500 MW Stator Lifting

Report on 500 MW Generator Stator Unloading , lifting and placement in TG Floor foundation at NTPC Kahalgaon - Stage-II for Unit # 5 & 6 ( 3 X 500 MW )

Brief History

As a standard practice followed earlier by BHEL-Power Sector Regions , the operation of  unloading , lifting and placement on TG Foundation for 500 MW Generator Stator  weighing around 265 MT for Thermal Power Stations used to be done with the help of  Portal Crane arrangement. At present 2 such Portal Crane sets are available with BHEL for  above type of jobs. In case of Kahalgaon Stage –II ( 3 X 500 MW ) , Portal crane was not available as the both the sets were pre-occupied for the projects under execution by PSSR & PSWR. To come out with a solution ,BHEL/ PSER/Kahalgaon Site started exploring alternative alternative feasibility in lieu of Portal Crane for doing stator unloading , lifting from zero meter and  placement on TG Floor foundation at 17.00 meter elevation. The idea of using strand jack method was thought as an alternative as Boiler Drum lifting was done for Kahalgaon Unit #5 , 6 & 7 ( 3 X 500 MW ) by this method. The concerned agencies M/s Fagioli PSC and M/s Freight Wings who have executed the job for 500 MW Boiler Drum Lifting weighing around 244 MT at an elevation of around 78.00 meters elevations were shown the details of the job. Both the parties have shown keen interest and  presentations were made by both the parties to NTPC and BHEL.

Brief History

As a standard practice followed earlier by BHEL-Power Sector Regions , the operation of  unloading , lifting and placement on TG Foundation for 500 MW Generator Stator  weighing around 265 MT for Thermal Power Stations used to be done with the help of  Portal Crane arrangement. At present 2 such Portal Crane sets are available with BHEL for  above type of jobs. In case of Kahalgaon Stage –II ( 3 X 500 MW ) , Portal crane was not available as the both the sets were pre-occupied for the projects under execution by PSSR & PSWR. To come out with a solution ,BHEL/ PSER/Kahalgaon Site started exploring alternative alternative feasibility in lieu of Portal Crane for doing stator unloading , lifting from zero meter and  placement on TG Floor foundation at 17.00 meter elevation. The idea of using strand jack method was thought as an alternative as Boiler Drum lifting was done for Kahalgaon Unit #5 , 6 & 7 ( 3 X 500 MW ) by this method. The concerned agencies M/s Fagioli PSC and M/s Freight Wings who have executed the job for 500 MW Boiler Drum Lifting weighing around 244 MT at an elevation of around 78.00 meters elevations were shown the details of the job. Both the parties have shown keen interest and  presentations were made by both the parties to NTPC and BHEL.

The matter was referred to many corners of BHEL/Manufacturing Units , but no concrete solutions came out. The matter was internally taken up by our Construction Manager Shri D. Guha/AGM with BHEL/Trichy Boiler Engg. Group informally as they do design of the Boiler Civil design aspects like heavy loading and moments coming on Boiler foundations etc. BHEL/Trichy design group after rechecking the available parameters parameters gave us clearance and they confirmed that the existing civil design of 6 nos. piles with raft can very well take care of the combined load of Generator stator Handling Structure and Generator Stator. This gave us confidence for using the Strand Jack Method for doing 500 MW Generator  Stator Handling and lifting. Finally the tender specifications were prepared jointly by BHEL/Kahalgaon Site , Kolkata /FEX & PMX Department. Finally the job was awarded to M/s Fagioli PSC,Mumbai. Tendering went a long drawn process as many clarifications and doubts were raised by the  bidding parties and NTPC. AA :: Important Features of the Strand Jack System

