Pipelines welding handbook_welding_techn

Pipelines Welding Handbook
• Welding techniques • Welding consumables
• Defects and remedies
MARCS-T-11K-202
Per saldature di qualità,
usate il telefono!
ESAB AB
Box 8004
SE-40277 Göteborg, Sweden
Phone: +46 31 509000 – Fax: +46 31 509390
E-mail: info@esab.se - web: www.esab.com
XA00105920

INTRODUCTION .............................................. 3
Joint details ............................................................. 4
Joint types ............................................................... 5
Electrode positioning angles ................................... 6
Pipe classification ................................................... 7
Consumption of electrodes ..................................... 11
ASME / EN positions .............................................. 13
THE MANUAL METAL ARC
PROCESS ........................................................... 15
General information .............................................. 16
Filler materials ........................................................ 17
Pipeweld cellulosic electrodes ................................ 17
Basic electrodes ...................................................... 19
Basic electrodes - Technical data ............................ 20
Cellulosic electrodes - Technical data..................... 22
WELDING TECHNIQUES
AND OPERATIVE PRACTICES ................. 25
Pipe welding in vertical down (downhill)
with cellulosic electrodes
1 - Preparation and tacking ..................................... 27
2 - Joint in 5G/PG position ...................................... 29
3 - Joint in 6G/H-L045 position ............................... 35
Welding of pipes in vertical up (uphill)
with mixed cellulosic/basic technique
1 - Preparation and tacking ..................................... 38
2 - Joint in 5G/PF position ...................................... 40
3 - Joint in 2G/PC position ...................................... 44
4 - Joint in 6G/H-L045 position .............................. 47
DEFECTS: CAUSES AND REMEDIES ...... 49
AUTOMATIC PIPE WELDING .................... 53
Filler materials ........................................................ 55
Welding techniques and operational practices ....... 57
Examples of WPS ................................................... 58
Comparison between three welding methods.......... 62
Defects and remedies ............................................. 63
List of contents
1

2
Presentation
Every day countless kilometres of steel pipelines are installed
worldwide for the most varied civil and industrial uses.
They form real networks comparable to a system of road networks,
which, although not so obvious, are definitely much more intricate and
carry fluids that have become essential for us.
To comply with technical specifications and fulfil the necessary safety
requisites, special materials and welding processes which have
evolved with the sector have been developed in recent years.
The main welding process used to install the pipelines is manual
welding with coated electrode, which, thanks to its ease and
versatility, is still the one most used.
However, to limit costs and increase welding productivity, particularly
on long routes, various constructors have adopted the semi-automatic
or completely automatic welding process with solid wire or wire
flux coated with gaseous protection.
This handbook describes both methods. Ample space has been
dedicated, in particular, to manual welding, with particular reference to
the operative practice and quality assessment, due to its considerable
use still today, but not neglecting more modern and productive
methods which will be increasingly used in future.
The presumption of this work is to be able to satisfy the most
demanding technician and welder, but, in particular, to supply each
user with useful information and a solid operative basis, as regards
the processes and filler materials and the welding equipment.

Butt Joint
1. Root gap: separation between the edges to be welded
at the root of the joint
2. Root face: surface of the joint preparation
perpendicular to the surface of the plate
3. Bevel surface: oblique surface of the joint preparation
4. Bevel angle: angle between the bevelled surface and
a plane perpendicular to the plate
5. Included angle: total angle between the two bevel
surfaces
6. Seam width: effective width of the joint (distance
between the bevels plus depth of penetration). The
width of the calking iron seam and groove iron are the
same thing
7. Thickness of the plate
Fillet Joint
1. Throat thickness: distance between seam root and
surface measured on the bisector of the angle
2. Leg lenght: distance between seam root and edge
3. Joint root: point in which the bottom of the seam
intersects the surface of the base metal
4. Joint edge: junction point between seam surface and
base metal surface
5. Joint surface: external surface of the seam
6. Fusion depth: depth reached by the fusion bath from
the surface of the base metal
7. Seam width: distance between the joint edges
Joint details
4

Many other variations are possible.
5
1. Butt joint
without bevel
2. Butt joint
with V bevel
3. Butt joint
with X bevel
4. Butt joint
with unilateral
bevel
5. Butt joint
with double
unilateral bevel
6. Butt joint
with U bevel
7. Butt joint
with double
U bevel
8. Butt joint
with J bevel
9. Butt joint
with double
J bevel
10. Fillet joint 11. Double fillet joint
Joint types

In this handbook the official AWS method is used to
define the positioning angles of the electrodes
(EN added).
Two angles are indicated: the feed angle and the work
angle.
The feed angle is called “TO BE PUSHED” when the
electrode points in the feed direction.
The feed angle is called “TO BE PULLED” when the
electrode points in opposite direction to the feed.
The work angle is given in relation to a reference plane
or work plane.
The figures illustrate the definition method of the angles.
Taking the clock face as reference, 1 minute corresponds
to 6°.
WORK PLANE
FEED
WELDING AXIS
FEED PLANE
ANGLE TO BE PULLED
ANGLE TO BE PUSHED
WORK PLANE
FEED PLANE
ANGLE TO BE PUSHED
ANGLE TO BE PULLED
FEED
WELDING AXIS
WORK PLANE
SYMMETRY AXIS
SYMMETRY AXIS
FEED PLANEFEED
ANGLE TO BE PUSHED ANGLE TO BE PULLED
Electrode positioning angles
6
Vertical
Horizonal

Pipe classification
Non-welded and welded pipes sized in accordance with ANSI B 36.10 and API standards
7

Prescriptions concerning the results of the traction and bending test for thicknesses ≤
25mm1
, and for the hydrostatic test
8
Designation of the steels Pipe body Welding seam Pipe
(unwelded and welded pipes)
HFW, SAW, SAW, COW
COW
Alphanumeric Numeric Unitary yielding Tensile Elongation3
Tensile Diameter of Hydrostatic
point strength (L0 = 5,65√S0 strength the spindle test
for bending
R10,5 Rm R10,5/Rm
2
A Rm test4
(see 8.2.3.5) (see 8.2.3.8)
MPa MPa % MPa
min. max. min. min.
L245NB 1.0457
from 245 to 440 415
0,80
22 3 T
L245MB 1.0418 0,85
L290NB 1.0484
from 290 to 440 415
0,80
21 3 T
L290MB 1.0429 0,85
L360NB 1.0582 0,85
L360QB 1.8948 from 360 to 510 415 0,88 20 4 T
L360MB 1.0578 0,85
L415NB 1.8972 0,85
L415QB 1.8947 from 415 to 565 420 0,88 18 5 T
L415MB 1.8973 0,85
L450QB 1.8952
from 450 to 570 535
0,90
18 6 T
L450MB 1.8975 0,87
L485QB 1.8955
from 485 to 605 570
0,90
18 6 T
L485MB 1.8977 0,90
L555QB 1.8957
from 555 to 675 625
0,90
18 6 T
L555MB 1.8978 0,90
1
The mechanical features of pipes with greater thickness values of up to 40mm must be agreed.
2
The values of the ratio between the unitary yield point and the tensile strength are applied for the “pipe” product.They cannot be requested for the
starting material.
3
These values are applied for transversal samples withdrawn from the body of the pipe. If longitudinal samples are tested, the elongation values
must be increased by 2 units.
4
T = prescribed pipe thickness.
The same va-
lues as the pipe
body are ap-
plied.
Each pipe must
take the test
without showing
losses or visible
deformations

Outside diameters and preferential thicknesses (indicated in the framed zone of the table,
including the frame itself)
Outside Thickness
diameter mm
mm 2,3 2,6 2,9 3,2 3,6 4 4,35 5 5,6 6,3 7,1 8 8,8 10 11 12,5 14,2 16 17,5 20 22,2 25 28 30 32 36 40
33,7
42,4
48,3
60,3
88,9
114,3
168,3
219,1
273
323,9
355,6
406,4
457
508
559
610
660
711
762
813
864
914
1 016
1 067
1 118
1 168
1 219
1 321
1 422
1 524
1 626
9

