erection procedure for boiler structures

ID.No.

ERECTION GUIDELINES

FOR

500 MW

BOILER STRUCTURES ( COAL FIRED CONVENTIONAL TWO PASS DESIGN)

BHARAT HEAVY ELECTRICALS LIMITED

POWER SECTOR – SOUTHERN REGION QUALITY DEPARTMENT CHENNAI – 600 035.

DOC.No: PS:QLY:050

REV.No:R00/09-2004

ERECTION GUIDELINES

FOR

500 MW – BOILER STRUCTURES

(COAL FIRED CONVENTIONAL TWO PASS DESIGN)

PREPARED &

APPROVED BY

BHEL:PS-SR:QUALITY

AUTHORISED

TO BE USED BY

HEAD-QUALITY,PS-SR:CHENNAI

DOCUMENT NO. PS-QLY:050

R00/09-2004

ID No.

DATE OF ISSUE

COPY No.: CONTROLLED/

INFORMATION

COPY

No.of

SHEETS

74

ISSUED BY

ISSUED TO : HEAD – QUALITY

BHARAT HEAVY ELECTRICALS LIMITED

POWER SECTOR – SOUTHERN REGION

QUALITY DEPARTMENT

CHENNAI – 600 035.

Doc. No. : PS: QLY: 050

Rev. No. : R00/ 09-2004

PSSR-QUALITY

INDEX

Sheet No. : 01 / 01

SL. NO. DESCRIPTION NO. OF

SHEETS

01. SUPPORTING STRUCTURE-INTRODUCTION

6

02. FOUNDATION CHECKS 8

03. PRE ASSEMBLY AND ERECTION OF COLUMNS 30

04. PRE ASSEMBLY AND ERECTION OF GIRDERS 23

05. PREPARATION FOR DRUM ERECTION 3

06 POST DRUM ERECTION CHECKS AND WORKS 2

07 HSFG BOLT TIGHTENING

Ref. Doc.No.2302-82 Released by BHEL-Tiruchy

1

01. SUPPORTING STRUCTURE-

INTRODUCTION

BOILER ERECTION

01. SUPPORTING STRUCTURES

A) Introduction

Boiler supporting structure forms 25% of the total weight of a steam generator. The entire

pressure parts are suspended from the structural steel work (Ref Fig.1) . In addition to the

above, air preheater load, partial load of ducting and piping are included. Also it forms

platforms at various levels for the movement of operator and space for maintenance of

various equipments (for Typical Key Plan Ref. Fig.2). Hence structural safety and stability

are the ultimate objectives of the design. The prime aim of an erector is to meet the design

requirements with optimum utilization of men, material and time. To achieve the above,

the erector shall adopt all technological improvements that have taken place in the area of

structural steel erection. The sequence of structural erection mainly depends on the

availability of major handling equipments like Tower crane, Crawler crane, etc.

The Supporting Structure arrangement is of welded plus (+) columns with bolted joint

design. The bolted joint design avoids heavy & critical welds between column pieces in

position, as required of tall columns & enables obtaining better alignment, also providing

ease of working. The joints are by using High Strength Friction Grip (HSFG) boltings,

which however, are able to be used carefully as per the specified procedure.

This section describes mainly boiler supporting structure erection upto drum lifting.

However erection activity of supporting structure for airheater, forming part of Boiler

supporting structure etc., continues, on similar lines, till completion. Refer the applicable

FQP for the logsheet formats to be filled and kept as record during structure erection.

B. Erection sequence with high capacity crawler cranes ( FMC/& Heavy duty cranes like

Manitowac & Sumitomo Cranes)

Sumitomo Crane ( 150 T capacity) has capability to lift to position the columns, bracings

etc. whereas FMC/MANITOWAC Cranes ( 250 T capacity) can position all structural

components including ceiling girders.

The suggested location and movement of the cranes is shown in Fig.3.

Crawler crane of 75T capacity may be employed for pre-assembly area, erecting small

frames, ladders etc.

1

BOILER ERECTION


ii) 3rd and 4th as well as 5th and 6th tier columns can be pre-assembled and erected, with

the help of high capacity cranes.

iii) To facilitate crane movement for column erection, defer the erection of a) rear side

Second MBL’s, middle columns like S15,S16, S17,S18, S19,S20 & S21 also height

of foundation of these columns, should be temporarily restricted below the ground

level till the crane is moved out of respective locations.

iv)

Between S8 and S9 (RHS) Ist tier columns the diagonal bracings can be deferred to

facilitate feeding of pressure parts.

Note: 1) Designers Clearance to be obtained before the above structural members

erection is deferred.

2) Any additional temporary bracings to be erected to take care of the structural

rigidity.

When the above cranes are not available, the following sequence can be followed using the

commonly available TATA 75 T crane.

1) 75 Tonne capacity crane can be deployed upto 2nd tier erection. The crane is

positioned inside the Boiler area. Sumitomo (150T) crane is used for further

erection. Bracings between columns, S1 and S2 (left) S7 and S8 (left) can be

deferred to bring in the Sumitomo crane and between column S7 and S8 ( Left) to

take out the same on erection completion of 5th tier.

2) Alternatively, if the full space is available around the boiler the Sumitomo crane can

be kept outside the Boiler when all bracings can be erected in normal sequence

(Generally the availability of space around the boiler is very less since other

agencies are also working). Up to the completion of 5th tier the Sumitomo crane is

used.