1. Right from the beginning BHEL:PSER informed all the concerned Units of BHEL to

2. In the tender , a condition was included that the executing vendor should get the total design to be vetted by a reputed 3

rd

party design consultant .This had to be done

 because as per Contract condition of NTPC, BHEL was supposed to do Generator  Stator lifting by Portal Crane and that is why NTPC wanted that this type of job  being a new one for the first time being executed by BHEL , total design needs to be rd

vetted by a reputed 3 party consultant. As a result , the Executing agency M/s Fagioli engaged M/s DCL,Kolkata as design consultant. Final concurrence was given by both M/s DCL and customer NTPC after  studying the detailed calculations and series of meetings had to be conducted for  clarification and approval. 3. Major components which were fabricated in Mumbai by M/s Fagioli were tested in  presence of our BHEL/Kolkata/FEX representative before arranging dispatch clearance. 4. Major items dispatched were brought from different parts of India and abroad .The

details of the consignments received are as per following details. Sl. No

Description

Ships name

Remarks/Mode of despatch

 foundation. No change was done on the construction of sizes of 6 nos. piles and  raft. The proposed design conditions were were reviewed by both NTPC and Design Consultant M/s DCL and both the agencies confirmed confirmed that the existing raft can accommodate 4 nos. of foundation footings with all the loads and moments coming on to the foundation within design limits. NTPC was convinced and  arranged 4 no. foundation footings instead of the earlier designed 2 no.  foundation footings footings BB :: Constructional features of Strand Jack System

The outside structure TG Hall has a feature of 4 columns of Tubular structure type ( Pipe size 457 mm OD X 16.00 mm thk ) with provision of flanges , attachments ,arrangement for bolting and other

lugs to

accommodate bracings and their 

fasteners in between for assembly of modular types of structures of different lengths to suit transportation

and ease of assembly at site.

The outside columns structure contains the following –  •

Base plates assembly with shear lugs on all 4 foundations. The bottom portion is square in construction and the top is of circular type. The height of stool is 400 mm. The plates are grouted with foundation. Foundation bolts size was

•

On the top of 2 similar to the 2

nd

nd

piece , 3

rd

piece of modular structure of 4.0 meter length

piece is assembled with bracings with similar types of pin

type fasteners and locking pins. The assembled weight of this item is 8.0 MT. •

th

On the top of it , 4 piece of modular structure of 2.0 meter length similar to the 3

rd

piece is assembled with bracings with similar types of

pin type

th

fasteners and locking pins. On the top of this 4 piece , a box type fabricated assembly with beams is done .The combined weight of this 2 meter long modular assembly and fabricated structure is 8.0 MT. The assembly is shown in Annexure -1. Over this piece , the girders are placed with one end at the top of outside structure and other end at the top of inside 2 column structure on TG deck. •

On the top of TG Deck , 2 base plates of 20 mm thick MS Plates of approx. 500 x 500 mm size with shear lugs of 200 mm size below it is installed. The 2 columns structures are assembled on the top of the base plates and bolted with  base plates. There are 2 types of bracings in the 2 column structures. First type is of diagonal bracings in 2 Column structures and assembled in 2

•

On the top of the outside Column structures outside TG Hall and inside TG hall 2 girders are installed. The weight of individual girders are 36 MT. CR100 Rails are installed on the top of these girders for movement of trolleys.

•

Each Girder is 34.700 meter long and dispatched in 2 pieces . Total no.of  girder pieces received are 4.The girders are of I-Section of built up beams 2.00 meter height and are assembled at site with splice plates assembled at the flanges and webs with bolts. Around 1600 nos. of bolts are required and these are tightened with electrically operated torque wrenches.

•

The girders are assembled inside TG Hall alongside of TG axis and lifted on the top of fabricated structures outside TG Hall and inside TG Hall with the help of TG Hall EOT Crane main hook. The girders are rotated slowly and taken outside for the portion projected outside TG Hall.

•

The total assembly of the Strand Jack System structure is explained in drawing no.HL1/F/004 of M/s Fagioli which was submitted

to

us

after 

approval of M/s DCL and NTPC. Railings and walkways

are assembled

on the top of girders for working at height. The assembly details are shown in Annexure-3.

are passed through the moving trolley jacks strand holders. A strand guide is made at the top of the moving trolley. This is explained in Annexure - 5. CC :: Activities involved in the process

(i)

Unloading of Generator Stator from the Generator Special Wagon on Aux. Pedestals with the help of Hydraulic Jacks (Pictorial view is as per Annexure-6) .

(ii)

Removal of the Load carrying beam from inside Generator Stator and taking it out completely from the Generator Stator (Pictorial view is as per Annexure - 7).

(iii)

Lifting of Generator stator from Aux. Pedestals with the help of Strand Jack  method (Pictorial view is as per Annexure - 8).