10
Mechanical features / Chemical compositions (A.P.I. steels)
A.P.I.
Mechanical prop. MPa Chemical composition %
Carbonium
specification Quality Yielding Tensile Carbon Manganese (max)
point strength (max) (max) equivalent

11
Consumption of electrodes
Pipeweld electrodes consumption (kg) in downhill vertical

12
Pipeweld electrodes consumption (kg) in uphill vertical
Note:forpipesoflessthan152mm(6”)diameter,withwallthicknessupto6.4mm,Pipeweld6010,diameter2.5mm,maybeusedforthefirstbead.
ApproximateweightofPipeweldelectrodes
Ø3.25approx.28grams

13
1G/1F (PA)
2G (PC)
3G/3F
1F (PA)
2F (PB) 3G/3F
4G
(PE) 5G
6G
PG - DOWNHILL
PF - UPHILL
PG - DOWNHILL
PF - UPHILL
PG - DOWNHILL
PF - UPHILL
(H-LO45)
ASME/EN positions

Pipelines welding handbook_welding_techn

16
General information
The main welding process used to weld pipelines is the
MMA method, manual welding with coated electrodes.
There are many reasons for this choice. The first is the
most obvious: the manual electrode is the first product
invented that is suitable for arc welding.
However, still today, when more sophisticated materials
and more productive and less expensive techniques are
at the users’ disposal, MMA welding remains a favoured
process to weld pipes. Its easy use, capacity to reach
positions of difficult accessibility, the simplicity of the
necessary generators (or the fact of being able to use
motor generators; network power is not always available
on installation sites), the fact that protective gases
(difficult to find in certain countries, in particular third
world countries), necessary in welding with solid or cored
wires, are not required, all these and others are the
reasons for this choice.
Some classes of cellulosic and basic electrodes have
been specially designed to meet the requirements of the
grade of steel used to manufacture the pipeline and the
safety specifications laid down by standards, but also to
equip the user i.e. welders with versatile products created
for this specific purpose.

Care and storage of cellulosic electrodes
Cellulosic electrodes need a definite amount of moisture,
normally between 3% and 9%, to give satisfactory
operation. Over drying this type of electrode will lead to
charring of the organic material within the coating. This
can give un-satisfactory welding performance, loss of arc
voltage and weld metal porosity. These types of
electrodes should NOT be re-dried.
Cans for transport and stockage in heavy
environments
The ESAB range of consumables for pipeline welding
has been developed to match the steel qualities and the
demands from the pipeline industry for reliable, easy to
17
OK PIPEWELD CELLULOSIC
ELECTRODES
OK Pipeweld electrodes have always been a safe and
productive solution in the welding of pipelines.
Features
• High Cellulose content in the electrode provides an
intense arc good penetration in all positions.
• High Cellulose content gives small slag covering of the
weld bead, although it is easily re-melted it is advisable
to remove before welding the next bead.
• The thin coating combined with the penetrating arc
enables a smaller root gap to be utilised and the
complete joint requires less weld metal to be
deposited.
• The rapid solidification of the weld metal allows truly all
positional welding
Recommended current ranges for the different
welding positions.
Welding equipment
The welding generators that can be used with OK
Pipeweld need to have a relatively high open circuit
voltage (OCV > 65V) and good dynamic characteristics.
This prevents the arc snapping out during the welding
operation.
Filler materials

use highly productive consumables. Our resources in
research and development around the world have made
it possible not only to meet the demands of today but
also to foresee the needs for tomorrow. Cellulosic
electrodes from ESAB are used for root pass, filling and
capping on a wide range of steels used in the pipeline
industry and pipework production.
ESAB Electrode Choice for each Bead Position
18
Pipe steel Root or
Hot pass Hot fill
Filler
Capping
and grade stringer passes
5L, A25 • • • • •
5L, 5LS, A • • • • •
5L, 5LS, B • • • • •
5LS, 5LX42 • • • • •
5LS, 5LX46 • • • • •
5LS, 5LX52 • ◊ • ◊ ◊ ◊ ◊
5LX56 • ◊ • ◊ ◊ ◊ ◊
5LX60 • ❋ • ❋ ❋ ❋ ❋
5LX65 • ❋ • ❋ ❋ ❋ ❋
5LX70 • ❋ • ❋ ❋ ❋ ❋
• = Pipeweld 6010 Plus
◊ = Pipeweld 7010
❋ = Pipeweld 8010
DOWNHILL VERTICAL
POSITION
UPHILL VERTICAL
POSITION
FINAL BEAD
ROOT PASS FILLING BEAD
1,2 ÷ 1,6 2,5 ÷ 3,2

19
BASIC ELECTRODES
When the pipeline steel has a strength higher than X70
the need of preheat and post weld heat treatment
becomes more stringent and the choice of using basic
electrodes offers advantages. The reason is, of course
the high amount of hydrogen in the weld metal from
cellulosic electrodes. The hydrogen is a greater risk for
cracks in high strength material, because of the
increased sensitivity to hardening in these steels.
The properties of the basic electrodes also mean much
better impact properties at low temperatures.
The disadvantage with basic electrodes welded vertically
up is the low current that has to be used resulting in low
productivity.
This can be avoided by using basic electrodes developed
specially for welding of pipelines in the vertical-down
position. These electrodes contain iron powder in the
coating and therefore have higher productivity than
cellulose electrodes since they also can be welded at
higher currents than cellulose electrodes.
Productivity is 25-30% higher than for cellulose
electrodes and 40-50% higher than for basic electrodes
in vertically up welding.
In the root, the penetration and force from a cellulose
electrode is however the most productive process since
they can manage a small root-opening with high current
resulting in fast progression. A basic electrode can be
used also for the root but requirements on alignment will
be higher because of the less forceful arc.
The best procedure for welding high strength pipelines is
therefore to use cellulose electrodes for the root pass and
basic vertical down electrodes for filling and capping passes.
The higher quality of the basic weld metal is
advantageous when a pipeline is exposed to stress.
When, during its route, an underground pipe (medium
and large diameters) crosses roads and railways, when
greater static and dynamic stress exists for external
reasons or when the pipes of medium and small
diameter are submitted to high temperatures, strong
pressure and vibration (heating plants, refineries etc.), it
is normally preferred to carry out the first bead with
Pipeweld and the filling with a basic electrode.
With this, the complete penetration that only Pipeweld
can guarantee and the maximum tenacity of the joint due
to the electrode with basic coating are obtained.
Some mechanical characteristics, in particular the values
of toughness and strength, were improved.
OK 48.00 is classified E 7018-1; this means that it
supplies resiliency values of over 27j at –46°C, thanks to
the purity of its components, in an even better developed
formula.
It can be used to weld steels with high values of
equivalent carbon and/or high elastic limit thanks to the
laying which guarantees values of diffusible hydrogen of
≤ 5 ml/100 gr. and consequently makes the risk of cold
cracks practically non-existent, also permitting a
reduction of the pre-heating temperature required for the
basic electrodes. In addition to these metallurgical and
productive aspects that are important for the constructor,
there is improved welding capacity. The excellent starting
and restarting, the constant and regular fusion and the
fine aspect of the weld seam in all positions are
characteristics of fundamental importance for the welder
and guarantee a high productivity.
The VacPac boxing (plastic inner box with Vac Packed
aluminium foil hermetically sealed) ensures these
characteristics, over a long time and allows the product
to be used without redrying.
A.P.I. Quality Suggested Electrode
Specification First root Filling
5L A 25 Pipeweld 6010 OK 48.00
5L – 5LS A Pipeweld 6010 OK 48.00
5L – 5LS B Pipeweld 6010 OK 48.00
5LX X42 Pipeweld 6010 OK 48.00

