welding manual nov 2010

2

INDEX

Sl.No. Description Page

No.

01 Cover Sheet 01

02 Index 02

03 Preface 03

04 Foreword 04

05 Approval Sheet 05

06 Important Note 06

07 Status of Amendments 07

A-1 Welding - General 08

A-2 Base Materials 15

A-3 Welding Material Specification and Control 24

A-4 Procedure for Welder Qualification 49

A-5 Inspection of Welding 66

A-6 Repair Welding 70

A-7 Safe Practices in Welding 72

B-1

Pre-Assembly & Welding of Ceiling Girders 78

Pre-Assembly of High Crown Plates 94

B-2

Erection Welding Practice for SA 335 P91 Material 95

Argon Purity Level 115

Use of resistance heating for PWHT of P-91 pipes 117

B-3 General Tolerances for welding structures - (Form and position) (Doc.

Ref. : AA0621105)

121

B-4 Welding of pipes and pipes shaped connections in Steam Turbines,

Turbo-Generators and Heat Exchangers (HW0620599)

125

B-5 Instructions for carrying out condenser plate and neck welding 128

B-6 Repair procedure of arresting the leakage of strength welds on tube to

tube sheet joints of „U‟ tube HP heater

132

B-7 Repair procedure of grey cast iron castings 135

B-8 Special Instructions for the repair of Steam Turbine Casings 139

B-9 Gas Metal Arc Welding 146

B-10 Orbital Welding 150

B-11 Edge Preparation Details 161

B-12 Erection Procedure for Rear Water box and Rear water Chamber in

condenser 164

B-13 Welding & HT details of thermo couple pads & clamps for SH & RH 170

B-14 Welding and PWHT sequence for lower ring header 172

B-15 Demagnetization Procedure 174

B-16 Erection Welding Practice for SA 213 T91 Material 175

B-17 Selection Chart for Dummy end Covers for Hydraulic test / Nipples

Free end Details (BHEL-Trichy) 182

B-18 Schedule of Pipes 185

6

I M P O R T A N T

THIS WELDING MANUAL PROVIDES BROAD BASED GUIDELINES FOR WELDING

WORK AT SITES. HOWEVER, SITES MUST ENSURE ADHERENCE TO THE

PRIMARY DOCUMENTS LIKE CONTRACT DRAWINGS, ERECTION WELDING

SCHEDULE, PLANT / CORPORATE STANDARDS, WHEREVER SUPPLIED,

STATUTORY DOCUMENTS, WELDING PROCEDURE SPECIFICATIONS,

CONTRACTUAL OBLIGATIONS, IF ANY AND SPECIAL INSTRUCTIONS ISSUED BY

RESPECTIVE MANUFACTURING UNITS SPECIFIC TO THE PROJECT.

WELDING MANUAL A1. WELDING-GENERAL 7

STATUS OF AMENDMENTS

Sl.No. Reference of Sheet(s)

Amended Amendment No. & Date Remarks


CHAPTER – A1

WELDING - GENERAL


WELDING-GENERAL

1.0 SCOPE:

This manual deals with activities and information related to welding for site

operations including P91 material. Where specific documents are supplied

by the manufacturers, the same shall be adopted.

2. DOCUMENTS REFERRED:

2.1 The following documents are referred in preparation of this manual.

1. AWS D1.1

2. ASME sections I, II (A&C), V & IX

3. ASME B31.1

4. IBR

5. BHEL Manufacturing Units‟ Standards & practices

3. PROCEDURE:

3.1 The following documents shall be referred as primary documents

- Contract drawings

- Erection Welding Schedule or equivalent

- Plant / Corporate standards, where supplied

- Statutory documents

- Welding Procedure Specifications

- Contractual obligations, if any.

3.2 Welder Qualification:

3.2.1 Ensure, personnel qualified as per statutory requirements are engaged, where required.

3.2.2 For welding not under the purview of statutory requirements, qualification of welders

shall be as in this manual.

3.3 Monitor performance of qualified butt welders as in this manual.

3.4 Ensure selection, procurement, storage, drying & issue of welding consumables, as detailed

in this manual.

3.4.1 List of approved vendors of general purpose welding electrodes as provided by BHEL,

Tiruchy Unit shall be used for selection of brands at sites . Alternatively specific

contractual requirements, if any may be followed.


3.4.1.1 Where Tiruchy list does not cover site requirements, such specific cases may be referred

to concerned unit and Head(Qly) of the region.

3.5 Welding in-charge shall assign a unique identification for all the butt welds coming

under the purview of statutory regulations. Such identification may be traceable through

documents like drawings, sketches etc.

3.5.1 A welding “job card” incorporating the welding parameters and heat treatment

requirements is recommended to be issued for all critical welds like pressure part welds,

piping welds, ceiling girder welds. A format of the job card is enclosed for illustration.

3.6 Heat Treatment:

3.6.1 Preheat, inter pass, post heat and Post Weld Heat Treatment (PWHT) requirements shall

be as per applicable documents; where these are not supplied, reference may be made to

Welding / Heat Treatment Manual.

3.6.2 Prior to PWHT operation, a “job card” containing material specification, weld

reference, size, rate of heating, soaking temperature, soaking time and rate of cooling

shall be prepared referring to applicable documents, and issued.

3.6.3 The PWHT chart shall contain the chart number, Weld Joint No., Temperature recorder

details (like Sl.No., make, range, chart speed) , date of PWHT, start and end time of

operation .

3.6.4 The chart shall be evaluated and results recorded on the PWHT job card. Refer Heat

Treatment Manual (Document No. PSQ-HTM-COM) for details.

3.7 Equipment & Instruments:

3.7.1 Equipment/accessories used shall be assessed for fitness prior to use.

3.7.2 Use calibrated temperature recorders.

3.7.3 Thermal chalks shall be batch tested prior to use.

3.8 Inspection:

3.8.1 Inspection of welding may be done as per Chapter A5 and records maintained as

appropriate.


3.8.2 Weld log containing the following information shall be prepared for all completed

systems.

- Project / Unit reference

- Drawing No.

- Weld Joint No.

- EWS / Equivalent

- Material specification

- Welder code

- Date of welding

- NDE report No. and results (including repair details)

- PWHT Chart No. and results

- Remarks, if any.

3.9 Safety:

3.9.1 Safe access to weld area shall be provided.

3.9.2 Adequate protection shall be provided against excessive wind and rain water entry

during welding.

3.10 Records:

3.10.1 All records, as required, shall be maintained by welding in-charge.


WELDING JOB CARD

Page 2 of 2

FILLER WIRE / ELECTRODE CONSUMPTION

GTAW Filler wire :

SMAW 2.5 mm :

3.15 mm :

4.0 mm :

Date of LPI for RG Plug :

Remarks :

Date of Return :

WELDING JOB CARD

Page 1 of 2

Project :

Unit No. : Area: Boiler / TG / PCP

Job Card No. : Date:

Joint No. :

Drawing No. :

System Description :

Size (Dia. x thick) :

Material Specification :

Welder No.(s) :

Date of welding :

Filler wire Specification :

Electrode Specification :

Preheat temperature :

Inter pass temperature :

Post Heat temperature :

PWHT temperature :

Welding Engineer


JOB CARD

(WELDING, HEAT TREATMENT & ND EXAMINATION)

FOR P91 WELDS

Card No.: Date:

Project

:

Unit No. Contractor:

System: Drawing No.

PGMA: DU No.: Joint No.:

Material Specification: + OD (mm): Thick(mm)

Filler

metal: GTAW SMAW

Joint fit-up: Min. WT: Root

gap:

Root

mismatch:

Log sheet

filled: Y / N

No. of T/Cs: Location

: Distance from EP edge: mm

Welders‟ ID: M/c No.:

Preheat Temp.: C Minimum Rate of heating: C per hour

Purging flow rate: Litres / min. Purging time: Minutes

Shielding flow

rate: Litres / min. for GTAW Distance bet. dams: Metres

Interpass Temp.: C Maximum Rate of cooling: C per hour

Holding Temp.: C for min. 1 hour. for post heating

PWHT: C Rate of heating / cooling: C per hour

Soaking time Minutes (2.5 minutes per mm) Cooling to: 300 C

Preheating started at Hrs. on Preheating completed at Hrs.

Root welding started at Hrs. Root welding completed at Hrs.

Welding started at Hrs. Welding completed at Hrs.

Interpass temp. maintained between C and C

Holding temp. reached at Hrs. Holding completed at Hrs.


:

PWHT started at Hrs. on . Soaking started at Hrs.

.

Soaking completed at Hrs. 300C reached at Hrs.

UT Equipment used: Calibration validity:

UT carried out on Result : OK / Not OK

MPI Equipment used: Calibration validity:

MPI carried out on Result: OK / Not OK

Hardness test Equipment used: Calibration validity:

Hardness test carried out on Value:

History of interruption if any, with time:

Contractor BHEL Customer


JOB CARD

(WELDING, HEAT TREATMENT & ND EXAMINATION)

FOR T91 WELDS

Card No.: Date:

Project

:

Unit No. Contractor:

System: Drawing No.

PGMA: DU No.: Joint No.:

Material Specification: + OD (mm): Thick(mm)

Filler

metal: GTAW SMAW

Joint fit-up: Min. t: Root

gap:

Root

mismatch:

Log sheet

filled: Y / N


: Distance from EP edge: mm

Welders‟ ID: M/c No.:

Preheat Temp.: C Minimum Rate of heating: C per hour

Purging flow rate: Litres / min. Purging time: Minutes

Shielding flow

rate: Litres / min. for GTAW Distance bet. dams: Metres

Interpass Temp.: C Maximum Rate of cooling: C per hour

Holding Temp.: C for min. 1 hour. for post heating

PWHT: C Rate of heating / cooling: C per hour

Soaking time Minutes (2.5 minutes per mm) Cooling to: 300 C

Preheating started at Hrs. on Preheating completed at Hrs.

Root welding started at Hrs. Root welding completed at Hrs.

Welding started at Hrs. Welding completed at Hrs.

Interpass temp. maintained between C and C

Holding temp. reached at Hrs. Holding completed at Hrs.


:

PWHT started at Hrs. on . Soaking started at Hrs.

.

Soaking completed at Hrs. 300C reached at Hrs.

UT Equipment used: Calibration validity:

UT carried out on Result : OK / Not OK

MPI Equipment used: Calibration validity:

MPI carried out on Result: OK / Not OK

Hardness test Equipment used: Calibration validity:

Hardness test carried out on Value:

History of interruption if any, with time:

Contractor BHEL Customer

WELDING MANUAL A2 BASE MATERIALS 15

CHAPTER – A2

BASE MATERIALS

WELDING MANUAL A2 BASE MATERIALS 16

BASE MATERIALS

1.0 SCOPE:

1.1 This chapter contains tabulations of chemical compositions and mechanical properties of

various materials generally used in BHEL sites.

2.0 CONTENTS:

CHEMICAL COMPOSITION AND MECHANICAL PROPERTIES

Table A2.1 - Pipes (ASME)

Table A2.2 - Tubes (ASME)

Table A2.3 - Forgings (ASME)

Table A2.4 - Castings (ASME)

Table A2.5 - Plates / Sheets (ASME)

Table A2.6 - Pipes (Other specifications)

Table A2.7 - Tubes (Other specifications)

3.0 The data are for general information purposes. The corresponding P numbers are also

indicated.

4.0 For materials not covered in this chapter, the supplier shall be contacted.

WELDING MANUAL 17

Table- A2.1 Pipes

CHEMICAL COMPOSITION AND MECHANICAL PROPERTIES

Sl. No.

P.No. / Group No.

Material Specification

Chemical Composition (%) Mechanical Properties

(Min.)

C Mn P S Si Ni Cr Mo V

T.S Kg / mm2

(MPa)

Y.S Kg / mm2

(MPa)

% E Min.

1 P 1 / 1

SA 106 Gr. B

(Remarks:

Carbon

restricted to

0.25% Max.)

0.30

Max. 0.29-1.06

0.035

Max.

0.035

Max.

0.10

Min.

0.40

Max.

0.40

Max.

0.15

Max. 0.08

Max 42(415) 25(240) 30

2 P 1 / 2

SA 106 Gr. C

(Remarks:

Carbon

restricted to

0.25% Max.)

0.35

Max.

0.29-

1.06

0.035

Max.

0.035

Max.

0.10

Min.

0.40

Max. 0.40

0.15

Max. - 49(485) 28(275) 30

3 P 4 / 1 SA 335 P 12 0.15

Max.

0.30-

0.61

0.025

Max.

0.025

Max.

0.50

Max. -

0.80-

1.25

0.44-

0.65 - 42(415) 21(220) 30

4 P 5A / 1 SA 335 P 22 0.15

Max.

0.30-

0.60

0.025

Max.

0.025

Max.

0.50

Max. -

1.90-

2.60

0.87-

1.13 - 42(415) 21(205) 30

5 P 15E /1 SA 335 P91 0.08-

0.12

0.30-

0.60

0.02

Max.

0.01

Max.

0.20-

0.50

0.40

Max.

8.00-

9.50

0.85-

1.05 0.18-0.25 60(585) 42(415) 20

WELDING MANUAL 18

Table-A2.2 Tubes

Sl.

No.

P.No. /

Group No.


(ASME)

Chemical Composition (%) Mechanical Properties (Min.)


T.S

Kg / mm2

(MPa)

Y.S

Kg / mm2

(MPa)

% E

Min.

1 P 1 / 1 SA 192 0.06-0.18 0.27-0.63 0.035

Max.

0.035

Max. 0.25 Max. - - -

33(325) 18(180) 35

2 P 1 / 1

SA 210 Gr A1

(Remarks: Carbon

restricted to 0.25% Max.)

0.27 Max. 0.93 Max. 0.035

Max.

0.035

Max. 0.10 Max. - - -

42(415) 26(255) 30

3 P 1 / 1 SA 179 0.06-0.18 0.27-0.63 0.035

Max.

0.035

Max. - - - -

33(325) 18(180) 35

4 P 1 / 2

SA 210 Gr C

(Remarks: Carbon

restricted to 0.30% Max.)

0.35 Max. 0.29- 1.06 0.035

Max.

0.035

Max. 0.10 Max. - - -

49(485) 28(275) 30

5 P 3 / 1 SA 209 T1 0.10- 0.20 0.30- 0.80 0.025

Max.

0.025

Max. 0.10- 0.50 - - 0.44-0.65

39(380) 21(205) 30

6 P 4 / 1 SA 213 T11 0.05-0.15 0.30-0.60 0.025

Max.

0.025

Max. 0.50-1.00 -

1.00-

1.50 0.44-0.65

42(415) 21(205) 30

7 P 4 / 1 SA 213 T12 0.05-0.15 0.30-0.61 0.025

Max.

0.025

Max. 0.50 Max. -

0.80-

1.25 0.44- 0.65

42(415) 22(220) 30

8 P 5 A / 1 SA 213 T22 0.05-0.15 0.30-0.60 0.025

Max.

0.025

Max. 0.50 Max. -

1.90-

2.60 0.87- 1.13

42(415) 21(205) 30

9 P 5 B / 1 SA 213 T5 0.15 Max. 0.30-0.60 0.025

Max.

0.025

Max. 0.50 Max. -

4.00-

6.00 0.45- 0.65

42(415) 21(205) 30

10 P 5 B / 1 SA 213 T9 0.15 Max. 0.30-0.60 0.025

Max.

0.025

Max. 0.25-1.00 -

8.00-

10.00 0.90- 1.10 - 42(415) 21(205) 30

11 P 1 5 E / 1 SA 213 T91 0.07- 0.14 0.30- 0.60 0.02

Max.

0.01

Max. 0.20- 0.50

0.40

Max.

8.00-

9.50 0.85- 1.05 0.18-

0.25 60(585) 42(415) 20

12 P 8 / 1 SA 213 TP 304 H 0.04- 0.10 2.00 Max. 0.045

Max.

0.03

Max. 1.00 Max.

8.00-

11.00

18.00

-

20.00

- - 53(515) 21(205) 35

13 P 8 / 1 SA 213 TP 347 H

(Cb + Ta Stabilised) 0.04- 0.10 2.00 Max.

0.045

Max.

0.03

Max. 1.00 Max.

9.00-

13.00

17.00

-

19.00

- - 53(515) 21(205) 35

WELDING MANUAL 19

Table A2.3 Forgings

Sl.

No.

P.No. /

Group No.

Material

Specification



T.S

Kg / mm2

(MPa)

Y.S

Kg / mm2

(MPa)

% E

Min.

1 P 1 / 2

SA 105

(Remarks:

Carbon

restricted to

0.25% Max.)

0.35

Max.

0.60-

1.05

0.035

Max.

0.04

Max.

0.1-

0.35.

0.40

Max.

0.30

Max.

0.12

Max.

0.08

Max 49(485) 25(250) 30

2 P 4 / 1 SA 182 F11

Class 3

0.10-

0.20

0.30-

0.80

0.04

Max.

0.04

Max.

0.50-

1.00 -

1.00-

1.50 0.44-0.65 - 49(515) 28(310) 20

3 P 4 / 1 SA 182 F 12

Class 2 0.10-0.20 0.30-0.80

0.04

Max.

0.04

Max. 0.10-0.60 - 0.80-1.25 0.44-0.65 - 49(485) 28(275) 20

4 P 5 A / 1 SA 182 F 22

Class 3

0.15

Max. 0.30-0.60

0.04

Max.

0.04

Max.

0.50

Max. - 2.00-2.50 0.87-1.13 - 53(515) 32(310) 20

5 P 1 5 E / 1 SA 182 F91 0.08-0.12 0.30-0.60 0.02

Max.

0.01

Max. 0.20-0.50

0.40

Max. 8.00-9.50 0.85-1.05 0.18-0.25 60(585) 42(415) 20

WELDING MANUAL 20

Table A2.4 Castings

Sl.

No.

P.No. /

Group No.


(ASME)


C Mn P S Si Ni Cr Mo

T.S

Kg / mm2

(MPa)

Y.S

Kg / mm2

(MPa)

% E

Min.

1 P 1 / 2

SA 216 WCB

(Remarks: Carbon

restricted to 0.25%

Max.)

0.30 Max. 1.00 Max. 0.04 Max. 0.045

Max. 0.60 Max. 0.50 Max. 0.50 Max. 0.20 Max. 49(485) 25(250) 22

2 P 1 / 2 SA 216 WCC 0.25 Max. 1.20 Max. 0.04 Max. 0.045

Max. 0.60 Max. 0.50 Max. 0.50 Max. 0.20 Max. 49(485) 28(275) 22

3 P 4 / 1 SA 217 WC6 0.20 Max. 0.50-0.80 0.04 Max. 0.045

Max. 0.60 Max. - 1.00-1.50 0.45-0.65 49(485)

28(275) 20

4 P 5 A / 1 SA 217 WC 9 0.18 Max. 0.40-0.70 0.04 Max. 0.045

Max. 0.60 Max. - 2.00-2.75 0.90-1.20 49(485) 28(275) 20

5 P 8 / 1 SA 351 CF 8 0.08 Max. 1.50 Max. 0.04 Max. 0.04 Max. 2.00 Max. 8.00-

11.00

18.00-

21.00 0.50 Max. 49(485) 21(205) 35

6 P 8 / 1 SA 351 CF 8M 0.08 Max. 1.50 Max. 0.04 Max. 0.04 Max. 1.50 Max. 9.00-

12.00

18.00-

21.00 2.00- 3.00 49(485) 21(205) 30

7 P 8 / 1 SA 351 CF 8C 0.08 Max. 1.50 Max. 0.04 Max. 0.04 Max. 2.00 Max. 9.00-

12.00

18.00-

21.00 0.50 Max. 49(485) 21(205) 30

8 P 8 / 2 SA 351 CH 20 0.04-0.20 1.50 Max. 0.04 Max. 0.04 Max. 2.00 Max. 12.00-

15.00

22.00-

26.00 0.50 Max. 49(485) 21(205) 30

WELDING MANUAL 21

Table A2.5 Plates / Sheets

Sl.

No.

P.No. /

Group No.

Material

Specification

Chemical Composition (%) Mechanical Properties

(Min.)


T.S

Kg / mm2

(MPa)

Y.S

Kg / mm2

(MPa)

% E

Min.

1 P 1 / 1 SA 36 0.25-0.29 0.80-1.20 0.04 0.05 0.40

Max. - - - - - - -

2 P 1 / 1 SA 516 Gr 60 0.21-0.27 0.55-1.30 0.035

Max.

0.035

Max. 0.13-0.45 - - - - 53(415) 21(220) 25

3 P 1 / 2 SA 516 Gr 70 0.31

Max. 0.79-1.30

0.035

Max.

0.035

Max. 0.13-0.45 - - - - 49(485) 27(260) 21

4 P 1 / 2 SA 299 0.30

Max. 0.84-1.62

0.035

Max.

0.035

Max. 0.13-0.45 - - - - 53(515)

29(275) 19

5 P 1 / 2 SA 515 Gr 70 0.35

Max.

1.30

Max.

0.035

Max.

0.035

Max. 0.13-0.45 - - - - 49(485) 27(260) 21

6 P 4 / 1 SA 387 Gr 12

Class 2

0.17

Max. 0.35-0.73

0.035

Max.

0.035

Max. 0.13-0.45 - 0.74-1.21 0.40-0.65 - 46(450) 28(275) 22

7 P 5 A / 1 SA 387 Gr 22

Class 2

0.15

Max. 0.25-0.66

0.035

Max.

0.035

Max.

0.50

Max. - 1.88-2.62 0.85-1.15 - 52(515) 32(310) 18

8 P 1 5 E / 1 SA 387 Gr 91 0.06-0.15 0.25-0.66 0.025

Max.

0.012

Max. 0.18-0.56

0.43

Max. 7.90-9.60 0.80-1.10 0.16-0.27 60(585) 42(415) 18

9 P 8 / 1 SA 240 TYPE

304

0.08

Max.

2.00

Max.

0.045

Max.

0.03

Max.

0.75

Max.

8.00-

10.50

18.00-

20.00 - - 53(515) 21(205) 40

10 IS 2062 Gr.A 0.23

Max.

1.50

Max.

0.050

Max.

0.050

Max. - - - - - 42 25 23

11 IS 2062 Gr.B 0.22

Max.

1.50

Max.

0.045

Max.

0.045

Max.

0.40

Max. - - - - 42 25 23

12 IS 2062 Gr.C 0.20

Max.

1.50

Max.

0.040

Max.

0.040

Max.

0.40

Max. - - - - 42 25 23

13 IS 8500-540 0.20

Max.

1.60

Max.

0.045

Max.

0.045

Max.

0.45

Max. - - - - 55 40 20

14 BSEN10025Gr

420N

0.20

Max. 1.0-1.7 0.03 Max

0.025

Max.

0.60

Max.

0.80

Max.

0.30

Max.

0.10

Max.

0.20

Max. (500-650 320-420

18-

19

WELDING MANUAL 22

Table-A2.6 Pipes (Other Specifications)

Sl.

No.

P.No. /

Group

No.

Material

Specification


C Mn P S Si Ni Cr Mo V T.S

Kg / mm2

Y.S

Kg / mm2

% E

Min.

1 P 1 / 1 DIN St. 35.8 0.17

Max.

0.40-

0.80

0.04

Max.

0.04

Max. 0.10-0.35 - - - -

36.70-

48.96 24 25

2 P 1 / 1 DIN St. 45.8 0.21

Max. 0.45-1.20

0.04

Max.

0.04

Max. 0.10-0.35 - - - -

41.80-

54.10 26 21

3 P 1 / 1 BS 3602 / 410 0.21

Max. 0.40-1.20

0.045

Max.