(iv)

Rotation of the Generator Stator to suit insertion of the stator inside A Row as the  position of the Stator on the Rail track is 500 mm offset. For Unit # 5 , the rotation was done after crossing TG Floor elevation as the operating floors at 17.00 meter was ready (Pictorial view is as per Annexure - 9). In case of Unit # 6 , the rotation was done at zero meter as there was no operating floor either at 8.5 meters and 17.0 meters elevation at TG Building towards A-Row adjacent to TG Deck (Pictorial view is as per Annexure - 10).

(vii) Placement of Generator Stator on TG Hall foundation (Pictorial view is as per  Annexure - 13). (viii) Joining of the 2 parts of Special wagons of Generator for dispatching of the Generator Special wagon for arranging departure to BHEL/Hardwar (Pictorial view is as per Annexure - 14). DD :: Chronological events of Unit # 5 & 6 Sl.No.

Description of the activity

Duration Unit # 5

Unit # 6

01

Arrival of Generator Stator at Site

15.04.2006

29.04.2006

02

First time No Load Run of Engine on rail track 

22.04.2006

Not required

03

Generator Stator placed on rail-track

26.04.2006

17.06.2006

04

Stator unloading on Aux. Pedestals

04.05.2006

26.06.2006

05

Strand jack system dismantling from  Not applicable

11 to 16.06.2006

Unit # 5 for installation in Unit # 6 06

Strand

jack

system

assembly

and 04.05.2006

to 17 to 24.06.2006

the bogies. Pictorial view is enclosed in Annexure-2. Necessary Railway clearances were obtained by BHEL/PSER in consultation with BHE/ROD Kolkata Office.

FF :: Job description The scope of the vendor was (i)

Supervision of Unloading of Generator and arranging all necessary logistics and this includes design of the required fixtures and accessories ,

(ii)

Design , Supply , Erection of Strand Jack System for lifting of Generartor  Stator from Rail line alongside A-row and placement on TG Floor foundation.

GG :: Major T&P arranged by BHEL •

EOT Crane in TG Hall.

•

8/10/12 MT Hydra for Transportation and erection of materials.

•

18/25 MT Mobile Crane for pre-assembly of modular column structures and assembly .

•

20 MT Truck for transportation of materials inside plant premises. Majority of the big consignments were unloaded at site.

•

100 MT Mobile Crane with boom length of 70 meters for Pre-assembly and erection of  Strand Jack System Outside TG Hall alongside A-Row.

HH :: Methodology adopted by M/S Fagioli is briefly explained below.

1.0 DESIGN CRITERIA

2.0 EQUIPMENT USED BY M/S FAGIOLI PSC The main equipment used are as follows: 

1 no. L300 strand jack with Standard Fagioli PSC Strand dia. 18 mm of 29 meters length ( total 19 nos. strands were used).



1 no. Power Pack with total hydraulic systems of high pressure armoured hoses with needle valves was designed to suit the load condition for connecting to different points as per load requirement.



1 number L300 fixed anchor swivel



1 Trolley with 4 Nos. Skate Rollers (50 t capacity and part of the moving trolley)



2 Hydraulic Pullers of 15MT Capacity each to drag the Generator from A row side to B-row Side and 2 Mechanical Max pullers of 5.0 MT Capacity to move the Generator  towards A-row from B-row.

Each and every Equipment was subjected to periodic inspections, moreover prior to commencement of the operation the equipment was checked according to the daily inspection checking list. Standard rigging hardware (as slings, grommets, shackles etc.) were selected to work within the manufacturer’s Safe Working Load and were subsequently provided with Manufacturer  Test /Fitness Certificates and were inspected before the use.

3.0 OPERATIONS

•

The packer sizes were 20 mm thk – 6 nos. on 4 Aux. pedestals of sizes 750x150 mm. 30 mm thk – 18 nos. on each pedestals of size 150 x 100 mm 10 mm thk – 18 nos. on each pedestals of size 150 x 100 mm and other sizes plus condenser packer plates as per requirement.