20
Basic electrodes for steels with medium
and high yield strength
Electrode type OK 48.00 OK 53.70 OK 74.70
Coating Basic Basic Basic
Classifications
Recovery 115 115 115
Mechanical properties
All weld metal
analysis wt %
Applications
Welding Current DC+ AC, DC+(–) DC+
Welding parameters Ø Amp
2.5 60 ÷ 90
3.2 90 ÷ 130
4 140 ÷ 180
5 190 ÷ 220
Ø Amp
2.5 60 ÷ 90
3.2 80 ÷ 130
4 115 ÷ 190
5 180 ÷ 290
Ø Amp
2 50 ÷ 80
2.5 70 ÷ 100
3.2 90 ÷ 140
4 120 ÷ 180
5 180 ÷ 230
Electrode used for welding
high tensile low alloyed
steels API 5L X60, X65, X70
A low hydrogen AC/DC
electrode for one side
welding of pipes and gen-
eral structure. The root
penetration is good, leav-
ing a flat bead with easy
removable slag. Suitable
for welding of pipeline up to
API 5L X56 it is aiso suit-
able for root pass welding
up to API 5L X80
Electrode suitable for weld-
ing in all positions of carbon
steels with medium and
high yeld strength. The low
hydrogen content in the
deposited metal minimises
the risk of cracks. Excellent
radiographic qualities. For
naval constructions, struc-
tural fabrication, boilers, etc.
Excellent welding aspect
also in a vertical position.
R ≥ 510 MPa
S ≥ 420 MPa
A ≥ 26%
KV ≥ 48J at – 40° C
KV ≥ 27J at – 46° C
C ≤ 0.06 ÷ 0.1
Mn ≤ 1.3 ÷ 1.6
Si ≤ 0.25 ÷ 0.50
Mo 0.3 ÷ 0.5
R ≥ 550 MPa
S ≥ 430 MPa
A ≥ 26%
KV ≥ 150J at – 20° C
KV ≥ 100J at – 46° C
C ≤ 0.04 ÷ 0.08
Mn ≤ 0.95 ÷ 1.35
Si ≤ 0.3 ÷ 0.6
Ni < 0.1
R ≥ 510 MPa
S ≥ 420 MPa
A ≥ 26%
KV ≥ 48J at – 40° C
KV ≥ 27J at – 46° C
C ≤ 0,10
Mn ≤ 1,60
Si ≤ 0,60
AWS A/SFA 5.5:
E8018-G
EN 499:
E46 Mu Mo B 32
AWS A/SFA 5.1:
E7016-1
EN 499:
E42 5 B 12 H5
ISO 2560:
E51 5 B 24 H
AWS A/SFA 5.1:
E7018
EN 499:
E42/46 4 B 42 H5
ISO 2560:
E51 5 B 120 20 H

21
Basic electrodes for vertical-down
welding
Electrode type Filarc 27P Filarc 37P Filarc 108MP
Coating Basic Basic Basic
Classifications
Recovery 120 120 120
All weld metal
analysis wt %
Applications
Welding Current DC+ DC+ DC+
3.2 110 ÷ 150
4 180 ÷ 220
4,5 230 ÷ 270
Ø Amp
3.2 110 ÷ 150
4 180 ÷ 220
4,5 230 ÷ 270
Ø Amp
2.5 80 ÷ 100
3.2 110 ÷ 150
4 180 ÷ 220
4,5 230 ÷ 270
Suitable for welding high
strength pipe steels such
as API 5LX80.
Performance and produc-
tivity is similar to Filarc
27P.
Suitable for welding high
strength pipe steels such
as API 5LX75.
Performance and produc-
tivity is similar to Filarc
27P.
Filarc 27P is specially desi-
gned for downhill welding of
circumferential welds joints
in pipes. Suitable for pipe
steels API 5LX52 – X70
TS > 690 MPa
YS > 620 MPa
A5 ≥ 22%
C: 0,06-0,09
Si: 0,30-0,70
Mn: 1,6-2,0
Ni: 1,30-1,60
TS > 620 MPa
YS > 550 MPa
A5 ≥ 24%
C: 0,06-0,09
Si: 0,30-0,70
Mn: 1,0-1,4
Ni: 0,6-0,99 1,0
Mo: 0,3-0,6
TS > 550 MPa
YS > 460 MPa
A5 ≥ 25%
C: 0,06-0,09
Si: 0,30-0,70
Mn: 1,0-1,4
AWS A/SFA 5.5:
E10018-G
EN 757:
E55 4 Z B 41 H5
AWS A/SFA 5.5:
E9018-G
EN 499:
E55 5 1NiMo B 41 H5
AWS A/SFA 5.5:
E8018-G
EN 499:
E46 5 B 41 H5

22
Cellulosic electrodes for pipes
Electrode type Pipeweld 6010 PLUS Pipeweld 7010
Coating Cellulosic Cellulosic
Classifications
Recovery 90 90
All weld metal analysis wt %
Applications
Welding Current DC+(-) DC+
3.2 60 ÷ 110
4 90 ÷ 140
5 110 ÷ 170
Ø Amp
2.5 60 ÷ 80
3.2 80 ÷ 140
4 100 ÷ 180
5 150 ÷ 250
Electrode suitable for welding in all
positions of pipes in steel type API
5LX – X63 – X65 – X70. Easy to
use, smooth running and penetrat-
ing. Particularly suitable for welding
on site, in downhill and overhead.
Excellent radiographic qualities.
Electrode suitable for welding of root
pass on every API 5L grade pipe,
designed for vertical down DC –
(main line welding)
R ≥ 560 MPa
S ≥ 480 MPa
A ≥ 20%
KV ≥ 27J at – 30° C
C р 0,12
Mn 0,30 ÷ 0,60
Si р 0,30
Ni 0,50 ÷ 0,80
Mo 0,10 ÷ 0,25
R ≥ 420 MPa
S ≥ 350 MPa
A ≥ 22%
C р 0,13
Mn р 0,4
Si р 0,25
AWS A/SFA 5.5:
E7010-G (P1)
EN 499:
E42/3 Z C 21
ISO 2560:
E51 4 C 10
AWS/SFA 5.1:
E6010
EN 499:
E 38/3 C 21

23
Pipeweld 8010 Pipeweld 9010
Cellulosic Cellulosic
90 90
DC+(-) DC+
Ø Amp
3.2 60 ÷ 110
4 90 ÷ 140
5 110 ÷ 170
Ø Amp
3.2 60 ÷ 110
4 90 ÷ 140
5 110 ÷ 170
5LX – X65 – X70 – X75 – X80.
Easy to use, smooth running and
penetrating. Particularly suitable for
welding on site, in descending ver-
tical and overhead. Excellent radi-
ographic qualities.
5LX – X63 – X65 – X70. Easy to
use, smooth running and penetrat-
ing. Particularly suitable for welding
on site, in downhill and overhead.
Excellent radiographic qualities.
R ≥ 630 MPa
S ≥ 540 MPa
A ≥ 18%
KV ≥ 27J at – 30° C
C р 0,12
Mn р 1,0
Si р 0,30
Ni 0,60 ÷ 0,80
Mo 0,20 ÷ 0,30
R ≥ 560 MPa
S ≥ 480 MPa
A ≥ 20%
KV ≥ 27J at – 30° C
C р 0,12
Mn 0,30 ÷ 0,60
Si р 0,30
Ni 0,50 ÷ 0,80
Mo 0,10 ÷ 0,25
AWS A/SFA A5.5:
E9010-G
EN 499:
E50 3 Z C 21
AWS A/SFA 5.5:
E8010-G (P1)
EN 499:
E46/3 Z C 21

WELDING TECHNIQUES AND
OPERATIVE PRACTICES

26
Cellulosic electrodes, suitable for use in vertical up and
vertical down directions, are normally chosen to weld
steel pipes. The fastest and therefore most productive
method is welding downhill with cellulosic electrodes.
However, when it is necessary to guarantee particularly
high integrity for pipes submitted to high static or
dynamic stress (for example, underground pipes of
medium or large diameter in the crossing of roads or
railways, or small or medium pipes subject to vibrations,
temperature, pressure), the technique of mixed welding,
cellulosic plus basic in vertical up, is sometimes
preferred. The following chapters illustrate the most
frequent operating practices used in manual pipe welding
and the different techniques adopted, starting from
preparation and closing with a thorough examination of
the potential defects, their causes and the necessary
remedies.
General information

