ERECTION STRATEGY FOR BOILER –
NTPC RIHAND STPP STAGE - 2
BASIC STRATEGY:
Basic strategy shall be to go in for cycle time reduction in every area by
taking up erection of all possible fronts Parallelly , system completion at first
go itself and by applying innovative ideas and modern erection practices. To
achieve this we shall have highly experienced and effective execution team
posted at site with back up of strong infrastructural support made available
to them. They shall be always aiming for achieving the project milestones as
planned by changing the intermediate course of direction depending on
availability of inputs. The infrastructural support and basic erection
sequences / strategy are explained below.
SUBCONTRACTING STRATEGY:
Subcontractors shall be finalized from the list of vendors duly approved by
NTPC (as applicable as per agreement) for following packages,
1) Main boiler and Rotating equipments
2) ESP and Flue gas duct beyond boiler
3) Power Cycle piping
4) Lining and insulation
INSPECTION & QUALITY:
An exclusive ‘Quality group’ at site ensures all installation checks and stage
protocols with respect to approved quality plans for individual system,
involving Consultant/ Customer representatives.
In addition to this, to ensure system completion, before execution of a
defined Mile Stone activity during installation, an audit team from PS-WR HQ
visits the site before Construction Manager is permitted to execute the Mile
Stone activity.
SAFETY:
An exclusive officer shall be deployed at job site to guide, monitor and
control all HSE related activities as per company’s HSE instructions. He shall
directly report to Construction Manager. Also our erection agencies shall
nominate exclusive safety supervisor to assist us.
MATERIAL MANAGEMENT:
Unique identification system for components is utilized by all BHEL units. A
strong team of officers and supervisors shall keep intensive track records of
dispatches, receipt, storage and issues of components using modern
electronic media.
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On receipt, components shall be inspected and verified before storage.
Exclusive Material Receipt cum Inspection Reports shall be prepared along
with Consultant/Customer representative.
Components shall be stored in Open, Semi-closed, closed or special
environment conditions as applicable. They shall be preserved during storage
and installation stages as per the instruction given in our preservation
manual.
A comprehensive tracking system, with appropriate records shall be
maintained for all issues.
DOCUMENTATION AT SITE:
A totally computerized documentation system shall be adopted at site to
keep track of total drawings and manuals required to complete installation to
ensure proper monitoring of receipt, issue and revisions.
FACILITY ENGINEERING AT SITE:
An exclusive executive shall be deployed to supervise and monitor the
availability of T&P’s being provided by BHEL.
TOOLS AND PLANTS:
Sufficient numbers of T&P s shall be deployed either by BHEL or by their
erection agencies.
MANPOWER DEPLOYMENT:
Sufficient number of BHEL staff shall be posted for installation of this
package.
Following shall be tentative manpower (main category) deployment plan per
unit by erection agencies;
Boiler erection agency: Engineer- 7 , supervisors- 15 ,Rigger foreman- 2 ,
Fitters- 27 , Structural welder – 30 , HP welder – 12 , Gas cutter - 4 ,
Grinder – 10 , SR technician – 4 , Radiographic Technician- 4
ESP erection agency: Engineer- 1 , supervisors- 4 ,Rigger foreman- 1 ,
Fitters- 12 , Structural welder – 15 , Gas cutter- 2 , Grinder-2
Piping erection agency: Engineer- 3 , supervisors- 6 ,Rigger foreman- 2 ,
Fitters- 12 , Structural welder – 10 , HP welder – 10 , Gas cutter - 2 ,
Grinder- 6 , SR technician – 4 , Radiographic Technician- 4
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ERECTION SEQUENCE:
BOILER SUPPORTING STRUCTURE:
Main supporting structure columns (Nos. S1to S6 L&R, S7 to S12 L&R,
S13L&R, shall be erected in following combinations:
Bottom tier - single piece
2nd & 3rd tier combined with Tata 75 MT and Link Belt LS 248H
4th & 5th tier combined
6th & 7th tier combined ---------------- with FMC LS 718 HLA 330 ft boom
+ Jib
All connected horizontal beams, MBL members, and vertical diagonal
bracings as required to maintain verticality of the columns shall be erected
before proceeding to next level. All MBL members between box of four
columns shall be judiciously pre assembled on ground to ensure better
workmanship and speedy erection. Erection of all balance items of such
components shall precede parallels and shall be completed prior to ceiling
girder lifting.