3) Heavy duty crane is now located on the Furnace cavity of Boiler . 6th & 7th tier

columns are pre-assembled and erected.

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BOILER ERECTION


Note:

i) 6th & 7th tier cannot be erected separately since Heavy duty crane boom will be

touching 5th tier when 6th tier erection is being done. Outer columns are to be erected

first before taking up the erection of inner columns to avoid fouling with crane boom.

ii) While erecting the first piece of all columns ensure correct orientation of its faces with

respect to boiler axis.

4) Complete the structure erection by pre-assembly and assembly of ceiling girders A,

B, C, D, E.

Note :

The handling equipments manufacturer recommendations are to be strictly followed while

lifting the load, especially with respect to :

- Lifting load with respect to boom angle shall be monitored.

Positioning and the movement of crane shall be only on the consolidated and leveled ground.

- Boom swing speed with load shall be monitored.

C Measuring Instruments:

The following measuring and test equipments calibration to be done and made

available prior to start of structural erection.

Tape 5 M ,30 M Adequate Quantity

Torque Wrench 650 – 1000 ft Lbs

Bolt tension calibrator, torque wrench calibrator.

Temperature recorder (range 0 to 1000º C)

Theodolite – Minimum 2 Nos. ( One second accuracy. One number for

verification and other one for checking column verticality).

In addition to the above piano wire without knots and kinks plumb bob with oil dash pot and

thermal chalks to be made available.

Calibration:

All the instruments are to be calibrated. The calibration Certificate should have cross

reference of master calibrator and identify with the National Standards.

5

02. FOUNDATION CHECKS

BOILER ERECTION


A. Civil Foundations:-

I) Refer Fig. 4A for typical arrangement of column foundation.

ii) Check the following.

- Top level of each foundation with reference to bench mark, as obtained from

Civil group.

- Check for the availability of Boiler axis as marked on the civil foundation.

- Mark the axis of each pedestal.

- Disposition of pedestal with respect to reference axis ( Boiler longitudinal and

transverse axis)

- Spacing between adjacent pedestals – Ref. Fig. 4B

- Diagonals distance between pedestals – Ref. Fig.4C

- Foundation bolt disposition with respect to pedestal axis and diagonals – Ref.

Fig.4D.

- Shear lug openings length, width and depth.

iii) Chip off the pedestal top surface to remove loose layer.

iv) Clean the foundation top surface, bolt pockets and shear lug opening.

v) Check foundation bolt for verticality and condition & correctness of threads and ensure

the freeness of nut movement.

vi) Pre –determine the packer thickness for each column, as required to get all the

column-top in same level.

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BOILER ERECTION


- Required packer thickness “t” mm

- Distance between Zero metre

elevation marking to bottom of “A” mm

base plate in column

- Elevation of top of pedestal “B” mm

- Thickness of packer required = (-B) – (-A) = - “t” mm

- If ‘t’ is less than 20 mm top of pedestal to be chipped off to achieve minimum grouting

gap of 20 mm.

- If ‘t’ is more than 70 mm the same may be informed to manufacturing unit for

acceptance.

- The thickness of packers shall be selected in such a way to use maximum of only 5

numbers. If shims are used the same shall be placed between the packers.

B) Position of Packers (Refer Fig. No. 5A, 5B & 5C)

i) Check packers are free from undulation.

ii) Chip the pedestal surface at packer location for proper seating of packer.

Or

The first packer can be aligned over the rough concrete (without chipping for level)

using high strength quick setting cement. Allow the mix to cure as per the

manufacturer’s recommendation.

Locate packers such that Grouting holes are not covered. If the shear lugs interfere,

the packers are to be cut & dressed suitably – Ref.Fig. 5B.

iii) Set the required thickness of packer assembly using minimum number of packers,

possible.

iv) Position of packers below column flange sections - Ref. Fig. 5B

6

03. PRE ASSEMBLY AND ERECTION

OF COLUMNS

BOILER ERECTION

03. PRE-ASSEMBLY AND

ERECTION OF COLUMNS

A) Pre Assembly of Column

i) Preparation of pre assembly bed is very much essential for pre-assembly of columns

keeping the piece in ‘+’ position. The pre assembly bed shall be arranged in such a

manner that each column piece should have minimum three bottom supports (one at

the middle and other two one meter away inside from the column ends) to avoid excess

sagging or over hanging of pieces at ends. The bed shall be prepared over a

consolidated and hard ground to avoid any possible sinking of bottom supports during

loading with column pieces. The span between the supports to be decided based on

the individual piece length. The width of the bed shall be minimum 6 metres so that

three or four individual column pieces can be pre-assembled at a time, with the help of

gantry crane. The bed preparation should suit the pre-assembly of ceiling girders and

pressure parts also and located as near as possible to the boiler area.

The suggested pre-assembly bed arrangement is indicated in Fig.No.6.

Note : Top level of all support beams shall be maintained with in ± 3mm using water

level. Minor adjustments to be made using shims to accommodate the section variation

of individual column pieces.

ii) Identify the individual column pieces, by

- Work order no. PGMA – DU No. & Column designation, which are stenciled/punched

on each piece at the works. Figures 7A, 7B, 7C, 7D indicate the identification details.

iii) Position the column pieces on the pre-assembly bed as shown in Fig. 6. The pre-

assembly bed shall be treated as firm/hard earth, prepared for the purpose.

1

BOILER ERECTION


ERECTION OF COLUMNS

Note :

1)The match marks on the column pieces shall be strictly used for assembly to

avoid interchanging / rotation.

