welding manual for power sector nov2010
TRANSCRIPT
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
3
5
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
WELDING MANUAL A1. WELDING-GENERAL 8
CHAPTER – A1
WELDING - GENERAL
WELDING MANUAL A1. WELDING-GENERAL 9
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.
WELDING MANUAL A1. WELDING-GENERAL 10
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.
WELDING MANUAL A1. WELDING-GENERAL 11
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 MANUAL A1. WELDING-GENERAL 12
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
WELDING MANUAL A1. WELDING-GENERAL 13
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.
No. of T/Cs: Location
:
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 A1. WELDING-GENERAL 14
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
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.
No. of T/Cs: Location
:
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.
Material Specification
(ASME)
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 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
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 / 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.
Material Specification
(ASME)
Chemical Composition (%) Mechanical Properties (Min.)
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.)
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 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
Chemical Composition (%) Mechanical Properties (Min.)
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
Chemical Composition (%) Mechanical Properties (Min.)
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
Total other Elements 0.50
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
Total other Elements 0.50
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
Total other Elements 0.50
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
3 SFA-5.5 E(X)XX10-X
3 SFA-5.5 E(X)XX11-X
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-5.4 other than austenitic and duplex EXXX(X)-16
4 SFA-5.4 other than austenitic and duplex EXXX(X)-17
4 SFA-5.5 E(X)XX15-X
4 SFA-5.5 E(X)XX16-X
4 SFA-5.5 E(X)XX18-X
4 SFA-5.5 E(X)XX18M
4 SFA-5.5 E(X)XX18M1
WELDING MANUAL 43
Table- A3.9
F.No. ASME Specification No. AWS Classification No.
5 SFA-5.4 austenitic and duplex EXXX(X)-15
5 SFA-5.4 austenitic and duplex EXXX(X)-16
5 SFA-5.4 austenitic and duplex EXXX(X)-17
6 SFA-5.2 All classifications
6 SFA-5.9 All classifications
6 SFA-5.17 All classifications
6 SFA-5.18 All classifications
6 SFA-5.20 All classifications
6 SFA-5.22 All classifications
6 SFA-5.23 All classifications
6 SFA-5.25 All classifications
6 SFA-5.26 All classifications
6 SFA-5.28 All classifications
6 SFA-5.29 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
F.No. ASME Specification No. AWS Classification No.
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
F.No. ASME Specification No. AWS Classification No.
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
36 SFA-5.7 ERCuAl-A2
36 SFA-5.7 ERCuAl-A3
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
F.No. ASME Specification No. AWS Classification No.
45 SFA5.11 ENiCrMo-11
45 SFA5.14 ERNiCrMo-1
45 SFA5.14 ERNiCrMo-8
45 SFA5.14 ERNiCrMo-9
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
WELDING MANUAL CHAPTER - A4 50
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.
WELDING MANUAL CHAPTER - A4 51
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:
WELDING MANUAL CHAPTER - A4 52
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
WELDING MANUAL CHAPTER - A4 53
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).
WELDING MANUAL CHAPTER - A4 54
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.
WELDING MANUAL CHAPTER - A4 55
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.
WELDING MANUAL CHAPTER - A4 57
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.
WELDING MANUAL CHAPTER - A4 58
TACK WELDER QUALIFICATION
WELDING MANUAL CHAPTER - A4 59
WELDING MANUAL CHAPTER - A4 60
WELDING MANUAL CHAPTER - A4 61
WELDING MANUAL CHAPTER - A4 62
WELDING MANUAL CHAPTER - A4 63
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
Type of Bend Results
Type of Bend 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
WELDING MANUAL CHAPTER - A4 64
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.
WELDING MANUAL CHAPTER - A4 65
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
WELDING MANUAL A5. INSPECTION OF WELDING 67
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
WELDING MANUAL A5. INSPECTION OF WELDING 68
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
WELDING MANUAL A5. INSPECTION OF WELDING 69
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
WELDING MANUAL A7. SAFE PRACTICES IN WELDING 73
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.
WELDING MANUAL A7. SAFE PRACTICES IN WELDING 74
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.
WELDING MANUAL A7. SAFE PRACTICES IN WELDING 75
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
22 5 Weld three run at web
23 6 Weld three run at web
24 7 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
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
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
05 OPI services,
Pune
Mr. Sathe
Cell: 9822499002
WELDING MANUAL B-3 GENERAL TOLERANCES FOR WELDING STRUCTURES –
(FORM AND POSITION) 121
CHAPTER - B3
GENERAL TOLERANCES FOR WELDING STRUCTURES – (FORM AND POSITION)
WELDING MANUAL B-3 GENERAL TOLERANCES FOR WELDING STRUCTURES –
(FORM AND POSITION) 122
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
WELDING MANUAL B-3 GENERAL TOLERANCES FOR WELDING STRUCTURES –
(FORM AND POSITION) 123
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 B-3 GENERAL TOLERANCES FOR WELDING STRUCTURES –
(FORM AND POSITION) 124
WELDING MANUAL - 125
CHAPTER - B4
WELDING OF PIPES AND PIPES SHAPED CONNECTIONS IN STEAM TURBINE, TURBO-GENERATORS AND AUXILIARIES
WELDING MANUAL - 126
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.
WELDING MANUAL - 127
ANNEXURE-I
WELDING MANUAL - 128
CHAPTER - B5
INSTRUCTIONS FOR CARRYING OUT CONDENSER PLATE AND NECK WELDING
WELDING MANUAL - 129
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.
WELDING MANUAL - 130
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
WELDING MANUAL - 131
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
WELDING MANUAL B-6 REPAIR PROCEDURE FOR ARRESTING THE LEAKAGE OF STRENGTH WELDS ON TUBE TO TUBE 133
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.
WELDING MANUAL B-6 REPAIR PROCEDURE FOR ARRESTING THE LEAKAGE OF STRENGTH WELDS ON TUBE TO TUBE 134
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
WELDING MANUAL B-7 REPAIR PROCEDURE FOR GREY CAST IRON CASTINGS 136
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.
WELDING MANUAL B-7 REPAIR PROCEDURE FOR GREY CAST IRON CASTINGS 137
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.
WELDING MANUAL B-7 REPAIR PROCEDURE FOR GREY CAST IRON CASTINGS 138
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
WM B8 SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS 140
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.
WM B8 SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS 141
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.
WM B8 SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS 142
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.
WM B8 SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS 143
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.
WM B8 SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS 144
8.0 REPAIR WELDING PROCEDURE
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.
3 Welding procedure :
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.
WM B8 SPECIAL INSTRUCTIONS FOR THE REPAIR OF STEAM TURBINE CASINGS 145
9.0 REPAIR WELDING PROCEDURE
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.
3 Welding procedure :
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
WELDING MANUAL B 9 GAS METAL ARC WELDING 147
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
WELDING MANUAL B 9 GAS METAL ARC WELDING 148
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 MANUAL B 9 GAS METAL ARC WELDING 149
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.
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B-17
SELECTION CHART FOR DUMMY END COVERS
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WELDING MANUAL 184
WELDING MANUAL 185
B-18 SCHEDULE OF PIPES
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WELDING MANUAL 187