27
Preparation and tacking
The scope of this chapter is to suggest a preparation and
tacking procedure for the construction of a standard joint
on sections of mild steel pipe, for the purposes of
developing welding procedures or welder training. Note
that for welding procedure qualification, EN 288-9
requires that tests be made between full pipe lengths
unless otherwise agreed between the contracting parties.
Eliminate burrs caused by the grinding operation.
Welding parameters for tacking
Electrode E6010 Ø 2.5 mm, Current 70 ÷ 100A
or
Electrode E6010 Ø 3.2 mm, Current 100 ÷ 120A
Operations
Rest one of the pipe sections on the worktop with the
bevelled edge facing upwards.
SPACING WIRE
INCLUDED ANGLE
ROOT GAP
BEVEL ANGLE
ROOT FACE
STANDARD JOINT
1,2 Ϭ1,6 mm
Place a spacing wire of 1.6 mm diameter on the bevelled
edge then rest the second pipe section on the spacing
wire with the bevelled edge facing downwards. Align the
two sections to form the desired bevelling.
In accordance with the API code the misalignment must
not exceed 1.6 mm.
At this point start the tacking operation, laying a 12 to
22mm long seam.
The tack bead should penetrate the root in order to form
an internal projection of 1.6 mm and both edges of the
bevel must be fused.
READ TACK
PENETRATION
1.6 mm
EXCESS WELD METAL AT THE ROOT
CORRECT ALIGNMENT MAXIMUM MISALIGNMENT
Pipe welding in vertical down (downhill)
with cellulosic electrodes

28
Then reposition the spacing wire and deposit a
second tack.
Remove the spacing wire. If in root gap is uneven, make
a third tack where the gap is greatest, in such a way that
weld shrinkage will close it up. If the distance between
the edges on the most open side is too great to permit
the third tack, first correct the distances compressing the
most open side.
Place the third and fourth tacks at right angles to the first
and second.
GAP TOO
NARROW
GAP TOO WIDE
ONE OF THE
TACKS
SECOND TACK
FIRST TACK
Grind the external surface of the tacks in such a way that
their thickness is approximately 1.6 mm, to facilitate the
start of the first bead.
To obtain a quality weld, correct joint preparation and
accurate tacking are necessary. Faulty tacking will cause
defects in the final welding.
PART TO BE REMOVED
APPROXIMATELY 1.6 mm
ROUND THE CONNECTING
EDGES BETWEEN THE TACK
AND THE ROOT FACE
OF THE BEVEL
CONNECT THE ENDS
OF THE TACK

29
2 - Joint in 5G / PG
This type of joint and position is commonly used to weld
a line of steel tubes of medium-large diameters, of 8” and
more.
Welding parameters
Electrode E6010 Ø 4.0 mm, DC+, Current 120 ÷ 160A
(root)
Electrode E7010-G-(P1)* Ø 4.0 mm, DC+, Current
150 ÷ 1 60A (hot pass)
Electrode E7010~G~(P1)* Ø 5.0 mm, DC+, Current
150 ÷ 160A (fill and cap)
* or alternatively, according to the type of base steel to
be welded, substitute with electrode E8010-G-(P1) or
E9010-G.
It is important that the generator has a minimum open
circuit voltage of 70V.
Operations
After having carried out the preparation and tacking as
described in chapter 1, use pliers and clamps to fix the
piece in a horizontal position with the tacks placed at 3,
6, 9 and 12 o’clock. It is recommended to place the tack
with the smallest root gap at 12 o’clock.
Make the root (stringer) bead with a 4.0 mm diameter
electrode. The current must be set at 120 ÷ 160A.
Start with the electrode at 12 o’clock, with a trailing
electrode angle of 10 ÷ 15° and the electrode in the
plane of the joint.
FEED
VERTICAL AXIS
10° - 15°
PLIERS
TACKS
POSITIONS
OF TACKS
Start the arc at the root of the joint (never on the edge of
the tack towards the external surtace of the pipe), push
the electrode into the joint and advance in a regular
manner.
To better check the weld pool, it may be necessary to
vary the trail angle from 10 ÷ 15° to 0 ÷ 30°. Use the
dragging or “hidden arc” technique, always keeping the
electrode at the bottom of the joint. A “keyhole” groove,
which follows the top of the electrode in its movement, is
thus formed.
SEAM
MELTED METAL WHICH FLOWS UPWARDS
“KEYHOLE” GROOVE
ELECTRODE TIP
PUSH THE ELECTRODE
INTO THE JOINT
VERTICAL AXIS

30
If blowholes form, slightly swing the electrode from one
side to the other as shown in the figure.
If it is necessary to interrupt the arc before the run is
ended, the tip of the electrode must be rapidly snapped
down.
This prevents slag inclusion in the weld pool. Remove
the slag from the crater and from the last 50 mm of the
weld. The restart should be made starting on the weld
metal approximately 12 mm before the crater and
moving towards it with an arc length slightly above
normal. Then push the electrode to the bottom of the
joint to fill the crater and continue welding in the normal
manner.
RESTARTING PROCEDURE
START HERE
SEAM
ELECTRODE
ELECTRODE
The finished bead must form a 1.6 mm thick weld
reinforcement at the root.
When the first half of the bottom bead is completed,
remove the slag then repeat the process on the second
half of the joint.
LEVELED TO 1.6mm
ROOT PENETRATION
UNDERCUTS

31
For the hot pass use E7010-G(P1), E8010-G(P1) or
E9010-G electrodes, depending on the class of the steel
to be welded, in 4.0 mm diameter
Start with the electrode at 12 o’clock, maintaining the
same angles indicated for the bottom bead, towards 6
o’clock. Use a light up and down movement to check the
weld pool. Move the tip in the forward direction for a
length equal to the diameter of the electrode to allow the
pool to solidify slightly then move the tip back for a length
equal to half of the diameter. At this point wait until the
crater is full before moving onwards.
Maintain an arc length equal to the electrode diameter.
Do not increase the arc length during movement. If the
arc is interrupted before the bead is complete, remove
the slag from the crater, restart the arc starting on the
bottom bead, approximately 12 mm in front of the second
bead and move back up to the crater.
START HERE
12 mm
CRATER
DWELL POINTS
DOWN FOR
1 ELECTRODE
DIAMETER
UP FOR 1
/2
ELECTRODE DIAMETER
ELECTRODE
ARC LENGTH EQUAL
TO ELECTRODE
DIAMETER
WELDING
DIRECTION
Make sure that you have filled the crater then restart
welding as indicated previously. Carry out the second half
of the run with the same procedure.
It should be noted that the “pulling” technique with which
the root bead is laid causes an incomplete fusion and
slag inclusion (“tramlines”) at the seam edges.
Due to the higher current used, the second or “hot” pass
does not transfer much metal to the joint, but its greater
heat frees the slag and completes the fusion between
the weld edges and the base metal.

32
To carry out the filling pass (third pass), the starting
position and trailing angles of the electrode are the same
as indicated for the root and hot passes, but electrodes
of 5.0 mm diameter with current set at 150-1 80A must
be used. Use a swinging movement, maintaining an arc
length equal to the electrode diameter. Pause with the tip
of the electrode on the edge of the previous bead. Move
towards the opposite edge with descending by half the
electrode diameter.
If it is necessary to restart the arc use the same
procedure as indicated for the second pass. After having
welded the second half of the joint, completely remove
the slag.
PENULTIMATE
BEAD
0.8 mm
To fill the joint up to 0.8 mm from the external pipe
surface it may be necessary to deposit additional
passes on the whole circumference.
These beads should generally add a 1.6 mm thick layer.
Use the same techniques indicated for the previous
passes. Often, after having made all these layers, the
joint is thicker in the upper and lower zone than in the
side zones of the pipe, making it necessary to fill it
evenly before making the cap. In this case stripper
beads are laid with the same techniques illustrated
previously.
12:00
ZONES WHICH
MAY NEED
LEVELLING BEADS

33
The technique used for the cap pass is the same as
indicated for the penultimate bead, but the swinging
movement must be wider. Dwell with the tip of the
electrode on the edges of the previous bead.
Use a Z or half-moon oscillation with adequate arc
length, travel speed and electrode slope.
HALF-MOON
OSCILLATION
Z - OSCILLATION
STOP HERE
ELECTRODE
LAST BEAD
Advance at a speed that makes it possible to obtain a
0.8 to 1.6 mm thick reinforcement and an overlap of
approximately 1.6mm at the edges.
1.6 mm
WELD METAL
1.6 mm
OVERLAP
1.6 mm
ROOT WELD METAL

34
API standards provide visual analysis and relevant
quality assessment of the weld sample. After having
carried out the preparation and tacking, the piece is
marked for identification then welded in the 5G position
as previously indicated. A visual analysis of the weld is
then carried out.
Acceptability criteria are as follows:
• Cracks: the weld must not present cracks.
• Penetration: the joint root must show complete
penetration.
• Fusion: fusion between the base metal and filler metal
must appear complete.
• Slag inclusion: the hollow in the melted zone containing
slag must not exceed 3.2 mm for each 152 mm of weld.
• Gaseous inclusion: a section affected by porosity
cannot be longer than 1.6mm and their total must not
exceed the length of 3.2mm each 6.5 cm2 of weld
surface.
• Undercuts: they must not exceed a width of 0.8mm, a
depth of 0.8 mm and their total length must not exceed
50.8mm in each 152mm of weld or 5% of the wall
thickness, if the weld is shorter.
• Weld metal: the surface and root reinforcements must
not exceed the indicated dimensions, must be evenly
connected with the surfaces of the base metal and their
edges must be free from undercuts.