2) Fig.8 shows the typical erection joint (bolted) as prepared at the works.

3) Avoid slinging structural members without a protective material like flexible thick non

metallic piece.

iv) Check and measure the individual column pieces & ensure that the following are within

the limits.

- Camber

- Sweep

- Shear lug location in case of first column base plate.

Refer to manufacturing unit for repair procedure / Comments wherever required.

v) Ensure cleanliness of cover plate area in the flange and web in the column joint area.

vi) Align all the pieces by pulling each piece to have no gap at erection joints.

vii) The details of centerline marking done at shop is indicated in Fig. 9.

viii) Align flange to flange match marks for both the flanges as per the erection joint details.

B PREPARATION FOR ERECTION OF COLUMNS

i) Check for punch mark to indicate the elevation at every 5 meter distance. ( Say 61. xx,

60, 55, 50 …..5,1 and 0) Refer Fig. 11.

ii) Accordingly punch mark the 1M elevation over the bottom piece.

iii) Measure and record the distance from ‘o’ Meter to bottom of the base plate. Based on

this the packer thickness for individual column is decided.

iv) Cleat angles / seating plate to be welded at the appropriate level for the placement of

horizontal members on flange and web side. (Ref. Fig.10A & 10B).

v) Fix the verticality stickers over individual column pieces on both the flanges (90º apart)

in two places (near MBL locations). Ref.Fig.12.

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BOILER ERECTION


ERECTION OF COLUMNS

- For bottom piece at 1 ‘M’ elevation and below the bolt joint area at the convenient

level.

- For other pieces near ends (just near erection joint area) at the convenient level.

Note: The centerline of stickers shall be matched with centerline marking of web and

flanges (shop punched). Refer Fig.12.

vi) Dismantle the column pieces from the pre assembly bed and stack it near the erection

area to suit the sequence of erection, from bottom to top.

C) Erection of columns & Bracings:

i) Lift the First column bottom piece as shown in the Fig.13A.

ii) Place the Bottom column piece over the foundation with out damaging the bolt

threads, while lowering the piece through the bolts. Tighten the bolts, prior to

releasing the load from the crane.

iii) Erect all the first pieces of the columns in this manner.

iv) Align the individual pieces (verticality etc.) for the following (Refer Fig.14A, 14B &

14C).

- Elevation (1 meter punch mark shall be taken as reference for all column pieces)

- Spacing between adjacent column with respect to reference axis of boiler.

v) Tighten the foundation nut and recheck the alignment. In case of any disturbance noted,

alignment procedure to be repeated.

vi) Check the spacing between columns at horizontal beam level.

vii) Box up the column as follows:

Box I S1-S2-S7-S8 (Left and Right) Refer Fig. 15A.

Connect with horizontal members and complete cleat welding ( Fig.16).

viii) BOX II S3-S4-S9-S10 (Left & Right). Refer Fig. 15B.

Connect with horizontal members and complete the cleat welding (Fig.16)

Align Columns S4-S10 (Left & Right). Refer Fig. 15C.

ix) Erect the horizontal members between the aligned boxes (Fig 16) Length variation if

any may be corrected.

x) Complete the welding of cleat angle with horizontal member and column (between

boxes).

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BOILER ERECTION


ERECTION OF COLUMNS

xi) Erect and align the vertical bracings. Refer Fig. 17A, 17B, 17C, 17D, 17E. Position,

align and weld the gusset plate at its location.

xii) Erect the remaining boxes of columns as explained for other pieces.

xiii) Erect and align the horizontal members and vertical bracings and complete the

welding

xiv) Complete the erection alignment and welding of Main Brace level (MBL) members in

the boxed up section.

xv) Recheck the verticality of all columns.

xvi) Grouting column base plates and cure with Portland cement.

xvii) Prepare the protocol for the completion of first piece erection and obtain clearance for

second piece erection.

Note: Second tier erection is started after 7 days from the date of grouting. With quick set

Grout material second tier shall be started after 72 Hrs. Strength of grout should be

ensured by means of cube test.

xviii) The above steps in general are to be followed for subsequent tiers ( Fig. 18)

- While erecting the second column piece align for erection joint matching, tighten

the hold down bolt with stopper / end plate.

- Provide the splice plate and hand tighten HSFG bolts as per shop match marks.

Note: The second piece is held in position with the crane till the completion of splice

plate and fixing of HSFG bolts.

- Erection, alignment and bolting sequence explained above shall be followed for the

subsequent pieces erection.

Note: (a) The vertical bracings at the top levels may be deferred till the erection and

alignment of ceiling girder for easy adjustment. For rest of the columns erect

the vertical bracings and do final welding.

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BOILER ERECTION


ERECTION OF COLUMNS

(b) Verticality of columns are to be checked before the erection of ceiling girder.

(c) Prior to erection of top column piece, the girder pin connection matching and welding of

support plate with column top shall be completed as explained below:

- The girder pin connection assembly is applicable for S8, S9, S10 & S11 Columns

(both right & left)

- Align the axis of girder pin bottom part and column top.

- Typical girder pin connection details are shown in the Fig. 20A & 20B.

- Check the contact surface between bottom part of girder pin with flange web and

stiffener portion of column top using feeler gauge. (Blue matching not required).

- Assemble the holding down plate with fasteners and align with column top and pin

assembly bottom part on either side of the flange.

- Tack weld the holding down plate with column and bottom part of pin connection.

