2. WELDING
Welding is a process of joining two or more pieces of the
same or dissimilar materials to achieve complete
coalescence.
DEFINITION AS PERAWS /ASME
A localised coalescence of metals or non-metals produced
either by heating the materials to the welding temperature
with or without the application of pressure alone, and with
or without the application of filler material.
3.
4.
5. WELDING PROCESSES
1. Shielded Metal Arc Welding (SMAW)
2. Submerged Arc Welding (SAW)
3. Gas Metal Arc Welding (GMAW )
1. - MIG , MAG
4. Gas Tungsten Arc Welding (GTAW /
TIG)
6. SELECTION OF WELDING PROCESS
DEPENDS ON
Thickness & Size of part to be welded
Location and position of weld joints
Joint design
Welding equipment availability
Process and operation requirement
Production cost
7. SHIELDED METAL ARC WELDING
SMAW process defined as an arc welding
process which produces coalescence of metals
by heating them with an arc between a covered
metal electrode and the work-piece.
Shielding is obtained from decomposition of the
electrode covering.
Pressure is not used and filler metal is obtained
from the electrode.
9. MODE OF OPERATION
Arc melts parent plate and electrode to form a weld
pool which is protected by flux cover.
Operator adjusts electrode feed rate, I.e. hand
movement to keep arc length constant. Slag must be
removed after depositing each bead. Normally a
small degree of penetration, requiring plate edge
preparation. Butt welds in thick plate or large fillets
are deposited in a number of passes.
The process can also be used to deposit metal to
form a surface with alternative properties.
10. CONSUMABLES
Metal rods 1.5 - 8mm diameter with flux
covering (1-5mm radial thickness).
Widely used: 2.5x 250, 3.15 x350/450,
4 mm x 450 mm
The characteristics of manual metal arc
electrodes, i.e., arc stability, depth of
penetration, rate of deposition, position of
welding, depends on the chemical composition
of the electrode coating classified by AWS
specifications.
11. SMAW- OPERATING PARAMETERS
Current range : 75-300 A
Open Circuit Voltage : 65 - 80 V
Range of Thickness: 2mm upwards
Deposition rate : 2-11 lb/Hr
Types of joint : All
Welding position : all (depending on flux
coating)
Access : Good
Portability : Good
12. MATERIALS
Mostly confined to ferrous alloys, but can be
used for some others.
TYPICAL APPLICATIONS
Structural steel work.
Ship Building
Repair and Hard facing of construction
plant.
13. OVERALL ADVANTAGES
Low Equipment Cost
Usage possible with restricted access.
OVERALL LIMITATIONS
Skilled operator is required for good quality welds.
Slow, mainly because flux must be chipped away.
SAFETY
Arc emits visible and ultraviolet radiation.
High open circuit voltage present while electrode
is fitted to holder.
14. SUBMERGEDARC WELDING
SAW is defined as an arc welding process in
which an arc is maintained between an end of a
bare wire electrode and work piece.
The arc is fully submerged in a layer of dry
granular flux.
Pressure is not used and filler metal is obtained
from the electrode.
20. OVERALL ADVANTAGES
High weld metal Quality
Smooth and uniform weld bead with no spatters.
Extremely high deposition rate and welding speed.
Current Range: 450 - 3000 A
High Arc time can be achieved through automation.
Minimum operator fatigue.
OVERALL LIMITATIONS
High initial cost
Limited welding positions.
Requirement of special jigs and fixtures.
Difficulty in welding low thickness metals.
21. GAS METAL ARC WELDING
GMAW is defined as an arc welding process which
produces coalescence of metals by heating them
with an arc between a continuous filler metal
(consumable) electrode and the work piece.
Shielding is obtained entirely from an externally
supplied gas or gas mixture.
23. TYPE OF OPERATION : Semi-automatic /
Fully automatic.
EQUIPMENT : Power Source
Wire feed Unit
Welding gun or torch
Gas supply system travelling
unit, if fully mechanised.
GAS METAL ARC WELDING
24. An arc is maintained between the end of the bare
wire electrode and the work. The wire is fed at a
constant speed, selected to give the required
current, and the arc length is controlled by the
power source. The operator is not therefore
concerned with controlling the arc length and can
concentrate on depositing the weld metal in the
correct manner. Hence the name ‘semi-automatic’
for manual operation, in which wire, gas and
power are fed to a hand held gun via a flexible
conduit.
GAS METAL ARC WELDING
Contd.
25. The process can be operated at high currents
(250-500A) when metal transfer is in the form of
‘spray’ but except for aluminium, this technique is
confined to welding in the flat and horizontal
positions. For welding in the vertical and
overhead positions. Special low-current
techniques must be used, I.e. ‘dip transfer’ or
pulsed arc shielded by a stream of Gas.