It may be noted that all columns for Rihand shall be trial assembled in full
length at Trichy, hence pre assembly and joint matching at site shall not be
required.
Once the structure as mentioned above are erected and verticality of
columns are ensured Ceiling girder erection shall start. Ceiling Girder
Erection shall be done in following sequence:
With 1st rigged position of FMC - Girder '0', Girder-A, Girder-'B'
With 2nd rigged position of FMC -Girder-'C', Girder-'D'
With 3rd rigged position of FMC - Girder-'E'
Ceiling girders will be supplied in three pieces and shall be pre assembled on
ground before lifting. It may be noted that casting of foundation
pedestal of FD fan-B to be hold till ceiling girder C&D is shifted to
boiler cavity after pre assembly. Also it may be noted that the bottom
most vertical diagonal bracing between columns S10 R&S11R will not
be erected for this purpose. Designer clearance towards this is already
obtained.
For erection of structure as mentioned above the basic sequence of erection
will be from front to rear i.e. from Row-D to L keeping the crane inside boiler
cavity. Entries of cranes are envisaged from right side of boiler through rear
of boiler i.e. from between boiler rear and mill bay col. i.e between Row-L&M.
For movement of crane inside boiler cavity it will be necessary to hold
erection of middle /air pre heater columns namely Columns Nos.
S15L&R , S16L&R, S17, S18, S19L&R, S20L&R, S21, S24R, S25R,
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S29R,FH-11R,FH-12R, Mill bay M & N row columns. Also it should be
ensured that the foundation pedestals of columns S15L&R, S16L&R,
S17, S18, S19L&R, S20L&R, S21, Mill bay M row cols 2nos at center
do not project above ground.
Columns nos. S15L&R, S16L&R and its connecting bracings will be erected
as soon as FMC moves out to clear the area after Ceiling girder A&B is
erected, but necessarily have to be erected before Ceiling girder –C erection.
Columns nos. S17 , S18 and its connecting bracings will be erected as
soon as FMC moves out to clear the area after Ceiling girder C & D is
erected , but necessarily have to be erected before Ceiling girder –E
erection.
Columns Nos S14L&R and its connecting bracings shall be erected
immediately after boiler drum is erected.
Erection of balance columns Nos. S19L&R , S20L&R , S21, S22L&R , S24L&R
, S25L&R , S26L&R , S27L&R , S28L&R , S29L&R and its connecting bracings
shall be erected independently after ceiling girder erection is completed and
FMC crane is moved out.
BOILER DRUM UNLOADING AND ERECTION:
In case of unit-3 the boiler drum will be received by rail near to boiler LHS
i.e. co-ordinate approx 2075N, 2250E. Boiler drum will be unloaded with the
help of two cranes namely LS248H 180MT and Manotowoc 250MT by the
boiler erection agency. The drum then shall be dragged onto temporary rails
to boiler cavity.
In case of unit-4 the boiler drum will be unloaded at the same location and
the drum shall be dragged on to temporary rails to unit-4.
Boiler drum will be lifted in single stage with help of two nos 15MT electric
winches and pulleys suspended from temporary structure (will be either
fabricated at site or will be diverted from other site) at top. Winches will be
placed in front of ESP and will be anchored with the help of concrete
counterweights of FMC crane placed in pit. After the drum is aligned the
lifting arrangement will be removed and pressure part erection will follow.
PRESSURE PART ERECTION AND HYDRAULIC TEST:
Being top suspended type of boiler, general sequence of erection of
pressure part will be from top to bottom and from outside to in side . Actual
sequence of erection will be decided at site depending on the sequence of
material receipt at site. However our aim shall be to go for maximum
possible pre assembly of pressure part components on ground or
optimization at works , so that to reduce numbers of lifts and to achieve
better quality which will effectively reduce erection cycle time.