Provide stiffener to avoid welding distortion.

- Dismantle the assembly

- Preheat and Complete the welding

- Flush grind the weld in the matching surface.

Note : LATERAL STABILITY OF COLUMN WITH HORIZONTAL & VERTICAL BRACINGS

( REF. FIG : 21)

26

BOILER ERECTION


ERECTION OF COLUMNS

i) Vertical bracing gives lateral stability to column offering resistance to horizontal forces coming on the structure & transferring the forces to column base / foundation safely.

ii) To maintain column stability in both X, Y direction against lateral buckling, lateral supports are to be given.

iii) Lateral support is given by the net work of horizontal bracings at about 8 to 10M height interval.

iv) Horizontal bracing gives resistance to lateral buckling of columns due to wind / seismic / stability force.

v) The horizontal force through the horizontal bracing system is transferred to vertical bracing nodal points, and from there to the ground without causing undue sway to column.

vi) Discontinuity in horizontal bracing will result in ineffectiveness & will not give resistance to the sway of column effectively.

vii) To transfer the lateral forces effectively to ground continuity of vertical / diagonal bracing from ceiling to column base is very much essential.

d) Welding, Pre-heating and Non-Destructive Examination and post heat treatments requirements.

1.0 Welding a) Welders shall be qualified as per Welding Manual. b) Welding consumables conforming to the design requirements shall be used. c) Selection of welding consumable shall be out of the “Approved list of welding

consumables “ issued by Welding Technology Centre, Trichy. d) Manufacturer’s batch certificates are also to be verified.

e) Welding consumables used for this are to be stored properly and issued after necessary baking. Electrodes issued for job should be kept in holding ovens and maintain the temperature. The above are to be carried out as per Welding Manual.

f) Welding shall not be done when the surfaces are wet, oil traces are seen or exposed to rain or high wind or when the welders are exposed to inclement conditions.

g) The sizes and length of weld shall not be less or substantially in excess than that specified in the drawing.

2.0 Preheating and Post Weld Heat Treatment

Refer Welding Manual

3.0 NDE Requirements

Refer NDE Manual

30

04. PRE ASSEMBLY AND ERECTION

OF GIRDERS

BOILER ERECTION

04. PRE-ASSEMBLY AND ERECTION OF GIRDERS

A) Preassembly of Ceiling Girder:

- Identify the pieces for the following: - Work order no. - PGMA - DU No. - Girder designation.

- Position the girder pieces over the pre assembly bed inside the furnace cavity

keeping left, middle and right side pieces following shop punch mark details. Typical details of girder pieces are given in Annexure I.

- Check and measure the following: - Camber Length & diagonal - Sweep - Twist - Edge preparation and condition.

- Web height at extended portion and compare with flange to flange inner distance ( For easy insersion 1 mm gap to be ensured on either side. If required grind web ends to achieve the above).

Major deviation if any, to be informed to manufacturing unit for Corrective action. Rectify the deviations accordingly.

B) Final Check and finishing.

i) Repeat the dimensional check, carried out prior to welding, after Post Weld Heat Treatment and compare the two.

ii) Clean and paint the weld region.

iii) Check the holes drilled in the web of ceiling girder (distance from the end and Centreline distance of each group of holes, which is the Centreline distance of Welded beams).

iv) Check the size and location of pad plates welded on the web of ceiling girder. These pad plates are to be welded only on sides and bottom face.

v) Ensure pre-assembly bed is made on the leveled and consolidated area to avoid

sinking during placement of girders on the bed. vi) Ensure the pre –assembly bed members are properly spaced to avoid sagging of

girder pieces when they are placed over it. ( Refer Fig . 22); vii) Match the pieces as per match marks provided in the pieces. Ensure the

orientation of girder pieces as per drawing (Ref.Fig. 23 A & 23B)

1

BOILER ERECTION


ERECTION OF GIRDERS

1.0 Fit Up :

a) While leveling the pieces, the reference lines punched on the web at about 1 to 1.5M level from bottom flange may be taken as reference.

b) While adjusting the overall length of the girder, check the distance between girder pin connection bolt hole centers which is marked in the bottom flange and as well as on the top flange.

c) While adjusting the overall straightness of the girder piece the longitudinal centerline of the girders and web line marked on the pieces may be taken as reference.

d) While matching the piece, flange root gap and web root gap shall be maintained between 4 to 6mm and 6 to 8mm respectively in the field joint areas (Ref. Fig.23B).

e) The parts to be joined by fillet welds shall be brought as close as practicable.

f) Butting parts to be joined by butt welds shall be carefully aligned. An offset exceeding 10% of the thickness of the thinner part, but in no case more than 3.2mm may be permitted.

g) Members to be welded shall be properly aligned and held in position by bolts, clamps, wedges and other suitable devices until welding is completed.

h) No tack weld to be made in the web for aligning. Instead ‘L’ clamps and wedges shall

be used for web alignment to keep the joint free during the welding of flange joint. i) Ensure after dimensional check-up the girder assembly is properly locked in position by

using stoppers, ‘L’ clamps, wedges, guy ropes and struts or by any suitable device to avoid distortion during welding and Post Weld Heat Treatment operations. Ensure proper locking, in such a way that the girder assembly can move longitudinally during welding and Post Weld Heat Treatment operations to avoid accumulation of thermal stress.