0.045

Max.

0.35

Max. - - - -

41.82-

56.10 25 22

4 P 1 / 1 BS 3602 / 460 0.22

Max. 0.80-1.40

0.045

Max.

0.045

Max.

0.35

Max. - - - -

46.90-

61.20 28.60 21

5 P 4 / 1

BS 3604

620-460 HFS

or

CDS 620-440

0.10-0.15 0.40

Max.

0.04

Max.

0.04

Max. 0.10-0.35 - 0.70-1.10 0.45-0.65 -

46.90-

62.22 18.36 22

0.10-0.18 0.40-0.70 0.04

Max.

0.04

Max.

0.10-

0.35 - 0.70-1.10

0.45-

0.65 -

44.90-

60.20 29.58 22

6 P 5 / 1

BS 3604

622

HFS or CDS

0.08-

0.15

0.40-

0.70

0.04

Max.

0.04

Max.

0.50

Max.

-

2.00

2.50

0.90-

1.20

-

48.80 26.80 17

7 -

BS 3604

HFS 660

Or

CDS 660

0.15

Max.

0.40-

0.70

0.04

Max.

0.04

Max. 0.10-0.35 - 0.25-0.50 0.50-0.70 0.22-0.30 47.30 30 17

8 P5B / 2 X20CrMoV121

DIN17175 0.17-0.23 1.00

0.030

Max.

0.030

Max. 0.50 0.30-0.80

10.00-

12.50 0.80-1.20 0.25-0.35 70-86 50 17

WELDING MANUAL 23

Table-A2.7 Tubes

Table- A2.7 Tubes (Other Specifications)

Sl.

No.

P.No. /

Group

No.

Material

Specification


C Mn P S Si Ni Cr Mo V T.S

Kg / mm2

T.S

Kg / mm2

% E

Min.

1 P 1 / 1 DIN St. 35.8 0.17

Max.

0.40-

0.80

0.04

Max.

0.04

Max. 0.10-0.35 - - - -

36.70-

48.96 24 25

2 P 1 / 1 DIN St. 45.8 0.21

Max. 0.40-1.20

0.04

Max.

0.04

Max. 0.10-0.35 - - - -

41.80-

54.06 26 21

3 P 1 / 1 BS 3059 / 360 0.17

Max.

0.40-

0.80

0.045

Max.

0.045

Max.

0.35

Max. - - - -

36.70-

51.00 22 24

4 P 1 / 1 BS 3059 / 440 0.12-0.18 0.90-1.20 0.040

Max.

0.035

Max. 0.10-0.35 - - - -

44.88-

59.20 25 21

5 P 3 / 1 15 Mo3

DIN17175 0.12-0.20

0.40-

0.80

0.035

Max.

0.035

Max. 0.10-0.35 - - 0.25-0.35 -

45.90-

61.20 27.50 22

6 P 4 / 1 13 Cr Mo 44

DIN17175

0.10-

0.18

0.40-

0.70

0.035

Max.

0.035

Max. 0.10-0.35 - 0.70-1.10

0.45-

0.65 -

44.88-

60.18 29.60 22

7 P 4 / 1 BS 3059 / 620 0.10-0.15 0.40-

0.70

0.040

Max.

0.040

Max. 0.10-0.35 - 0.70-1.10

0.45-

0.65 -

46.90-

62.20 18.40 22

8 P 5 / 1 10 Cr Mo 910

DIN17175 0.08-0.15 0.40-0.70

0.035

Max.

0.035

Max.

0.50

Max. - 2.00-2.50 0.90-1.20 -

45.90-

61.20 28.60 20

9 P 5 / 1 BS 3059 (622) -

440 0.08-0.15 0.40-0.70

0.04

Max.

0.04

Max.

0.50

Max. - 2.00-2.50 0.90-1.20 -

44.90-

60.18 17.85 20

10 P 5 / 1 BS 3059 (622) -

490 0.08-0.15 0.40-0.70

0.040

Max.

0.040

Max.

0.50

Max. - 2.00-2.50 0.90-1.20 -

49.98-

65.00 28.05 20

11 - 14 Mo V 63

DIN17175 0.10-0.18 0.40-0.70

0.035

Max.

0.035

Max. 0.10-0.35 0.30-0.60 0.50-0.70 0.22-0.32

46.90-

62.22 32.60 20

12 P5B / 2 X20CrMoV121

DIN17175 0.17-0.23 1.00

0.030

Max.

0.030

Max. 0.50 0.30-0.80

10.00-

12.50 0.80-1.20 0.25-0.35 70-86 50 17

WELDING MANUAL 24

CHAPTER - A3

WELDING MATERIAL SPECIFICATION AND CONTROL

WELDING MANUAL 25

WELDING MATERIAL SPECIFICATION AND CONTROL

1.0 SCOPE:

This chapter gives details for welding material specification and control at sites.

2.0 CONTENTS:

1. Table- A3.1 - Weld Metal Chemical Composition.

2. Table-A3.2 - Mechanical property requirement for all-weld metal.

3. Receipt inspection of welding electrodes/filler wires.

4. Storage and identification of welding electrodes/filler wires.

5. Drying and holding of welding electrodes.

6. Selection and issue of welding electrodes/filler wires.

7. Table-A3.3 - Selection of GTAW filler wire, SMAW electrodes for butt welds in

tubes, pipes, headers.

8. Table-A3.4 - Selection of electrodes for welding attachments to tubes.

9. Table-A3.5 - Selection of electrodes, preheat, PWHT for attachment to

attachment welds.

10. Table-A3.6 - Selection of electrodes for welding nozzle attachments, hand hole

plate, RG plug etc. to headers, pipes.

11. Table-A3.7 – Selection of filler wire and electrodes for non-pressure parts

( including structures )

12. Table-A3.8 - A numbers

13. Table-A3.9 - F numbers

14. SFA Classification

3.0 For welding consumables not covered in this chapter, relevant details may be obtained

from the Manufacturing Units.

WELDING MANUAL 26

Table – A3.1 WELD METAL CHEMICAL COMPOSITION

Electrode SFA No. Weight, % Other Elements %

C Mn Si P S Ni Cr Mo V Cu

E 6010 5.1 0.20 1.20 1.00 NS NS 0.30 0.20 0.30 0.08 NS

Combined Limit for

Mn+Ni+Cu+Mo+V=1.75

E 6013 5.1 0.20 1.20 1.00 NS NS 0.30 0.20 0.30 0.08 NS

E 7018 /

E 7018-1 5.1 0.15 1.60 0.75 0.035 0.035 0.30 0.20 0.30 0.08 NS

E 7018-A1 5.5 0.12 0.90 0.80 0.03 0.03 NS NS 0.40-0.65 NS NS

E 8018-B2 5.5 0.05-0.12 0.90 0.80 0.03 0.03 NS 1.00-1.50 0.40-0.65 NS NS

E 9018-B3 5.5 0.05-0.12 0.90 0.80 0.03 0.03 NS 2.00-2.50 0.90-1.20 NS NS

E 9015-B9 /

E 9018-B9 5.5 0.08-0.13 1.20 0.30 0.01 0.01 0.80

8.00-

10.50 0.85-1.20 0.15-0.30 0.04-0.25

E 308 5.4 0.08 0.50-2.50 1.00 0.04 0.03 9.00-

11.00

18.00-

21.00 0.75 NS 0.75

E 308-L 5.4 0.04 0.50-2.50 1.00 0.04 0.03 9.00-

11.00

18.00-

21.00 0.75 NS 0.75

E 309 5.4 0.15 0.50-2.50 1.00 0.04 0.03 12.00-

14.00

22.00-

25.00 0.75 NS 0.75

E 309-L 5.4 0.04 0.50-2.50 1.00 0.04 0.03 12.00-

14.00

22.00-

25.00 0.75 NS 0.75

E 347 5.4 0.08 0.50-2.50 1.00 0.04 0.03 9.00-

11.00

18.00-

21.00 0.75 NS 0.75

Cb+Ta 8XC Min. to 1.00

Max.

ENi-Cl 5.15 2.00 2.50 4.00 NS 0.03 85 d min NS NS NS 2.5

e Fe Al others

8.0 1.0 Total 1.0

ENiFe-Cl 5.15 2.00 2.50 4.00 NS 0.03 45d-60 NS NS NS 2.5

e Fe Al others

Remf 1.0 Total 1.0

Note : Single values are maximum permissible limits. NS – Not Specified

WELDING MANUAL 27

Table – A3.1(Contd…) WELD METAL CHEMICAL COMPOSITION

Electrode SFA

No.

Weight, % Other Elements %

C Mn Si P S Ni Cr Mo V Cu

ER70S-2 5.18 0.07 0.90-1.40 0.40-0.70 0.025 0.035 0.15 0.15 0.15 0.03 0.50b

Ti Zr Al

0.05- 0.02- 0.05-

0.15 0.12 0.15

ER80S-G 5.28 Not Specified

ER90S-G 5.28 Not Specified

ER80S-B2 5.28 0.07-0.12 0.40-0.70 0.40-0.70 0.025 0.025 0.20 1.20-1.50 0.40-0.65 NS 0.35c

Total other Elements 0.50

ER90S-B3 5.28 0.07-0.12 0.40-0.70 0.40-0.70 0.025 0.025 0.20 2.30-2.70 0.90-1.20 NS 0.35c


ER80S-D2 5.28 0.07-0.12 1.60-2.10 0.50-0.80 0.025 0.025 0.15 NS 0.40-0.60 NS 0.50c


ER90S-B9 5.28 0.07-0.13 1.20 0.15-0.30 0.01 0.01 0.80 8.00-

10.50 0.80-1.20 0.15-0.23 0.20


ER 308 5.9 0.08 1.00-2.50 0.30-0.65 0.03 0.03 9.00-

11.00

19.50-

22.00 0.75 NS 0.75

ER 309 5.9 0.12 1.00-2.50 0.30-0.65 0.03 0.03 12.00-

14.00

23.00-

25.00 0.75 NS 0.75

ER 309-L 5.9 0.03 1.00-2.50 0.30-0.65 0.03 0.03 12.00-

14.00

23.00-

25.00 0.75 NS 0.75

ER 347 5.9 0.08 1.00-2.50 0.30-0.65 0.03 0.03 9.00-

11.00

19.00-

21.50 0.75 NS 0.75

Cb+Ta 10XC Min.

to 1.0 Max.

Note : Single values are maximum permissible limits. NS – Not Specified

WELDING MANUAL 28

TABLE – A3.1 (Contd…)

WELD METAL CHEMICAL COMPOSITION

a) These elements may be present but are not intentionally added.

b) The maximum weight percent of copper in the rod or electrode due to any coating

plus the residual copper content in the steel shall be 0.50.

c) The maximum weight percent of copper in the rod or electrode due to any coating

plus the residual copper content in the steel shall comply with the stated value.

d) Nickel plus incident Cobalt.

e) Copper plus incident Silver.

f) “Rem” stands for remainder.

g) Manufacturer‟s certification to have met the requirements of ASME Sec. II

Part C is acceptable in cases where the chemical analysis are not reflected.

h) Single values are maximum.

WELDING MANUAL 29

Table-A3.2

MECHANICAL PROPERTY REQUIREMENT FOR ALL-WELD METAL

Electrode SFA No.

Tensile Strength Ksi / MPa

Yield Strength at 0.2% of

Proof Stress, ksi/ MPa

Elongation In 2 inch (50.8 mm) %

E6010 5.1 60 / 430 48 / 330 22

E6013 5.1 60 /430 48 / 330 17

E7018 5.1 70 / 490 58 / 400 22

E7018-1* 5.1 70 / 490 58 / 400 22

E7018-A1 5.5 70 / 490 57 / 390 22

E8018-B2 5.5 80 /550 67 / 460 19

E9018-B3 5.5 90 /620 77 / 530 17

E9018-B9 5.5 90 /620 77 / 530 17

E308 5.4 80 / 550 - 35

E308L 5.4 75 / 520 - 35

E309 5.4 80 / 550 - 30

E309L 5.4 75 / 520 - 30

E347 5.4 75 / 520 - 30

ENi-CI 5.15 40-65 / 276-448 38-60 / 268-414 3-6

ENiFe-CI 5.15 58-84 / 400 -579 43-63 / 294 -434 6-18

ER70S-2 5.18 70 /490 58 / 400 22

ER80S-B2 5.28 80 / 550 68 / 470 19

* - These electrodes shall meet the lower temperature impact requirement of average minimum

20 ft-lb at - 50°F. ( 27 Joules at – 46° C)

WELDING MANUAL 30

Table- A3.2 (Contd..)

MECHANICAL PROPERTY REQUIREMENT FOR ALL-WELD METAL

Electrode SFA No.

Tensile Strength Ksi / MPa

Yield Strength at 0.2% of

Proof Stress, ksi / Mpa

Elongation In 2 inch (50.8 mm) %

ER90S-B3 5.28 90 / 620 78 / 540 17

ER80S-D2 5.28 80 / 550 68 / 470 17

ER90S-B9 5.28 90 / 620 60 / 410 16

ER308 5.9

These values are not required in the test certificate

ER308L 5.9

ER309 5.9

ER309L 5.9

ER347 5.9

NOTE:

a) Single values are minimum.

b) Manufacturer‟s certification to have met the requirements of ASME-Section II Part C is

acceptable in cases where the mechanical properties are not reflected.

c) 1ksi is approximately equal to 6.89 Mpa.

WELDING MANUAL 31

RECEIPT INSPECTION OF WELDING ELECTRODES / FILLER WIRES

1. All electrodes/filler wires received at site stores shall be segregated for type and size of electrode.

2. Ensure that electrode packets received are free from physical damage.

3. Where electrodes are damaged, the same shall be removed from use.

4. Only electrodes identified in the “list of approved vendors of welding electrodes” are to be accepted.

5. Where filler metals are supplied by manufacturing unit, inspect for damages, if any.

6. Ensure availability of relevant test certificates. Refer tables of chemical compositions and

mechanical properties for acceptance.

7. Endorse acceptance/rejection on the test certificate.

WELDING MANUAL 32

STORAGE & IDENTIFICATION OF WELDING ELECTRODES/FILLER WIRES

1.0 SCOPE:

1.1 This procedure is applicable for storage of welding electrodes/filler wires used at sites.

2.0 PROCEDURE:

2.1 Only materials accepted (based on receipt inspection) shall be taken into account for storage.

2.2 Storage Facility:

2.2.1 The storage facility shall be identified.

2.2.2 Access shall be restricted to authorised personnel.

2.2.3 The storage area shall be clean and dry.

2.2.4 Steel racks may be used for storage. Avoid storing wood inside the storage room.

2.2.5 Maintain the temperature of the storage facility above the ambient temperature. This can be

achieved by the use of appropriate heating arrangements.

2.3 The electrodes/filler wire shall be segregated and identified for

a. Type of electrode e.g. E7018.

b. Size of electrode e.g. Dia 3.15 mm.

2.4 Colour coding for filler wires:

2.4.1 On receipt of GTAW filler wires, codify the filler wires as below, in case embossing is not available

on either ends. Both ends shall be colored.

Specification Brand Name* Colour Code

RT 1/2 Mo (ER80S-G / ER 70S-A1) TGS-M / Union1 Mo Green

RT 1 Cr 1/2 Mo (ER80S-G / ER 80S-

B2) TGS 1CM Silver grey /

White

RT 2 1/4 Cr 1 Mo (ER90S-G/ ER 90S –

B3)

TGS 2CM / Union1CrMo

910

Brown / Red

RT 9 Cr 1Mo 1/4 V(ER90S-B9 ) MTS-3 Yellow

RT 347 (ER347) TGS – 347/ Thermanit H-

347

Blue

(*or other approved equivalents)

2.4.2 Where another set of colour code is followed, maintain a record of coding used.

2.4.3 Where the filler wire is cut, apply the appropriate colour code at both ends of the piece.

2.4.4 For other filler wires, a suitable colour distinct from Table 1 shall be applied.

2.4.5 AWS No. or brand name embossed end to be retained for identification.

WELDING MANUAL 33

DRYING AND HOLDING OF WELDING ELECTRODES

1.0 SCOPE:

1.1 This section details activities regarding drying and holding of welding electrodes used at sites.

2.0 PROCEDURE:

2.1 While handling, avoid contact of oil, grease with electrodes. Do not use oily or wet gloves.

2.2 It is recommended that not more than two days‟ requirements are dried.

3.0 GTAW Filler Wires:

3.1 These wires do not require any drying.

4.0 Covered Electrodes:

4.1.0 Drying and holding :

4.1.1 Identify drying oven and holding oven.

4.1.2 They shall preferably have a temperature control facility upto 400°C for drying oven and 200°C for

holding oven.

4.1.3 A calibrated thermometer shall be provided for monitoring temperature.

4.2.0 On opening a packet of electrodes, segregate and place them in the drying oven. Avoid mix up.

4.2.1 After loading, raise the drying oven temperature to the desired range as per table in 4.2.5.

4.2.2 Note the time when the temperature reaches the desired range. Maintain this temperature for the

duration required as per Table in 4.2.5.

4.2.3 On completion of drying, transfer the electrodes to holding oven; maintain a minimum temperature

of 150°C till issue.

4.2.4 The electrode shall not be subjected to more than two cycles of drying.

WELDING MANUAL 34

4.2.5 Maintain a register containing following details:

Date Sl.No.

Brand

Name

Batch

No.

Size

Dia Qty.

Baking

Temp.

reach time

Time of

transfer to

holding

oven

Remarks

1

2

3

Redrying and Holding Parameters

AWS

Classification

Redrying (*) Minimum

Holding

Temperature °C

(@) Temperature °C Time (Hours)

E7018 250 - 300 2 150

E7018-1 250 - 300 2 150

E7018-A1 250 - 300 2 150

E8018-B2 250 - 300 2 150

E9018-B3 250 - 300 2 150

E8018-B2L 250 - 300 2 150

E9018-B3L 250 - 300 2 150

E9018-B9 250 - 300 2 150

E309 & E347 250 - 300 1 150

Note : (*) Guideline has been given however, supplier‟s recommendations shall be followed.

Note : (@) Maintain the temperature in the oven till issue.

4.2.6 After issue, maintain the electrodes in a portable oven at a minimum temperature of 65°C till use

(not applicable for E6013 electrodes)

4.3 Unused, returned electrodes shall be segregated and kept in the holding oven.

WELDING MANUAL 35

SELECTION AND ISSUE OF WELDING

ELECTRODES / FILLER WIRES

1.0 SCOPE:

1.1 This procedure details methods for selection and issue of welding electrodes/filler wires

for site operations.

2.0 PROCEDURE:

2.1 Selection:

2.1.1 The type of filler wire/electrode for welding shall be based on the details given in the

contract documents like Erection Welding Schedule, drawings, Welding Procedure

Specifications as supplied by the manufacturing units.

2.1.2 Where not specified by the manufacturing units, selection shall be based on the tables

enclosed.

2.1.3 Where electrodes/ filler wires are not covered in the documents mentioned in 2.1.1.,

2.1.2, refer to manufacturing units.

2.2 Issue :

2.2.1 Issue of welding electrodes / filler wires shall be based on authorised welding electrodes

issue voucher.

2.2.2 It is recommended to restrict quantity issued to not more than 4 hours‟ requirements.

2.2.3 Redried low hydrogen electrodes shall be carried to the work spot in a portable oven.

2.2.3.1 Maintain the temperature in the portable oven at the work spot above 65°C.

2.2.4 Unused electrodes shall be returned and kept in the holding oven till reissue.

WELDING MANUAL 36

Table- A3.3

SELECTION OF GTAW FILLER WIRE, SMAW ELECTRODE FOR BUTT WELDS IN TUBES, PIPES AND HEADERS

Material Welding

Process

P1 Gr 1

P1 Gr 2 P3 Gr 1 P4 Gr 1 P5A Gr 1 P15 E Gr 1 P8 Cr Mo V

P1 Gr 1 GTAW ER 70S-A1

P1 Gr 2 SMAW E7018-1

Note 1

P3 Gr 1 GTAW ER 70S-A1

ER 70S-A1

SMAW E7018-1 E7018-A1

P4 Gr 1 GTAW ER 70S-A1 ER 70S-A1 ER 80S-B2

SMAW E7018-1 E7018-A1 E8018-B2

P5A Gr 1 GTAW ER 70S-A1 ER 70S-A1 ER 80S-B2 ER 90S-B3 ER 90S-B3

SMAW E7018-1 E7018-A1 E8018-B2 E9018-B3 E9018-B3

P15 E Gr 1 GTAW ER90S-B9

P15 E Gr 1

GTAW ER90S-B9

Note-3

SMAW E 9015-B9 /

E 9018-B9

P8 GTAW ERNiCr3 ERNiCr3 ER347

SMAW ENiCrFe3 ENiCrFe3 E347

CrMoV

Note 2

GTAW ER 90S-B3 ER 90S-B3

SMAW E9018-B3 E9018-B3

Note-1 : E7018-A1 for P1 Gr2 + P1 Gr2 when PWHT is involved.

Note-2 : DIN14MoV63 or equivalent

Note-3 : For t > 20 mm,use ER 90S –B3 for the root welding

WELDING MANUAL 37

Table- A3.4

SELECTION OF ELECTRODES FOR WELDING ATTACHMENTS TO TUBES

Tube Material Attachment Material

P1 Group 1 P4 Group 1 P5A Group 1 P8

P1 Group 1

P1 Group 2 E 7018 E 7018 E 7018 E 7018-A1

P3 E 7018-A1 E 7018-A1 E 7018-A1 E 7018-A1

P4 Group 1 E 8018-B2 E 8018-B2 E 8018-B2 E 7018-A1

P5A Group 1 E 9018-B3 E 9018-B3 E 9018-B3 E 7018-A1

P8 E 309 E 309 E 347

WELDING MANUAL 38

Table- A3.5 SELECTION OF ELECTRODES, PREHEAT, PWHT FOR ATTACHMENT TO ATTACHMENT WELDS

(Seal Bands, High Crown Bars, End Bars, End Bar Lifting Lugs and Collector Plates etc.)

Material Welding

Requirements P1 P4 P5 A P8 Group 1 P8 Group 2

P 15E / 1

P1

Electrode

Preheat

PWHT

E7018

Nil

Nil

P4

Electrode

Preheat

PWHT

E7018 (Note 2)

150 (Note 4)

Nil (Note 2 & 3)

E8018-B2

150 (Note 4)

Nil (Note 3)

P5 A

Electrode

Preheat

PWHT

E7018

150C (Note 4)

Nil (Note 1 & 2)

E8018-B2

150C (Note 4)

Nil (Note 1)

E9018-B3

150C (Note 4)

Nil (Note 1)

P8

Electrode

Preheat

PWHT

E309

Nil

Nil

E309

Nil

Nil

E309

Nil

Nil

E347

Nil

Nil

E309

Nil

Nil

P 15 E / 1

Electrode

Preheat

PWHT

- -

E9018-B3

220C

745 + 15 C

ENi Cr Fe3

220C

745 + 15 C

ENi Cr Fe3

220C

745 + 15 C

E9015-B9

220C

760 + 10 C

Note – 1 : When P5 A material thickness is more than 10 mm, PWHT is required.

Note – 2 : Electrode, preheat and PWHT requirement for welding end bar lifting lug are as follows:

End Bar Lifting

Lug End Bar Electrode Preheat C PWHT C

P1 P4 E8018-B2 150 640 – 670

P1 P5 E9018-B3 150 680 – 710

Note – 3: When P4 material thickness is more than 13 mm PWHT required. Note – 4 : Preheat is not required for P4up to 16 mm & for P5 A up to 12 mm, if PWHT is carried out. Note - 5: For load carrying members, PWHT is required irrespective of thickness.