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Following pre assemblies / optimization at works are envisaged:
a) All headers above roof will be assembled in single piece
b) All possible assemblies to handle able sizes in lines and links above
roof
c) All crown plates with end bars for coil suspension above roof
d) Furnace radiant roof – Front - in seven assemblies (each block of
suspension arrangement), Inlet header shall be lifted separately in
single piece and joining with tubes shall be done in position. Rear – in
two assemblies (each block with piece of out let header )
e) Back pass furnace roof with all hanger tubes above it along with inlet
header in single assy.
f) Back pass front wall hanger tubes with suspension end bars.
g) Back pass front wall upper with lower panels
h) Back pass side wall upper panels to inter panels
i) Back pass rear wall upper panels to inter panels
j) Back pass rear lower walls with two headers(complete assy)
k) Extended water wall upper panel with lower(individual)
l) Furnace rear wall upper panels with hanger tubes and arch tubes(
individual panel)
m) Burner panels with lower inter panels ( individual panels)
n) Furnace side Lower inter walls with lower walls ( individual panels)
o) Furnace front and rear lower panels with floor panels( individual
panels)
p) LTSH upper coils to lower coils. ( individual coils)
q) Economizer upper with intermediate coils( individual coils)
r) Sh. Divisional panels front assy to rear assy (individual panels)
s) Furnace bottom Z panels with floor panels and loose tubes
t) All buck stays with stirrups and key buck stays
u) Super heater and Re heater spray control stations
However a judicious re look into above assemblies will be essential after
detailed engineering of pressure part is completed.
Material feeding for first pass will mostly be done from RHS of boiler
between columns S8&9 on temporary rail. For back pass material shall be
fed from rear side. Also modern erection practices like use of omega lugs,
anti deformation frame for handling of Eco , Super heater and Re heater coils
, special lifting tackle for coil lifting will be inducted for safe and quicker
erection of pressure part.
Hydraulic test of boiler will be done in three parts. Drainable part includes
the circulation system and drainable portion of the super heater. During this
the link connecting the non drainable portion of super heater shall be
dummied. This will facilitate early clearance for insulation of water walls
and back pass walls required for light up. Non drainable part, which
includes the non drainable portion of the super heater system also, will be
done just prior to boiler light up so that preservation and rusting of super
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heater system can be avoided. Re heater hydraulic test shall be done along
with reheat system piping before steam blowing operation.
AIR AND FLUE GAS DUCTING ERECTION:
Air and flue gas ducting erection shall be taken up parallelly with boiler
pressure part so as to reduce the gap between boiler hydro test and light up.
Almost all duct (excepting duct like below back pass U-headers etc. ) shall be
pre assembled on ground and shall be kerosene tested to reduce ,number
of lifts and work in position which will in turn reduce erection cycle time.
The assembled duct will mostly be fed with help of crane from sides of
boilers. However the inter connecting hot secondary air duct will be
assembled below boiler, for straight lift.
AIR PRE HEATER ERECTION:
Air pre heater erection shall be taken up immediately after the structure is
getting ready after ceiling girders lifting. Most of components will be lifted
with crane (Monitowoc-250MT and FMC –350 MT one on either side)
depending on accessibility which will help in reducing erection cycle time.
FANS ERECTION:
This being independent parallel activity it will be taken up as early as possible
depending on availability of foundations. There is fixed sequence of erection
of fans as specified in erection manual, the same shall be followed strictly.
MILLS ERECTION :
Shall be taken up after availability of foundations. There is fixed sequence of
erection of mills as specified in erection manual, the same shall be followed
strictly. Major components like mill base, air compartment, separator body,
mill top / classifier assy, MDV assy will be placed with crane KH500. NTPC to
coordinate with mill bay structure erection agency regarding hold in
structural bracings etc. for crane approach.
ESP ERECTION:
This is altogether an independent island. ESP erection shall be started as
soon as column foundations and material is available. It has an almost fixed
sequence of erection. In ESP also we shall go for all possible pre assembly
like casing walls, hopper walls etc. Collecting electrode will be inserted from
bottom.