2.0 Dimensional check-up:

a) Section depth and flange width can be checked as cross reference since these are already checked up in shop. Tolerance : Section depth upto 1 M - ± 3mm

Above 1 M upto 2 M - ± 4.5mm

Above 2 M - +7.5mm

- - 4.5mm

Flange width - ± 3mm

BOILER ERECTION


ERECTION OF GIRDERS

2.0 b) Check the following dimensions prior to clearing the assembly for welding and are to be recorded in the log sheet.

1. Level of the girder assembly 2. Deviation in straightness on both flanges. 3. Flatness of web on both vertical and horizontal axis. 4. Out-of squareness of the assembly. 5. Flange and web join alignment. 6. Overall length of the assembly and Girder pin bolt hole to hole distance 7. Flatness of bottom flange in girder pin locations. 8. Longitudinal and cross diagonals of the assembly. 9. Welded beam location distance on either side of the field joint.

3.0 Dimensional tolerance:

1. Individual piece camber and sweep - Max. 5mm 2. Individual piece length - ± 5 mm 3. Level of girder assembly - Max. 5mm 4. Deviation in straightness on total length - Max. 15mm 5. Flatness of Web - Max. 10mm 6. Out-of squareness of assembly - Max. 8mm 7. Overall length of assembly - ± 15mm

(With the recommended gap for welding of web and flange at field joints, the overall length of the girder shall be achieved within limits after allowing weld shrinkage).

8. Flatness of bottom flange at girder pin connection location . - Max.2mm 9. Longitudinal and cross diagonal of assembly(difference) - Max.15mm

4.0 Pre-heating

a) Pre-heat temperature required for various range of plate material thickness is as follows: t : upto 19mm - Nil t : over 19mm upto 38mm - 65º C t : over 38mm upto 63mm - 100ºC t : over 63mm - 150 ºC

b) It is desirable to pre-heat using electric resistance coil heaters. Use of self pre-heat is not permitted.

c) When electrode of 3mm and below are used the minimum pre-heat temperature shall be increased by 50º C from the pre-heat temperature mentioned above.

5

BOILER ERECTION


ERECTION OF GIRDERS

5.0 Welding

a) Welders shall be qualified as per Welding Manual.

b) Welding consumables conforming to the design requirements shall be used.

c) Selection of welding consumable shall be out of the “Approved list of welding consumables” issued by WTC, Trichy.

d) Welding consumables used for this are to be stored properly and issued after necessary baking. Electrodes issued for job should be kept in holding ovens and maintain the temperature. The above are to be carried out as per welding manual.

e) Pre-heating requirements for materials shall be strictly followed as mentioned.

f) The sequence of welding to be followed as indicated in Fig.24A

g) Complete the root plus three runs on inner side as per the sequence shown in Fig. 24A.

h) Back gouge/chip the weld from outer side and carryout LPI/MPI tests for ensuring defect free root weld.

i) Complete the outer side weld for three runs as per the sequence indicated in Fig. No.24A.

j) Complete the flange joint weld, around 60% thickness of the joint on both sides of flange alternately ( inner and outer) as per the sequence shown in Fig. 24B

k) After completion of 60% of flange welding check the web alignment (adjust with wedges to achieve web alignment if required.)

l) Check the root gap. If required, ground to get the gap.

m) Preheat to 150º C and adopt the weld sequence for the web root welding plus two runs as shown in Fig. 24A.

n) Back gouge /chip the second side of the weld to achieve defect free root weld. o) Carryout LPI/MPI on the weld joint on root side. p) Complete the two runs of weld on the second side as per the sequence shown in

Fig.24B. q) Complete the balance flange joint and then the balance web joint as per the

sequence indicated respectively in Fig. 24A & 24B.

Note: The welding sequence of flange and web can be changed depending

on the number of welders engaged.

6

BOILER ERECTION


ERECTION OF GIRDERS

r) Complete the fillet welding between flange and web on both sides.

s) Carry out the post heating of weld joint for 1 hour at 250ºC

t) Welding shall not be done when the surfaces are wet, oil traces are seen or exposed to rain or high wind or when the welders are exposed to inclement conditions.

u) The sizes and length of weld shall not be less or substantially in excess than the specified in the drawing.

6.0 Post Weld Heat Treatment

For C&C-Mn Steel : ( IS 2062, ASTM A36 BS 4360 Gr 43D, DIN 17100 ST 37.3, JIS 3106 SM 41, 3192)

a) Butt welds in plates over 50mm thick shall be subjected to Post Weld Heat Treatment. For unequal thickness of plates, the groove depth at the weld shall be considered for Post Weld Heat Treatment.

b) The fillet welds for fixing attachments like pads etc. made on tension flanges over 50mm thick shall also be post weld-heat treated.

For high tensile steels : ( DIN 17100 ST 52.3, IS 961 – HTW)

a) Butt welds in plates 50mm and above thick shall be Post Weld Heat Treated. For unequal thickness of plates, the groove depth at the weld shall be considered for Post Weld Heat Treatment.

b) The fillet welds for fixing attachments like pads etc. made on tension flanges 50mm and above thickness shall also be post weld heat treated.