GAS METAL ARC WELDING
26. GMAW- OPERATING PARAMETERS
Current range : 65-500 A
Metal Transfer modes:
Globular - in CO2 welding ( Non-axial metal transfer) for
Structures
Spray Transfer - Thk > =6mm; in MIG ( Axial Transfer) for
piping ( with Argo-CO2 shield) high thickness range.
Dip Transfer ( Short Circuit ) - suitable for thin sheet metal
works ( thk @ 3 mm or less)
: Dip transfer, pulsed arc –Above 0.5mm
Spray transfer 6mm upwards
Deposition rate :12-10 Kg/Hr (2-20 Lb/Hr)
Types of joint : All including spot welds
27. Consumables
Electrodes, bare wire (m.s. is normally copper coated)
0.6-1.6mm dia. Layer wound on spools 0.5-12 Kg (1-
25lb) weight. Composition of wire selected to suit parent
material; wire specifications covered by BS 2901.
Electrodes, flux cored are available for high deposition
rate welding.
Shielding gas in cylinders containing compressed gas
which will expand to 7Cu.M (250 Cu.Ft) at atmospheric
pressure. Composition to suit parent material – usually
carbon dioxide (CO2) for mild steel, argon for non-
ferrous materials and argon with 1.5% oxygen or 5-20%
CO2 for high strength and corrosion resisting ferrous
alloys.Other mixtures are used in special circumstances.
28. TYPICAL APPLICATIONS
CO2 Welding ( MAG )- For structures
MIG Welding with Argon / Helium/ Mixed
Gases - for Low Alloy, Mild Steel, Aluminium alloy,
Copper and Copper allloys
Spray Transfer method - for heavy
wall thickness pipes, structures
Dip Transfer ( Short Circuit) - for Thin
sheet metal working. Vehicle
manufacturing.
29. OVERALL ADVANTAGES
Continuous process
Reduced finishing operations
Thin sheets can be welded in all positions by dip
transfer mode.
OVERALL LIMITATIONS
No independent control of filler addition.
Range of action limited by wire feed.
SAFETY
Arc emits visible and ultraviolet radiation.
30. GAS TUNGSTEN ARC WELDING
GTAW is defined as an arc welding process which
produces coalescence of metals by heating them
with an arc between a tungsten (non- consumable)
electrode and the work piece.
Gas Tungsten Arc Welding (GTAW) uses a non
consumable tungsten electrode which must be
shielded with an inert gas.
The arc is initiated between the tip of the electrode
and work to melt the metal being welded, as well
as the filler metal, when used.
A gas shield protects the electrode and molten
weld pool, and provides the required arc
characteristics.
35. OVERALL ADVANTAGES
Superior quality welds
Welds can be made with or without filler metal
Precise control of welding variables (heat)
Free of spatter
Slag free
Low distortion
OVERALL LIMITATIONS
Requires greater welder dexterity than MIG or stick
welding
Lower deposition rates
More costly for welding thick sections
36.
37.
38.
39. RECOMMENDED ELECTRODES / FILLER WIRES
COATED ELECTRODES FILLER WIRES
ASME AWS ASME AWS
CARBON STEEL SFA 5.1 E 7018 SFA 5.18 ER 70 S2
CARBON MOLY SFA 5.5 E 7018 A1 SFA 5.28 ER 80 SB2
11
/4 Cr - 1
/2 Mo P11 SFA 5.5 E 8018 B2 SFA 5.28 ER 80 SB2
21
/4 Cr - 1 Mo P22 SFA 5.5 E 9018 B3 SFA 5.28 ER 90 SB3
5 Cr - 1
/2 Mo P5 SFA 5.4 E 502 SFA 5.9 ER 502
9Cr - 1 Mo P9 SFA 5.4 E 505 SFA 5.9 ER 505
18 Cr 8 Ni SFA 5.4 E 308 SFA 5.9 ER 308
16 Cr 13 Ni Mo SFA 5.4 E 316 SFA 5.9 ER 316
18 C 10 Ni cb SFA 5.4 E 347 SFA 5.9 ER 347
18 Cr 10 Ni Tl SFA 5.4 E 347 SFA 5.9 ER 347
23 Cr 12 Ni SFA 5.4 E 309 SFA 5.9 ER 309
25 Cr 20 Ni SFA 5.4 E 310 SFA 5.9 ER 310
Miscelleneous SFA 5.11 E Ni Cr Fe2 SFA 5.14 ER Ni Cr3
BASE MATERIAL
40.