WELDING MANUAL 39

Table- A3.6

SELECTION OF ELECTRODES FOR WELDING NOZZLE ATTACHMENTS, HAND HOLE PLATE, RG PLUG ETC. TO HEADERS, PIPES.

Header, Pipe

Material

Attachment Material

P1 P3 P4 P5 A P15 E/1 P8

P1 E7018-1 - E7018-1 - - ENiCrFe3

P4 - - E8018-B2 E8018-B2 - -

P5 A - - - E9018-B3 E9018-B3 ENiCrFe3

P15 E/1 - - - E9018-B3 E9015-B9 /

E9018-B9 ENiCrFe3

CrMoV Note 1 - - - E9018-B3 - ENiCrFe3

Note 1 : DIN 14MoV63 or equivalent.

WELDING MANUAL 40

Table – A3.7

SELECTION OF ELECTRODES FOR NON-PRESSURE PARTS

(INCLUDING STRUCTURES) (NOTE 1)

Material SMAW Electrodes

SAW Wires

C O2 Wires

P1 + P1

For butt welds 6 mm: E 6013

> 6 mm: E 7018

For fillets 8 mm : E 6013

>8 mm: E 7018

EL 8

EM 12 K

EL 8

EM 12 K

Carton Steel

+ P1 E 6013 or E 7018

EM 12 K

Carton Steel

+ Carton

Steel

E 8018 – B2

EB 2

E 81 T 1 – B2

Note 1 : E 6013 Electrodes can be used for all non-load carrying welds of all thickness of IS 2062 plates upto 20 mm thickness and

8 mm fillets.

E 71 T - 1

WELDING MANUAL 41

TABLE- A3.8

A NUMBERS CLASSIFICATION OF FERROUS WELD METAL ANALYSIS FOR

PROCEDURE QUALIFICATION

A.

No. Types of Weld Deposit

Analysis, % (Note 1)

C Cr Mo Ni Mn Si

1 Mild steel 0.20 – – – 1.60 1.00

2 Carbon-Molybdenum 0.15 0.50 0.40-0.65

– 1.60 1.00

3 Chrome (0.4% to 2%)- Molybdenum

0.15 0.40-2.00

0.40-0.65

– 1.60 1.00

4 Chrome (2% to 6%)- Molybdenum

0.15 2.00-6.00

0.40-1.50

– 1.60 2.00

5 Chrome (6% to 10.5%)- Molybdenum

0.15 6.00-10.50

0.40-1.50

– 1.20 2.00

6 Chrome-Martensitic 0.15 11.00-15.00

0.70 – 2.00 1.00

7 Chrome-Ferritic 0.15 11.00-30.00

1.00 – 1.00 3.00

8 Chromium-Nickel 0.15 14.50-30.00

4.00 7.50-15.00

2.50 1.00

9 Chromium-Nickel 0.30 19.00-30.00

6.00 15.00-37.00

2.50 1.00

10 Nickel to 4% 0.15 – 0.55 0.80-4.00

1.70 1.00

11 Manganese-Molybdenum 0.17 – 0.25-0.75

0.85 1.25-2.25

1.00

12 Nickel-Chrome-Molybdenum 0.15 1.50 0.25-0.80

1.25-2.80

0.75-2.25

1.00

Note 1: Single values shown above are maximum.

WELDING MANUAL 42

Table- A3.9

F.No. ASME Specification No. AWS Classification No.

Steel and Steel Alloys

1 SFA-5.1 EXX20

1 SFA-5.1 EXX22

1 SFA-5.1 EXX24

1 SFA-5.1 EXX27

1 SFA-5.1 EXX28

1 SFA-5.4 EXXX(X)-26

1 SFA-5.5 EXX20-X

1 SFA-5.5 EXX27-X

2 SFA-5.1 EXX12

2 SFA-5.1 EXX13

2 SFA-5.1 EXX14

2 SFA-5.1 EXX19

2 SFA-5.5 E(X)XX13-X

3 SFA-5.1 EXX10

3 SFA-5.1 EXX11



4 SFA-5.1 EXX15

4 SFA-5.1 EXX16

4 SFA-5.1 EXX18

4 SFA-5.1 EXX18M

4 SFA-5.1 EXX48

4 SFA-5.4 other than austenitic and duplex EXXX(X)-15






4 SFA-5.5 E(X)XX18M

4 SFA-5.5 E(X)XX18M1

WELDING MANUAL 43

Table- A3.9


5 SFA-5.4 austenitic and duplex EXXX(X)-15



6 SFA-5.2 All classifications











6 SFA-5.30 INMs-X

6 SFA-5.30 IN5XX

6 SFA-5.30 IN3XX(X)

Aluminium and Aluminium-Base Alloys

21 SFA-5.3 E1100

21 SFA-5.3 E3003

21 SFA-5.10 ER1100

21 SFA-5.10 R1100

21 SFA-5.10 ER1188

21 SFA-5.10 R1188

22 SFA-5.10 ER5183

22 SFA-5.10 R5183

22 SFA-5.10 ER5356

22 SFA-5.10 R5356

22 SFA-5.10 ER5554

22 SFA-5.10 R5554

22 SFA-5.10 ER5556

WELDING MANUAL 44


22 SFA-5.10 R5556

22 SFA-5.10 ER5654

22 SFA-5.10 R5654

23 SFA-5.3 E4043

23 SFA-5.10 ER4009

23 SFA-5.10 R4009

23 SFA-5.10 ER4010

23 SFA-5.10 R4010

23 SFA-5.10 R4011

23 SFA-5.10 ER4043

23 SFA-5.10 R4043

23 SFA-5.10 ER4047

23 SFA-5.10 R4047

23 SFA-5.10 ER4145

23 SFA-5.10 R4145

23 SFA-5.10 ER4643

23 SFA-5.10 R4643

24 SFA-5.10 R206.0

24 SFA-5.10 R-C355.0

24 SFA-5.10 R-A356.0

24 SFA-5.10 R357.0

24 SFA-5.10 R-A357.0

25 SFA-5.10 ER2319

25 SFA-5.10 R2319

Copper And Copper Alloys

31 SFA-5.6 ECu

31 SFA-5.7 ERCu

32 SFA-5.6 ECuSi

32 SFA-5.7 ERCuSi-A

TABLE- A3.9(CONTD.)

F NUMBERS GROUPING OF ELECTRODES AND WELDING RODS FOR QUALIFICATION

WELDING MANUAL 45

TABLE- A3.9 (CONTD.) F NUMBERS

GROUPING OF ELECTRODES AND WELDING RODS FOR QUALIFICATION


33 SFA-5.6 ECuSn-A

33 SFA-5.6 ECuSn-C

33 SFA-5.7 ERCuSn-A

34 SFA-5.6 ECuNi

34 SFA-5.7 ERCuNi

34 SFA-5.30 IN67

35 SFA-5.8 RBCuZn-A

35 SFA-5.8 RBCuZn-B

35 SFA-5.8 RBCuZn-C

35 SFA-5.8 RBCuZn-D

36 SFA-5.6 ECuAl-A2

36 SFA-5.6 ECuAl-B

36 SFA-5.7 ERCuAl-A1



37 SFA-5.6 ECuNiAl

37 SFA-5.6 ECuMnNiAl

37 SFA-5.7 ERCuNiAl

37 SFA-5.7 ERCuMnNiAl

Nickel And Nickel Alloys

41 SFA-5.11 ENi-1

41 SFA-5.14 ERNi-1

41 SFA-5.30 IN61

42 SFA-5.11 ENiCu-7

42 SFA-5.14 ERNiCu-7

42 SFA-5.14 ERNiCu-8

42 SFA-5.30 IN60

WELDING MANUAL 46

TABLE- A3.9 (CONTD.)

F NUMBERS GROUPING OF ELECTRODES AND WELDING RODS FOR QUALIFICATION


45 SFA5.11 ENiCrMo-11

45 SFA5.14 ERNiCrMo-1



45 SFA5.14 ERNiCrMo-11 45 SFA5.14 ERNiFeCr-1

Titanium And Titanium Alloys

51 SFA-5.16 ERTi-1

51 SFA-5.16 ERTi-2

51 SFA-5.16 ERTi-3

51 SFA-5.16 ERTi-7

52 SFA-5.16 ERTi-4

53 SFA-5.16 ERTi-9

53 SFA-5.16 ERTi-9ELI

54 SFA-5.16 ERTi-12

55 SFA-5.16 ERTi-5

Zirconium And Zirconium Alloys

61 SFA-5.24 ERZr2

61 SFA-5.24 ERZr3

61 SFA-5.24 ERZr4

Hard-Facing Weld Metal Overlay

71 SFA-5.13

E Co Cr – A & All

classifications

72

SFA-5.21 ER Co Cr – A & All

classifications

WELDING MANUAL 47

SFA CLASSIFICATION

SFA NO. DESCRIPTION

5.01 Filler Metal Procurement guidelines

5.1 Carbon Steel Electrodes for Shielded Metal Arc Welding

5.2 Carbon and Low Alloy Steel Rods for Oxy fuel Gas Welding

5.3 Aluminium and Aluminium Alloy Electrodes for Shielded Metal Arc Welding

5.4 Stainless Steel Electrodes for Shielded Metal Arc Welding

5.5 Low-Alloy Steel Electrodes for Shielded Metal Arc Welding

5.6 Covered Copper and Copper Alloy Arc Welding Electrodes

5.7 Copper and Copper Alloy Bare Welding Rods and Electrodes

5.8 Filler Metal for Brazing and Braze Welding

5.9 Bare Stainless Steel Welding Electrodes and Rods

5.10 Bare Aluminium and Aluminium Alloy Welding Electrodes and Rods

5.11 Nickel and Nickel Alloy Welding Electrodes for Shielded Metal Arc Welding

5.12 Tungsten and Tungsten Alloy Electrodes for Arc Welding and Cutting

5.13 Surfacing electrodes for shielded metal arc welding

5.14 Nickel and Nickel Alloy Bare Welding Electrodes and Rods

5.15 Welding Electrodes and Rods for Cast Iron

5.16 Titanium and Titanium Alloy Welding Rods and Electrodes

5.17 Carbon Steel Electrodes and Fluxes for Submerged Arc Welding

5.18 Carbon Steel electrodes and rods for Gas Shielded Arc Welding

5.20 Carbon Steel Electrodes for Flux Cored Arc Welding

WELDING MANUAL 48

SFA CLASSIFICATION

SFA NO. DESCRIPTION

5.21 Bare electrodes and rods for surfacing

5.22 Stainless Steel Electrodes for Flux Cored Arc Welding and Stainless Steel

Flux Cored Rods for Gas Tungsten Arc Welding

5.23 Low Alloy Steel Electrodes and Fluxes for Submerged Arc Welding

5.24 Zirconium and Zirconium Alloy Welding Electrodes and Rods

5.25 Carbon and Low Alloy Steel Electrodes and Fluxes for Electro-slag Welding

5.26 Carbon and Low Alloy Steel Electrodes for Electro-gas Welding

5.28 Low-Alloy Steel Electrodes and Rods for Gas Shielded Arc Welding

5.29 Low Alloy Steel Electrodes for Flux Cored Arc Welding

5.30 Consumable Inserts

5.31 Fluxes for Brazing and Braze Welding

5.32 Welding Shielding gas

WELDING MANUAL CHAPTER - A4 49

CHAPTER - A4

PROCEDURE FOR WELDER QUALIFICATION


PROCEDURE FOR WELDER QUALIFICATION

1.0 SCOPE:

1.1 This chapter details the procedure for qualification of welder and performance

monitoring.

2.0 CONTENTS:

1. Qualification of Welder.

2. Table- A4.1 - Welder Qualification Requirements.

3. Figure-1 Fillet Weld Break Specimen.

Figure- 2 Method of Rupturing.

Figure- 3 Positions.

Figure- 4 Plate Butt Weld Specimen.

Figure- 5 Pipe Butt Weld Specimen.

Figure- 6 Bend Test Specimen.

Figure- 7 Bend Test Jig.

4. Record of Welder Performance Qualification Tests.

5. Welder performance monitoring.


QUALIFICATION OF WELDER

1.0 BASE METAL:

1.1 For selection refer Tables in Chapter II.

2.0 TEST COUPON:

2.1 Depending on the range to be qualified, choose the appropriate test coupon from

Table – A4.1

2.2 For plate butt welds, details of edge preparation shall be as per Figure-4.

2.3 For pipe butt welds, details of edge preparation shall be as per Figure-5.

2.4 For structural tack welds, refer Figure-1.

3.0 REQUIREMENT OF TESTS:

3.1 For Structural Tack Welders:

3.1.1 Break Test as per Figure-2.

3.2 For Plate Butt Welds:

3.2.1 Minimum of 2 specimens for bend test; one for root bend and other for face

bend. Width of specimen shall be 38 mm for plate thickness upto 10 mm. For

Plate thickness greater than 10 mm, side bend test ( 2 Specimens) shall be done

and the width of specimens shall be 10 mm .

3.3 For Pipe Welder :

3.3.1 The order of removal of test specimens shall be as per Figure-6.

3.3.2 For width and number of bend specimens, refer below:


OD W No. of Bend Specimens

Face Root Side

> 101.6 38.0 2 2 (**)

50.8 - 101.6 19.0 2 2 (**)

< 50.8 10.0 2 2 (**)

<= 25.4 (++) 2 2 -

(**) for thickness greater than 10.0 mm, side bend test of width 10.0 mm may be

substituted.

(++) Cut into 4 equal sections (with allowance for saw cuts or machine cutting); sharp

corners to be rounded off.

OD - Outer diameter of pipe in mm.

W - Width of bend test specimen in mm.

3.4 For bend test jig refer Figure-7, for thickness of bend specimen 10.0 mm; for other

thicknesses (t) the dimension shall be as below :

A = 4t

B = 2t

C = 6t + 3.2 mm

D = 3t + 1.6 mm

The above values are nominal.

3.5 Radiographic examination of test welds may be carried out in lieu of bend tests.

Procedure and acceptance criteria are as per NDE Manual.

4.0 ESSENTIAL VARIABLES :

4.1 Changes to the following variables require requalification.

4.1.1 Process :

Example : Change from GTAW to SMAW or vice versa.

4.1.2 Joint :

A change from one type of bevel to another. Example : „vee‟ bevel to „u‟ bevel.

4.1.3 Base Metal :

A change in thickness or pipe diameter beyond the limits prescribed in Table- A4.1


4.1.4 Filler Metal:

A change from one F number to another F-number, except as specified in Table-A4.1

4.1.5 Positions:

This procedure envisages qualification of welders to perform in all positions. Deviation

to this is not recommended.

4.1.6 Gas:

This procedure envisages test to pre-prescribed gas as for production welds. Deviation

to this is not recommended.

4.1.7 Electrical Characteristics:

a) AC to DC and vice versa.

b) In DC, DCEN (Electrode Negative) to DCEP (Electrode Positive) and vice versa.

4.1.8 Technique :

This procedure envisages only use of uphill progression technique.

ACCEPTANCE CRITERIA :

Structural Tack Welding :

No cracks.

No lack of fusion.

Undercut not exceeding 1 mm.

Not more than 1 porosity (max. diameter of porosity 2 mm).

Plate/Pipe Welding :

Visual Inspection :

a) No cracks.

b) No lack of fusion or incomplete penetration.

c) Not more than 1 porosity in a length of 100 mm of length of weld (max. porosity

diameter 2mm).


5.0 Acceptance Criteria - Bend Tests ( ASME Sec IX- QW-163 )

The weld and heat-affected zone of a transverse weld-bend specimen shall be

completely within the bent portion of the specimen after testing.

The guided –bend specimens shall have no open discontinuity in the weld or heat-

affected zone exceeding 1/8 in.(3 mm), measured in any direction on the convex

surface of the specimen after bending. Open discontinuities occurring on the corners

of the specimen during testing shall not be considered unless there is definite evidence

that they result from lack of fusion, slag inclusions, or other internal discontinuities.

For corrosion –resistant weld overlay cladding, no open discontinuity exceeding 1/16

in. (1.5 mm), measured in any direction, shall be permitted in the cladding, and no

open discontinuity exceeding 1/8 in.(3mm) shall be permitted along the approximate

weld interface.

6.0 RETESTS:

6.1 A welder who fails to meet the acceptance criteria for one or more test specimens, may

be retested as per this procedure after adequate practice.

7.0 VALIDITY :

7.1 When a welder meets the requirements of this procedure, the validity will be for a

maximum of 2 years from the date of test, limited to validity specified by statutory

authority, as applicable.

The validity may be extended by one year each time, based on satisfactory

performance, with sufficient back up records.

8.0 REQUALIFICATION :

8.1 Requalification is required for the following :

a. Where there is a specific reason to doubt the skill of the welder.

b. Due to non-engagement of the welder for a continuous period of 6 months.


9. RECORDS:

The welding in charge at site shall maintain the following records:

a) Record of Welder Performance qualification Test (as per format).

b) Register of qualified welders (employer-wise) containing the following details:

1) Name of welder.

2) Age.

3) Tested for pipe / tube / plate / tack.

4) Performance Test No.

5) Validity.

6) Welder Code.

7) Remarks.

The above register shall be updated for deletions also.

Copies of welder identity card (including details as in 9 b and relevant variables

qualified). Pertinent radiography reports.

10.0 ENCLOSURES :

1. Table -A4.1 : Welder Qualification Requirements.

2. Record of Welder Performance Qualification Test.

3. Figure-1: Structural Tack Weld Specimen.

4. Figure-2 : Break Test.

5. Figure-3 : Weld Positions.

6. Figure-4 : Plate Butt Weld Specimen.

7. Figure-5 : Pipe Butt Weld Specimen.

8. Figure-6 : Order of Removal of Test Specimen.

9. Figure-7 : Bend test Jig.

WELDING MANUAL CHAPTER - A4

WELDER QUALIFICATION REQUIREMENTS Table – A4.1

Sl.No. Test For

Base6

Metal

Note 1

Test

Coupon

Dimension

OD, t

Electrode6

to be used

Note 2, 4

Weld

Positions

Reference

Figure

Range

Qualified

Dia. & T

Position

Qualified

Electrode

Qualified

Note 2, 4

Remarks

1 Structural tack P1 Gr 1 t=10mm or

12mm

(E6013) F2 3F & 4F Fig. 1 & 2 T-Unlimited All F2, F1 Refer

Fig. 1,3

(E7018) F4 3F & 4F Fig. 1 & 2 T-Unlimited All F4 &

Below

Refer

Fig. 1,3

2 Plate Welder

(Structural) - do -

t25mm F4 3G & 4G Fig.3 T3.2mm* All F4 &

Below

t<25mm F4 3G & 4G Fig.3 T>3.2mm*

2t All

F4 &

Below

3

Plate Welder

(Other than

structural)

- do -

t13mm F4 2G, 3G &

4G Fig.3

T-Unlimited

OD610mm All

F4 &

Below

t<13mm F4 2G, 3G &

4G Fig.3

T2t

OD610mm All

F4 &

Below

4 Pipe Welder - do -

OD<25mm F4 6G Fig.3 Test piece

Dia.& above All

F4 &

Below

OD25mm

& 73mm F4 6G Fig.3

25mm &

above All

F4 &

Below

OD>73mm F4 6G Fig.3 73mm &

above All

F4 &

Below

t<13mm F4 6G Fig.3 T2t All F4 &

Below

t13mm F4 6G Fig.3 T-Unlimited All F4 &

Below

* Also qualifies for welding fillet welds on material of unlimited thickness.


Table – A4.1 (contd...)

NOTES:

1. For P grouping refer Chapter II.

2. For F grouping refer Chapter III.

3. Base material limitation:

a. Where test coupons belong to P1 thro‟ P15F, welder is qualified for base

materials P1 thro‟ P15F.( ASME Sec IX QW 423, Alternate base material

for welder qualification)

It means, if a welder is qualified with carbon steel material, he is also qualified

for alloy steel and vice versa.

b. Use appropriate F group electrodes.

4. Qualification in one F number, qualifies for that F-number only, except as stated below

in A, B, C & D.

A. Qualification in F4 qualifies for F4 and below.

B. Qualification in F5 qualifies for F5 only.

C. Qualification in any of F41 thro‟ F45 qualifies for F41 thro‟ F45.

D. For non-ferrous materials, the base materials shall be typical of production

material and appropriate filler materials shall be selected. Qualification is limited

to the base material, process and filler F group. Diameter and thickness

limitations apply as per Table –A4.1

OD = outer diameter, t = thickness of test coupon; T = thickness qualified.

5. Where qualification is for GTAW followed by SMAW, the welder is also qualified

upto 6 mm thickness by GTAW process.

6. Base material indicated is carbon steel; for other base materials, corresponding electrodes

are to be chosen. Also for GTAW process, the corresponding filler wire should be

chosen.


TACK WELDER QUALIFICATION


RECORD OF WELDER PERFORMANCE – QUALIFICATION TEST

Performance Test No.

Site: Date:

Welder’s Name & Address: Welder Code:

Material Groupings permitted: Welding Process:

Thickness Qualified: Position(s) Qualified:

(This performance test is as per Dia Qualified:

Procedure No. )

TEST MATERIAL

Specification: Filler Material:

Thickness (and Dia. of pipe): SFA No.:

Shielding Gas(es) AWS Classification:

PROCESS VARIABLES

Position of test weld: Current: Polarity:

Pre-heat temp: Inter Pass Temp: Post-heat Temp:

Test Joint Sketch Test Results

Type of Bend Results




Radiography Ref. & Results:

Agency Conducting Test :

We certify that the statement in this record is correct and that the test weld were prepared, welded

and tested in accordance with requirements.

This is valid upto __________________________

Welding In-charge / BHEL


WELDER PERFORMANCE MONITORING

1.0 PURPOSE:

This procedure deals with monitoring the performance of welders engaged at sites.

This procedure is applicable where radiography is performed.

2.0 PROCEDURE:

2.1 The welder performance shall be monitored on a calendar month basis.

2.2 Extent of radiography shall be representative of weekly outputs of the welder.

2.3 Quantum of radiography shall be as per contractual requirements.

2.4 Evaluation of welds radiographed shall be as per NDE manual or other documents as

specifically applicable.

2.5 Welder performance evaluation:

2.5.1 For welds dia. 88.9 mm:

2.5.1.1 The percentage of defects is calculated as a percentage of number of unaccepted welds

to those radiographed.

2.5.1.2 Upto and including 5% defects: Performance is satisfactory else unsatisfactory.

2.5.2 For welds dia. > 88.9 mm and plate welds:

2.5.2.1 The percentage of defects is calculated as a percentage of length of defects to the

length radiographed.

2.5.2.2 Upto and including 2.5% defects: performance is satisfactory else unsatisfactory.

2.6 When a welder gives unsatisfactory performance for a continuous period of 3 months,

he shall be requalified.

2.6.1 Requalification of welder shall be called for when there is a specific reason to question

his ability to make acceptable welds. This shall override requirements of clause 2.6.

2.7 Welds produced during any month shall be radiographed and evaluated latest by 10th

of the succeeding month.

2.7.1 Under circumstances when clause 2.7 is not satisfied for any particular welder, he may

be disengaged from the job till such time his performance is evaluated for the month in

study.


2.7.2 Site in-charge may waive the restriction imposed in 2.7.1 reviewing the situations for

non-compliance with Cl.2.7 and may allow engagement of the welder in question for a

period not exceeding one successive month to the month in study.