For the fillet welds joining the tension flange to web need not be out post weld heat treated. All the post weld heat treatment cycle range shall be 600ºC to 650ºC. The above cycle shall be controlled within a tolerance of ± 10ºC. The recommended temperature for Post Weld Heat Treatment must be selected as the mid point of the recommended range. Soaking time for Post Weld Heat Treatment shall be 1 hr. /25mm thick upto 50mm and 2 hr +15 minutes for each additional 25mm thickness over 50mm. The heating rate above 400ºC and cooling rate after Post Weld Heat Treatment upto 400ºC shall be as follows:

Thickness range Rate of

Heating (Max)

Rate of Cooling ( Max)

Upto 25mm thick 220ºC /hr 110ºC/hr

Over 25 – 50mm thick 110ºC/hr 110ºC/hr

Over 50 – 75mm thick 75ºC/hr 110ºC/hr

Over 75mm thick 55ºC/hr 65ºC/hr

10

BOILER ERECTION


ERECTION OF GIRDERS

Autographic calibrated recorder shall be used to record rate of heating, soaking and rate of cooling. Fixing and location of thermocouple shall be made as per details in Welding Manual. (Typical case – Refer to Fig. 25 & 26). 7.0 Non –Destructive Examination ( N.D.E.) Ceiling girder assembled keeping web vertical. Cut edges

a) Flame cut welding edges for thickness over 38mm – 100% MPI b) Random MPI for all edges of thickness above 20mm

Weld build up areas Weld build up areas in flanges and web – 100% MPI/LPI. Flange butt joint 100% MPI for thickness 25mm and above. 100% RT for thickness 32mm and above. Web butt joint a) 100% LPI for back gouged/chipped area before second side welding.

b) SPOT RT – 10% The defective areas shall be further repaired and re-radiographed. Fillet welds a) Fillet weld between ( tension) bottom flange and web – 100 % MPI

b) When both flange and web are above 25mm – 100% MPI c) Other fillet welds – random MPI.

8.0 Final check –up and finishing:

After Post Weld Heat Treatment, surface to be cleaned properly and painted with two coats of red oxide primer.

Cement washed surfaces are to be cleaned properly in the HSFG bolt area including cleat angles.

Dimensional check-up of girder shall be carried out and to be recorded in the log sheets.

‘No stray arc’ shall be done on heat treated members.

B. Erection of Ceiling Girders

The dimension of ceiling girder after full assembly shall be checked and recorded. The erection activity is detailed in 5 parts.

A) Preparation of structure for girders lifting. B) Preparation of heavy duty crane 250 MT capacity ( FMC crane LS – 718 –42 ) for girders lifting. C) Preparation of girder to be lifted. D) Tools and tackles. E) Erection of girder.

(A) Preparation of structure for Girder lifting

1. All the main columns except middle columns shall be erected, welded and bolt tightened.

2. All main horizontal members, diagonal bracing shall be erected in that particular span where the girder is lifted.

3. Verticality of columns shall be checked and logged.

4. One side of staircase shall be completed upto 75 metres so as to facilitate easy movement of persons during erection.

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ERECTION OF GIRDERS

5. Temporary platform shall be made around the column top so as to facilitate column bolting with the ceiling girder.

6. Connected welded beams shall be kept ready for erection immediately after girder erection.

7. Guy ropes with pulling machines shall be tied to the columns and anchored at both sides of columns so as to have adjustment at the top during erection.

(B) Preparation of Heavy duty crane ( FMC crane) for girder lifting

After completion of preassembly of girders all the four ceiling girders are erected with the help of FMC crane/ Heavy duty crane with ringer attachment.

The FMC crane LS 718 HL 250 T cap. /heavy duty crane shall be assembled with 310 ft boom with ringer attachment. The crane shall be assembled near Electrostatic Precipitator area and moved inside the furnace cavity.

Heavy duty crane with ring horse attachment involves following assembles.

a) Crawler and cabin b) Ringer attachement c) Mast assembly d) Boom assembly e) Arrangement of jacks f) Reeving of boom wire rope. g) Loading of counter weights. h) Fixing of jib.

After complete assembly, the crane shall be moved to the furnace cavity.

Girders shall be erected from the predetermined positions in furnace cavity as per Fig.27 welded beams on front side, Girder – B & Girder – C shall be lifted from position – I. The girder ‘D’ & ‘E’ shall be lifted from position – II.

(C) Preparation of the girder to be lifted

1. Preassembled ceiling girder shall be shifted from preassembly bed to the nearest columns.

2. The girder shall be assembled with pin connection assemblies at both ends.

3. The girder shall be kept over the wooden sleepers.

4. The girder shall be kept at angle of 20 degree to the horizontal plane as the length of the girders is more compared to the span of the column.

5. Temporary Platform shall be made around girder for easy movement at top. The typical arrangement is shown in Fig. 28.

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ERECTION OF GIRDERS

(D) Tools and tackles readiness

1. 80mm wire rope 16 M long – 2no’s shall be tied to the girder at the center as

shown in Fig. 29. 2. Two Nos. D-Shackles shall be tied to each one of top portion of slings. 3. Two Nos arrestor channels shall be provided to keep both the slings at a

distance. 4. The details of slinging is shown in Fig.29

5. Small tools like spanners, pulling machine etc. shall be kept ready.

6. The list of Tools and Tackles for ceiling girder lifting is given in Annexure – II.

(E) Erection plan for girder

1. Erection check list shall be completed before erection of ceiling girder. Typical

check list is shown in Annexure – III. 2. Heavy duty crane shall be positioned at a predetermined distance in the

furnace cavity. 3. It is preferable to start girder erection early morning so as to avoid heavy wind. 4. The girder shall be lifted slowly at an inclined direction with respect to

horizontal plane.