3.0.2 :: UNLOADING OF GENERATOR STATOR FROM SPL WAGON & POSITIONING ON   AUX. PEDESTALS AND PACKERS. •

•

•

•

•

The Stator comes in hanging condition over the Carrier Beam, Which passes through the inside void portion of the Stator and remains supported from the temporary end shield bearings of Stator at both ends, while the Beam ends are mounted on the top of the two end segments of the special carrier wagon and the whole unit is pulled by Railway engine. Once the 500 MW Generator Stator weighing 275MT is received at site, the same is brought on to the Railway track alongside the TG Building A-row. Stator is to be lifted by around 300 mm. with 4 no Jacks of 120 MT Capacity each. Saddles/Trunnions available on the sides of the Stator Body are used for this purpose . One Motor operated Hydraulic operated high pressure pumping unit for controlling movement of all 4 above jacks is used for unloading of Stator on Aux. Pedestals and packers. Slowly the load is released from the temporary end-shield bearings so that the carrier beam becomes free and rests only at the ends on the top of wagon segments. During this time , the total load of the Stator and Carrier beam i.e. 275 + 90 = 365 T is to be handled by the lifting arrangement, and the Jacks are to be of that capacity. One Fabricated moving Trolley structurally suitable to bear the self load of about 100T of  the carrier beam with a hydraulic Telescopic jack of at least 150 T capacity( Since the weight of carrier beam is approximately 90 MT) is placed between the stator and Powered end of the wagon. This temporary support is required to take the load of carrier beam when it comes out of stator, so that free end of the beam does not strike and damage the stator core. The trailing end of the beam is made free from the wagon and the carrier beam is pulled

□

Overall vertical dimension of the system is checked that , these are within the tolerance limit as the access over T.G. deck is very narrow.

□

The transverse centre line of the Stator is marked at its location on the TG deck.

□

Proper checking & ensuring of the longitudinal centre line is marked on the Stator body. This is done just to facilitate matching with the Centre line of the skid Trolley.

□

In the next step , pulling is done with the Trolley/Strand Jacks together with the Generator, along the skid tracks by using the L15 MT capacity pulling jacks, restrained at the end of the skidding beam.

□

The Rotation of the generator is done with the help of Slings and the shackles connected to the lifting beam assembly or on the generator body at the ground. This is done manually. The Stator is rotated to the required angle. Once the generator is rotated it is pulled with the help of strand jack until it clear the Column along grid line A.

□

On completion of the above activities , the Generator is made parallel to column line A after it clears the Column A/6.

□

The Generator stator is further pulled and lifted with the help of the strands using the strand jack up to an elevation of 17m (bottom of generator stator). The generator should be lifted to a clearance of 500mm above the TG Deck top.

□

The Two main Skid Beams over which the Stator lifting trolley is going to skid has to be properly braced together for stability.

□

At the time of skidding care should be taken that only four brace between the two skid beams is removed while longitudinal movement for access & the same shall be braced

JJ :: Comparison between Strand Jack method and Portal Crane.

Sl.No. Description 01.

Foundation

Portal Crane method on 2

TG Deck

02.

03.

Foundation

Raised

foundation

Strand Jack Method of  2 base plates of 500 x 500 mm

around 500 mm height with

size with shear lugs and M36

packer plates and foundation

Foundation bolts. The base plate

of 580 Package.

level is almost on TG Floor.

on 2

Raised

foundation

of  4 base plates of 500 x 500 mm

Outside TG Hall around 250 mm height with

size with shear lugs and M36

alongside A-row

packer plates and foundation

Foundation bolts. The base plate

of 580 Package.

level is almost on TG Floor.

Used

Not

Package No.580

required

leads to around

and

this

savings of  Rs.2.0

lakhs

approx. per 500 MW Unit. 04.

Erection Time

3 weeks

For 1 st Unit – 25 days including fabrication of many items . For 2nd Unit – 7 days.

05.

Transportation Cost

Rs.2.0 Lakhs(approx.)

Rs.5.0 Lakhs(approx.)

06.

Erection cost

Rs.2.0 Lakhs(approx.)

Rs.1.0 Lakhs(approx.)

07.

Maintenance

Rs.1.0 Lakhs(approx.)

Lump sum

4 Base Stools bolted with base plates

4 Nos, Base plates with Shear lugs levelled and grouted

Annexure –1 ( 1) Assembly of Base plates and 1st Set of Stools

Assembly of 1st Modullar Column set with bracings ( length 12 meters and weight 22 MT)

Base Stools – 4 Nos.