41.
42.
43. STANDARD REBAKING PROCEDURE
FOR LOW HYDROGEN ELECTRODES
1. Rebake the electrodes at 250-300 Deg. C for
one hour.
2. Cool them in the same oven to 100 Deg. C
3. Transfer them to a holding oven maintained at
60-70 Deg. C
4. Draw from this oven for use.
5. Do not keep the rutile type electrodes in the
same oven.
44.
45. WELDING PROCEDURE
SPECIFICATION (WPS)
• WPS shall be written as per ASME Section IX or IS 7307
• ( For Cross Country Pipelines: API 1104)
• WPS is a written qualified welding procedure prepared to
provide direction for making production welds to code
requirements.
• The WPS or other documents may be used to provide
direction to the welder or welding operator to assure
compliance with the code requirements.
• WPS shall describes all of essential, non-essential and
supplementary variables for each welding process.
46. PROCEDURE QUALIFICATION
RECORD (PQR)
• PQR shall be written as per ASME Section IX or IS 7307.
• PQR is a record of the welding data used to weld a test
coupon.
• The PQR is a record of variables recorded during the
welding of the test coupons.
• It is a record of what happened during a particular welding
test.
47. WELDERS PERFORMANCE
QUALIFICATION (WPQ)
• WPQ shall be written as per ASME Section IX or IS 7310.
• WPQ test shall be welded in accordance with qualified
WPS.
• Each manufacturer or contractor shall qualify each welder
or welding operator for each welding process to be used in
production welding.
48. Company Name Larsen & Toubro Limited - ECC Construction Group
Welding Procedure Specification no L&T/CPCL/ Rev. 0 Date 29.12.2K
Supporting PQR No.(s) Rev. - Date -
Welding Process(es) SMAW Type(s) Manual
JOINTS (QW-402)
Joint Design Double 'V' Groove
Backing Yes / No
Backing Material (Type) Nil
(Refer to both packing and retainers)
Metal Non Fusing Metal
Non mettalic Other
BASE METALS(QW-403)
P.No. 01 Group No 02 to P.No. 01 Group No. 02____
or
Specification Type & Grade ASTM SA 516 GR 70
to Specification Type & Grade ASTM SA 516 GR 70
or
Chem.Analysis and Mech. Prop. -
to Chem.Analysis and Mech. Prop. -
Thickness Range
Base Metal Groove 4.76 - 50 mm Fillet All
Pipe Dia Range Groove All Fillet All
Other -
FILLER METALS(QW-404)
Process
Spec. No (SFA)
Aws. No(Class)
F.No.
A.No
Size of Filler metals
Electrode Flux(class)
Flux Trade Name
Consumable Insert
Other
NA
NA
04
01
2.5, 3.15 & 4.0mm
NA
QW-482 WELDING PROCEDURE SPECIFICATIONS (WPS)
(See QW-200.1,Section IX ASME Boiler and Pressure Vessel Code)
5.1
E7018
SMAW
2.5+0.5mm
mm
1.5 .5mm
60º
t
49. WPS No. L&T/CPCL/ Rev. 0
POSITIONS (QW-405) POST WELD HEAT TREATMENT(QW-407)
Position(s) of Groove Any Temparature Range 595 to 650 Deg. C
Welding Progression : Up Yes Down X Heating & Cooling Rate 160 Deg. C / Hr
Positions of Fillet All GAS (QW-408)
Percent Composition
PREHEAT(QW-406) Gas(es) Mixture Flow Rate
Preheat Temp. Min 150 Deg. C for T > 19mm Shielding NA
Interpass temp.Max 250 Deg.C Trailing NA
Preheat Maintanence - Backing NA
(Contininous or special heating w here applicable should be recorded)
ELECTRICAL CHARECTRASTICS (QW-409)
Current AC or DC DC Polority SMAW - RP
Amps (Range) 60-180 Volts Range 18 - 24 V
(Amps and volts range should be recorded for each electrode size,position, and thick etc.