5. Manila rope tied at the both ends shall be controlled to avoid sway during erection.

6. After reaching top of column, the girder shall be made parallel to column and kept over the columns.

7. Erection crew is to be arranged at top of temporary platform around columns on both sides.

8. Girder pin connections shall be bolted to the column top.

9. Immediately after girder erection , 2 Nos. welded beams shall be erected so as to connect the girder with other ceiling structure.

13

ANNEXURE – I

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BOILER ERECTION


ERECTION OF GIRDERS

ANNEXURE - I

DIMENSIONS AND WEIGHT DETAILS OF CEILING GIRDERS (TYP.)

Sl

No

CEILING

GIRDER

DESIG.

LENGTH

IN MM

WIDTH

IN MM

THICKNESS

OF MIDDLE

FLANGE MM

THICKNESS

OF END

FLANCE MM

THICKNESS

OF WEB MM

DEPTH

IN MM

WEIGHT

MT

01.

B

25710

1000

63

50

MID : 25

END : 32

3788

50

02

C

25710

1300

50

40

MID : 25

END : 36

3780

54

03

D

25700

1400

56

50

MID : 25

END : 36

3788

60

04.

E

29510

1500

100

75

MID : 32

END : 50

3800

103

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ERECTION OF GIRDERS

ANNEXURE – II

TOOLS AND TACKLES USED FOR CEILING GIRDER LIFTING

1. HEAVY DUTY CRANE – 250 T CAPACITY ( FMC CRANE)

WITH RINGER ATTACHMENT

- 1 No

2. 80MM DIA WIRE ROPE SLINGS ( 16 METER LONG)

- 2 Nos

3. ‘D’ SHACKLES – 100 MT. CAP

- 4 Nos

4. PULLING MACHINE – 6 T CAP

- 4 Nos

5. MANILA ROPE – 200 METERS

- 2 Nos

6. SMALL TOOLS LIKE SPANNERS & WINCHES

- 2 SETS

7. 3/4" GUY ROPE ( EACH 150 METERS) - 2 NOS

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BOILER ERECTION


ERECTION OF GIRDERS

ANNEXURE : III

SHEET : 01/04

CEILING GIRDER ERECTION

CHECKS FOR LIFTING

CONTRACTOR NO. : __________________________

CEILING GIRDER NO. : __________________________

REFERENCE DRG.NO. : __________________________

SL.No. PARTICULARS CHECKS SIGNATURE REMARKS

1. Inspection of lifting tackles

(wire ropes, slings, shackles,

clamps. Etc.)

2. Position of crane on ringer

3. Check for proper slinging

4. Positioning of frame, pipe sleeves

timber, etc.

5. Trial lift

6. Trial to be taken for crane boom

clearance

7. Guide ropes at either end

8. Arrangement of guys, maxpullers,

etc.(for columns)

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BOILER ERECTION


ERECTION OF GIRDERS

Annexure : III

Sheet : 02/04

9. Persons to be recognized for

Lifting directions.

10. Communication arrangement

11. Manpower availability

12. Check items of attached annexure

Remarks CONTRACTOR

Remarks BHEL/ERN.

Remarks BHEL/QAE

CUSTOMER

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ERECTION OF GIRDERS

ANNEXURE : III

SHEET : 03/04

SL

NO

PARTICULARS CHECKS SIGNATURE REMARKS

1. Girder supporting columns.

2. Verticality of columns

(All required).

3. Level of top of columns.

4. Marking of column top bolt holes center

5. Distance between two column centers at

top

6. Tightening of column bolts

7. All the necessary horizontal beams and

bracings to be aligned, welded & bolted

8. Main brace level structure at 9M, 21M,

31.2M, 43M, 56M & 68M on left, right and

front to be completed.

9. Cleaning of all mating surfaces like

column top, ceiling girder bottom, pin

connection surfaces.

10. Bolts to be tried thru holes for no

obstruction.

11. Lubrication of pin surfaces.

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ERECTION OF GIRDERS

Annexure : III

Sheet : 04/04

12. Bolting of pin connection on top of column & checking

of gaps prior to ceiling girder erection

13. Inspection of locking plate for pin connection.

14. Inspection of welding of bolt hole lugs to pin

connection

15. Pre-assembly clearance of ceiling Girder

( Dimensional & welding, NDT and stress relieving)

16. Fixing (Clamping) of temporary rails on top of the

flange of ceiling Girder for safety use. Welding of

temporary ladders on sides of girder.

17. Clamping of temporary angles on bottom flange of

ceiling girders for facilitating the scaffolding making

after erection.

18. Cross beams required to-connect should be kept

ready.

19. Arrangements for lifting and fixing of cross beams.

23

05. PREPARATION FOR

DRUM ERECTION

BOILER ERECTION

05. PREPARATION FOR

DRUM ERECTION.

1. Mark the drum axis from ‘A’ girder centerline and arrive at furnace axis.

2. The drum, furnace and boiler axis shall be punch marked over WB’s and ceiling girder.

(For drum and pressure parts erection reference).

3. Erect, align and weld the drum suspension support beam on either side of boiler axis.

4. Carry out LPI on welds.

5. Erect, align, and weld cat head structure (‘A’ frame) for the purpose of drum lifting

arrangement as per contract drawing.

6. Erect, align and weld staircase on both sides up to drum level (Ref. Section on Stairways

& Galleries).

7. Provide temporary approach ladder (From drum level to ceiling girder level) and platform

for drum lifting operation.

8. The minimum structural requirements are to be completed in all respect and the structure

shall be cleared for drum erection.