POWER CYCLE PIPING ERECTION:
This will be treated as a highly specialized work, especially in case of P-91
(High Crome alloy steel). The erection can start from any side terminal point,
however normal sequence shall be from boiler end to turbine building as the
boiler side terminal point will be ready earlier. Utmost care shall be taken by
highly experienced engineers / supervisors w.r.t. welding , preheat / post
heat treatment of welds , NDT , free floating of lines before connecting to
equipments.
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SPECIAL ERECTION PRACTICES:
Following special erection practices will be followed,
1. Permanent flooring of boiler cavity prior to BES: NTPC to
provide permanent flooring in boiler cavity (leaving the area for
foundations under hold), around boilers and below ESP before start of
erection. This will create a very convenient work atmosphere which will
help us in maintaining good house keeping also it will avoid
unnecessary re handling of material / temporary installations to
facilitate flooring at later stage.
It may be noted that the flooring should have load bearing capacity of
2.5 Kg/Cm2
2. Usage of passenger cum goods erection elevator: BHEL shall
provide one no. of passenger cum goods elevator in each boiler which
will be installed by our erection agency. This will transport people and
gas cylinders to higher location which will help in effective supervision
and higher productivity.
3. Usage of waste disposal chute: BHEL shall provide and erection
agency will install one no. waste disposal chute in each boiler running
vertically with branch in each floor.
4. Construction Power distribution system : BHEL shall ensure that
erection agencies follows a standard construction power distribution
system as explained below,
a) Agency for Main Boiler package:
They will lay individual construction power cable from main Sub Station
to DBs for individual welding generators booth at 5 locations as follows .
These DBs will be provided with ELCB’s and the cables will be run
underground before reaching boiler island and within the boiler island the
cable will be run on cable trays (vertical run will be along column no.
S12L&R)
o On ground floor between column box S11L-12L-6L-5L – will
have provision for 10 welding m/cs - 200 Amps – from SS- 9
for U-3 from SS – 10 for U-4
o On boiler floor at 18M elevation between column box S11R-12R-
6R-5R- will have provision for 10 welding m/cs – 200 amps –
from SS –8 for U-3 from SS – 13 for U-4
o On boiler floor at 31M elevation between column box S11R-12R-
6R-5R- will have provision for 10 welding m/cs – 200 amps –
from SS-9 for U-3 from SS – 10 for U-4
o On boiler floor at 62 M elevation between column box S9L-10L-
4L-3L- will have provision for 10 welding m/cs – 200amps –
from SS-8 for U-3 from SS – 13 for U-4
o In pre assy yard – for 10 m/cs –200 amps – from SS-6
Tentative quantity of Cable 240sq.mm, three core, Al. cable – 2000 M
and cable tray 8” – 500M, DB (200amps) – 5 per boiler will be
required.
All such DB’s will cater the need of power supply for Post Weld Heat
Treatment also.
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Above locations of DB and booth installation and routing of Power
cable for above are indicative, exact location shall be decided at site in
consultation with NTPC.
Other than welding booth they will provide a power distribution board
every after two floors with at least ten points, with standard industrial
socket arrangement for miscellaneous use of hand tools and hand lamps.
These boards will be connected with nearest DB of welding booth
b) Agency for ESP and ducting:
They shall lay construction power cable from main Sub station to DB
for welding booth as follows
At ground floor on LHS of ESP – 10 welding m/cs – 200 amps –
from SS-9 for U-3 from SS – 10 for U-4
At ground floor on RHS of ESP – 10 welding m/cs – 200 amps–
from SS-8 for U-3 from SS – 13 for U-4
DBs will be provided with ELCBs. The cables will be run underground
before reaching ESP island and within the ESP island the cable will be run
on cable trays.
Tentative quantity of Cable 240sq.mm,three core ,Al. cable – 600 M
and cable tray 8” – 150M No. of DB (200 amps )-2 per ESP will be
required.
Above locations of DB and booth installation and routing of Power
cable for above are indicative, exact location shall be decided at site in
consultation with NTPC.