35
3 - Joint in 6G / H-L045
Use: welding all mild steel pipes of 8” (203 mm) diameter
and wall thickness of 8.2mm.
Welding parameters
Electrode E6010 Ø 2.5mm, Current 70 ÷ 100A
Electrode E6010 Ø 3.25mm, Current 100 ÷ 120A
The generator must have an open circuit voltage of 70V
Operations
After having carried out the preparation and tacking
operation as described in chapter 1, fix the piece using
pliers and/or clamps with its axis at 45° to the horizontal
plane and with tacks placed at 3, 6, 9 and 12 o’clock.
Place the tack where there is the smallest root gap at
12 o’clock.
6G POSITION
Carry out the root bead with the same technique used in
chapter 2, page 29.
Keep the electrode parallel to the plane of the joint and
use a trailing angle of 10÷15°. It the electrode coating
melts in an irregular manner, slightly move the tip from
one edge to the other. Weld both halves of the joint with
the same technique. The bottom bead should penetrate
inside the pipe not more than 1.6 mm.
FEED
SIDE VIEW
DIRECTION
10° - 15°

36
For the hot pass use E6010 electrodes of 3.25 mm
diameter. Start the arc at 12 o’clock with the same
electrode angles used for the bottom bead.
Use a similar movement to that described for the second
bead in chapter 2, page 29.
For the filling passes start from 12 o’clock with a work
angle of 80-90° to the pipe axis supported at the sides at
the top of the seam.
FEED
DWELL
POINTS
DIRECTION
90°
10°-15°
25°-30°
Advance from 12 o’clock to 6 o’clock using an elongated
oscillating movement, then, if necessary, execute leveling
beads.
Execute the capping pass using the same electrode
angles and technique as the filling technique. The
external bead should create a 1.6 mm thick
reinforcement and penetrate the beveled edge up to 1.6
mm. Weld both halves of the joint then remove the slag.
SURFACE WELD
METAL1.6mm
SEQUENCE OF THE BEADS
EDGE FUSION
1.6mm

37
To pass the qualification test in a welding process in
the 6G position — which covers all the others– some
mechanical tests must be performed on a sample. For
this purpose prepare and tack a piece as described in
chapter 1.
Carry out the welding as described in this chapter. Take
care to remove the largest irregularities using a grinder with
flexible disk and fine grain before laying the second bead.
Make a visual check as indicated in chapter 2, page 29.
From the welded piece will be obtained six sections
which must be previously marked for identification by the
operator. Proceed with pipe cutting to obtain six strips of
a width of 25mm, as illustrated below.
REVERSE BEND
NICK BREAK
NICK BREAK
FACE BEND
ROUND THE CONNECTING
EDGES BETWEEN
THE TACK AND THE SHOULDERS
OF THE BEVEL
SHARPEN THE ENDS
OF THE TACK
The coupons for the bend tests must be ground on
both surfaces of the weld up to the thickness of the pipe
wall, but without notching the base metal.
Using a jig, bend the strips over a mandrel 3 times the
pipe thickness, one with the root on the outside and
one the opposite way.
The acceptability standard is satisfied if no cracks or
other defects of over 3.2 mm or half the wall thickness, if
this is lower, appear after bending in the weld seam or
fusion zone in each direction. No cracks starting from the
edge of the samples, if smaller than 6.4 mm measured in
each direction, should be taken into consideration, unless
accompanied by other defects.
To carry out the nick break tests, a notch is made in the
centre of the weld with the 3.2 mm deep saw cut on all
sides of the sample. The internal and external
reinforcement must not be removed.
The samples may be broken under tension with a
special machine, or by striking their centre with a
hammer after having supported their ends, or striking
one end of them after having fixed the other. The
acceptability standard is satisfied when the exposed
surfaces of each sample show complete penetration
and fusion. The maximum size of porosity must not
exceed 1.6mm and the total porosity areas must not
exceed 2% of the examined surfaces. Slag inclusion
must not exceed 0.8mm in depth, 3.2mm in length, or
half the wall surface if this is smaller. Furthermore,
there must be at least 12mm of sound metal between
one inclusion and the other.
THE EDGES MUST BE
REGULAR AND PARALLEL
DO NOT REMOVE THE WELD METAL
19,1 mm
APPROXIMATELY
3.2mm

38
1 - Preparation and tacking
The scope of this chapter is to provide correct
preparation and tacking procedure for a standard joint on
pipe sections with 8” diameter (203 mm). The joint is
prepared by making a bevel as indicated in the figures.
Remove burrs caused by the grinding operation.
Welding parameters for tacking
Electrode E6010 Ø 3.2mm, DC+, Current 85 ÷ 110A
If the power source has no ammeter, the current may be
empirically set by proceeding as follows: place a 6mm
thick strip of mild steel in horizontal position, start the arc
and lay down a straight seam, which must be even, with
a regular ripple and 1.6 mm thick. If the seam is uneven
and strongly convex, the current must be increased. If it
is flat and there is excessive spatter, the current must be
reduced.
INCLUDED ANGLE
ROOT GAP
BEVEL
ANGLE
ROOT FACE
STANDARD JOINT DIMENSIONS
CHARACTERISTICS OF THE BEVEL
75°
37 1/2°
2,0 - 2,5 mm2,4 - 3,2 mm
Operations
Rest one of the pipe sections on the worktop with the
bevelled edge facing downwards.
Place a spacing wire of 3.2mm diameter on the
bevelled edge then rest the second pipe section on the
spacing wire with the bevelled edge facing downwards.
Align the two sections to form the desired joint
preparation. In accordance with the ASME code,
misalignment must not exceed 1.6mm.
CORRECT ALIGNMENT MAXIMUM MISALIGNMENT
SPACING WIRE
Welding of pipes in vertical up (uphill) with mixed
cellulosic/basic technique
Low
current
High
current OK

39
At this point the tacking operation starts, laying a 12 to
20mm long bead.
The tack must penetrate the root so as to form a bead
1.6mm high inside the pipe and both sides of the
preparation must be fused. Then reposition the spacing
wire and deposit a second tack.
FIRST
TACK SEAM
SECOND
TACK SEAM
TACK
PENETRATION
WELD METAL AT THE ROOT
1.6mm
Remove the spacing wire. If in one of the spans the root
gap is greater than on the opposite side, place a third
tack where the gap is widest, so that weld shrinkage will
even the difference. If the gap at its widest point is too
great to permit a third tack, first correct the gap by
compressing the most open side. Make the third and
fourth tacks at right angles to the first and second.
To obtain a quality weld, correct joint preparation and
accurate tacking are necessary. Faulty tacking will
cause defects in the final welding.
TOO TIGHT
TOO
OPEN SPACE
ONE OF THE
FIRST TACKS