3.0 RECORDS:

3.1 Welding in-charge shall prepare and maintain Welder Performance Records, welder-

wise.

WELDING MANUAL A5. INSPECTION OF WELDING 66

CHAPTER - A5

INSPECTION OF WELDING


INSPECTION OF WELDING

1.0 PURPOSE:

This procedure provides details for performing visual inspection of weld fit-ups, welding in

progress and completed welds.

2.0 REFERENCE:

2.1 Contract drawings.

2.2 Erection Welding Schedule (supplied by Units) or equivalent.

2.3 Welding Procedure Specification, where supplied.

2.4 Indian Boiler Regulations (for boilers erected in India)

3.0 GENERAL REQUIREMENTS:

3.1 Ensure that the components to be welded are in accordance with the contract drawings,

Welding Schedule and other relevant documents.

3.2 The condition of welded surfaces to be inspected must be clean and dry.

3.3 There shall be sufficient lighting to allow proper interpretation of visual inspection.

4.0 WELD FIT-UP INSPECTION:

4.1 The surface to be welded shall be smooth and free from deep notches, irregularities, scale, rust,

oil, grease and other foreign materials.

4.2 Piping, tubing and headers to be joined shall be aligned within allowable tolerances on

diameters, wall thicknesses and out-of-roundness as below:

Maximum permissible mis-alignment at bore

Bore (mm) Max. Misalignment (mm)

For GTAW For SMAW

Upto 100 1.0 1.0

Over 100 to 300 1.6 1.6

Over 300 1.6 2.4

4.3 While fit up, components to be welded shall not show any appreciable off-set or misalignment

when viewed from positions apart.

4.4 The root opening of components to be joined shall be adequate to provide acceptable

penetration.

4.5 On fillet welds, the parts to be joined shall be brought as close to contact as practical, although

in most instances a small opening between the parts is desirable.

4.6 Root gaps shall be maintained at 1.6 mm - 2.4mm (refer relevant document).

NOTE : Wherever pre heating is done, ensure the root gap before welding


4.7 Weld area should be protected from drafts and wind, to maintain inert gas shield.

5.0 CHECKS DURING WELDING OPERATION:

5.1 Ensure the required minimum preheat temperature is maintained during welding.

5.2 Ensure correct electrode / filler metal is used for welding.

5.3 Tack welds are examined by the welder before they are incorporated in the final weld.

5.4 Ensure proper re-drying / holding of electrodes prior to use.

5.5 Ensure inter pass temperature is not exceeded during welding.

5.6 Ensure proper cleaning of weld between beads.

6.0 CHECKS ON THE COMPLETED WELD:

6.1 No visible cracks, pin-holes or incomplete fusion.

6.2 The weld surface must be sufficiently free of coarse ripples, grooves, overlaps, abrupt

ridges and valleys, visible slag inclusions, porosity and adjacent starts and stops.

6.3 Undercuts not to exceed 0.8 mm or 10% of wall thickness whichever is less.

6.4 Where inside surface is readily accessible, the same shall be inspected for excess

penetration and root concavity. The permissible limits are given below :

Root concavity: max of 2.5 mm or 20% of thickness at weld, whichever is lesser,

provided adequate reinforcement is present.

Excess penetration: up to and including 3.2 mm.

6.5 For plate butt welds, the weld reinforcement should not exceed 3.2 mm.

6.6 For circumferential joints in piping and tubing the maximum weld reinforcements

permitted are given below :

Maximum Permissible Reinforcements ( ASME Sec I –PW 35)

Thickness of base metal in mm Reinforcement in mm

Upto 3.0 2.5

Over 3 to 5 3.0

Over 5 to 13 4.0

Over 13 to 25 5.0

Over 25 to 50 6.0

Over 50 Max of 6.0 or 1/8 of weld

width


6.7 There shall be no overlaps.

The faces of fillet welds are not excessively convex or concave and the weld legs are

of proper length.

6.8 In case of weld joints in pressure parts and joints like ceiling girder, the weld joint must

be suitably identified.

WELDING MANUAL A6. REPAIR WELDING 70

CHAPTER - A6

REPAIR WELDING

WELDING MANUAL A6. REPAIR WELDING 71

REPAIR WELDING

1.0 PURPOSE:

1.1 This procedure details steps to be taken for weld repairs.

2.0 PROCEDURE:

2.1 Unacceptable welds, based on visual inspection or NDE, shall be repaired.

2.2 Removal of Defects:

2.2.1 The identified defect area shall be marked on the part.

2.2.2 The defects may be removed by grinding/thermal gouging.

2.2.2.1 Where thermal gouging is done, adopt the requirements of preheating as detailed in

Heat Treatment Manual.

2.2.2.2 However, only grinding is permitted for the last 6 mm from the root.

2.3 Removal of defects shall be verified by visual inspection, PT, MT, RT as appropriate.

2.4 The profile of ground portion shall be smooth and wide enough to permit proper fusion

during repair welding.

2.5 Repair welding shall be carried out as per the procedure for the initial weld.

2.6 Repair weld shall undergo the same type of NDE as the initial weld.

2.7 Repeat steps 2.1 to 2.6 till acceptable weld is made.

2.8 Where the defect volume is high, Cut and weld of joints is recommended.

3.0 Where a specific repair procedure is supplied by the Manufacturing Unit, the same

shall be followed.

4.0 RECORDS :

4.1 Records pertaining to the repairs like Welder, NDE records shall be maintained.

WELDING MANUAL A7. SAFE PRACTICES IN WELDING 72

CHAPTER - A7

SAFE PRACTICES IN WELDING


A7. SAFE PRACTICES IN WELDING

(Non-mandatory Information)

SAFE PRACTICES IN WELDING

(This is included for information purposes only.)

This covers many of the basic elements of safety general to arc welding processes. It

includes many, but not all, of the safety aspects related to structural welding. The hazards

that may be encountered and the practices that will minimize personal injury and property

damage are reviewed here.

J1 Electrical Hazards

Electric shock can kill. However, it can be avoided. Live electrical parts should not be

touched. Read and understand the manufacturer‟s instructions and recommended safe

practices. Faulty installation, improper grounding, and incorrect operation and

maintenance of electrical equipment are all sources of danger.

All electrical equipment and the work-pieces should be grounded. A separate

connection is required to ground the work-piece. The work lead should not be mistaken

for a ground connection.

To prevent shock, the work area, equipment, and clothing should be kept dry at all times.

Dry gloves and rubber soled shoes should be worn. The welder should stand on a dry

board or insulated platform.

Cables and connections should be kept in good condition. Worn, damaged or bare cables

should not be used. In case of electric shock, the power should be turned off immediately.

If the rescuer must resort to pulling the victim from the live contact, non-conducting

materials should be used. A physician should be called and CPR continued until

breathing has been restored, or until a physician has arrived.

J2 Fumes and Gases

Many welding, cutting, and allied processes produce fumes and gases which may be

harmful to one‟s health. Fumes and solid particles originate from welding consumables,

the base metal, and any coating present on the base metal. Gases are produced during the

welding process or may be produced by the effects of process radiation on the

surrounding environment. Everyone associated with the welding operation should

acquaint themselves with the effects of these fumes and gases.


The possible effects of over-exposure to fumes and gases range from irritation of eyes,

skin, and respiratory system to more severe complications. Effects may occur

immediately or at some later time. Fumes can cause symptoms such as nausea,

headaches, dizziness, and metal fumes fever. Sufficient ventilation, exhaust at the arc, or

both, should be used to keep fumes and gases from breathing zones and the general work

area.

J3 Noise

Excessive noise is a known health hazard. Exposure to excessive noise can cause a loss

of hearing. This loss of hearing can be either full or partial, and temporary or permanent.

Excessive noise adversely affects hearing capability. In addition, there is evidence that

excessive noise affects other bodily functions and behavior. Personal protective devices

such as ear muffs or ear plugs may be employed. Generally, these devices are only

accepted when engineering controls are not fully effective.

J4 Burn Protection

Molten metal, sparks, slag, and hot work surfaces are produced by welding, cutting and

allied process. These can cause burns if precautionary measures are not used.

Workers should wear protective clothing made of fire resistance material. Pant cuffs or

clothing with open pockets or other places on clothing that can catch and retain molten

metal or sparks should not be worn. High top shoes or leather leggings and fire resistant

gloves should be worn. Pant legs should be worn over the outside of high top boots.

Helmets or hand shields that provide protection for the face, neck, and ears, should be

worn, as well as head covering to protect. Clothing should be kept free of grease and oil.

Combustible materials should not be carried in pockets. If any combustible substance is

spilled on clothing it should be replaced with fire resistance clothing before working with

open arcs or flame.

Appropriate eye protection should be used at all times. Goggles or equivalent also should

be worn to give added eye protection.

Insulated gloves should be worn at all times when in contact with hot items or handling

electrical equipment.


J5 Fire Prevention

Molten metal, sparks, slag, and hot work surfaces are produced by welding, cutting, and

allied processes. These can cause fire or explosion if precautionary measures are not

used.

Explosions have occurred where welding or cutting has been performed in spaces

containing flammable gases, vapours, liquid, or dust. All combustible material should b e

removed from the work area. Where possible, move the work to a location well away

from combustible materials. If neither action is possible, combustibles should be

protected with a cover or fire resistant material. All combustible materials should be

removed or safely protected within a radius of 35 ft. (11m) around the work area.

Welding or cutting should not be done in atmospheres containing dangerously reactive or

flammable gases, vapours, liquid, or dust. Heat should not be applied to a container that

has held an unknown substance or a combustible material whose contents when heated

can produce flammable or explosive vapours. Adequate ventilation should be provided in

work areas to prevent accumulation of flammable gases, vapours or dusts. Containers

should be cleaned and purged before applying heat.

J6 Radiation

Welding, cutting and allied operations may produce radiant energy (radiation) harmful to

health. Everyone should acquaint themselves with the effects of this radiant energy.

Radiant energy may be ionizing (such as X-rays) or non-ionizing (such as ultraviolet,

visible light, or infrared). Radiation can produce a variety of effects such as skin burns

and eye damage, if excessive exposure occurs.

Some processes such as resistance welding and cold pressure welding ordinarily produce

negligible quantities of radiant energy. However, most arc welding and cutting processes

(except submerged arc when used properly), laser welding and torch welding, cutting,

brazing, or soldering can produce quantities of non-ionizing radiation such that

precautionary measures are necessary.

WELDING MANUAL 76

1. Welding arcs should not be viewed except through welding filter plates.

2. Transparent welding curtains are not intended as welding filter plates, but rather,

are intended to protect passers by from incidental exposure.

3. Exposed skin should be protected with adequate gloves and clothing as specified.

4. The casual passers by to welding operations should be protected by the use of

screens, curtains, or adequate distance from aisles, walkways, etc.

5. Safety glasses with ultraviolet protective side shields have been shown to

provide some beneficial protection from ultraviolet radiation produced by

welding arcs.

WELDING MANUAL 77

PART - B

WELDING MANUAL 78

CHAPTER - B1

PRE-ASSEMBLY AND WELDING OF CEILING GIRDERS

WELDING MANUAL 79

PRE - ASSEMBLY AND WELDING OF CEILING GIRDERS

A) PREPARATION FOR PRE-ASSEMBLY:

Prepare pre-assembly bed preferably inside boiler (Sketch -1A / Sketch 1B) - Boiler Main

Columns on LHS & RHS may be used for supporting bottom beams of pre-assembly bed

(Sketch-1A).

Ensure bottom support members are uniformly spaced and closer (approximately 1 metre) on

either side of the joint to facilitate locking all around and avoid sagging during welding &

PWHT.

Identify Girder pieces – Check Work order / PGMA / DU No, girder designation etc.

Place girder pieces on bed for pre-assembly in sequence as per drawing.

Check and repair damages of edge preparation of individual pieces, if any, after placement on

bed before fit up.

Check width between flanges and web height at fillet joint location (LHS & RHS) (Reduce

web height before fit up, if required by grinding, so as to ensure minimum 3 mm gap at top &

bottom for free expansion of web inside flanges on pre-heating).

B) PRE-ASSEMBLY FIT UP & ALIGNMENT:

Do pre-assembly fit up and alignment of girder pieces following shop match marks. Use „L‟

clamps and wedges ( Tack welds are not permitted on the weld joints ) for web alignment to

keep the joint free during welding of flange joints to facilitate weld shrinkage.

Check, measure and record the following for the pre-assembly before welding (Sketch-2A/

Sketch 2B) (Also to measure & record after welding & PWHT)

- Sweep by piano wire on bottom flange (max 3mm at joints & 10mm for assy)

- Camber by water level on bottom flange (max 3mm at joint & 10mm for assy)

- Length between girder pin bolt hole centers (overall max 15 mm)

- Diagonal difference (max 15 mm)

- Root gap (Flange=4 to 6mm; Web=6 to 8mm)

- Web verticality by plumb (To monitor distortion before & after welding)

- Distance between punch marks at weld joints (To monitor weld shrinkage)

NOTE:

1 . Flange root gap will be absorbed during welding as weld shrinkage.

2 . Tolerances given above are indicative.

3 . To accommodate weld shrinkage ,ensure

- Web root gap 3-4 mm more than flange root gap

- Length before welding = Drg length + root gap of flange joints 4 . Ensure temporary locking & welding of the pre-assembly before start of

girder welding (Sketch-3) with provision for longitudinal movement during

welding to avoid accumulation of thermal stresses & facilitates controlled weld

shrinkage.

WELDING MANUAL 80

C) PRE-ASSEMBLY WELDING WITH PRE-HEAT & POST-HEAT

Weld thermocouples on top & bottom flange and web joints (Sketch-4). Arrange

pre-heating of flange and web joints with electric resistance coil heaters.

Record entire cycle of preheat, inter pass & post-heat temp of joints during welding

including intermissions/stoppages with a calibrated temperature recorder.

Engage qualified welders for welding. Issue weld job card (Refer Exhibit) . Ensure

usage of approved welding electrodes with necessary baking before use. Carry

electrodes always in portable ovens.

Start welding after ensuring required pre-heat and follow recommended weld

sequence ( sketch-5 with 2 welders per joint) for effective control of weld

shrinkage.

Ensure pre-heating temperature after back grinding.

On completion of welding dress grind the welds for conducting NDE

D) NON-DESTRUCTIVE EXAMINATION (NDE):

FLANGE BUTT JOINT:

Root Back grinding : 100% LPI

Intermediate radiography for thickness > 80mm ( desired)

On completion of weld 100 % RT for thickness >32mm & < 80mm

100 % UT for thickness > 80mm

100 % MPI for thickness > 25mm (after PWHT)

WEB BUTT JOINT:

Root Back grinding : 100% LPI

On completion of weld

Spot RT for thickness <32mm

100% RT for thickness >32mm

FILLET WELDS:

Between flange and web 100% MPI (after PWHT)

WELDING MANUAL 81

E) PRE-HEATING, POST HEATING & PWHT REQUIREMENTS :

Refer WPS & Heat Treatment Manual

PWHT CYCLE:

Weld thermocouples on top & bottom flange and web joints (as per sketch-4).

Arrange PWHT of flange and web joints with electric resistance coil heaters.

Issue PWHT job card. (Refer Exhibit) Select midpoint of temperature range and

control cycle within a tolerance of 15°C. Record PWHT cycle with a calibrated

temperature recorder

Identify PWHT chart with chart No & date and PWHT cycle with weld joint number.

Review the cycle and record observations / acceptance on chart .

F) FINAL INSPECTION (AFTER PWHT):

Grind / buff the Flange Butt & Fillet joints (site welds) and conduct MPI.

Clean all Site welds and paint with two coats of red oxide primer.

Repeat all checks under section B and record measurements ( Sketch – 2A / 2B).

Punch centre line of girder on flange thicknesses and top surface of top flange

G) OTHER PREPARATORY WORKS FOR ERECTION:

Blue match girder pin bottom piece with column and complete support lugs welding in

position. Subsequently blue match girder pin top piece with girder, tack weld support

lugs in position, remove and complete lugs welding. Conduct LPI & maintain record.

Open the girder pin assembly, buff clean the pin and seating surfaces, apply grease, re-

assemble and lock the pin with pin assembly by tack welding of lock plates.

Mount the girder pin assembly on ceiling girder for easiness of erection of girder pins.

Buff Clean Cement wash in the HSFG bolt area and cleat angles at WB‟s location

WELDING MANUAL 82

CHAPTER – B1

PRE – ASSY SKETCHES

WELDING MANUAL 83

WELDING MANUAL 84

WELDING MANUAL 85

WELDING MANUAL 86

WELDING MANUAL 87

WELDING MANUAL 88

WELDING MANUAL 89

WELDING MANUAL 90

Weld Sequence Sht. 1 of 2

WELDING MANUAL 91

WELDING SEQUENCE FOR CEILING GIRDER

Weld Sequence Sht. 2 of 2

Sl.

No.

SEQ.

No.

WELDING SEQUENCE

1 1 Pre heat and weld root run at flange

2 2 Weld root run at flange

3 Repeat step 1 and 2 and weld three runs

Post heat and cool to room temperature

4 Back grind and do LPI (at flange)

5 3 Pre heat and weld Root + Three runs (at other side of the flange)

6 Follow steps 1, 2 and 3 alternatively and welding upto 60% of the thickness of the

flange 7 Correct the mismatch and check the root gap of the web and grind if required

8 4 Weld root run (at web)

9 5 Weld root run (at web)

10 4 Weld two run (at web)

11 5 Weld two run (at web), post heat and cool to room temperature

12 Back grinding and do LP (at web)

13 Grind the flange welding and take intermediate RT if required

14 6 Root run (at other side of the web)

15 7 Root run (at other side of the web)

16 6 Weld two run at web

17 7 Weld two run at web

18 1,2 Weld three run at flange

19 3 Weld three run at flange

20 Follow steps 1,2 and 3 alternatively and complete the flange welding

21 4 Weld three run at web




25 Follow steps 4, 5,6,7 alternatively and complete the web welding

26 8 Weld root +two run (at flange +web) - Fillet weld

27 9 Weld root +two run (at flange +web) - Fillet weld

28 Follow step 8 and 9 alternatively(each three run and complete flange +web fillet

welding)

WELDING MANUAL 92

BHEL : ___________________ SITE

Unit No.: _________________________

WELDING JOB CARD

Unit no.

:

Area : Boiler/TG/PCP

Card no. : 002 Date 26/11/2000

PGMA, DU : 35/211

Joint No. : GRBLHS

Drg Ref : Flange Web

Dia X Thick : PL 100X75

PL 40 x 25

Material : IS8500Fe540

IS2062Fe410B

Welder no.(s) : ST043(BOTTOM)

ST082(TOP)

Date of welding : 26/11/200

Filler wire : -

Electrode : E8018B2

E7018

Preheat : 150 deg.c

150 deg c

Post heat : 250 deg.c/1 hour

150deg.c/1 hour

Inter pass temp : 300 deg.c max

300 deg.c max

Welding Engr.

WELDING MANUAL 93

BHEL : ______________SITE

Unit : ______________ (PWHT) Stress Relief (S.R.) JOB CARD

Unit no.

:

Area :

Boiler/TG/PCP

Card no. : 007 Date 04/01/2001

PGMA, DU :

Joint No. : GRERWS (Unit-111)

Drg Ref : Flange Web

Dia x Thick : PL 100X75

PL 36 x 25

Material : IS8500Fe540

IS2062Fe410B

NDE Cleared on : 04/01/2001 Report

no.

Required

Actual

Rate of heating Max deg c / hour 55

52

Soak temperature deg c : 635+/-15

630

Soak time Minutes : 165

165

Rate of cooling Max deg.c/hour : 65

62

Welding Engr.

WELDING MANUAL 94

WELDING MANUAL 95

CHAPTER - B2

ERECTION WELDING PRACTICE FOR SA335 P91 MATERIAL

WELDING MANUAL 96

ERECTION WELDING PRACTICE FOR SA335 P91 MATERIAL

1.0 SCOPE:

1.1 This document details salient practices to be adopted during erection of SA335 P91 material.

2.0 MATERIAL:

Pipe materials shall be identified as follows:-

1) Colour Code : Brown & Red

2) Hard Stamping : Specification, Heat No, Size.

3) Paint / Stencil : WO DU, as per the relevant drg & document.

2.1 When any defect like crack, lamination, deposit noticed during visual examination the same shall

be confirmed by Liquid Penetrant Inspection. If confirmed, it shall be referred to unit.

3.0 ERECTION:

3.1 Edge Preparation and fit up

3.1.1 Cutting of P-91 material shall be done by band saw / hacksaw / machining / grinding only.

Edge preparation (EP) shall be done only by machining. In extreme cases , grinding can be

done with prior approval of Welding Engineer/Quality Assurance Engineer. During

machining /grinding, care should be taken to avoid excessive pressure to prevent heating up

of the pipe edges.

3.1.2 All Edge Preparations done at site shall be subjected to Liquid Penetrant Inspection (LPI).

Weld build-up on Edge Preparation is prohibited.

3.1.3 The weld fit-up shall be carried out properly to ensure proper alignment and root gap.

Neither tack welds nor bridge piece shall be used to secure alignment. Partial root weld

of minimum 20mm length by GTAW and fit-up by a clamping arrangement is

recommended. Use of site manufactured clamps for fit up is acceptable .The necessary

preheat and purging shall be done as per clause 4.1 and 3.2.2

3.1.4 The fit-up shall be as per drawing. Root gap shall be 2 to 4 mm; root mismatch

shall be within 1-mm. Suitable Reference punch marks shall be made on both the pipes

(at least on three axis).

a) At 200 mm from the EP for UT.

b) At 1000 mm from the EP for identifying weld during PWHT.

3.2.0 FIXING OF THERMOCOUPLE (T/C) AND HEATING ELEMENTS DURING

PREHEATING AND PWHT

3.2.1 No Preheating is required for fixing T / C with resistance spot welding

Following are the equipment / facilities for heating cycles.

(1) Heating methods: Induction heating

(2) Thermo couples : Ni-Cr / Ni-Al of 0.5 mm gauge size.

(3) Temp.Recorders : 6 Points / 12 Points.

WELDING MANUAL 97

3.2.2 ARRANGEMENT FOR PURGING :

Argon gas of 99.99% conforming to Gr 2 IS 5760 –1998 shall be used for purging the

root side of weld. The purging dam (blank) shall be fixed on either side of the weld bevel

prior to pre-heating. The dam shall be fixed inside the pipe and it shall be located away

from the heating zone. Purging is to be done for root welding(GTAW) followed by two filler

passes of SMAW in case of butt welds. Purging is not required in the case of nozzle and

attachment welds, when they are not full penetration joints. The Argon to be used shall be

dry.

The flow rate is to be maintained during purging is 10 to 26 litres/minute and for shielding

during GTAW is 8 to14 litres/minute.(A minimum flow rate as per welding Procedure

specification shall be maintained).

Start purging from inside of pipe when root temperature reaches 220deg C. Provide continuous

and adequate Argon Gas to ensure complete purging in the root area.

The minimum pre-flushing time for purging before start of welding shall be 5 minutes,

irrespective of the pipe size.

Wherever possible, solid purging gas chambers are to be used which can be removed after

welding. If not possible, only water-soluble paper is to be used. Plastic foils that are water-

soluble are NOT acceptable.

3.2.3 USING ALUMINIUM DAM ARRANGEMENT:

In order to retain the Argon gas at the inside of the pipe near root area of the weld

joint, the purging dams made of Aluminium (or other suitable material like mild steel)

and permanent gaskets may be provided during the weld fit-up work as indicated in

the sketch.