 Annexure – I ( 2 ) Outside Structure Assembly

 Annexure-1( 3 ) 1st Modular Column is being lifted for  erection in position

4th Modular  Column  Assembly of  2.0 mt.length

Fabricated box assembly

3rd Modular Colums assembly 4.0 mt length 2nd Modular Colums assembly 4.0 mt length

1st Modular Colums assembly 12 mt length

 Annexure-1 ( 4 ) Assembly of Outside TG Hall Structure Assembly

Diagonal bracings in between columns

 Annexure- 2 ( 1 ) Assembly of Inside 2 Column Strcture inside TG Hall

Bracings weldded and bolted with columns and strctures for  arresting movement of Strand Jack structure towards B-row during Dragging of the Stator  from A to B Row.

 Annexure – 2 ( 2 ) Diagonal bracings taken from 2 coulmn structure with TG Hall Aux.Column and beam

 Annexure – 3 ( 1 ) Girders pieces unloaded in TG Hall for joining with splice plates and bolts and assessment is being done

 Annexure – 3 ( 2 ) Girders are joined with splice plates and bolts

Walkways , railing are ready

 Annexure – 3 ( 3) Girders lifting with TG Hall EOT Crane

Annexure – 3 ( 4 ) Lifting of Girders .The lifting lugs angles are so set , that minimum clearance between below hook of main hoist of TG Hall EOT Crane is maintained and girders are placed on top of strand jack strucrures (both outside TG Hall & inside TG Hall )

 Annexure – 4 ( 1 ) Moving Trolley alongwith Powerpack ready for lifting on Girders top

 Annexure – 4 ( 2 ) Moving Trolley being lifted on Girders by 100 MT Mobile Crane from outside TG Hall

Rails are welded on top of the girders and welded at regular intervals

Rollers are fixed below trolley for reducing friction during dragging of Stator 

 Annexure – 4 ( 3 ) Moving trolley on top of the Girders with strand arrangement

 Annexure – 5 ( 1 ) Swivelling beam with strands and lifting slings

 Annexure – 5 ( 2 ) Strands Guide coming out from top of the powerpack

 Annexure – 6 ( 1) Hydraulic Jacks – 4 nos. of 120 MT Capacity each for  Unloading of Generator Stator on Aux. Pedestals

 Annexure – 6 ( 2 ) Generator Stator unloaded on Aux.Pedestals with the help of Hyd.jacks

 Annexure – 6 ( 3 ) Unloading of Stator completed –total view

 Annexure – 7 ( 1 ) Arrival of Stator with Load Carrying beam inside and hanging from both side of Spl. Rly.Wagon.

Annexure – 7 ( 2 ) Removal of load carrying beam from Stator  inside

 Annexure – 7 ( 3 ) Fixing of 150 MT Hydraulic Jack at the front side of the Spl.wagon for taking out load carrying beam

 Annexure – 7 ( 4 ) Load carrying beam almost out of the Stator 

 Annexure – 7 ( 5 ) Load carrying beam removal completed and ready for joining with Rly. Spl.Wagon totally

 Annexure – 8 ( 1 ) Generator Stator Lifting from Aux. Pedestals

 Annexure – 8 ( 2 ) Stator lifting from Aux. Pedestals

 Annexure – 8 ( 3 ) Stator Lifting is in progress

 Annexure – 9 - Rotation of Stator in Unit #5 above TG Floor 

 Annexure – 10 - Rotation of Stator at zero meter floor in Unit # 6 as TG Floor  was not ready

 Annexure – 11 ( 1 ) Dragging of Stator from A – Row towards B- Row

Dragging with 2 Hydraulic Jacks of 15 MT Capacity

 Annexure – 11 ( 2 ) Dragging of Stator towards B-Row from A-row

 Annexure – 12 ( 1 ) Stator brought on TG Floor near axis before rotation along TG Axis.

Annexure – 12 ( 2 ) Rotation of Stator towards TG Axis (View -1 )

Annexure – 12 ( 3 ) Rotation of Stator towards TG Axis (View – 2 )

 Annexure – 12 ( 4 ) Stator axis made parallel to TG Axis and ready for  placement on TG Foundation

 Annexure – 13 ( 1 ) Generator Stator placement on TG Foundation

 Annexure – 13 ( 2 ) Stator placement on TG stator completed

The load carrying beam is being joined after  the stator is cleared from the lifting point

 Annexure – 14 ( 1 ) Joining of Spl. Rly. Wagons