Other than welding booth they shall provide a power distribution board
at least ten points one casing manhole door platform and one in pent
house of each pass, with standard industrial socket arrangement for
miscellaneous use of hand tools and hand lamps. These boards will be
connected with nearest DB of welding booth.
c) Piping erection agency: They shall lay construction power cable
from main Sub station (No. to DB for welding booth as follows:
At 4.5 M in B- C bay near column 48- 10 welding m/cs - 200
amps + 1 induction heating m/c – 200 amps from SS-7 for
both units.
On boiler floor At 31 M near col. S7L will have provision for 10
welding m/cs – 200 amps. Induction Heating m/c will later be
shifted from 62M along with power cable to 31M from SS-7 in U-
3 and from SS-11 in unit-4
On boiler floor at 62 M elevation between column box S9L-10L-
4L-3L- will have provision for 10 welding m/cs - 200 amps -
from SS-11 in both units + 1 induction heating m/cs – 200amps
from SS-7 in both units.
The cables will be run underground before reaching boiler island and
within the boiler island and in power house the cable will be run on cable
trays . Vertical run in boiler will along cable-S7L
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It may be noted that Sub Station (SS) -7 shall be provided with back
up DG set power supply to avert power failure to Induction Heating M/c.
Tentative quantity of Cable 200sq.mm three core al. cable – 2000 M
and cable tray 8” – 500M, DB (200apms) - 5 per boiler will be required.
Other than welding booth they shall provide a power distribution board
at least ten points at least in five suitable locations, with standard
industrial socket arrangement for miscellaneous use of hand tools and
hand lamps. These boards will be connected with nearest DB of welding
booth.
Above locations of DB and booth installation and routing of Power
cable for above are indicative, exact location shall be decided at site in
consultation with NTPC.
Location of substation and tentative routing of construction power
cables is shown in Annexure-8
.
5. Winch locations : selected number of winch will be positioned as
follows by our erection agencies,
Boiler Area:
a. 2 nos of 5MT winch on ground floor near S5L and near S5R
b. 1no of 3 MT winch on boiler floor at 50M near column S4R
c. 2 nos of 2MT winch on boiler floor at 75 M near column S4R and
S4L
ESP area:
No winch is envisaged for ESP erection
Piping area;
a) One 3MT winch on LHS near column no. S7L
b) One 3MT winch on LHS near column no. S7R
Operation of all these winches shall be controlled by Walkie Talkies
from remote. Locations of the winches are indicative. Actual location
can be decided at site.
6. Gas cutting sets: Our erection agencies shall use a set of one DA
cylinder and three oxygen cylinders mounted on trolley to be operated
on ground floor. Also for transportation of such gas cylinders they shall
use hand trolley.
7. Small Workshop: Our erection agencies shall install small workshop
containing drill m/c and bench grinder.
8. Erection Techniques: Following erection fixtures will be used for
pressure part erection. this will ensure safe and faster erection of
pressure part coils / panels,
a) Omega lugs: An attachment made of tubes and flat will
be welded to pressure part tubes will be used to hang
and align pressure part headers to panel, panels to
panels, panels to headers , hanger tube to coils , coils to
coils etc. BHEL Trichy shall supply the lugs along with a
load table. PSWR shall arrange for bolts. Location at
winch the lugs to be welded shall be decided by
engineers at site and shall be welded accordingly prior
to lifting of components. This will help in quick erection
of pressure part components and will facilitate easy
alignment.
b) Lifting Tool for pressure part Coils: This is a hinged
type clamp which develops grip due to self weight of the
component being lifted.. This will be fabricated at site
by our erection agency. This will be used to lift pressure
part vertical coils of super heaters and re heaters.
c) Anti deformation frame for coils: The anti
deformation frame will be fabricated ( considering
actual size of coil ) at site and used for handling longer
and heavy pressure part coils like Platen super heater ,
re heater front , super heater division panel , assembled
LTSH / ECO coils , to avoid permanent distortion while
lifting..
d) Floating Pulley system for LTSH and economizer
coil erection: An arrangement of a ropeway and a
floating pulley will be used for erection of LTSH and
Economizer coils. This will reduce erection cycle time to
great extent otherwise we would have lost lot of time in
changing lifting arrangement after every few coils.