The Aluminium discs shall be firmly secured with a thin wire rope. After completion of

the root welding followed by two filler passes, the disc may be pulled outwards softly.

CAUTION : ENSURE REMOVAL OF PURGE DAM ARRANGEMENT AFTER

WELDING

WELDING MANUAL 98

.3.2.4 USING OF WATER SOLUBLE PAPER:

The dams can be made of water-soluble paper for creating the purging chamber.

The advantage in such dam arrangement is that dissolving in water can flush the

dams. The following are different methods used.

3.2.4:-

WELDING MANUAL 99

4.0 WELDING / WELDERS QUALIFICATION:

Only qualified welding procedures are to be used. Welders Qualified as per ASME Sec IX

and IBR on P91 material shall only be engaged. Welders log book to be maintained and

welders performance to be monitored by site welding engineer / Quality assurance

engineer. The applicable WPS for P91+P91 shall be WPS N0.1034.

4.1 PREHEATING:

Prior to start of pre heating ensure that surfaces are clean and free from grease, oil and

dirt. Preheating temp shall be maintained at 220 deg C (min) by using Induction

heating. The Temperature shall be ensured by using a Calibrated autographic recorder

and two calibrated thermo couples fixed at 0 deg and 180 deg positions on both pipes

50 mm away from the EP. The thermocouple shall be welded with the condenser

discharge portable spot welding machine. The preheating arrangements shall be

inspected and approved by welding engineer /Quality Assurance Engineer.(Ref Fig - 1)

Alternate arrangements shall be made during power failure. Two additional spare

thermocouple to be fixed(as described above) for emergency use. Gas burners shall be

employed to maintain the Temperature until the power resumes.

4.2 WELDING:

Root Welding shall be done using GTAW process ( as per WPS) five minutes after the

start of argon purging. Filler wire shall be cleaned and free from rust or oil. Argon

Purging shall be continued minimum two filler passes of SMAW.

4.3 STORAGE OF WELDING CONSUMABLES:

a. Welding consumables are received with proper packing and marking which includes the

relevant batch number for easy identification.

b. Electrodes are stored in their original sealed containers / packages until issued and kept

in dry and clean environment as per the instructions of electrode manufacturers, taking

care of shelf life.

c. Welding filler wires are received with proper packing and marking which includes the

relevant batch number for easy identification.

d. The filler wires are stored in their original packages until issue and kept in dry and

clean environment.

4.3.1 The electrode GTAW wires issued to the welders should be controlled through issue slips.

SMAW electrodes used must be dried in drying ovens with calibrated temperature

Controller. The drying temp shall be as recommended by the electrode manufacturer. The

drying Temp shall be 200 - 300 deg C for two hours if it is not specified by the

manufacturer. Portable flasks shall be used by the welders for carrying electrodes to the

place of use. The electrodes shall be kept at minimum100 deg C in the flask. Welding shall

be carried out with short arc and stringer bead technique only.

4.4 The inter-pass temperature shall not exceed 350 deg C. After completion of Welding

bring down the temp to 80 - 100 deg C and hold it at this temp for one hour minimum. The

PWHT shall commence after completing one hour of soaking.

CAUTION:- No LPI / Wet MPI shall be carried out on weld before PWHT.

WELDING MANUAL 100

5.0 POST WELD HEAT TREATMENT:

Arrangements: - A minimum of four thermocouples shall be placed such that at least two

are on the weld and the other two on the base material on either side of the weld within the

heating band at 180 degrees apart about 50mm from the weld joint. Two stand by thermocouple

shall also be provided on the weld in case of any failure of the thermocouple. The width of the

heated circumferential band on either side of the weld must be at least 5 times the thickness of the

weld. In case of fillet joints the heating band shall be six times the thickness of the base material.

(Ref Fig - 2). An insulation of about 10mm thickness shall be provided between the cable and weld

joint.

5.1 Obtain the clearance for post weld heat treatment cycle from QAE / Welding Engineer.

The PWHT temp for P91 with P91 material shall be 760 + 10 deg C and the soaking time

shall be 2.5 minutes per mm of weld thickness, subject to a MINIMUM OF TWO HOURS.

All records shall be reviewed by Welding Engineer prior to PWHT clearance. Heating shall be

done by Induction heating only.

The rate of heating / cooling :- Thickness up to 50mm - 110 deg C / hr.(max)

(above 350 deg C) Thickness 50 to 75mm - 75 deg C / hr.(max)

Thickness above 75mm - 55 deg C / hr.(max)

Thickness = Actual thickness as measured.

5.2 INSULATION: The width of the insulation band beyond the heating band shall be at least

two times the heating band width on either side of the weld ment.

The recording of time & temp shall be continuously monitored with a calibrated recorder

right from preheating. This will be ensured at every one hour by site authorized personnel.

5.3 PREVENTIVE MEASURES DURING POWER FAILURE AND NON-FUNCTIONING

OF EQUIPMENT'S:

No interruption is allowed during welding and PWHT. Hence all the equipment for the

purpose of power supply, welding , heating etc., shall have alternative arrangements.

(diesel generator for providing power to the welding and heating equipments, standby

welding and heating equipments, reserve thermocouple connections, gas burner arrangement

for maintaining temp etc.) Following preventive measures shall be adopted until normal

power supply or backup power supply through diesel generator is restored.

(a) During start of preheating:

In case of any power failure/interruption during preheating, the weld fit-up shall be insulated

and brought to room temperature. After the electric supply resumes the joint shall be

preheated as per Clause No: 4.1. (Ref: Fig 3)

(b) During GTAW / SMAW:

Use gas burner arrangement to maintain the temperature at 80 deg - 100 deg C upto a

length of 50mm on either side from weld centre line along the complete circumference of

the pipe. Root welding shall be continued after power is restored and preheating

temperature is raised to 220 deg C. During the above period temperature shall be recorded

through contact type Thermometer. (Ref : Fig4)

WELDING MANUAL 101

(c) During cooling cycle after SMAW welding to holding temperature at 80 to 100 deg C for

one hour. (Ref: Fig 5)

Care shall be taken to avoid faster cooling rate by adequate insulation. The required temp 80

- 100 deg C shall be maintained by gas burner arrangements till power resumes / start of

PWHT.

(d) During post weld heat treatment;

The following shall be followed

*1) During heating cycle

The whole operation to be repeated from the beginning. (Ref: Fig 6)

*2) During soaking

Heat treat (soak) subsequently for the entire duration. (Complete period). (Ref: Fig 7)

The heating rate shall be as per the chart.

3) During cooling (above 350 deg C ).

Reheat to soaking temperature and cool at the required rate. ( Ref : Fig 8)

* Temp should not be allowed to fall below 80 – 100 deg C. Gas burner arrangement shall

be used to maintain the temperature.

5.4 In all the above cases (a to d) the temp. Measurement on the weld joint by means of contact

type calibrated temp. Gauges shall be employed to record the temperature at regular

Intervals of 15 minutes in the log book by Quality Assurance Engineer /Welding Engineer.

5.5 TEMPERATURE MONITORING:

The welding and heat treatment chart given in Figure 9 shall be followed for the following

details. The actual PWHT chart shall be monitored for the following:

a) Preheat

b) Inter pass Temperature (GTAW + SMAW)

c) Controlled cooling and Holding at 80-100 Deg C for minimum one hour under insulation.

Start PWHT after minimum one hour of soaking.

d) Heating to PWHT

e) Soaking at PWHT

f) Cooling to 350 Deg C

g) Cooling to Room Temperature (under insulation)

5.5 CAUTION:

THE PWHT TEMP. SHALL NOT DEVIATE FROM THE VALUES SPECIFIED IN THE CHART

RANGE SINCE ANY DEVIATIONS TO THE SPECIFIED HOLDING TEMPERATURE

RANGE, WILL ADVERSLY AFFECT THE MECHANICAL PROPERTIES OF THE

WELDMENT AND MAY LEAD TO REJECTION OF THE WELDMENT. THE WELD

JOINTS SHOULD BE KEPT DRY.UNDER NO CIRCUMSTANCES ANY

WATER/LIQUID IS ALLOWED TO COME IN CONTACT WITH WELD AS

WELL AS PREHEATED PORTION OF PIPE.

WELDING MANUAL 102

1

2

3 4

50mm

50mm

30

mm Insulation

4 X T Min OR as

recommended

by equipment supplier.

1

2

3 4

50mm

50mm

30mm

INDUCTION HEATING (for all Thickness)

Fig - 1

Insulation

Induction Cable

4 X T Min OR as recommended

by equipment supplier.

THERMOCOUPLE (TC) ,PREHEATING ARRANGEMENT

1&2 Measurement TC, 3&4 Spare TC

TOP

WELDING MANUAL 103

ARRANGEMENT FOR POST WELD HEAT TREATMENT

1&2 Measurement TC, 3&4 Spare TC

Insulate 2 Times Heating Band Width fibre glass cloth or

Ceramic wool

Heating Band W= 8 X T min

TC2

TC 3

TC 4 at 180° apart

TC5, TC6 ( Spare TC) shall be fixed at 90°, 270° to TC3

Fig-2

Induction Cable

TC1

or as recommended by the

equipment supplier

50mm

50mm

WELDING MANUAL 104

BHARAT HEAVY ELECTRICALS LIMITED PIPING CENTRE CHENNAI PAGE 2

OF 25

BHARAT HEAVY ELECTRICALS LIMITED PIPING CENTRE CHENNAI PAGE 2

OF 25

RT

Power Failure during Preheating

220

350

80

Time

100

Temp

in deg c

Theoretical curve

Actual curve

After power resumes

RT

Power Failure during GTAW/SMAW

220

350

80

Time

100

During power cut

Theoretical curveActual curve

After power resumes

Maintain 80 - 100°c by immediate

insulation and heating by burners

Temp

in deg c

Fig - 3

Fig - 4

Immediately cover the joint by insulation, if

welding has not been started. Start preheat as

per Cl.4.1 after power resumes

POWER CUT

WELDING MANUAL 105

RT

Power Failure during cooling / holding

220

350

80

Time

Temp

in deg c

100

Theoretic al curve

Actual curve

During power cut

After power resumes

Maintain 80 -100°C for a min period

one hour by immediate insulation and

heating by gas

Fig - 5

WELDING MANUAL 106

RT

Power Failure during PWHT heating cycle

220

350

80

Time

100

760 ± 10

Temp

in deg c

RT

Power Failure during PWHT soaking cycle

220

350

80

Time

100

760 ± 10

Temp

in deg c

Theoretical curve

Actual curve

Power cut

T

T1 =T

Actual curve

Theoretical curve

Power cut

T1

Fig - 6

Fig - 7

Rate of heating shall be adhered

WELDING MANUAL 107

RT

Power Failure during PWHT cooling cycle

220

350

80

Time

Temp

in deg c

760 ± 10

100

Free fall

(While heat insulated)

Actual curve

Theoretical curve

Fig - 8

Rate of cooling shall be adhered

WELDING MANUAL 108

WELDING MANUAL 109

5.7 CALIBRATION:

All equipments like recorder, thermocouple, compensating cable, oven thermostat etc. should have

valid calibration carried at BHEL approved labs. The calibration reports shall be reviewed and

accepted by Calibration In-charge at site prior to use.

6.0 NONDESTRUCTIVE EXAMINATION ( Refer NDE Manual ) :

6.1 All NDE shall be done after PWHT only.

Prior to testing all welds shall be smoothly ground.

All weld s (fillet & butt) shall be subjected to MPI (MPI shall be done by YOKE type only).

In addition to MPI, butt-welds and all full penetration welds shall be examined by UT.

LPI procedure shall be BHE: NDT : PB : P T : 01 and

MPI procedure shall be BHE: NDT : PB : MT: 05

The penetrant materials (Dye Penetrant, Solvent cleaner & Developer) and medium (dry/wet

particles) used in MPI shall be of BHEL approved brands only.

UT procedure shall be as per BHE:NDT:PB: UT21 with additional requirements

as in (a) through (e)

a) The calibration blocks used shall be of same material specification (P91) dia &

thickness.

b) The UT equipment shall be calibrated prior to use and should be of „digital type‟ –

Krautkramer Model USN 50 or equivalent or higher version , capable of storing

calibration data as well as ultrasonic test results as per UT-21

c) All record able indications will be stored in memory of – either the digital flaw

detector or a PC for review at a later period.

d) The equipment calibration data for specific weld as well as the hard copy of „Static

echo-trace pattern‟ – Showing the flaw-echo amplitude with respect to DAC, flaw

depth, projection surface distance (probe position) and beam-path shall be attached

to UT test report. This hard-copy of echo-trace with equipment calibration data

will form part of test documentation.

e) The examination as well as evaluation will be performed by a qualified Level II

personnel, and a test report will be issued. Any defect noticed during NDT shall be

marked with marker.

WELDING MANUAL 110

7.0 REPAIR OF WELD JOINTS:

(A) WELD REPAIR AT ROOT:

On visual examination during root welding if it reveals any surface defects, the same shall be

removed by grinding maintaining temperature 80 - 100 deg. C and re welded with GTAW

maintaining 220 deg. C before starting SMAW.

(B) WELD REPAIR ON COMPLETION:

Any defect observed on the weld shall be brought to the notice of Quality assurance

engineer. The size and nature of defect shall be reviewed. Any repair on weld to be carried

on their approval only.

If any defects are noticed on the fully completed weld while performing U.T after

completion of PWHT, the same may be assessed in order to find the seriousness of the defect

and to locate where exactly the defect lies from the weld outside surface. The defect area

shall be marked and repaired as below:

a) The weld shall be removed by grinding (gouging not permitted) such that the area for

repair welding is free from sharp corners and provided with sufficient slope towards the

weld face sides. Incase of cut & weld joints HAZ (5mm) will have to be removed by

grinding.

b) Surface examination (MPI/LPI) on the ground and welded area to be performed to

ensure a sound base metal before depositing weld layers using SMAW.

c) The temp. of the weld is to be maintained at preheat temp.

d) Carry out SMAW using the same procedure as that of welding.

e) All the specified precautions w.r.t to welding consumables, heating cycles, post weld heat

treatment etc. as followed for original welding, shall be strictly adhered.

The NDE shall be conducted for the entire weld joint.

f) If any further defects are observed on the repaired weld, the same may be further

reworked as mentioned above.

8.0 HARDNESS SURVEY:

The equipment recommended to measure the hardness are EQUOTIP or MICRODUR make

or equivalent portable equipment.

The equipment used for the hardness measurement shall be calibrated as recommended by the

manufacturer and also on a P91 calibration block provided by PC.

The surface shall be cleaned and prepared as per hardness test instrument manufacturer‟s

recommendation prior to hardness survey.

Hardness survey shall be done on each joint at three locations along the circumference. At

each location three readings shall be taken on weld and parent metal .The readings on the

parent metal shall be taken within 15mm from the weld fusion line.

All the hardness values shall be recorded.

WELDING MANUAL 111

The max allowable hardness at weld and parent metal shall be 300 HV10. Joints having

hardness above 300 HV shall be reheat treated and hardness shall be checked again. If

hardness is still more refer to unit.

PM 1 WELD

PM 2 0

270 90

180

Figure – 10

LOCATION PM 1 WELD PM 2

READINGS 1 2 3 AVE 1 2 3 AVE 1 2 3 AVE

0

90

180

270

PM : PARENT MATERIAL AVE : AVERAGE

9.0 COMBINATION WELDING:

For other combination of material like P22 with P91, and X22 with P91 the applicable WPS

for the involving material shall be obtained from equipment supplier / WTC / PC and the same

shall be used .

9.1 SOAKING TIME FOR COMBINATION WELDING:

WPS N0. Material Temp., Soaking time

1035 P91+P22 74515C 2.5mts / mm minimum one hour

MS W0454. P91+X22 75010C 2.5mts / mm minimum two hour for thickness upto

50 mm and minimum four hours for thickness

above 50 mm.

However the precautions as required for P91shall be fully taken care of.

10.0 DEMAGNETISATION:

Refer NDE Manual Ch 1.11

11.0 TRAINING:

11.1 The personnel engaged in P91 piping fabrication shall be trained in the following

areas.

a. Method and Care during fit-up.

b. Argon gas root purging arrangement.

c. Fixing of thermocouple and wires.

d. Arrangements for Pre/Post heating requirements and methods.

e. Adjustment of heating pads/cables at the time of controlling the temperature within

specified tolerance limits during welding or PWHT in case of induction heating.

f. Good appreciation of the WPS requirements.

g. Handling of P91 welding consumables and re-drying conditions.

h. Special precautions during the power/equipment failure.

i. Weld joints of dissimilar thickness / material specification.

WELDING MANUAL 112

j. Weld defect control and weld repair systems.

11.2 SPECIFIC TRAINING FOR WELDERS:

a. The qualified welders who will be engaged in P91 welding shall be given

training on pipe joints simulated with P91 welding and heating cycle

conditions.

b. The acquaintance on welding positions, as applicable shall be given using

P91 pipes and P91 welding consumables.

c. Welding techniques and instructions on Dos and DON‟Ts of P91 welding.

d. Welders only who are qualified on P91 welding alone shall be engaged.

e. Whenever new welders have to be engaged they shall undergo all the

training as above and shall be qualified with P91 material only.

11.3 CONTROL ON WELDERS:

The welder during welding at site follow the following procedures.

The welder shall interact with the HT operator (Induction equipment operator) to ensure that

preheat and interpass temperature during welding are maintained as per requirements.

The welder shall not mix the welding electrodes with that of the other welder. At the end of

the shift, the unused electrodes shall be returned to the stores.

11.4 PERSONNEL / CONTRACTORS ENGAGED FOR HEATING CYCLES (HT Operator):

11.4.1 The Personnel / Contractor shall have adequate heat treat experience on P91 or similar

material.

11.4.2 HT operator shall be aware of the following:

a) The equipment used and its working principle and operation.

a) The procedures to be followed in using heating equipments.

b) Procedure to be followed in case of power failure or equipment non-functioning so that

heating cycle is not disrupted.

c) Calibration of equipments.

d) Method of fixing thermocouples and compensating cables leading to HT recorder.

e) Fixing of heating pads or elements on the pipe joints and also in maintaining the

temperature within the specified limits.

11.5 NDE PERSONNEL QUALIFICATIONS:

All NDE personnel performing NDT like UT & MPI/LPI shall be qualified in accordance

with BHEL Procedure meeting the requirements of recommended practice SNT – TC - IA.

MPI & LPI shall be carried out by level I qualified personnel and shall be evaluated by level

II qualified personnel. However UT examination and evaluation shall be done by level II

qualified personnel.

11.6 LEVEL OF SUPERVISION

Site Incharge shall be responsible for the completion of all activities from weld fit-up to

final clearance of weld joints after satisfactory NDE and acceptance by

BHEL/Customer/IBR.

WELDING MANUAL 113

12.0 DO‟s and DON‟T‟s during P 91 welding, heat treatment and NDE at construction site:

12.1 DO‟S:

a) Cutting by Band saw/Hack saw/Machining.

b) Pipes Edge Preparation by machining. Machining shall be done without excessive pressure to

prevent heating up of pipe

c) Grinding may be done on exceptional cases after approval and taking adequate care to prevent

overheating.

d) Thermocouple wire (hot/Cold junctions) shall be welded with condenser discharge portable

spot-welding equipment.

e) Reserve Thermocouples shall be made available , incase of failure of connected thermocouple

elements.

f) Ensure adequate Argon Gas for complete purging of air inside the pipe before starting GTAW

root welding.

g) Ensure Preheating at 220 Deg.C minimum before GTAW root welding.

h) Start preheating only after clearance from Welding engineer / Quality assurance engineer

for weld fit-up and alignment of the joint as well as fixing of Thermocouple connections ( for

Induction heating)

i) Do visual inspection on root weld maintaining weld preheating temp.

j) Continue Argon purging until the GTAW root welding followed by minimum two filler

passes of SMAW, is completed.

k) Perform partial root welding to facilitate fit-up if necessary.

l) Ensure that only one layer of root welding using TGS 2CM filler wire (2 ¼ Cr 1 Mo) is

deposited. (wherever specified).

m) Ensure proper use of TIG wires as identified by colour coding or suitable hard punching.

n) Keep the GTAW wires in absolutely clean condition and free from oil , rust, etc.

o) Dry the SMAW electrodes before use.

p) Ensure the interpass temperature is less than 350 Deg.C.

q) Hold at 80-100 Deg.C for a period of Minimum 1 hour before the start of PWHT.

r) Record entire heating cycle on Chart through recorders.

s) Exercise control during grinding of weld and adjoining base metal while removing

surface/sub-surface defects or during preparation for NDE.

t) Ensure no contact with moisture during preheat, welding, post heat and PWHT of Weld

Joints.

u) Ensure removal of argon purging arrangements after welding.

v) Use short Arc only. The maximum weaving shall be limited to 1.5 times the dia of the

electrode.

WELDING MANUAL 114

13.0 DON‟T‟s:

a) Avoid Oxy-Acetylene flame cutting.

b) Avoid Weld-build up to correct the weld end-d1 or to set right the lip of the weld bevel.

c) Avoid Arc strike on materials at the time of weld fit up or during welding.

d) Do not Tack weld the Thermocouple wires with Manual Arc/TIG welding.

e) NO GTAW root welding without thorough purging of root area.

f) Do not use Oxy-acetylene flame heating for any heating requirements.

g) Do not use Thermal chalks on the weld groove.

h) Do not stop argon purging till completion of GTAW root welding and two layers of SMAW.

i) No Tack welding or Bridge piece welding is permitted.

j) Do not use unidentified TIG wires or electrodes.

k) Do not exceed the maximum interpass temperature indicated in WPS

l) Do not allow moisture, rain, water, cold wind, cold draft etc. to come in contact with the weld

zone or heating zone during the entire cycle from preheat to PWHT.

m) Do not exceed the limits of PWHT soaking temperature.

n) Do not Interrupt the Welding/heating cycle except for unavoidable power failures

o) Do not use uncalibrated equipment for temperature measurement during heating, welding,

post weld, heat treating etc.,

14.0 NDE Consumables:

1) For LPI consumables list refer NDE Manual CH 1.1

2) Dry Magnetic powder:

(a) MAGNAFLUX - PRODUCT GREY; 8A – RED

(b) FERROCHEM PRODUCT NO: 266

(c) K-ELECTRONICS PRODUCT – RD- 200 (SPECIAL)

3) Non-fluorescent magnetic ink:

(Prepare bath as instructed by supplier)

a) MAGNAFLUX – Product 9C RED with MX/MG carrier II oil vehicle.

b) FERROCHEM–PRODUCT NO: 146 A with oil vehicle (with high flash point 92C)

c) SARDA MAGNA CHECK INK with oil vehicle (with high flash point 92C)

4) Fluorescent magnetic ink:

(Prepare bath as instructed by supplier)

a) MAGNA FLUX – Product 14A with MX/MG carrier II oil vehicle.

b) MAGNA FLUX – Product 14 AM – Prepared bath of 14A and MG/MX carrier II

ready to use without measuring and Mixing in aerosol container with MX/MG

carrier II oil vehicle

15.0 DOCUMENTATIONS:

The documentation shall be as per the customer approved BHEL Quality Plan.

WELDING MANUAL 115

TECHNICAL DIRECTIVE

Sht no.: 1 of 2

ARGON PURITY LEVEL

WHAT IS ARGON:

Argon is chemically-inert, monatomic gas, heavy and available in quantity at reasonable

cost. Its chemical symbol is Ar. Atomic weight is 40. Molecular weight is 40.