40
2 - Joint in 5G / PF
This type of joint and position is used to weld moulded
bends, flanges, forged pieces, concentrated works, in all
diameters. The following example regards the welding of
pipes with 8” (203 mm) diameter.
Welding parameters (*)
Electrode E6010 Ø 3.2mm, DC+, Current 85 110A root
Electrode E7018 Ø 2.5 / 3.25mm, DC+, Current 85 ÷
110A filling
cap
The power source must have an OCV of at least 70 V
(*) For process with mixed cellulosic/basic technique
Operations
After having carried out the preparation and tacking as
described in chapter 1, use pliers and clamps to fix the
piece in a horizontal position with the tacking placed at 2,
5 ,8 and 11 o’clock. The tack with the smallest root gap
should be at 6 o’clock.
To carry out the root bead start with the electrode at
6:30, at right angles to both the pipe axis and the pipe
surface. Start the arc at the root of the joint (never on the
edge of the tack or the external pipe surface). Maintain
an arc length double the electrode diameter and swing
from one edge to the other, to and fro, to pre-heat the
edges of the shoulders.
90°
PLIERS
TACK
POSITIONS
OF THE TACK
After two or three movements reduce the arc length to
one electrode diameter and form the “keyhole” crater,
then keep the arc on the edge of the shoulders and
advance. Use a light up and down swinging movement.
To maintain a crater of the correct dimensions the
movements must be rapid and precise.
1 ELECTRODE DIAMETER
1/2 ELECTRODE DIAMETER
SHOULDER EDGE
5mm “KEYHOLE”
CRATER
ELECTRODE
ELECTRODE
ANGLE
POSITION AT 6.30

41
When approaching a tack, reduce travel speed and
slightly increase arc length. If the crater tends to close,
use a trailing angle (pulling) of 5 ÷ 10° and/or reduce
feed speed. If instead it tends to widen, use a leading
angle (pushing) of 5 ÷ 10° and/or increase feed speed.
If necessary interrupt the arc before the seam is finished,
form a “keyhole” crater of approximately 5 mm diameter
by rapidly pushing the electrode point through the joint
for approximately 13 mm, then completely withdraw the
electrode. In this way complete penetration is assured at
restart.
ELECTRODE
CRATER WIDENING
5-10° TO BE PULLED
5-10° TO BE PUSHED
4:00
Remove the slag from the crater and from the last 25
mm of seam. Restart should be carried out starting on
the weld approximately 20 mm before the crater and
moving towards it with a slightly higher than normal arc
length. Move back and forth on the crater to preheat the
edges then reset the normal arc length.
When the first half of the bottom bead has ended,
remove the slag then repeat the operation on the second
half of the joint.
The finished bead should have a slightly convex surface
and be up to 1.6mm high.
At this point, the filling and capping passes may be
executed either continuing with cellulosic electrodes or
using the mixed cellulosic/basic technique.
WELD METAL AT ROOT
SLIGHTLY CONVEX
START HERE
RESTARTING PROCEDURE
25mm
SLAG REMOVED
APPROXIMATELY
5mm DIAMETER
“KEYHOLE” CRATER

42
Filling and capping beads with basic electrodes
If after the first bead you wish to use electrodes with a
basic coating, proceed as follows:
For the second bead use E7018 electrodes with 2.5 /
3.5mm Ø. Start the arc at 6:30 and stabilise it at 6
o’clock keeping a rather small arc length at angles as
shown in the following figure.
DWELL POINTS
Z OSCILLATION
ELECTRODE ANGLES
STARTING POINT
5-10° TRAILING
5-10° LEADING
5-10° TRAILING
Use a Z oscillating movement, pausing with the electrode
at the joint edges. The travel speed and dwell time
determine the result. Too slow a speed or an excessive
dwell cause the pool to be too wide and difficult to
control, while too fast a speed and a short dwell create
lack of fusion on the previous seam, with a very convex
seam and undercut.
A correct joint filling reaches approximately 1.6mm from
the pipe surface. If the penultimate bead does not reach
this level, carry out another with E7018 Ø 2.5 (or 3.2)
mm using the same procedure. If the arc is interrupted
before the bead is complete, remove the crater slag,
restart the arc starting on the last bead approximately
12mm in front of the crater then turn back until the crater
is full and resume normal travel. Finally, remove the slag
from the weld ends and carry out the second half of the
joint.
TOO SLOW FEED OR
TOO LONG
DWELLS
ELIMINATING UNDERCUTS

43
For the cap bead use E7018 electrodes in Ø 3.2mm,
using the same technique as the filling beads but with a
wider swinging movement, pausing on the joint edges.
The overlap on the joint edges must measure
approximately 1.6mm and the thickness of the weld
metal from 0.8 to 1.6mm.
OVERLAP
OVERLAP
ASME (*) standards provide a visual analysis and
relevant quality assessment of the weld on a sample,
After having carried out preparation and tacking, the
piece is marked for identification then welded in the 5G
position as previously indicated. A visual examination of
the weld is then carried out.
The acceptability criteria are as follows:
• Penetration: the joint root must show complete
penetration.
must appear complete.
• Slag inclusion: the cavities in the melted zone
containing slag must not exceed 3.2 mm for each 152
mm of weld.
cannot be longer than 1.6 mm and their total must not
exceed the length of 3.2mm each 6.5 cm2
of weld
surface.
depth of 0.8mm and their total length must not exceed
not exceed the indicated dimensions, must be
smoothly merged with the surfaces of the base metal
and their edges must be free from undercuts.
2.1 Cap and finishing beads by means of
cellulosic electrode
After the root bead made with Pipeweld 6010 Plus,
further filling and capping beads can be carried out using
cellulosic electrodes.
Proceed again in the vertical up position, by using the
3.2 mm diameter and the 4 mm if bevel and pipe
diameter are suitable.
Welding current should be lower than that used in the
root and is determined by the pipe size.
Current values normally used are:
Ø 3,2mm – 60A ÷ 100A
Ø 4mm – 80A ÷ 120A
Depending on the width of the bevel, welding is carried
out with Z or half-moon weaving movements, pausing
with the electrode at the joint edges.

44
3 - Joint in 2G / PC
This type of joint and position is used on pipes, piles,
small vessels. The following example relates to the
welding of pipe with 8” (203 mm) diameter.
Electrode E6010 Ø 3.2mm, DC+, Current 85 ÷ 110A root
filling
Electrode E7018 Ø 3.2mm, DC÷, Current 110 ÷ 140A
cap
Operations
After having carried out the preparation and tacking, fix
the piece in the 2G position (vertical axis).
Then make the root bead with E6010 electrodes of 3.2
mm diameter.
ELECTRODE
WORK ANGLE
The electrode must be held horizontally with a trailing
angle of 5 ÷ 10°. Start the bead 50 mm from the tack,
form the “keyhole” crater and advance with a slightly
swinging movement similar to that used for the 5G
position. Keep the electrode on the edges of the
shoulder.
ROOT FACE
5mm “KEYHOLE”
CRATER
STOP POINTS
1 ELECTRODE DIAMETER
1/2 ELECTRODE DIAMETER
DIRECTION OF TRAVEL
ELECTRODE ANGLE

45
If the crater tends to widen, increase the trailing angle
from 5 to 10°. If the electrode tip is pushed too far into
the joint, undercuts form along the root and excessive
penetration and defects occur. If the electrode is not
pushed deep enough into the joint, insufficient
penetration and undercuts on the beveled surfaces of the
preparation are obtained.
If the arc is interrupted before the bead is complete,
clean the crater and restart as described in the previous
paragraph, not forgetting to fill the crater.
ALWAYS FILL THE CRATER
CRATER
ELECTRODE PUSHED
TOO FAR INTO THE JOINT
UNDERCUTS
DIRECTION
5°-10°
The second or filling bead pass be carried out with
an E7018 electrode in 2.5 mm diameter.
The electrode must be held horizontally with a trailing
angle of 5 ÷ 10°.
Use a perpendicular W motion, with pauses at the points
indicated in the figure to correctly fill the welding crater.
Keep the arc as short as possible. The bead must be flat
or slightly convex with good fusion on the edges.