e) Erection method of Super heater hanger tubes: a
very simple method of lifting SH Hanger tube will be
used which will facilitate faster erection.
f) Temporary Rail for material feeding: A temporary
rail line will be laid between boiler column no. S8-S9
through and through both boilers. Boiler pressure part
materials like water wall panels and SH/RH Coils will be
transported on to this rail with help of dip trolley. The
rail will be laid on sleepers at 1m spacing. For
transportation / dragging of boiler drum over the same
rail continuous sleepers will be laid for two lengths of
drum and rolled on. Requirement of material for this
purpose will be as follows,
Rail - 350 RMS
Sleeper – 400 nos. (200 for normal material feeding +
200 will be used for drum dragging)
Rail coupler / fish plate with fastener – suitable for 350
RMS rail
Rail fixing clips – suitable for 350 RMS rail
The portion of rail between two boilers will be made
removable type ( in panel form ), so that the same can
be temporarily removed to give access to other agency’s
T&P movement.
g) Temporary Urinal System : A header of 4”PVC pipe
shall be run on column S7R with urinal pan connected to
10 floors minimum on boiler and with suitable
underground pit arrangement.
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MATERIAL FEEDING AND CRANE PARKING DURING BOILER
ERECTION (major portion):
i) For main boiler supporting structure erection up to drum lifting
:
Crane movement / Parking: within boiler cavity.
Crane: FMC LS 248H 180MT from 1st to 3rd month, FMC LS 718 with
ringer and 330’ boom and jib thereafter.
Tentative Duration: from 1st to 5th month from BES of each unit.
Material feeding:
Unit-3-
From Storage yard / pre assembly area by road though Unit-4
(either between mill bay-M row and boiler rear or between mill bay N row
and ESP)
Unit-4 –
From Storage yard / pre assembly area on road
ii) Pressure part erection:
Crane: All erection will be done with help of winches. For unloading of
material 75 MT crane will be located on RHS of each boiler.
Tentative Duration: from 6th to 18th month from BES of each unit
Material feeding:
Unit-3-
From Storage yard / pre assembly area by road though Unit-4 (either
between mill bay-M row and boiler rear) then on rail to boiler cavity in
case of first pass and through boiler rear in case of second pass. After
drum lifting of unit- 4 is over the materials can be fed on temporary rail
through boiler-4
Unit-4 –
From Storage yard / pre assembly area on road then on rail to boiler
cavity in case of first pass and through boiler rear in case of second pass.
iii) For balance component like roof structure, silencer, duct, air
pre heaters, fans (FD and PA) erection:
Unit-3 LHS –
Crane: Manitowoc –250MT (6th to 10th month ) , LS 248H (10th to 18th
month)
Tentative Duration: from 6th to 18th month from BES of unit-3
Material feeding:
From Storage yard/ pre assembly area by road though Unit-4 (between
mill bay-M row and boiler rear or between mill bay N row and ESP)
Unit-3 RHS –
Crane: FMC LS718 –350MT ( 6th to 12th month ) , Manitowoc –250MT (
12 th to 18th month )
Tentative Duration: from 6th to 18th month from BES of unit-3
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Material feeding:
From Storage yard/ pre assembly area by road though Unit-4
(between mill bay-M row and boiler rear or between mill bay N row and
ESP)
Unit-4 LHS –
Crane: Manitowoc –250MT (6th to 18th month from BES of Unit-4)
Material feeding:
From Storage yard/ pre assembly area on road though Unit-4
(between mill bay-M row and boiler rear or between mill bay N row and
ESP)
Unit-4 RHS –
Crane: FMC LS 718 – 350 MT (6th to 18th month BES of Unit-4)
Material feeding:
From Storage yard/ pre assembly area by road.