APPLICATION OF ARGON IN BHEL:

In the welding process, Argon is used for SHIELDING and BACKING purpose. The

atmosphere in which we live is composed of about 4/5th of Nitrogen and 1/5th Oxygen.

The welding process when exposed to air, most metals exhibit a strong tendency to

combine with Oxygen, and to lesser extend with Nitrogen, especially when in the molten

condition. The rate of oxide formation will vary with different metals, but even a thin

film of oxide on the surface of metals to be welded can lead to difficulties. For the most

part, the oxides are relatively weak, brittle materials that in no way resemble the metal

from which they are formed. A layer of oxide can easily prevent the joining of two pieces

by welding.

Argon is a shield gas used in Gas Tungsten Arc Welding (GTAW), Root Shielding and

Plasma cutting. Argon protects welds against oxidation as well as reduces fume

emissions during welding.

PRODUCTION OF ARGON :

A co-product of oxygen and nitrogen production, argon is manufactured commercially by

means of air separation technology. In a cryogenic process, atmospheric air is

compressed and cooled. Following liquefaction, the air is fractionally distilled based on

the different boiling points of each component. (The boiling point of argon is between

those of nitrogen and oxygen.).

During distillation, liquid nitrogen is the first product extracted from the high-pressure

column. Next, a stream containing oxygen and argon (plus other gases) is withdrawn.

The crude stream, containing approximately 10 percent argon, is refined in a separate

distillation column to produce argon with 98 percent purity.

Manufacturers can further refine the stream by mixing the argon with hydrogen,

catalytically burning the trace oxygen to water, drying and, finally, distilling the stream

to remove remaining hydrogen and nitrogen. Using this process, producers can achieve

an argon product with 99.9995 percent purity.

WELDING MANUAL 116

TECHNICAL DIRECTIVE

Sht no.: 2 of 2

ARGON PURITY LEVEL

The compressed argon is supplied in cylinders and liquid argon is supplied in tanks. The

cylinder used for argon will have the body colour of BLUE without band, size of 25 cms

dia. & 1.5 m length, capacity of 6.2 M3 and pressure when fully charged at 150C (approx)

137 Kg/Cm2 (1949 psi).

PURITY LEVEL OF ARGON

INDIAN STANDARD for ARGON, Compressed & Liquid Specification no. IS 5760: 1998

shall be referred.

There are 3 grades of argon, namely:

• Grade 1 : Ultra high purity argon for use in electronics and allied industries

and indirect reading vacuum spectrograph,

• Grade 2 : High purity argon for use in lamp and allied industries and

• Grade 3 : Commercial grade argon for use in welding industry and for other

metallurgical operations.

Accordingly the argon shall comply with the requirements given below:

Sl.

No. CHARACTERISTIC

REQUIREMENT

Grade 1 Grade 2 Grade 3

i. Oxygen, ppm, Max. 0.5 5.0 10.0

ii. Nitrogen, ppm, Max. 2.0 10.0 300

iii. Hydrogen, ppm, Max. 1.0 2.0 5.0

iv. Water vapours, ppm. Max. 0.5 4.0 7.0

v. Carbon dioxide, ppm, Max. 0.5 0.5 3.0

vi. Carbon monoxide, ppm, Max. 0.5 0.5 2.0

vii. Hydrocarbons, ppm, Max. 0.2 0.5 -

PURCHASE SPECIFICATION FOR ARGON:

BHEL - WELDING TECHNOLOGY CENTRE, Trichy recommends the specifications for

purchasing the Argon for welding process is,

“Argon as per Grade 3 of IS-5760: 1998 Rev 02 with Oxygen & Water Vapours

restricted to max. 7 PPM each and with Argon purity level of min. 99.99%. The supply

should accompany Test Certificate for the batch indicating individual element „PPM‟

level and overall purity level.”

Hence, it is recommended to purchase the Argon with above specification by BHEL as well

as by our Sub-contractors engaged at sites.

---- O ----

WELDING MANUAL 117

Welding research institute Bharat Heavy Electricals Ltd. Tiruchirappalli-620014

Use of Resistance heating for Post weld heat treatment of P91 pipes.

(For Reference only – WPS of concerned Unit shall prevail)

The subject of the use resistance heating for PWHT has been raised over the

past few years especially for application to P91 steel pipes. In response to this WRI

had taken up extensive studies on the effectiveness of this method in P22, P91 and

SA106 Gr.B pipes using the conventionally used continuous coil type heating method

and flexible ceramic pad based resistance heating. The studies were primarily aimed at

evaluation of the effectiveness of the method to achieve close temperature gradients of

the order of 15C across the wall thickness of the pipe during soaking period of Post

weld heat treatment. In view of this thermocouples were attached on the inner walls of

the pipe also in this study, though it is not done in actual situations to enable

measurement of temperature gradients at various stages of PWHT across the wall

thickness. The studies were conducted with different parameters such as heating

dimensions, soaking times etc. The study reveled the following

1. Close temperature gradients up to 15C could be achieved across the

circumference of the pipe when an automatic heat treatment is carried out using

Flexible ceramic type pad elements along with Programmable temperature controller

energized by a thyristorised power source that gives an output supply of 65/80V and a

digital temperature indicator cum printer is used.

2. This automatic method could be easily used to control the preheat temperature as

well as the inter pass temperature required to be controlled during welding of P91

steels. The digital printer could give the temperature values along with real time and were found

to be reliable.

3. The conventional method of PWHT using continuous coil type heating method were found to

give higher temperature gradients of the order of 25C and required a close monitoring by

skilled personnel to obtain the right results.

Subsequent to this study, a workshop was conducted in Nov 2003 at PSSR chennai to

communicate the results to all construction engineers. Representatives from various power sector

regions attended this workshop. During deliberations, it was felt by all that the automatic

resistance based heat treatment can be applied in one of the 500 MW sites. Some people opined

that prior to the actual use it could be demonstrated in Bellary site as a next step for

implementation of the technique.

WELDING MANUAL 118

In the meanwhile, WRI was recently requested (July 2006) to assist L&T ECC division

to establish the resistance heating method for heating and PWHT of P91 pipes at SIPAT site for

the 660 MW boiler being erected by them. In response to this the same contractor who was

engaged earlier for WRI trials was engaged and a demonstration was carried out at SIPAT site.

The primary aim of this demonstration was to demonstrate the effectiveness of the automatic

method to get temperature gradients to levels of 15C in P91 pipes up to 30 mm thickness. In

tune with this two trials were conducted at site. The first pipe was a P91 pipe with 25 mm

thickness in which the entire preheating, interpass temperature control and during welding and

PWHT cycle was applied. The welded pipe was also subjected to procedure qualification tests at

WRI. Secondly one more pipe of 45 mm thickness was also tried to study the effectiveness of the

method with thermal cycle simulation only without welding. The results of the above study

reveal the following

1. Temperature gradients within 8-10C could be obtained between the outer and inner walls

with the automatic resistance heating method.

2. The temperature chart showed that no interruptions or kinks in the time-temperature

record indicating the steady maintenance of temperature throughout the PWHT cycle.

3. The method could be effectively used for the entire heating cycle, including preheating,

interpass temperature control during welding, cooling to intermediate temperature and regular

PWHT cycle.

4. Similar results were observed in the case of 45 mm thick pipe also and the results were

highly reliable.

5. The trials at WRI shop as well as SIPAT site has given good and satisfactory results

indicating that the automatic local PWHT is more reliable, consistent and can be applied in site

with ease.

In view of the above it can be concluded that the automatic resistance based heating

method can be used for the entire heating cycle for welding P91 grade pipes up to 32 mm to

achieve temperature gradients of the order of 10C which is required as per specification.

The details of the various components of the automatic resistance heating equipment and

system that are to be used in are given in Annex I.

The contact address of the contractor through whom the trials were carried out is given in

annex II.

Besides this, some more contractors have also shown interest in carrying out the PWHT

in the automatic mode. Their addresses are also given in annex II. As the entire set of

equipments is made indigenously many contractors would come up with the automatic heating

facilities when BHEL specifies the usage of this method.

In this context it is recommended to carry out Procedure qualification test with the largest

thickness pipe at site to establish the process with the contractors prior to application for the

actual pipe. This would enable the contractors to stabilize the process and serve as a measure of

quality assurance for site heat treatment.

WELDING MANUAL 119

Annex I

Details of the automatic resistance heating based equipment recommended for PWHT.

Sl.no Key components of the

equipment

Description of the items that are essential

01 Type of heating element Flexible ceramic pads containing stranded heating

elements of standard width and breadths to cover

various diameters of pipes.

The pads can be of 2.7/3.6 kW power with 65/80V

02 Power supply Power source: 50/70 KvA transformer power source

with 3 phase input supply with 415 / 440 V, 50 Hz

supply to provide a secondary output voltage of

65/85V and 225 Amps per phase. 6 way

thyristorised switching, energy regulators.

03 Controller Microprocessor based Programmable cycle

controller (0-1200°C) with easy setting of time and

temperature for setting heating/soaking and cooling

rates.

04 Temperature recorder Calibrated Digital multi point recorder (12

channel- 0 to 1200°C) cum printer with suitable

connecting cable for real time recording temperature

with time for the entire heating cycle.

05 Power cables Suitable plug in type copper cables, 2/3/4 way splitter

cables to connect heating pads and power source.

Suitable temperature compensating cables to connect

thermocouples and Power source and temperature

recorder

06 Accessories 1. Capacitor discharge based Thermocouple

fixing unit.

2. Calibrated thermocouples (type K).

3. Mineral wool /ceramic wool Insulation pads of

min 25 mm thick for insulation of the pipe.

4. Steel banding machine with 1” thick steel band

for securing the heating pads with the pipe.

WELDING MANUAL 120

Annex II

List of vendors /contractors who can carry out the automatic local PWHT at site

Vendor used for the study at WRI and at SIPAT site

01 Mr. Fernandez

Indo therm engineers Pvt.Ltd

Plot No. A-374,

Road No. 9

Wagle Industrial Estate

Thane –400 504

Phone

25822175,25830410,25805563, 25831948

Fax: 022- 25833882

Cell no: 9892592329

Email: [email protected]

Vendors who are ready to offer PWHT services with auto equipments

02 K.B. Jetly

East West Engineering & electronics

company

204, Acharya complex center

Dr. C. Gidwani road

Chembur, Mumbai

400 074

022 - 556 7654/ 5581766/556 6096

[email protected]

03 Shri .V. Kannan

Shastra NDT services

131,Aharya commercial center

Near Basant Cinema

Dr.C.G.Road Chembur

Mumbai –400 074

Ph: 022- 5575 1279

[email protected]

Mobile: 98213 29436

04 Injo tech services

Office No. 44, 5th

floor

Yugay Mangal complex

Near ICICI bank, Erandwane

Pune 411 038

Mr. Ingale

020-5621 2833,

5621 6833

Mobile of Mr. Ingale: 09822036600

[email protected]

05 OPI services,

Pune

Mr. Sathe

Cell: 9822499002

mailto:[email protected]

WELDING MANUAL B-3 GENERAL TOLERANCES FOR WELDING STRUCTURES –

(FORM AND POSITION) 121

CHAPTER - B3

GENERAL TOLERANCES FOR WELDING STRUCTURES – (FORM AND POSITION)



Doc. Ref.: AA 0621105

GENERAL TOLERANCES FOR WELDED STRUCTURES - (FORM AND POSITION)

Doc. Ref.: AA 0621105

B3. GENERAL TOLERANCES FOR WELDED STRUCTURES -

(FORM AND POSITION)

1.0 GENERAL :

1.1 Tolerance on form and position as defined in this standard are permissible variations

from the geometrically ideal form and position corresponding to the accuracies

commonly obtained in workshops. The standard covers tolerances on straightness,

flatness and parallelism.

1.2 This standard is based on DIN 8570 Part 3 - 1987

1.3 General tolerances for machined components are covered in corporate standard

AA 023 02 08.

1.4 Refer Corporate Standard AA 062 11 04 for general tolerances for lengths and angles of

welded components, assemblies and structures.

2.0 SCOPE :

2.1 This standard prescribes four degrees of accuracies taking into account the function

dependent and the fabrication dependent differences along with appearance aspects of

welded components, assemblies and structures.

2.2 For technical and economic reasons other degrees of accuracy may be appropriate which

have to be specifically stated.

3.0 DEVIATIONS :

3.1 The values of deviations for different classes of accuracies of straightness, flatness and

parallelism are given in Table-1. These values apply to overall dimension and to part

lengths.

4.0 REPRESENTATION ON DRAWING : 4.1 The required degree of accuracy shall be specified in all fabrication drawings. For

example Class E of AA 062 11 05 (DIN 8570 Part 3).

TABLE 1 : TOLERANCES ON STRAIGHTNESS, FLATNESS AND PARALLELISM

Grade

of accu-

racy

Nominal Dimension Range (larger side length of surface) - mm

Above

30 to

120

Above

120 to

315

Above

315 to

1000

Above

1000

to

2000

Above

2000

to

4000

Above

4000

to

8000

Above

8000

to

12000

Above

12000

to

16000

Above

16000

to

20000

Above

20000

E 0.5 1 1.5 2 3 4 5 6 7 8

F 1 1.5 3 4.5 6 8 10 12 14 16

G 1.5 3 5.5 9 11 16 20 22 25 25

H 2.5 5 9 14 18 26 32 36 40 40



5.0 TESTING :

5.1 Figures 1 to 3 illustrate the mode of testing for straightness, flatness and parallelism.

The test method should be selected on the basis of current measuring practice.

There should be no unusual temperature or weather conditions, e.g. strong sunshine.

The measured values apply to the conditions on the day of testing.

5.2 STRAIGHTNESS :

The edge of the welded component and the straight edge can be arranged in relation to

each other so that the end points of the measured length are the same distance apart

from the ends of the straight edge. The distances between the edge and the straight

edge should be measured.

5.3 FLATNESS :

A measuring plane can be set up outside the welded component parallel to the limiting

planes at any desired distance. For example this can be done with optical instruments,

flexible tube liquid levels, tension wires, clamp plates, surface plates and machine

beds.

5.4 PARALLELISM :

Any of the measuring devices mentioned above can be used to set up a measuring

plane outside the welded component parallel to its reference plane. The distance

from the actual surface to the measuring plane is measured.

The position of the reference surface (= surface after machining) is dimensionally

determined.

Dimension a1 gives the required finished height of the foundation. Dimension a2 gives

the minimum thickness of the support.

The distance between the reference plane and the measuring plane is greater than : hmax

by the minimum possible thickness of the machining allowance “b”. The variation of

the actual surface (=surface before machining) from the reference plane must be within

the tolerance on parallelism. Maximum variation is

hmax - hmin t

Note : The tolerance on form and position as per this standard may be mentioned on

the drawing in addition to the linear tolerances as per AA 062 11 04 wherever required.

WELDING MANUAL - 125

CHAPTER - B4

WELDING OF PIPES AND PIPES SHAPED CONNECTIONS IN STEAM TURBINE, TURBO-GENERATORS AND AUXILIARIES


WELDING OF PIPES AND PIPES SHAPED CONNECTIONS IN STEAM TURBINE, TURBO-GENERATORS AND AUXILIARIES Doc.Ref.: HW 0620599

1.0 SCOPE :

These guidelines cover edge preparation, method of welding for pipes and pipe shaped

connections to be used in Steam Turbine, Turbo-generator and heat exchanger of KWU

design. 2.0 WELD EDGE PREPARATION :

2.1 Various forms of edge preparation to be used for shop weld, site weld and edge

preparations for pipes manufactured from rolled plates are covered in this standard.

2.2 However, edge preparation may be altered in case where pipe connections are made

between customer‟s pipe line and BHEL supply. In all such cases edge preparation must

be given on the drawing.

3.0 ASSEMBLY AND WELDING PROCEDURES :

3.1 Before tacking the weld edges must be aligned. The linear misalignment between weld

edges must be maintained according to specifications No. HW 0620099.

3.2 Machined weld end preparations of the components being despatched to site must be

protected with a metal cover.

3.3 Shaped parts of piping e.g. flanges, reducer, elbows, T-sections etc. are ordered with edge

preparations carried out at supplier‟s work.

3.4 Welding processes are selected in accordance with Annexure-I.

3.5 Welders qualified as per ASME Section IX are to be employed.

3.6 The distinction is to be made between shop and site welds in the drawing as per Plant

Standard No. 0623.003.

3.7 Tack welds, if not to be removed, must be made with the same filler metal and must be

performed by qualified welder.

3.8 The weld joints are to be purged by inert gas in case of high alloy steels.

4.0 PIPES ROLLED FROM PLATES :

4.1 Weld seams of rolled pipe are welded by Shielded Metal Arc welding. The root is gouged /

ground and welded from back side.

5.0 INSPECTION :

5.1 The weld seams are subjected to internal examination in accordance with HW 0850199.

The external characteristics are examined in accordance with HW 0620099.


ANNEXURE-I


CHAPTER - B5

INSTRUCTIONS FOR CARRYING OUT CONDENSER PLATE AND NECK WELDING


INSTRUCTIONS FOR CARRYING OUT CONDENSER PLATE AND NECK WELDING

1.1 GENERAL:

1.1.1 The welding of the condenser is performed by „step back seam method‟ i.e. from tack

weld to tack weld.

1.1.2 Subsequent filling welds after tack welding are always performed in the opposite

direction. Welding to be carried out as per requirement envisaged in drawing / field

welding schedule.

1.1.3 Condenser Erection Manual as well as instructions issued by manufacturing unit may

also be referred in conjunction with this manual.

1.1.4 All the welding shall be carried out by qualified welders.

1.2 CONDENSER SHELL INTERNALS WELDING:

1.2.1 Tack weld the tube support plate sections aligned with the centre point to the slot

profiles on the bottom plate and the side walls. After tack welding, verify that the holes

in the support plates lie in the vertical and horizontal planes. Enter the actual

measurements on the measurement data record provided.

The thin steel wires and alignment devices can now be removed, as they are no longer

required for further assembly of the condenser shell internals.

Move the internals temporarily housed in the spaces in the tube support plate sections

into their correct positions, align and tack weld them in accordance with the plant-

specific drawing. Assemble the central fishing and the bracing assemblies such as flat

irons and tubes.

NOTE:The steam baffles and bracing units must not be tacked to the tube plates of the

water boxes. This operation is not performed until all internals have been welded

to one another.

Then align the various sections of the air extraction line, weld them together to form one

unit and tack weld to the tube support plates.

During alignment, ensure that the air extraction openings are directed towards the

bottom plate and that therefore the connection holes for the connecting piping systems

are necessarily in the correct positions. Pass out and fit the pipe work to the connecting

piping system through the connection holes. Assemble the shields for the cooler tube

nests. Set down the shields on the flat iron supports, align and tack weld.


After assembly of all the steam space internals which, to allow for welding warpage,

may only be tack-welded, commence welding of all the condenser shell internals, the

welding sequence being of up most importance.

NOTE: The feed water heater platform must be mounted and welded in place prior to

the assembly of the condensate drain sheets as there is only a gap of

approximately 200 mm between the feed water heater platform and the air cooler

sheet.

Then weld the vertical slot profile strips to the side walls and tube support plates. During

this procedure, welders should as far as possible work simultaneously.

When the condenser shell internals have been completely welded together, tack and

weld the steam baffle plates, the bracing assemblies and the air extraction line and the

connecting piping system at the front and rear tube plates. When all welding work has

been concluded, remove all weld residue from the weld seams and weld zones in the

entire condenser shell.

NOTE:To prevent welding warpage, all welds must be performed simultaneously from

both sides using the back-step method. Vertical joints must be welded from top

to bottom, i.e. from the upper edge of the tube support plate to the bottom plate.

ATTENTION:- THE PERTINENT WELDING PROCEDURE SPECIFICATION

AND WELDING INSTRUCTIONS MUST BE OBSERVED WHEN

WELDING.

1. Steam space (top view)

2. Tube support plate

3. Vertical slot profiles

4. Welding locations


1.3 WELD CONNECTIONS BETWEEN CONDENSER AND LOW PRESSURE

TURBINE

NOTE :- The assembly welding instructions given herein are of a general nature. Please

see also the assembly plans, drawings and other instructions for the plant in

question.

1.3.1 In any weld connection, the cooling of the locally heated material in the weld zone will,

by laws of physics cause transverse and longitudinal contractions, these giving rise to

stresses in the material.

In order to keep these stresses as low as possible, it is imperative that the weld is

prepared as specified in the drawings. Before welding is commenced the semi-circular

structural profiles must be bolted to the dome end walls.

1.3.2 WELDING THE CONDENSER TO THE LOW-PRESSURE TURBINE

After the condenser has been brought to operating weight and the spring supports have

been adjusted to compensate for welding contraction, prepare for welding the condenser

to the low-pressure turbine.

Erect scaffolding inside the condenser in accordance with applicable accident prevention

regulations to facilitate access to the weld locations. Then fit the intermediate, corner and

web plates (as called for) and prepare the weld edges. Tack these parts to the condenser

dome with welds with a tack length of three times the plate thickness at intervals of 25

times the plate thickness.

Weld the joint using the back-step method from tack to tack (see Fig.1). When the base

layer has been completed, make the following filler weld layers, each in a single pass,

and reversing direction for each layer (see Fig.2). After welding, clean the weld zone

using suitable tools.

ATTENTION:- THE PERTINENT WELDING PROCEDURE SPECIFICATION

AND

WELDING INSTRUCTIONS MUST BE OBSERVED WHEN

WELDING.

WELDING MANUAL B-6 REPAIR PROCEDURE FOR ARRESTING THE LEAKAGE OF STRENGTH WELDS ON TUBE TO TUBE 132

CHAPTER - B6

REPAIR PROCEDURE FOR ARRESTING THE LEAKAGE OF STRENGTH WELDS ON TUBE TO TUBE SHEET JOINTS OF ‘U’

TUBE H.P. HEATER


REPAIR PROCEDURE FOR ARRESTING THE LEAKAGE OF STRENGTH WELDS ON

TUBE TO TUBE SHEET JOINTS OF ‘U’ TUBE H.P. HEATER

1.1 Pressurise the shell side with Nitrogen or Pneumatic air to 7 Kg / cm2 and apply soap

solution over the complete area of welding on tube sheet.

1.2 Find out the leakage of tubes and identify by marking either with chalk or colour.

1.3 Reduce the pressure to zero and also ensure the removal of Nitrogen from the shell.

1.4 Face the defective weld as identified earlier by using face cutter and ensure the

elimination of defect by dye penetrant (LPI) test.

1.5 If found satisfactory, clean the penetrant thoroughly and weld with manual TIG using the

specific WPS according to Tube sheet material and tubes.

1.6 After welding test the weld by dye penetrant and ensure the sound weld metal deposition.

1.7 Pressurise the shell side again to 7 Kg / cm2 with Nitrogen or Pneumatic air and test the

soundness of welds.

1.8 Plugging of tube of „U‟ tube HP Heater on weld overlayed tube sheets.

This procedure explains the method of plugging of tubes on overlayed tube sheets of :

1. Carbon steel tubes on inconel weld overlayed tube sheets.

2. Inconel tubes to inconel weld overlayed tube sheets

3. Carbon steel tubes on stainless steel overlayed tube sheets.

4. Stainless steel tubes on Stainless steel overlayed tube sheets.

Procedure :

1. Face the tube end (to be plugged) such that the face of the tube is 4 mm below the

surface of the tube sheet using the facing cutter as shown in sketch.