46
The capping passes should be made with E7018
electrodes of 3.2 mm diameter. The work angle varies,
with respect to the horizontal plane, from 5° above for the
third bead, to 5° below for the fifth.
A correct work angle assures good fusion on the joint
edges. The beads must overlap up to half of the previous
one. Use the same swinging movement described for the
second bead. The finished joint must have a projecting
machine allowance of 1.6mm and the slightly convex
surface must not present undercuts.
OVERLAP UP TO HALF
THIRD BEAD
1.6mm WELD METAL
1.6mm WELD METAL
FIFTH BEAD
ASME (*) standards provide a visual analysis and
relevant quality assessment of the weld on a sample.
After having carried out the preparation and tacking, the
piece is marked for identification then welded in the 5G
position as previously indicated. A visual analysis of the
weld is then carried out.
The acceptability criteria are as follows:
• Penetration: the joint root must show a complete
penetration.
must appear complete
• Slag inclusion: the cavity in melted zone containing slag
must not exceed 3.2mm for each 152mm of weld.
cannot be longer than 1 .6mm and their total must not
exceed a length of 3.2mm each 6.5 cm2
of weld
surface.
depth of 0.8mm and their total length must not exceed
not exceed the indicated dimensions, must be evenly
connected with the surfaces of the base metal and their
edges must be free from undercuts.

47
4 - Joint in 6G / H-LO45
This type of joint and position is used to weld bends,
flanges, fittings. The following example shows the welding
of pipes of 8” (203mm) diameter. The 6G welding position
qualifies all the others.
Electrode E6010 Ø 3.2mm, DC÷, Current 85 ÷ 110A root
bead
filling
Electrode E7018 Ø 3.2mm, DC+, Current 110 140A cap
Operations
After having carried out the preparation and tacking, fix
the piece in the 6G position (axis 45° to the horizontal
plane) The tack must be placed at 2, 5, 8 and 11 o’clock.
Then carry out the root bead with E6010 electrodes of
3.2 mm diameter. Start with the electrode at 6:30, with
the electrode in the plane of the joint and at right angles
to the direction of travel.
FEED ANGLE WORKING ANGLE
6G POSITION
Use a light swinging movement. The tip of the electrode
should be kept on the edges of the shoulder but without
exerting pressure on them. If the crater tends to close,
use a slight trailing angle and/or reduce travel speed. If
the crater tends to widen, use a slight leading angle
and/or increase travel speed.
The arc interruption and reinsertion procedures are
similar to those described in chapter 2, page 40.
Execute both halves of the bead and remove the slag
before laying the second bead.
LIGHT CONVEXITY
ROOT REINFORCEMENT
HIGH DISTANCE
BETWEEN THE EDGES
NARROW CRATER
5-10° LEADING
5-10° TRAILING
FEED
WIDE CRATER
REDUCED DISTANCE
BETWEEN THE EDGES

48
The filling pass should be carried out starting the arc at
6:30 and stabilising it at 6 o’clock on a fairly reduced
width. Angles as per figure. Use E7018 electrodes of
2.5mm diameter. The filling pass should reach
approximately 1.6 mm from the external surface of the
pipe.
ELECTRODE ANGLES
5-10° TRAILING
5-10° LEADING
5-10° TRAILING
START HERE
WORK ANGLE
Then carry out the capping passes with E7018
electrodes of 3.2mm diameter, using a 110 ÷ 140A
current.
The electrode angles of the are the same as those used
for filling.
Take note of the number of beads for each layer.
OVERLAP UP
TO HALF
E7018 diameter 3.2mm
WORK ANGLES
BOTTOM BEAD:
SLIGHTLY SWINGING ACTION
FILLING BEAD:
LIGHT PENDULAR ACTION
DWELL POINTS:
DWELL A LITTLE
LONGER AT POINTS
ON THE HIGHEST EDGE
EXTERNAL BEADS:
OVERLAP UP TO HALF
OF THE PREVIOUS BEAD
MELT UP TO 1.6mm
OF THE BEVELLED EDGE

50
To find and possibly prevent welding defects, the
operator must acquire familiarity with the form and
dimension of the weld pool and its relation to the form
and appearance of the finished weld seam.
The filler metal is generated by the electrode, which
through the arc starts mixing with the melted base
metal. In vertical down welding, the arc force tends to
make the melted metal flow towards the rear part of the
crater to form the seam, while the force of gravity tends
to counterbalance that of the arc, making the fusion
pool flow in feed direction.
On the contrary, in vertical up welding, the force of the
arc and that of gravity push the melted metal back in
the crater to form the seam.
The movement of the melted metal towards the back of
the crater and its form provide the operator with a
means of continuous quality control, without interrupting
the arc. The essential variables by which the operator
interprets the fusion bath on which he must intervene to
prevent welding defects are: electrode diameter,
current, arc length, feed speed and electrode
positioning angles.
One of the most important factors is penetration.
There is correct penetration when the weld completely
crosses the joint thickness, leaving a small seam of
continuous penetration well-fused at the back. One of
the commonest defects in pipe welding is insufficient
penetration, which consists in discontinuity between
the two edges of the bevel due to the fact that the filler
metal has not completely penetrated the joint. This
takes place as, during welding, the groove starts to
close, the seam becomes narrow and the welding bath
stagnant. To prevent this problem, a possible remedy is
to decrease feed speed or reduce the electrode drive
angle to increase the temperature of the bath and
therefore the penetration. If this is not sufficient,
interrupt welding and increase the current or use the
grinder to redece the root face.
The opposite defect is excessive penetration, which is
marked by an excessive reinforcement on the back of
the joint, higher than required.
In this case, during welding the groove becomes too
wide and the weld pool control is difficult due to its size
and fluidity. To reduce penetration and eliminate this
problem feed speed may be increased, possibly also
increasing the electrode drive angle. If this is not
sufficient, interrupt welding and reduce the current.
An excessive heat supply may cause shrinkage This
makes the internal surface of the joint concave. It is a
common defect when welding overhead: the force of
gravity causes the internal surface of the seam to
become concave and the external surface convex.
In both cases it is necessary to reduce the heat supply
to the melted bath, the methods are the same as those
described in the previous case.

51
Vertical welding, too high a heat input causes burn
through and fall of melted metal.
Another cause of defects is often linked to an imperfect
restart of the arc, generally due to too low current or
insufficient pre-heating; the start of the connecting
seam is too wide and the end has a contour degrading
towards the crater.
To prevent this type of defect, the electrode must be
removed towards the end of the crater, keeping the arch
slightly long for pre-heating. At the end reduce the arc
length to melt the thin bridge of metal, waiting until the
seam is of equal length to the existing one, then restart
feed. When the arc is correctly started, the electrode
must be turned towards the end of the crater.
Also in the case of ascending restart with electrodes
with low alloy and/or low carbon contents (basic),
the arc must be restarted upstream of the crater then
moving towards the other end and should be kept
slightly longer than normal. To restart on the filling or
external beads, with cellulosic or basic electrodes,
switch on the arc approximately 13mm in front of the
crater then move back until it is filled. In this way the
previous seam is correctly pre-heated.
Another typical welding defect consists of undercuts.
These are furrows displayed at the seam edges at the
connection with the surface of the base metal. They
reduce thickness and cause burn through. This defect is
due to the excessive length of the arc. The larger the
arc cone, the wider the cuts will be, and the filler metal
is laid in drops and there is excessive spatter with
consequent loss of filler material.
Also the vertical down root often causes small
undercuts at the edges of the external surface of the
seam, but this is mainly due to an over-high travel
speed. The second bead usually fills the cuts at the
edges and prevents the lack of fusion and slag
inclusion.
The undercuts at the root inside the pipe are caused by
an over-short arc. The tip of the electrode is pushed
too far into the joint and the filler material which is
pushed through the joint is laid at the root.
Finally, we must draw your attention to a series of
welding defects caused by incorrect joint preparation.
The root gap, the root face and cleaning of the joint are
all factors directly related to the future quality of the
finished weld.
An excessive distance between the edges or a too
small may cause excessive penetration, shrinking
effect, breakage or undercuts. An excessive root gap
makes it necessary to increase travel speed otherwise
there would be an excessive heat supply with excessive
penetration or burn through. Similarly, if the shoulder
surface is too small, the arc heat makes the edges melt
at the root and this leads to the previous situation in
which the distance between the edges is excessive.
On the contrary, too small a root gap or too large a root
face may cause insufficient penetration, lack of fusion
and convexity of the seam surface with possible slag
inclusion. If the root face is too high, the arc cannot melt
the joint edges to create the groove and the metal is
laid between the edges with insufficient penetration.
Insufficient or inadequate cleaning of the joint and base
material before welding may cause further defects,
generally gaseous inclusion (porosity if ≤ 1mm,
blowholes if ≥ 1mm). The presence of oil or dirt on the
surfaces to be welded causes spherical porosity. Other
causes of porosity may be the presence of humidity on
the base metal, excessive feed speed or excessive
undulation of the electrode.
Finally, it is important to mention the effect of the
electrode angle as a means of temperature control.
The feed angles, “to be pushed” or “to be pulled”,
influence heat supply, arc force and the quantity of
material laid. Since the arc force is always exerted in
the same direction as the electrode, if this is not
centred on the joint the arc causes undercuts along the
edges. Welding in upwards, gravity moves the melted
metal towards the lowest point of the crater in which
large undercuts have not been filled. Undercuts, which
may however be caused by excessive arc length, may
also occur along the edges of the joint root.
To sum up, the quality of the weld depends on the
operator’s ability, on his knowledge of the appropriate
techniques and on his capacity to control the five
essential variables mentioned at the start. Joint
preparation, and its cleaning before welding, must be
accurate.
GOOD FUSION
LIGHT
CONVEXITY

