weld heat treatment along with final MPI, UT, DPT & Harness test of the joint also done.
Welding electrode used 9018 B3

MAJOR FINDINGS AND CORRECTIVE That foreign material causes severe damage
ACTIONS: (dent)on all blades of 16th stage of HPT rotor.
FINDINGS ON HP TURBINE : DPT and MPI done on 16th stage blades on their
HPT rear face run out observed 0.06.The same has presence and no crack observed during inspection.
been corrected. Polishing done on blade profile by BHEL OEM
A heavy weight (approx. 1.125”x2”) foreign representative.
material found in 17th stage stator blade of HPT
inner casing.

Another foreign material was stuck at 1st Stage
fixed blade.Some foreign materials also found
in stuck condition with balancing weight of HPT
rotor at two different positions. Also shifting of
17th Stage HPT stator blades observed and the
same had been rectified.

59

Bearing no-1 bottom part Babbitt found Turbine
damaged. Also pitting observed on torus and
support of all bearings. Bearing replaces with FINDINGS ON IP & LP TURBINE :
new one. Some problem found in IPT & LPT and the same
were corrected like IPT face correction, alignment
correction. All critical checks were conducted and
required correction done. HPT, IPT, LPT rotor
and casing alumina blasting done. Slow speed
balancing of HPT & IPT rotor also done. Critical
piping hangers of also checked.
All Stop & Control valves, MS & HRH strainer
servicing done.
After correction of all anomalies machine put
on barring gear on 18.08.2021 and after trim
balancing it was synchronized on 19.08.2021
Our main aim of capital overhauling was to
rectify long pending high vibration trouble and
a significant improvement of vibration level has
been observed at all loads.

ACKNOWLEDGEMENT:
The entire endeavor and success was achieved by following team members::
Sri Kousik Datta, ED(OS), Corporate Office
Sri Rabindranath Shahoo - GM, OS Cell, Corporate Office
Shri Jyoti Shankar Poddar, DGM(MM),SgTPP,WBPDCL
Shri Shibabrata Bhattacharjee, Sr. Manager & HOD (T&A), SgTPP,WBPDCL
Shri Pronab Guha, Sr. Manager (TM), SgTPP,WBPDCL
Shri Sourav Maji, Manager (TM), SgTPP,WBPDCL
Shri Biswajit Sharma, Manager (TM), SgTPP,WBPDCL
Special thanks to Mr. Promit Mukherjee , Engineer, M/s BHEL

KTPS switchyard

It’s not that we use Technology
We live Technology

Godfrey Reggio

BTPS Plant

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Readers’ Feedback

The 1st issue of WBPDCL’s professional journal PARADIGM has been published.
This is really a proud moment and when I even see it, I feel proud as a member of WBPDCL family.
1. The content are very rich and informative. It is having both technical and practical papers and when the senior
official are writing the papers are becoming very interesting and definitely widening the horizon of the readers.
2. Editorial part is very professional.
3. Printing and cover design are excellent.
Only thing is that the topics can be more divergent including Boundary management, Mining, Regulatory affairs
etc. Hope this will be done in coming issues. overall the journal is very attractive and at the same time informative.
I hope that like me all will be enriched. Awaiting for release of 2nd issue.

Susnata Aich

EXECUTIVE DIRECTOR (FUEL MANAGEMENT)

Nice to see sense and sensibility prevails in “Paradigm” over and above salability.
Wish to have more in future.

Abhijit Nandi

DGM (O & M-IC); SGTPP

A book is not to be judged by its cover. Yet the human brain is so conditioned as to judge.”Paradign” is truly a
paradigm shift for a professional journal.The article that I could most relate to is “ demographic study of Sg.T.P.P
. …. pandemic”. During the turbulent times of this unprecedented pandemic ,we at Sg.T.P.P Medical unit were in
dire need of some beacon of light to glide through.This study guided us substantially. Being a woman of Medicine
it would be a lie to state that I could fathom all the other texts. But some write ups that appealed were “ Fossil Fuel
and us”,” Journey with hydrogen “ and “ information security “.The first two have intrigued me to know more and
the last is such a fluid conversation on modern day menace i.e. spyware.Hope this endeavour continues to keep us
enthusiastic while grinding through everyday mundane jobs. All the best to “ paradigm”.

Soma Majumdar

Senior Medical Officer, SgTPP

PARADIGM is the first technical journal published by WBPDCL management. Goal of its journey is well reflected
in 18 informative articles. Continual analysis of its challenges and adopting optimal solution for the organization
is the most important managerial duty. Both hon’ble ACS, Dept. of Power, Govt. Of West Bengal and hon’ble
CMD indicated exploration of alternative source of energy and new technology like carbon capture and storage as
essential for survival of coal based power industry. A solution has been reflected in the write-up on use of hydrogen
as alternative source of energy by DGM (Engg.) - O & M Incharge, SgTPP. FGD technology is also discussed in the
article of Mgr (P & P). Director (O & M) described about the strength of our organization by statistical figures. CVO
& Ex-officio Director, provided the lesson learning and suggestion for developing professional approach to handle
unexpected situation. DGM (IT & C), Corporate Office shared his knowledge on information security and cyber
threats. Adaptation of medicos & Hr & A team to combat pandemic , good technical solution to reduce downtime,
to overcome problems faced in various plants, modification necessary for compliance of environmental regulation
are well documented in the journal.

Dipankar Sengupta

DGM(R & M)

We, the WBPDCL family comprise of different unit size of different plants and the lengths of operation of the
units are different. Although we have quarterly magazine “Prasanga Vidyut”, but it mainly deals with the events of
different plants. So, we had a lack of printed professional technical platform for sharing technical issues like other
esteemed organizations. In the sense PARADIGM is the most awaited professional journal which revealed itself as a
quench of thirst. We are overwhelmed to see the first issue of
PARADIGM (Jan-Mar 22) and want to congratulate the apex management for the birth of the technical journal.
The first issue has been arranged topic wise across all sections very precisely (Eighteen numbers of contents from
different wing). The content covered diversified issues like present condition of fuel, alternative fuel, and intricate
successful technical modifications, role of HR for smooth functioning, motivation and coordination, financing
dynamics of fossil fuel powered sector, upcoming technologies for environmental compliance, different studies
during pandemic by medical department make the first volume very enrich in knowledge and futuristic approach.
The size and volume of the journal is well balanced with super printing quality. We are mainly O&M Company with
diversified wing such as Project, Mining, R&M. So there are enormous technical issues to come up in future with
local solutions by our able employees and we hope the experience will be shared through this platform.We also
expect every issue will work as authentic data bank for future operations of organization. It is a coincidence to say
that PARADIGM has started its journey when WBPDCL achieved best ever performance and glittering in the Energy
Map of India.

Tamas Ranjan Mukherjee

Manager(PS),C&I,Stage-II, SgTPP

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SgTPP floating solar on raw water pond

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The West Bengal Power Development Corporation Limited
(A Government of West Bengal Enterprise)

Corporate Identity No. U40104WB1985SGC039154
Registered & Corporate Office: Bidyut Unnayan Bhaban, Plot No. 3/C, Block-LA, Sector-III
Bidhannagar, Kolkata-700106 | Email: [email protected] | Website: www.wbpdcl.co.in