2. Clean the hole inside thoroughly with the solvent.

3. Prepare the plug made of either SA 105 or 11416.1 to a length of 38 mm as shown in

sketch such that the OD of plug is machined for the interference fit with the tube hole

i.e. tight fit having plug Φ 0.05 mm less than the actual inside Φ of tube as shown in

sketch.


4. Fit tightly the plug inside the hole as shown in sketch and weld by GTAW (manual)

using the suitable filler rod.

5. Inspect the soundness of weld after each layer by dye penetrant.

6. After completing the weld pressurise the shell to the operating pressure and then inspect

the weld by dye penetrant.

TUBE PLUG PROCEDURE

SKETCH

WELDING MANUAL B-7 REPAIR PROCEDURE FOR GREY CAST IRON CASTINGS 135

CHAPTER - B7

REPAIR PROCEDURE FOR GREY CAST IRON CASTINGS


REPAIR PROCEDURE FOR GREY CAST IRON CASTINGS

1.0 SCOPE

1.1 This quality control procedure is valid for the repair of grey cast iron castings covering

the following specifications :

IS 210 Gr. 20 & Gr. 25

1.2 Defective castings can be salvaged by sound welding practices provided the defects are

accessible to repair are not extensive and are economical to reclaim by welding. Where

repairs are carried out on pressure retaining areas special care should be exercised to

ensure sound weld repair.

2.0 DEFECTS THAT DO NOT REQUIRE WELD REPAIRS :

2.1 Machinable surfaces :

Foundry defects can be left without weld repairs on Machinable areas provided the

depth of such defect is less than 50% of the machining allowance provided. Defects

revealed during machining shall undergo weld repairs. Isolated pores or sand inclusions

of size < 3 mm and separated from one another by atleast 25 mm can be left without

weld repairs.

2.2 Non-Machinable surfaces :

Foundry defects other than cracks, cold shuts, shrinkage etc. can be dressed smooth by

grinding provided the depth of such defect is < 5 % of the specified wall thickness, and

size < 10 mm, separated from one another by atleast 100 mm.

3.0 PREPARATION OF SURFACE :

3.1 The surface around the defective area shall be free from foreign materials such as oil,

grease, paint, rust, sand etc.

3.2 The defective area shall be ground or machined to obtain a sound base for welding. In

the case of surface defects, the skin should be similarly ground or machined.

3.3 Before starting weld repair free graphite shall be removed by flame heating and cleaned

with a wire brush.

3.4 Depending upon the size of the defect, shallow or deep grooves shall be formed by

grinding / machining.


3.5 Where defects are located in relatively inaccessible positions, sufficient material shall be

removed to permit a satisfactory welding operation.

4.0 ELECTRODES :

Low heat nickel iron electrodes (ENi CI and ENiFe-CI type) should be used.

The following brands are recommended for repairs :

ENi CI : 1) NFM (D&H Secheron) 2) CASTRON KALT ( Modi)

3) FERROLOID -4 (ESAB)

ENiFe-CI : 1) ESAB 802 2) 1111CI (D&H Secheron)

Any other equivalent approved by BHEL may also be used.

5.0 WELDING PROCEDURE :

5.1 To ensure maximum freedom from porosity in weld deposits, nickel iron electrodes

should be re-baked for atleast one hour at 260˚C in a well ventilated electric oven and

either used immediately or stored in a similar oven at 120˚C until used.

5.2 The welding current should be kept as slow as possible consistent with smooth operation

and a good wash at the sides of the joint.

5.3 Wherever possible the casting should be positioned for down hand welding operation.

When extra long welds or several repair positions are involved it is preferable to stagger

the welding operation to distribute the heat and to minimise the distortion.

5.4 Manipulation of the electrode :

It is preferable to use stringer bead technique, with beads not > 50 to 75 mm in length,

slight weaving of the electrode may be done to obtain better wash, but in no case the

width of the deposit should be > 3 times the nominal dia. of the electrode.

5.5 It is preferred to butter the surface of the weld preparation first and then fill gradually

towards the centre of the repaired area.

5.6 It is essential to clean the slag from each crater before making a re-strike and to remove

it completely from each weld run before depositing the adjacent weld.

5.7 To ensure maximum weld soundness the forward movement of the electrode tip should

be accelerated as the end of the weld run is approached, this will taper the run rather

than ending it abruptly in a large weld pool. When re-striking the arc should be started

ahead of the previous weld run, move back over the tapered portion, then continued

forward.


The defective zone must be adequately prepared to permit correct manipulation of the

electrode.

6.0 PREHEATING :

6.1 Preheating is normally not required. Where preheating is resorted to, the entire casting

should be preheated. Interpass temperature should not exceed 250˚C.

6.2 It is advisable to cool as slowly as possible after welding although in most cases, it is

sufficient merely to cool under a cover of heat insulating material such as asbestos, sand

or ashes.

6.2 Peening of the weldment after the weld cools down may be done to reduce the

shrinkage stresses.

7.0 WORKMANSHIP :

The weld profile should perfectly merge with the contour of the casting and shall be free

from spatter, slag etc.

8.0 INSPECTION :

In addition to visual examination, non-destructive tests like liquid penetrant inspection

might be employed on repaired areas to ensure freedom from cracks.

WM B8 SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS 139

CHAPTER - B8

SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS


SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS Note : These instructions are only guidelines. Specific written approval is to be taken

from the Manufacturing units prior to carrying out repair works.

1.0 GENERAL INSTRUCTIONS :

1.1 This instruction is valid for the repair of steam turbine castings by welding. The

materials for which this instruction is applicable are: CSN 422643, 422710, 422743,

422744, 422745, GS17CrMo55, GS C 25, SA216WCB, GS 17CrMoV511,

21CrMoV57V, 21Cr.MoV57.

1.2 The repair by welding may be carried out only by qualified welder having enough

experience in this line.

1.3 The castings of casings supposed to be repaired by welding must be in the heat treated

state specified in the respective drawing. It is forbidden to carry out any repair by

welding on castings which were not annealed or subjected to the prescribed heat

treatment.

2.0 DECISION ON REPAIR :

2.1 No repair must be carried out without the approval of the manufacturing unit.

2.2 The manufacturing department takes the decision about the repair based on a strict

visual and defectoscopic examination taking into consideration the type and size of the

defect and its location with regard to the possibility of repair. No repair must be

undertaken, would it endanger the proper operation and safety of the equipment.

3.0 EXECUTING THE REPAIR :

3.1 The defects in castings ascertained by the manufacturing unit, must be chipped off or

ground out or drilled out in such a way as to obtain a clean metallic surface. Gouging

by flame or arc - air method is permissible only with non alloyed cast steel like CSN

422643. Even then the gouged portion must be ground in order to obtain a metallic

surface. In case of doubts whether the defect has been completely removed or not, the

electro-magnetic crack test must be applied.

3.2 The defective portions must be removed in such a way as to enable the welder to carry

out the welding successfully. There must be no sharp edges and the transition from the

defective portion to the faultless material must be done in a smooth way. The welding

engineer has to certify whether the preparation has been carried out properly.


3.3 The exact procedure of welding different types of cast steels can be found in the

enclosure of this instruction.

3.4 In case cracks develop during welding, the welder is obliged to stop the welding

operation and call the welding engineer immediately who will instruct the welder how to

proceed further on.

3.5 If preheating for welding is prescribed, it is recommended to heat the whole casting

upto the required temperature. The preheating temperature has to be maintained

through out the welding operation. Heating by means of heating fixtures (producer gas)

is permissible. It is essential to protect the casting during welding against any sudden

cooling which could cause the increase of inner stresses. The surface exposed to the

atmosphere should be covered by suitable insulating materials (asbestos mats, glass

wool etc.). The temperature of preheating is being checked during welding by means

of suitable temperature indicating aids like thermo-chalks etc. If the preheating

temperature falls during welding below the minimum required value, welding must be

interrupted and the temperature regained.

3.6 Welding must proceed without any interruption. In case welding is interrupted for any

unexpected reason the casting must not cool down fast but must be heated by gas

burners in order to cool down slowly to the room temperature. The same procedure has

to be followed when concluding the welding operation.

3.7 In case of large welds intermediate annealing has to be carried out according to the

enclosure of this instruction.

4.0 INSPECTION OF THE REPAIR :

4.1 All major repairs done on casing by welding must be recorded. The manufacturing unit

/ inspection department is obliged to keep these records (including a sketch about the

location of the defect). Only small repairs like local porosity need not be recorded.

4.2 The welds shall be inspected visually. Larger repairs shall always be inspected by

applying defectoscopic methods. The weld must be homogenous without any cracks.

4.3 Defects found in the weld must be again repaired following the same procedure as stated

above.


5.0 HEAT TREATMENT :

5.1 The repaired and inspected castings must be again heat treated. The type of heat

treatment will be given by the welding engineering department from case to case.

6.0 RESPONSIBILITY :

6.1 The manufacturing unit is responsible for :

a) The exact determination of the repair to be carried out on the casing.

b) Ascertaining that the found defects were nicely removed.

c) Inspection of the executed repair.

d) Record keeping on repairs.

6.2 The welding engineering department / manufacturing unit is responsible for :

a) Certifying that the places on which welding is supposed to be done are properly

prepared for undertaking the repair.

b) Follow up of welding procedure specification.

c) Supervision of the welding operation.

d) Ascertaining that the preheating temperature has been reached if prescribed.

e) Cooperating with the manufacturing unit when evaluating the result of the

welding operation.

f) Prescribing the necessary heat treatment after welding if required.


7.0 REPAIR WELDING PROCEDURE

1 Material specification : GS-C25, 422710, 422643, SA 216

WCB

2 Removal of defects : Defects shall be removed by grinding /

machining.

3 Inspection of pre-welding : Complete elimination of defects shall

be ensured by LPI / MPI /

Radiography.

4 Welding procedure :

a) Welder : Qualified as per ASME Sec.IX / IBR

b) Process : SMAW

c) Electrode : E7018-A1. Properly baked electrodes

to be used.

d) Position : The welding shall be done in the flat

position as far as possible.

e) Arc current : Φ 2.50 mm (60-80 amps)

Φ 3.15 mm (90-130 amps)

Φ 4.00 mm (140-180 amps)

Φ 5.00 mm (190-240 amps)

f) Preheating : Upto 30 mm thickness } 10ºC

30-100 mm thickness } 100ºC

101-200 mm thickness } 150ºC

g) Inter pass te perature : 350ºC max.

5 Stress relief : Below 40 mm thickness no stress

relief is required.

Above 40-200 mm thickness stress

relieve at 600-620ºC for 3 hours.

6 Inspection of Post welding : MPI followed by UT.



1 Material specification : GS-17CrMoV511, 21CrMoV57V,

21CrMoV57, 422731.1, 422743.1,

422744.1, 422745.1

2 Removal of defects : Defects shall be removed by grinding

or machining and ensure complete

removal by LPI / MPI.


a) Welder : Qualified as per ASME Sec.IX / IBR

b) Process : SMAW

c) Electrode : E9018B3. Properly baked electrodes to

be used.

d) Arc current : Φ 2.50 mm (60-80 amps)

Φ 3.15 mm (90-130 amps)

Φ 4.00 mm (140-180 amps)

Φ 5.00 mm (190-240 amps)

e) Preheating : 300ºC, continue this temp. throughout

the welding operation.

f) Inter pass temperature : 375ºC max.

5 Post weld heat treatment : The casing has to be stress elieved as

per code of practice in welding

procedure specification.

6 Inspection after Post weld heat treatment : MPI followed by UT.



1 Material specification : GS-17CrMo55(P4), A182F12,

A217WC6, A387-12

2 Removal of defects : Defects shall be removed by grinding

or machining and ensure complete

removal by LPI.


a) Welder : Qualified as per ASME Sec.IX

b) Electrode : E8018B2. Properly baked electrodes

to be used.

d) Arc current : Φ 4.00 mm (140-180 amps)

Φ 5.00 mm (190-240 amps)

e) Preheating : 250ºC, maintain this temp. throughout

the welding operation.

f) Inter pass temperature : 350ºC max.

5 Post weld heat tr atment : Maintain the temp. at 300ºC for about

2-3 hours and allow it to cool under

asbestos.

6 Inspection after Post weld heat treatment : MPI followed by UT.

Note : If weld repair is extensive, i.e. thickness of weld metal is more than 10 mm,

the casing has to be stress relieved as per the code of practice.

WELDING MANUAL B 9 GAS METAL ARC WELDING 146

CHAPTER - B9

GAS METAL ARC WELDING


GAS METAL ARC WELDING

1. GENERAL

Gas Metal Arc Welding (GMAW) can be used as a faster alternative to Shielded Metal Arc

Welding (SMAW) . In GMAW the consumable is a wire spool, which is continuously fed

by a motor. This consumable as well as the shielding gas come out through a hand held

torch and the torch is moved manually.

This method thus combines the flexibility of manual methods with the high productivity of

motorised consumable wire movement. The method has two commonly used variants :

(a) Metal Inert Gas (MIG) welding (an example is the welding of aluminium bus

ducts at site)

(b) Metal Active Gas (MAG) welding (an example is steel chimney fabrication at

site)

While Argon is almost always used in MIG welding for shielding the arc, Carbon Dioxide

or Carbon Dioxide with Argon is used for MAG welding.

2. ADVANTAGES OF GMAW

The advantages of GMAW over SMAW are :

(a) High welding speed due to continuous feed of filler metal and high deposition rate

(b) No slag removal and no slag inclusion

(c) Higher deposition efficiency

(d) Higher arcing time

(e) Low hydrogen content in weld metal

3. VARIABLES AFFECTING WELD QUALITY

The variables which affect weld quality in GMAW ARE:

(a) Welding current

(b) Polarity

(c) Arc Voltage

(d) Travel speed

(e) Electrode extension

(f) Weld joint position

(g) Electrode diameter

(h) Shielding gas composition

(i) Gas flow rate


The optimum process variables, however, depend on type of base metal, electrode

composition, welding position and the specified quality requirements.

Some suggestive areas where this process can be used to great advantages are CW piping,

Power House Structurals, Ceiling Girders, Condenser etc.

The relevant information from welding techniques and welding procedure data used in one

of the BHEL sites in construction of steel chimney is given below for guidance.

If site wants to adopt GMAW process, procedure shall be developed at site and get it

vetted by respective Engineering centres / Manufacturing units.

WELDING TECHNIQUES Joint details : 8mm

8 mm Fillet 8 mm

Current range : 120 to 160 Amps

Voltage range : 19 to 22 Volts

Electrode consumed (cm / M) : 3 to 3.8 M / Min.

Current AC or DC : DC

Polarity : EP

Size of reinforcement : 1.5 to 2 mm

Whether removed : No

Inspection and test schedules : As per IS 7307 PT-1


WELDING PROCEDURE DATA SHEET Welding Process : Semi-Auto Material specification : IS 2062 Gr.A Thickness Plate : 8 mm Pipe diameter : -- Filler metal specification : IS-6419 84-C504 (ER-7086) Weld metal analysis : NA

FLUX OR SHIELDING GAS Flux trade Name or composition : NA Shielding gas composition : 99.7% CO2 Trade Name : NA Flow rate : 10-15 LPM Backing strip used : NA Pre-heat temperature range : 10C Min. Interpass temperature range : 265C Max. Post Weld Heat Treatment : NA

WELDING PROCEDURE Single or Multi-pass : Multi-pass Single or Multiple Arc : Single Welding position(s) : Horizontal – Vertical

FOR INFORMATION ONLY Electrode and filler wire diameter : 1.2 mm Trade Name : CTTOFIL(ADVANI) Type of backing : NA Fore hand and back hand : NA

WELDING MANUAL 150

CHAPTER – B 10

ORBITAL WELDING

WELDING MANUAL 151

ORBITAL WELDING ( FOR INFORMATION ONLY )

WHAT IS ORBITAL WELDING

1. Definition

The term Orbital-Welding is based on the Latin word ORBIS = circle. This has been adopted

primarily by aerospace and used in terms of Orbit (n.) or Orbital (adj.) for the trajectory of a man-

made or natural satellite or around a celestial body.

The combination Orbital and Welding specifies a process by which an arc travels

circumferentially around a work piece (usually a tube or pipe).

The concept Orbital Welding is basically a loosely defined term that is usually used for process

only, where the arc travels at least 360 degrees around the work piece without interruption.

Consequently, processes, which interrupt the full 360-weld sequence such as for better puddle

control (often used for MIG/MAG welding, using the down-hand welding sequence in 2 half-

circles), can not truly be called orbital welding.

Orbital Tube Welding

Understanding the basic principles behind orbital tube welding may help you arrive more

rapidly at the optimum weld procedure for your specific application.

by Bernard Mannion and Jack Heinzmann III

Orbital welding was first used in the 1960s, when the aerospace industry recognized the

need for a superior joining technique for aerospace hydraulic lines. A mechanism was

developed in which the arc from a Tungsten electrode was rotated around the tubing weld

joint. The arc welding current was regulated with a control system thus automating the

entire process. The result was a more precision and reliable method than the manual

welding method it replaced.

In the early 1980s, Orbital welding became practical for many industries when combination

power supply/control systems were developed that operated from 110 VAC. These

systems were physically small enough to be carried from place-to-place on a construction

site for multiple in-place welds

Modern day orbital welding systems offer computer control, where welding parameters for

a variety of applications can be stored in memory and later called up for a specific

application. Hence, the skills of a certified welder are thus built into the welding system,

WELDING MANUAL 152

producing enormous numbers of identical welds and leaving significantly less room for

error or defects.

Orbital Welding Equipment

In the orbital welding process, tubes/pipes are clamped in place, and an orbital weldhead

rotates an electrode and electric arc around the weld joint to make the required weld. An

orbital welding system consists of a power supply and an orbital weldhead.

The power supply/control system supplies and controls the welding parameters according

to the specific weld program created or recalled from memory. This supply provides the

control parameters, the arc welding current, the power to drive the motor in the weldhead,

and switches the shield gas(es) on/off as necessary.

Orbital weld heads are normally of the enclosed type, and provide an inert atmosphere

chamber that surrounds the weld joint. Standard enclosed orbital weld heads are practical

in welding tube sizes from 1/16 inch (1.6 mm) to 6 inches (152 mm) with wall thicknesses

of up to .154 inches (3.9 mm). Larger diameters and wall thicknesses can be

accommodated with open style weld heads.

Reasons for Using Orbital Welding Equipment

There are many reasons for using orbital welding equipment. The ability to make high

quality, consistent welds repeatedly, at a speed close to the maximum weld speed, offer

many benefits to the user:

1. Productivity. An orbital welding system will drastically outperform manual welders, many

times paying for the cost of the orbital equipment in a single job.

2. Quality. The quality of a weld created by an orbital welding system (with the correct weld

program) will be superior to that of manual welding. In applications such as semiconductor or

pharmaceutical tube welding, orbital welding is the only means to reach the weld quality

requirements.

3. Consistency. Once a weld program has been established, an orbital welding system can

repeatedly perform the same weld hundreds of times, eliminating the normal variability,

inconsistencies, errors, and defects of manual welding.

4. Skill level. Certified welders are increasingly hard to find. With orbital welding equipment,

you don't need a certified welding operator. All it takes is a skilled mechanic with some weld

training.

WELDING MANUAL 153

5. Versatility. Orbital welding may be used in applications where a tube or pipe to be welded

cannot be rotated or where rotation of the part is not practical. In addition, orbital welding may

be used in applications where access space restrictions limit the physical size of the welding

device. Weld heads may be used in rows of boiler tubing, where it would be difficult for a

manual welder to use a welding torch or view the weld joint.

Many other reasons exist for the use of orbital equipment over manual welding. For

example, applications where inspection of the internal weld is not practical for each weld

created. By making a sample weld coupon that passes certification, the logic holds that if

the sample weld is acceptable, that successive welds created by an automatic machine

with the same input parameters should also be sound.

General Guidelines for Orbital Tube Welding

For orbital welding in many precision or high purity applications, the base material to be

welded; the tube diameter(s); weld joint and part fit-up requirements; shield gas type and

purity; arc length; and Tungsten electrode material, tip geometry, and surface condition

may already be written into a specification covering the application.

Each orbital welding equipment supplier differs slightly in recommended welding practices

and procedures. Where possible, follow the recommendations of your orbital equipment

supplier for equipment set-up and use, especially in areas that pertain to warranty issues.

Note that, this section is only intended as a guideline for those applications where no

specification exists. The engineer responsible for the welding must create the welding set-

up, and derive the welding parameters, in order to arrive at the optimum welding solution.

WELDING BASICS AND SET-UP

The Physics of the GTAW Process

The orbital welding process uses the Gas Tungsten Arc Welding process (GTAW), as the

source of the electric arc that melts the base material and forms the weld. In the GTAW

process (also referred to as the Tungsten Inert Gas process - TIG) an electric arc is

established between a Tungsten electrode and the part to be welded. To start the arc, an

RF or high voltage signal (usually 3.5 to 7 KV) is used to break down (ionize) the insulating

properties of the shield gas and make it electrically conductive in order to pass through a

tiny amount of current. A capacitor dumps current into this electrical path, which reduces

the arc voltage to a level where the power supply can then supply current for the arc. The

power supply responds to the demand and provides weld current to keep the arc

WELDING MANUAL 154

established. The metal to be welded is melted by the intense heat of the arc and fuses

together.

Material Weldability

The material selected varies according to the application and environment the tubing must

survive. The mechanical, thermal, stability, and corrosion resistance requirements of the

application will dictate the material chosen. For complex applications, a significant amount

of testing will be necessary to ensure the long-term suitability of the chosen material from a

functionality and cost viewpoint.

In general, the most commonly used 300 series stainless steels have a high degree of

weldability with the exception of 303/303SE, which contain additives for ease of machining.

Four hundred series stainless steels are often weldable, but may require post weld heat

treatment.

Accommodation must be made for the potential differences of different material heats. The

chemical composition of each heat batch number will have minor differences in the

concentration of alloying and trace elements. These trace elements can vary the

conductivity and melting characteristics slightly for each heat. When a change in heat

number is made, a test coupon should be made for the new heat. Minor changes in

amperage may be required to return the weld to its original profile.

It is important that certain elements of the material be held to close tolerances. Minor

deviations in elements, such as sulfur, can vary the fluid flow in the weld pool, completely

changing the weld profile and causing arc wander.

Weld Joint Fit-Up

Weld joint fit-up is dependent on the weld specification requirements on tube straightness,

weld concavity, reinforcement, and drop through. If no specification exists, the laws of

physics will require that the molten material flow and compensate for tube mismatch and

any gap in the weld joint.

Tubing is produced according to tolerances that are rigid or loose according to the

application for which the tube was purchased. It is important that the wall thickness is

repeatable at the weld joint from part to part. Differences in tube diameter or out-of-

roundness will cause weld joint mismatch and arc gap variations from one welding set up

to another.

WELDING MANUAL 155

Tube and pipe end prep facing equipment is recommended in order to help ensure end

squareness and end flatness. Both the I.D. and O.D. should be burr free with no

chamfer.When two tubes are butted together for welding, two of the main considerations

are mismatch and gaps. In general, the following rules apply:

Any gap should be less than five percent of the wall thickness. It is possible to weld with

gaps of up to 10 percent (or greater) of wall thickness, but the resultant quality of weld will

suffer greatly, and repeatability will also become a significant challenge.

Wall thickness variations at the weld zone should be +/- five percent of nominal wall

thickness. Again, the laws of physics will allow welding with mismatch of up to 25 percent of

wall thickness if this is the only challenge. Again, the resultant quality of weld will suffer

greatly, and repeatability will become an issue.