Tungsten electrode Size and Type NA
Mode of metal Transfer for GMAW NA
Eletrode Wire feed speed range NA
TECHNIQUE (QW-410)
String or Weave Bead Both
Orifice or Gas Cup Size NA
Intial and Interpass Cleaning (Brushing,Grinding etc.) Wire Brushing, Grinding
___________________________________________________________________________________________
Method of Back Gouging Grinding
Ocillation NA
Contact tube to Work distance --
Multiple or Single pass (per side) Multipass
Multiple or Single Electrodes Single
Travel Speed ( Range) See Table
Peening NA
Other NA
___________________________________________________________________________________________
Weld Layers Process
Amp
Range
Volt
Range
Travel
speed
Range
Others
Class Dia Type Polority mm/min
01 SMAW E7018 2.5 DC RP 60-90 18-20 60-120 --
02 SMAW E7018 2.5 DC RP 60-90 18-20 60-120 --
03 SMAW E7018 3.15 DC RP 90-130 18-22 60-120 --
04 SMAW E7018 4.0 DC RP 130-180 18-24 60-120 --
Prepared by Reviewed and Approved by Reviewed and Accepted by
for LTCG for LTCG for CLIENT / CONSULTANT
Filler Metals Current
QW-482 (Back)
(Pure Tungsten,2% Thoriated etc)
Spray arc,short circuiting etc.
50. Company Name Larsen & Toubro Limited - ECC Construction Division
Procedure Qualification Record No. L&T/CPCL/ 01 Rev. 0 Date 15.02.2001
WPS No. L&T/CPCL/ 01 Rev. 0 Date
Welding Process(es) SMAW Type(s) Manual
JOINTS (QW-402)
BASE METALS(QW-403) POSTWELD HEAT TREATMENT(QW-407)
Material Spec. : ASTM SA 516 Temperature : 620 Deg. C
Type or Grade : Gr. 70 Time : One Hour
P.No. 01 to P.No. 01 Other :
Thickness of Test Coupon : 25mm Rate of Heating : 160 Deg. C/ Hr
Diameter of Test Coupon : NA Rate of Cooling: 130 Deg. C/ Hr
Other : NA GAS (QW408)
Percent Composition
Gas(es) (Mixture) Flow Rate
Shielding NA
FILLER METALS(QW-404) Trailing NA
SFA Specification 5.1 Backing NA
Aws. Classification E7018 ELECTRICAL CHARECTRASTICS (QW-409)
Filler Metal F.No. 04 Current DC .
Weld metal Analysis A.No 01 Polarity SMAW - RP .
Size of Filler metals 2.5, 3.15 & 4.0mm Amps 130 Ave Volts 18-21 V .
Other : NA .Tungsten Electrode Size NA .
Other NA
Weld Metal Thickness
POSITION(QW-405) TECHNIQUE(QW-410)
Position of Groove : 6G . Travel Speed : 60 - 120 mm / Min
Weld Progression (Uphill, Downhill) Uphill . String or Weave Bead:Root - String,Fillup-Weave
Other NA .Oscillation _________2.5 D
Multipass or Single pass (per side) Multipass
PREHEAT (QW-406 ) Multiple or Single Electrode Single
Preheat Temp : 150 Deg. C Other NA
Inter pass temp : NA
Other NA .
(See QW-200.1,Section IX ASME Boiler and Pressure Vessel Code)
Groove design of Test Coupon
QW-482 PROCEDURE QUALIFICATION RECORDS (PQR)
Record of Actual conditions used to Weld Test Coupon
2.5+0.5mm
mm
1.5 .5mm
60º
25mm
51. PQR No. L&T/CPCL/01
Specimen Width Thickness Area Ultimate Type of
No. unit Stress Mpa failure & Loc.
T1 12.6 25.1 316 496.74 Fractured away
T2 12.6 25.1 316 496.16 from the welded
area
Specimen Notch Specimen Test Drop Weight
No. Location Size Temp Ft. LBS % Shear Mils Break (Y / N)
NA NA NA NA NA NA NA NA
Result - Satisfactory : yes No penetration into parent metal:yesmetal : yes ______No _________
Macro--Results NA
Other Results NA
Type of test NA
Deposit analysis NA
other NA
Welder's Name A.ARUL SELVAM Clock no _____________ Stamp no ______________
Tests conducted by : __________________________Laboratory test No ______________________________M/s sargam metals Laboratory Test No SM/MT/256A/2000-2001 dated 14.02.2001
We certify that the statements in this record are correct and that the test welds were prepared, welded,
and tested in accordance with the requirements of section IX of the ASME Code.
Manufacturer : Larsen & Toubro Limited - ECC Division, Chennai
Date : 15.02.2001 By : P Sampathkumar
for L&T-ECCD for M/s SGS India Limited
Fillet - Weld (QW-180)
3. Face Bend FB3 No Significant defect
2. Face Bend FB2
4. Face Bend FB4 No Significant defect
Impact Values
Toughness Tests (QW-170)
QW-483 (Back)
Tensile Test (QW -150)
Ultimate Total
Load KN
Guided - Bend Tests (QW -160)
1.570669702
1.568835768
Type and Figure No
No Significant defect
Result
No Significant defect1. Face Bend FB1