9. The following are the minimum requirement of structure for drum erection.

1

BOILER ERECTION

05. PREPARATION FOR

DRUM ERECTION.

MINIMUM STRUCTURES REQUIREMENT FOR DRUMERECTION

(LIST OF REVAMPED PG –MA)

Sl.No. PG MA Description

01. 35 010 Foundation Materials

02. 35 111 Main Columns Left - Ist Pass

03. 35 112 Main Column s Left - 2nd Pass

04. 35 121 Main Columns Right - 1st Pass

05. 35 122 Main Columns Right - 2nd Pass

06. 35 130 Main Columns Middle, except S14 L ,S14 R and S17

07. 35 140 Auxiliary Columns Left

08. 35 150 Auxiliary columns Right

09. 35 190 Girder Pin Connection

10. 35 211 Ceiling Girder (fabricated) - 1st Pass

11. 35 212 Ceiling Girder (fabricated) - 2nd Pass

12. 35 213 Cross Girder - 1st Pass

13. 35 214 Cross Girder - 2nd Pass

14. 35 221 Ceiling – Rolled Shapes - 1st Pass @

15. 35 222 Ceiling – Rolled shapes - 2nd Pass @

16. 35 231 Ceiling Bracing - 1st Pass

17. 35 232 Ceiling Bracing - 2nd Pass

18. 35 311 Floor Bracing 1 MBL - 1st Pass

19. 35 312 Floor Bracing 1 MBL - 2nd Pass

20. 35 321 Floor Bracing II MBL - 1st Pass

21. 35 322 Floor Bracing II MBL - 2nd Pass

22. 35 331 Floor Bracing III MBL - 1st Pass

23. 35 332 Floor Bracing III MBL - 2nd Pass

24. 35 341 Floor Bracing IV MBL - 1st Pass

25. 35 342 Floor Bracing IV MBL - 2nd Pass

26. 35 351 Floor Bracing V MBL - 1st Pass

27. 35 352 Floor Bracing V MBL - 2nd Pass

28. 35 361 Floor Bracing VI MBL - 1st Pass

29. 35 362 Floor Bracing VI MBL - 2nd Pass

2

BOILER ERECTION

05. PREPARATION FOR

DRUM ERECTION.

MINIMUM STRUCTURES REQUIREMENT FOR DRUMERECTION

(LIST OF REVAMPED PG –MA)

30. 36 381 Landing Platforms - 1st tier *

31. 36 382 Landing Platforms - 2nd tier*

32. 36 383 Landing Platforms - 3rd tier*

33. 36 390 Drum Floor *

34. 36 441 Main Beams – Lower - 1st Pass

35. 36 442 Main Beams – Middle - 1st Pass

36. 36 443 Main Beams – Upper - 1st Pass

37. 36 451 Main Beams – Lower - 2nd Pass

38. 36 452 Main Beams – Middle - 2nd Pass

39. 36 453 Main Beam – Upper - 2nd Pass

40 36 511 Front Bracing – Lower

41. 36 512 Front Bracing – Middle

42. 36 513 Front Bracing – Upper

43. 36 521 Side Bracing – Lower

44. 36 522 Side Bracing – Middle

45. 36 523 Side Bracing – Upper

46. 36 531 Rear Bracing – Lower

47. 36 532 Rear Bracing – Middle

48. 36 533 Rear Bracing – Upper

50 36 700 Fasteners

51. 36 811 Floor grills & Guard Plate *

52. 36 821 Main Stairs – Lower

53. 36 822 Main Stairs – Middle

54. 36 823 Main Stairs – Upper

55. 36 851 Handrails & Posts*

@ - Rolled shapes which are required for drum lifting are to be erected and others as and when requirements arises. * - These items are not mandatory for drum lift, but may be important from statutory regulation, operation / erection and health/safety point of views. NOTE: For details refer applicable PGMA list.

3

06. POST DRUM ERECTION

CHECKS AND WORKS

BOILER ERECTION

06. POST DRUM ERECTION CHECKS

AND WORKS

1.0 After completion of drum erection the following activities are to be carried out immediately.

1.1 Check the verticality of column and cross refer to verticality readings taken after ceiling girder alignment.

1.2 The left out member in MBL for drum erection in the furnace region are to be erected.

1.3 Remove the temporary structure erected, if any after the erection of permanent members.

1.4 Erect the support structure for silencer.

1.5 Position the silencer on support structure and arrest temporarily for safety reason.

1.6 Erect align and weld all Rolled Beams for starting of pressure part work.

Note: Erection sequence for Sl.No. 1.4 to 1.6 is depending upon the availability of Tools

and Plant.

2.0 Heavy duty crane shall be deployed for completing the erection alignment and welding of monitor roof assembly ( Ref Fig.31A & 31B)

3.0 The balance members of PG-35 and PG-36 are to be erected aligned and welded in a phased manner for ease of pressure parts erection and approach to various locations.

4.0 Complete the erection, alignment and welding of PG 39 members (Fans and duct structure) in a phased manner as per site progress.

5.0 Complete the erection, alignment and welding of structure between units, boiler and ‘D’ row columns, boiler and bunker bay.

6.0 Do not cut structural members in case there is interference with boiler components. Consult the designer for comments/correction work.

1

HSFG BOLT TIGHTENING

REFER DOC.No.2302 –82

TIGHTENING PROCEDURE HSFG BOLTS

Released by BHEL-TIRUCHY

1

erection procedure for boiler structures

Documents