Alignment mismatch (high-low) should be avoided by using engineering stands and clamps

to align the two tubes to be welded. This system also removes the mechanical requirement of

aligning the tubes from the orbital weld head.

Shield Gas (es)

An inert gas is required on the tube O.D. and I.D. during welding to prevent the molten material from combining with the oxygen in the ambient atmosphere. The objective of the welder should be to create a weld that has zero tint at the weld zone I.D.

Argon is the most commonly used shield gas (for the O.D. of the tube) and the purge gas

(for the I.D. of the tube). Helium is often used for welding on copper material. Mixed gases,

such as 98 percent Argon/two percent Hydrogen; 95 percent Argon/five percent Hydrogen;

90 percent Argon/10 percent Hydrogen; or 75 percent Helium/25 percent Argon may be

used when the wall thickness to be welded is heavy (.1" or above). Using mixtures of 95

percent Argon/five percent Hydrogen is incompatible with carbon steels and some exotic

alloys, often causing hydrogen embrittlement in the resultant weld. As a general rule, for

simplicity and reduction of shield gas cost, use 100 percent Argon gas.

Gas purity is dictated by the application. For high purity situations, where the concern for

micro-contamination is paramount, such as semiconductor and pharmaceutical

applications, the shield and purge gases must minimize the heat tint that could otherwise

be undesirable. In these applications, ultra high purity gas or gas with a local purifier is

employed. For non-critical applications, commercial grade argon gas may be used.

Tungsten Electrode

The Tungsten welding electrode, the source of the welding arc, is one of the most

important elements of the welding system that is commonly ignored by welding systems

WELDING MANUAL 156

users. Users continue to manually grind and wonder why they produce inconsistent

results. Whether in manual or automatic welding, this is the area where manufacturing

organizations can improve the consistency of their welding output with minor effort.

Basically, the objective for the choice of Tungsten parameters is to balance the benefits of

a clean arc start and reduced arc wander with good weld penetration and a satisfactory

electrode life.

Electrode Materials

For quite some time, Tungsten manufacturers have added an oxide to pure Tungsten to

improve the arc starting characteristics and longevity of pure Tungsten electrodes. In the

orbital welding industry, the most commonly used electrode materials are two percent

thoriated Tungsten and two percent ceriated Tungsten.

Safety

The safety issues of Tungsten electrode material are now being looked at more closely.

Many users of the TIG welding process do not realize that the welding electrode they use

contains Thorium, a radioactive element added to the Tungsten. While the radioactivity is

of a low level, it brings an issue of danger, especially with the radioactive dust that is

generated when grinding the electrodes to a point for welding.

Alternative, non-radioactive Tungsten materials are now available, such as two percent

ceriated electrodes, which often offer superior arc welding. While these materials are

commercially available they have been largely ignored until recently. Recommended

Electrode Materials

Cerium, as a base material, has a lower work function than Thorium, offering superior

emission characteristics. So, not only do ceriated electrodes offer an advance in electrode

safety, they also improve the arc starting ability of the orbital equipment. However, as

mentioned earlier, it is always best to follow the advice of your orbital equipment

manufacturer.

Electrode Tip Geometry

Given the ever-increasing weld quality requirements of the final weld, more and more

companies are looking for ways to ensure that their weld quality is up to par. Consistency

and repeatability are key to welding applications. The shape and quality of the Tungsten

electrode tip is also being recognized as a vital process variable. Once a weld procedure

has been established, it is important that consistent electrode material, tip geometry, and

surface condition be used.

WELDING MANUAL 157

Welders should follow an equipment supplier's suggested procedures and dimensions first,

because they have usually performed a significant amount of qualifying and

troubleshooting work to optimize electrode preparation for their equipment. However,

where these specifications do not exist, or the welder or engineer would like to change

those settings to possibly improve and optimize their welding, the following guidelines

apply:

Electrode Taper

This is usually called out in degrees of included angle (usually anywhere between 14° and

60°). Below is a summary chart that illustrates how different tapers offer different arc

shapes and features:

Sharper Electrodes Blunter Electrodes

Last less than blunt Last longer

Less weld penetration Better weld penetration

Wider arc shape Narrower arc shape

Handle less amperage Handle more amperage

Less arc wander Potential for more arc wander

More consistent arc Less consistent arc

To demonstrate graphically how the taper selection will effect the size of the weld bead

and the amount of penetration, the following drawing shows typical representations of the

arc shape and resultant weld profile for different tapers.

Electrode Tip Diameter

Grinding an electrode to a point is sometimes desirable for certain applications, especially

where arc starting is difficult or short duration welds on small parts are performed. In most

cases, however, it is best for a welder to leave a flat spot or tip diameter at the end of

electrode. This reduces erosion at the thin part of a point, and reduces the concern that the

tip may fall into the weld. Larger and smaller tip diameters offer the following trade-offs:

Smaller Tip Larger Tip

Easier to start Usually harder to start

Less arc wander More chance of arc wander

Less electrode life More electrode life

Less weld penetration More weld penetration

Tungsten Electrode Grinders and Pre-Ground Electrodes

WELDING MANUAL 158

Using electrodes pre-ground to requirements or a dedicated commercial electrode grinder

to provide electrode tip quality and consistency, offers the following benefits to the user in

their welding process:

Improved arc starting, increased arc stability, and more consistent weld penetration.

Longer electrode life before electrode wear or contamination.

Reduction of Tungsten shedding. This minimizes the possibility of Tungsten inclusions

in the weld.

A dedicated electrode grinder helps ensure that the welding electrodes will not become

contaminated by residue or material left on a standard shop grinder wheel.

Tungsten electrode grinding equipment requires less skill to ensure that the Tungsten

electrode is ground correctly and with more consistency.

Pre-Ground Electrodes

Rather than risk electrode radioactivity issues, and constantly endure the variability of each

operator grinding the electrodes with a slightly different touch, many manufacturing

organizations have chosen to purchase electrodes pre-ground. Since a small difference in

the dimensions of an orbital electrode can produce a big difference in the weld results, pre-

ground electrodes are the preferred electrode choice to maintain the consistency of your

welding. This low-cost option ensures that the electrode material quality, tip geometry, and

ground electrode surface input to the welding process is constant. Consult electrode charts

or a pre-ground electrode supplier to obtain the electrode diameter and tip geometry that is

most suitable for your welding application.

Conclusion

In conclusion, the important points to remember are:

Orbital welding has been used by many industries to improve the quality and quantity of

tube welding when compared to what can be accomplished by manual welders.

The effective cost of an employee computes to be significantly more than just his base

salary. The output of a $20 per hour skilled welder actually costs over $72,000 per year (almost

twice his yearly base wage).

If a complete orbital welding system costs between $15,000 and $20,000 and can output

over twice the amount of welding that a manual welder can produce then the equipment will pay

for itself in a matter of months.

WELDING MANUAL 159

Finally, the volume of welds that are produced by an automated welding system will far

exceed that of a manual welder. In addition to weld quality improvements, this will bring two

additional financial benefits: One, increased output per day at lower cost. Two, lowered scrap

and rework costs due to improved weld consistency.

Tubesheet Weld Heads - Orbital Welding Equipment

/ Automated Welding Equipment

These Magnatech weld heads are specifically designed for making tube-to-

tubesheet welds. Configured for fast and simple operation, the Head is inserted into

the tube to be welded, and the operator pushes the START WELD switch.

Multiple torch positioning adjustments allow virtually all tubesheet joint

designs to be welded. All three models weld a wide range of tube sizes and

operate in any position.

For welds requiring filler wire addition, an optional wire feeder can be

mounted on the weld head. A standard wire spool, mounted directly on the

Head, provides precise and positive wire feeding, not possible with floor-

mounted feeders.

These weld Heads bring the productivity and repetitive precision of machine

welding to the fabrication and repair of steam generators and heat

exchangers.

All three weld Heads models are used with Magnatech power sources,

ranging form simple to operate analog models to microprocessor-based

systems with program storage capability.

TUBE GEOMETRIES

Model 424 is ideal for all tubesheet geometries.

Model 425 with AVC is for multipass welding

Model 426 is ideal for fusion welding where preheat is not required.

Process: GTAW

Weld Head

Type:

Open arc.

Tube Size Model 424: 10mm - 78mm (0.4" - 3.07") OD

WELDING MANUAL 160

Range: Model 425: 10mm - 140.2mm (0.4" - 5.52") OD

Model 426: 10mm - 70.1mm (0.4" - 2.76") OD

Features:

Water-cooled torch and weld Head body (models 425 &

426 only) allow use on pre-heated tubesheets

Lifting eye allows use on a counterbalance for weightless

operation

Multiple torch angle and wire feed positioning mechanism

allow optimum torch position and wire entry angle

Simple centering cartridge design allows quick

installation without requiring prior installation of

expensive custom-fabricated locating fixtures

Inexpensive centering cartridges fit the exact tube ID

Filler wire spool rotates with the torch - eliminating wire

entry problems common with floor-mounted feeders

(Models 424 & 425)

No cable wrap-up

Options: Filler Wire feeder using standard 1kg (2lbs.) spools

Three point standoff for welding "extended tube"

geometries

Transparent purge gas chamber for titanium floods the

enclosed weld area independent of torch shielding gas,

reducing purge time and weld oxidation

Arc Voltage Control parallel to tungsten electrode - even

when the torch is angled for a fillet weld

Torches for internal bore welding

Extension Cables

Dual Head Switcher allows two Heads to be used

alternately maximizing "arc on" duty cycle

Applications: Heat exchanger seal and strength welds

Power generation

Petrochemical

Sanitary

Food and beverage

@@@@

WELDING MANUAL 161

CHAPTER – B11

EDGE PREPARATION DETAILS

FOR PIPES

WELDING MANUAL 162

WELDING MANUAL 163

WELDING MANUAL 164

CHAPTER – B12

Erection Procedure for Rear Water Box & Rear water Chamber

WELDING MANUAL 165

Erection Procedure for Rear Water Box & Rear water Chamber

Condensers supplied by Haridwar for 210/250/500 MW ratings are having flanged connection

between water box and water chamber at both the ends. (Front & rear). This is to facilitate re-

tubing in case it is required. With the use of stainless steel, reliability of condenser tube material

has increased and chances of failures and re-tubing has reduced tremendously.

In Amarkantak 210 MW, flanges have been removed from rear water box & water chamber and

both have been directly welded together. Space for re-tubing has been kept on front water box

side.

A- Pre assembly

1. Place both Rear water chambers on horizontal surface with water side surface of tube

plate on top position. Level the water chambers w.r.t tube plate. Mark top & bottom

position of water chambers.

2. Weld backing strip on all four walls of water chambers as shown in Fig.I. In Rear

water chamber (GS) backing strip will be welded inside on all the four walls and on

Rear water chamber (TS) it will be welded inside on three walls and outside on

vertical wall near condenser centre line.

3. Measure tube sheet flatness as per recommended procedure and record the

dimensions in log sheet L-02.

4. Water box inside length & width and corresponding dimensions of water chamber to

be checked w.r.t. horizontal & vertical centre lines and recorded in log sheet to

ascertain trueness of dimensions.

5. If logged dimensions indicate any mismatch, same may be corrected

6. Match Rear water Box (TS/GS) by lowering it over respective water chamber /

backing strip such that the weld edges of water chamber and water box match for

proper welding. In case of mismatch, the same to be rectified.

B - Assembly :

Assembly can be done in two ways as per site‟s convenience.

Option –1

1. Remove the water box after completing the activity as per A (6) above.

2. Weld 4 number channels (2 horizontal & 2 vertical) of size 100x50 along the length and

width to stiffen the water chamber. Refer Fig. I. Holes in the tube plate to be suitably

protected.

WELDING MANUAL 166

3. Lower the water chamber (without water box) on bottom plate for erection as per

standard procedure.

4. Tack weld / final weld water chamber with side walls and bottom plate.

5. Carry out tubing.

6. Weld the water boxes using proper welding sequence as given (C ) below.

Option – II (Refer Fig.-2)

1. Weld water box and chamber with the help of technological plates (12 x 100 x 250)

as shown in the drawing.

2. Lower water box and chamber together for erection.

3. Tack weld / Final weld water chamber with side walls and bottom plate.

4. Remove water box to facilitate tubing & expansion by cutting stiffening plates.

5. Carry out tubing.

6. Weld the water boxes using proper welding sequence as given (C ) below.

C- Welding sequence for water box & water chamber (Refer Fig-3)

1. Tack weld Water box (GS) and Chamber(GS) -100 (200).

2. Root run on all sides.

3. Final welding to be done as per Detail-I.

4. Welding of Generator side water box-Water chamber to be completed first as it has all

welds from outside.

5. Bring Turbine side water box in position. Repeat steps 1-4 indicated above.

6. All welding is from outside except vertical welding of Rear water box & water chamber

(TS) near condenser centerline which is from inside.

7. Direction of welding shall be as indicated in the drawing.

8. Over head welding is required for carrying out bottom welding of water boxes and water

chambers.

(Naveen Prakash) (S.K.Baveja) (Lalit Kishore)

WELDING MANUAL 167

WELDING MANUAL 168

WELDING MANUAL 169

WELDING MANUAL 170

CHAPTER – B13

WELDING & HT DETAILS OF THERMOCOUPLE PAD & CLAMPS

FOR SH & RH

WELDING MANUAL 171

WELDING & HT DETAILS OF THERMOCOUPLE PAD & CLAMPS

FOR SH & RH

Pad / Clamp Material : SS 304, 316, 321, 310

Sl.No Tube Material

(SH & RH)

Thickness in mm

(t – max).

Thermocouple pad

Material

Pre-heat

(min)

Post-weld heat

Treatment

Consumable

Electrode

1 SA210 Gr. A1 7.6

SS 304, 316, 321,

310 NIL NIL E7018 A1

2

SA213 T11

8.6

SS 304, 316, 321,

310 1250C NIL E7018 A1

3

SA213 T22

t<8.0

SS 304, 316, 321,

310 1500C NIL E7018 A1

8.0 to 12.0

SS 304, 316, 321 NIL NIL E 309

8.0 to 12.0

SS 310

1500C ON

T22 Side NIL E 309

4

SA213 T91

ALL THICKNESS

SS 304, 316, 321,

310

2200C ON

T91 Side

7500C to

7700C

(min, 30

minutes)

E 309

5 SA213 TP347 H ALL THICKNESS SS 304, 316, 321 NIL NIL E 347

6 SA213 TP347 H 12.0 (max.) SS 310 NIL NIL E 309

NOTE :

1 The above can be taken as the general guidelines for all the boilers.

2 Electrode size : 2.50 mm

3 Welder shall strike ARC on Thermocouple pad or "Run-on Run-off" Block and bring arc up to side

of thermocouple pad using as low a current as possible to avoid burn-through.

WELDING MANUAL 172

CHAPTER – B14

WELDING AND PWHT SEQUENCE FOR LOWER RING HEADER

WELDING MANUAL 173

WELDING AND PWHT SEQUENCE FOR LOWER RING HEADER

1.0 PURPOSE

1.1 To describe the welding, NDE and Post Weld Heat Treatment (PWHT) sequences for the

four field welds in the lower ring header assembly.

2.0 WELDING & INTERSTAGE RADIOGRAPHY TESTING (RT)

2.1 One of the sequence 2.1.1 or 2.1.2 given below is to be followed while welding the four

joints in the lower ring header assembly.

2.1.1 All four corner joints are to be welded simultaneously upto 60 mm thickness and

inter stage RT shall be taken. After inter stage RT clearance, balance welding of all four

corner joints are to be welded simultaneously and completed.

2.1.2 Diagonally opposite two joints are to be welded simultaneously upto 60 mm thickness

and inter stage RT shall be taken. After inter stage RT clearance, balance welding of first

two joints are to be welded simultaneously and completed.

Then balance two joints are to be welded simultaneously and completed upto 60 mm

thickness and inter stage RT shall be taken. After inter stage RT clearance, balance

welding of last two joints are to be welded simultaneously and completed.

Note: To reduce cycle time, last two joints welding upto 60 mm shall be taken up

immediately after completing first two joints welding upto 60 mm.

3.1 ULTRASONIC TESTING

3.1 All weld joints shall be dressed smoothly for UT and ultrasonic testing shall be carried

out for all four joints.

4.0 PWHT

4.1 PWHT of each weld joint shall be done individually or in any other order.

WELDING MANUAL 174

CHAPTER B 15

DEMAGNETISATION PROCEDURE

Refer NDE Manual Chapter 1.11

WELDING MANUAL 175

CHAPTER B 16

ERECTION WELDING PRACTICE FOR SA 213 T 91 MATERIAL

WELDING MANUAL 176

ERECTION WELDING PRACTICE FOR SA 213 T 91 MATERIAL

1.0 Scope :

1.1 This document details salient practices to be adopted during welding of SA213 T91

material.

2.0 MATERIAL

2.1 SA213 T91 Dia, and thickness will be as per Erection Welding Schedule for the site

2.2 When any defect like crack, lamination, deposit noticed during visual examination, the

same shall be confirmed by Liquid Penetrant Inspection. If confirmed, it shall be referred

to unit.

3.0 ERECTION

3.1 EDGE PREPARATION AND FIT UP

3.1.1 Cutting of T-91 material shall be done by band saw/hacksaw/machining/ grinding only.

Edge preparation (EP) shall be done only by machining. In extreme cases, grinding can be

done with prior approval of Welding Engineer/ Quality Assurance Engineer. During

machining/ grinding, care should be taken to avoid excessive pressure to prevent

heating up of to the tube edges.

3.1.2 All Edge Preparations done at site shall be subjected to Liquid Penetrate Inspection (LPI).

Weld build-up on Edge Preparation is prohibited.

3.1.3 The weld fit-up shall be carried out properly to ensure proper alignment and root gap.

Neither tack welds nor bridge piece shall be used to secure alignment. Fit-up by a

clamping arrangement is recommended. Coil load to be transferred to crown plate/ end

bar assembly. Ensure that coil load should not come on stubs/header. Use site fabricated

clamps for fit up. The necessary preheat and purging shall be done as per clause 4.1 and

3.2.2 ref. WPS No. 1036 Rev 04 dt 02 04 04.

3.1.4 The fit-up and root gap shall be as per drawing.

3.2.0 FIXING OF THERMOCOUPLE (T/C), DURING PREHEATING AND PWHT

3.2.1 No. Preheating is required for fixing T/C with resistance spot welding.

Following are the equipment/ facilities required for heating cycles.

(1) Heating methods: Resistance heating

(2) Thermo couples: Ni-Cr/ Ni-Al of 0.5mm.

(3) Temp. Recorders: 6 Points/12 Points.

WELDING MANUAL 177

3.2.2 ARRANGEMENT FOR PURGING:

Argon gas with requisite quality shall be used for purging the root side of weld. The

purging dam (water soluble paper) shall be fixed on HDR Nipple side of the weld bevel

prior to fit-up and pre-heating. Purging is to be done from cross over tube down stream

end. (Sketch 3). Ensure that atmosphere air is completely purged out through the root gap

before starting welding and welding can be continued with Argon backing.

The flow rate is to be maintained for purging is 6 to 8 litres/ minute and for GTAW is 8-

12 litres/ minute.

3.2.3 When root temperature reaches 220oC, start purging through cross over tube down stream

end for 5 minutes. Then the root gap to be covered by asbestos rope. Provide continuous

and adequate argon gas to ensure complete purging in the root area. Only water-soluble

paper is to be used. Plastic foils that are water-soluble are NOT acceptable.

3.2.4 USING OF WATER SOLUBLE PAPER

The dams can be made of water-soluble paper for creating the purging chamber. The

advantage in such dam arrangement is that the dissolving paper dam gets flushed during

hydraulic test. The following is the method to be used:

Simply stuff water-soluble paper into the Header Nipples at specified distance from the

weld as per attached sketch 1

SKETCH - 1

WELDING MANUAL 178

4.0 WELDING/WELDERS QUALIFICATION:

Only qualified welding procedure is to be used. Welders qualified as per ASME Sec IX and IBR and

on T91 material shall be engaged. Welders log book shall be maintained and welders performance to

be monitored by site welding engineer/ Quality assurance engineer. The applicable WPS for T91+T91

shall be WPS No. 1036/04 dt. 02/04/04.

4.1 PREHEATING (Bunching of tubes can be followed):

Prior to start of pre heating ensure that surface are clean and free from grease, oil and dirt. Preheating

temp shall be maintained at 220oC (min) by using resistance heating. Sufficient number of thermo

couples shall be fixed on both coils and header nipples away from the EP. The thermocouple shall be

welded with the condenser discharge portable spot welding machine. The pre heating arrangements

shall be inspected and cleared by welding engineer/ Quality Assurance Engineer before start of

preheating. Ref . Sketch 2

4.2.1 WELDING:

Welding shall be done using GTAW process (as per WPS). Filler wire shall be clean and free from

rust or oil. Argon Purging shall be continued till completion of welding.

5.0 POST WELD HEAT TREATMENT (PWHT) – RESISTANCE HEATING METHOD

(Bunching of tubes can be followed):

Arrangements: Sufficient number of thermocouples shall be placed covering weld and the base

material. The width of the heated circumferential band on either side of the weld must be at least

100mm. ( Sketch 2)

5.1 Obtain the clearance for PWHT cycle from QAE/ Welding Engineer. The PWHT temp for T91 with

T91 material shall be 760 ± 10oC and the soaking time shall be 90 minutes.

5.2 Welding and Heat treatment chart given in ( Sketch 4) shall be followed for pre-hating, welding,

PWHT, rate of heating/ cooling etc.

6.0 NDE: Carry out Non-Destructive Examination (RT) as per Field Welding Schedule.

7.0 HARDNESS SURVEY:

100% hardness survey shall be conducted on welds and parent material in first five coils. Based on

satisfactory results, the hardness survey can be reduced to 10% covering all the heat treatment cycles.

The equipment recommended to measure the hardness is EQUOTIP or equivalent. Portable equipment

used in the hardness measurement shall be calibrated .

The surface shall be cleaned and prepared as per hardness test instrument manufacture‟s

recommendation prior to hardness survey. Hardness survey of weld and parent metal (both tubes)

shall be carried out. All the hardness values shall be recorded. The maximum allowable hardness at

WELDING MANUAL 179

weld and parent material shall be 300HV10.

WELDING MANUAL 180

WELDING MANUAL 181

ERECTION WELDING PRACTICE FOR SA 213 T 91 MATERIAL .

WELDING AND HEAT TREATMENT CHART

Temp ˚C

760˚± 10˚C

350˚

220˚

100˚

80˚

HT

1 2 3 4 5 6 7 8

SKETCH- 4

Sl.

No.

Operation Temp ˚C Rate of cooling/Heating

1 Preheat 220˚C (Min.) 120˚C /hr (Max.)

2 Welding by GTAW 350˚C (Interpass-Max.)

3 Cooling 80˚- 100˚C 120˚C /hr (Max.)

4 Holding at 80-100 C to minimum 30 minutes. Holding shall continue till the start

of PWHT

5 Heating to PWHT Reach 760˚ ± 10˚C 120˚C /hr (Max.)

6 Soaking at PWHT 760˚ ± 10˚C for 90

minutes (Min.)

7 Cooling Cooling to 350˚C 120˚C /hr (Max.)

8 Cooling Cooling to Room

temperature under

insulation.

WELDING MANUAL 182

B-17

SELECTION CHART FOR DUMMY END COVERS

WELDING MANUAL 183

WELDING MANUAL 184

WELDING MANUAL 185

B-18 SCHEDULE OF PIPES

WELDING MANUAL 186

WELDING MANUAL 187

welding manual nov 2010

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