iv)Mill erection:
Unit-3
Crane: KH-500
Tentative Duration: 14th to 20th month from BES of unit-3
Material feeding:
From Storage yard / pre assembly area on road though Unit-4 (
between mill bay-M row and boiler rear or between mill bay N row and
ESP)
unit-4
Crane : KH-500
Tentative Duration: 14th to 20th month from BES of unit-4
Material feeding :
From Storage yard / pre assembly area on road
v) ESP erection:
Crane movement / Parking: all around ESP island
Crane: 75MT , KH500
Tentative Duration: 1st to 18th month from ESP erection start of each
unit
Material feeding :
Unit-3 –
From Storage yard/ pre assembly area on road though Unit-4
(between mill bay N row and ESP & between ESP and ID fan)
Unit-4
From Storage yard/ pre assembly area on road
HOLDS ON CIVIL FOUNDATIONS / OTHER CONSTRUCTION :
a) Civil Foundations: S15L&R, S16L&R, S17, S18, S19L&R, S20L&R,
S21, Mill bay M row columns 2nos at center and FD fan –B (RHS) in
each boiler
This is required for erection crane movement / parking inside boiler
cavity and for ceiling girder pre assembly as explained in erection
sequence.
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Hold lift – Hold shall be lifted as soon as crane is moved out after
ceiling girders erection i.e. 5th month from boiler erection start.
Agency to act: NTPC
b) Other Construction:
i) Mill bay ‘M’ & ‘N’ – row structure in each unit
This will be required for FMC entry / exit and parking during boiler
structure erection in each unit.
Hold Lift: Hold shall be lifted as soon as crane is moved out
after ceiling girders erection i.e. around 5th month from boiler
erection start.
Agency to act : NTPC
ii) Inter Connecting Duct / platform between boiler and mill
bay in each unit :
This is required for moving out erection crane parked on LHS of
boiler for erection of roof structure / fans / APH
Hold Lift: the hold is planned to be lifted in 12 th to 14 th
month from BES.
Agency to act: BHEL
iii) Duct support structure between mill bay and ESP in each
unit:
This will be required to facilitate crane movement for Mill
heavier components and ESP erection.
Hold lift: the hold is planned to be lifted progressively from 18th
month from BES
Agency to act: BHEL
iv) Duct support structure between ESP and ID fan:
This is required to facilitate crane movement for ESP erection
and ID fan heavier component erection.
Hold Lift: Hold is planned to be lifted progressively from 14th
month from Boiler erection start.
Agency to act: BHEL
v) Mill bay N row bracings :
This will be required to facilitate crane approach for erecting mill
heavier components. The particular bracing items need to be
hold will be decided at site in consultation with NTPC.
Hold Lift: hold is planned to be lifted progressively from 14th
month of BES
Agency to act : NTPC
ADDITIONAL INPUTS (Not Envisaged Originally ) TO BE TIED UP :
By NTPC :
a) Hold on foundations / structure as mentioned above
b) Finished flooring in / around boiler island and below ESP
c) Finished flooring / consolidated area for laying temporary rail
By BHEL :
a) Temporary rail / sleepers etc.
b) Bolt for omega lugs
c) Temporary structure for drum lifting
d) DESH Link temporary Dummy plates for non drainable HT
e) DG set 500KVA for Induction Heating m/c
By erection agencies:
a) Construction Power Distribution board
b) Construction power cables
c) Cable trays for above
d) Portable Cutting Gas cylinder skid
e) Cutting gas cylinder transportation trolley
f) Small workshop
g) Walkie talkies for winch control
h) Urinal arrangement on boiler
TENTATIVE ERECTION PLAN : With all above we shall complete
erection of boiler package as per the plan enclosed .
ERECTION STRATEGY IS A BASIC DOCUMENT TO BE FOLLOWED
HOWEVER FOLLOWING CHANGES ARE MADE BASED ON
ERECTION FEEDBACKS AND SITE CONDITIONS:
1. Proposed temporary rail track between boiler columns no. S8-S9
through and through both boilers and up to pre assembly yard
(refer annexure 6) was restricted to cover the boiler cavity of
each boiler between column S8 & S9, since inter connection
between two boilers and boiler 4 to pre assembly yard was
obstructing the erection work of civil agencies.
2. For unloading of boiler drum for unit#3, 2 nos 75MT and 1 no
150MT (KH700) cranes were used instead of 1 no 150MT
(LS248) and 250MT ( Manitovoc) cranes.
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