54
General information
For decades the largest companies specialising in pipe
construction at world level have adopted automatic
welding systems, immediately finding their choice
rewarded.
The main reasons for the conversion are:
• Increased productivity
• Lower welding costs
• Use of fewer staff
• Operators (welders) are trained in a few weeks
• Lower repair percentage
• Perfect repeteability of a test joint
Different alternatives can be chosen when the conversion
has to take place:
• One side welding with internal line-up clamp using
copper backing
• Performing of internal root pass with a “welding internal
line-up clamp”
Both of those give good productivity and low repairing
rate, but their respective advantages are:
One side welding
• Low cost equipment
• Higher speed on root pass (the first pass gives the
production speed to the main line welding phase)
Internal pass
• Can be used when copper backings are not allowed
• Can ensure better penetration on high-low conditions

55
Filler materials
SOLID WIRES
ESAB, which follows the natural development of the
sector, has set up and has now sold for years to all
companies in the sector a complete range of solid
wires for pipe welding which covers the entire range of
steels.
OK Autrod 12.66
Classification
SFA/AWS A5.18-93 : ER 70S-6
EN 440 : G 42 2 C G4Si1
EN 440 : G 46 3 M G4Si1
OK Autrod 12.66 is a copper-coated solid wire with
low content of impurity elements for downhill
circumferential GMAW welding on pipe qualities such
as API 5L, grade X52 to grade X70. The wire permits
welding with high current (spray-arc) and also with
short-circuiting transfer in all positions. Shielding gas
Ar/CO2.
Typical all-weld metal composition - %
C = 0.07
Si = 0.8
Mn = 1.4
Typical properties all-weld metal
Yield stress : 535 Mpa
Tensile strength : 600 Mpa
Elongation : 26%
Charpy V : 100J at –20°C
OK Autrod 13.13
Classification
SFA/AWS A5.28 : ER 100S-G
EN 12534 : GMn3NiCrMo
A copper-coated, low-alloy, chromium-nickel-
molybdenum (0.5% Cr, 0.5% Ni, 0.2% Mo), solid wire for
the GMAW of high tensile strength steels with a minimum
yield strength (0.2% offset) of less than 610 MPa and a
minimum tensile strength exceeding 710 Mpa. Also
suitable when welding steels where good impact strength
at lower temperatures is required.
OK Autrod 13.13 is usually welded with Ar/CO2 as the
shielding gas. The mechanical properties are given in the
as-welded condition. After stress relieving, the
mechanical properties decrease by about 30 Mpa in the
case of yield and tensile strength.
C = 0.1
Si = 0.7
Mn = 1.4
Cr = 0.6
Ni = 0.6
Mo = 0.2
Yield stress : 690 MPa
Tensile strength : 770 MPa
Elongation : 20%
Charpy V :
80J at 0°C
50J at –60°C

56
CORED WIRES
For even more extreme applications, where productivity,
quality and mechanical features must be guaranteed,
ESAB, thanks to its preferred partner relationship with
large contractors specialised in the offshore sector, has
prepared a series of cored wires which permit a
considerable increase in productivity.
FILARC PZ6104
Classification
SFA/AWS A5.18 : E70C-GM H4
EN 758-1997 : T42 5 Z MM 2 H5
Metal-cored wire providing a ductile weld metal alloyed
with 1% Ni for good CVN toughness down to –50°C.
Developed for applications involving thick plates, high
restraint and/or low-temperature toughness
requirements, as in offshore construction. Primary use
comprises multi-layer butt and fillet welds in the downhill
and horizontal/vertical positions. Root passes without
backing are welded in the short-arc mode. Pulsed MIG
operation is applied to optimise the filling of positional
joints, using Ar/8%CO2 shielding gas. Suitable for
semiautomatic and fully automatic orbital welding
machines.
C = 0.03 – 0.07
Si = 0.4 – 0.7
Mn = 1.2 – 1.6
Ni = 0.7 – 0.95
Yield stress : 420 MPa
Tensile strength : 520 - 620 MPa
Elongation : 22%
Charpy V :
54J at -40°C
47J at –50°C

57
Welding with mixed technique
Electrode+wire welding may be considered the first step
towards complete automation of the welding process;
although large companies adopted this solution in the
early Eighties to limit investments in the first phase.
It could work on a standard API bevel (30°+30°) without
using bevelling machine (very expensive device),
performing root and hot passes by cellulosic electrodes
and filling and cap by solid or cored wires. Very common
using of self-shielded cored wire where good quality of
gas is not easy to find.
Wire welding
Wire welding, with reduced bevel and use of an internal
clamp with copper supports is definitely the cheapest,
safest and most productive solution to adopt and has
been used for years to construct sea and land pipes by
numerous companies in the sector.
How automatic equipment works
The welding torch moves downhill at a speed
programmed by a selector. The speed is determined for
each pass, on the half circumference. At the end of each
pass the torch moves back to the starting position and
restarts, after the welding parameters have been
regulated or automatically set. The operation is carried
out by means of two carriages on the same weld, to
increase productivity.
Advantages
Operators, even if recruited among generic personnel,
can be trained in two-weeks time.
Number of personnel dedicated to the welding phase can
be reduced by 30% (it’s not necessary to grind and brush
joints – welding wire does not produce slag).
Working time is completely productive. Dead times
between each pass are reduced to a minimum.
Welding techniques and operational practices
for automatic orbital welding
DEPOSITION RATE
Weld metal deposition per hour
Electrode Cored Automatic
wire-manual welding
DEPOSITION EFFICIENCY
Ratio of weight of weld metal deposited to the weight used
wire-manual welding
DUTY CYCLE FACTORS
Ratio of arc time to working time
wire-manual welding
1,36 kg/hr 1,8 kg/hr 3,6 kg/hr
35% 35% 80%
65% 85% 90%

58
Examples of WPS - Welding Procedure
Specifications

60
Examples of WPS - Welding Procedure
Specifications

62
Comparison between three welding methods
36” pipe, 14 mm thickness
Electrode Electrode + wire Wire + copper backing
Type of bevel
Welding Procedure
Specification
I° pass Pipeweld 6010 Plus ∅ 4 mm Pipeweld 6010 Plus ∅ 4 mm OK Autrod 12.66 ∅ 1 mm
II° pass Pipeweld 7010/8010 ∅ 4 mm Pipeweld 7010/8010 ∅ 4 mm OK Autrod 12.66 ∅ 1 mm
Filling Pipeweld 7010/8010 ∅ 5 mm OK Autrod 12.66 ∅ 1 mm OK Autrod 12.66 ∅ 1 mm
Capping Pipeweld 7010/8010 ∅ 5 mm OK Autrod 12.66 ∅ 1 mm OK Autrod 12.66 ∅ 1 mm
The joint could be also filled
with self shielded cored wire
(Coreshield 8NiA)
or OK Tubrod 15.17 in
semiautomatic technique
Times
Arc time 64 minutes 41 minutes 25 minutes
Efficiency 35% 35% + 80% 80%
Total time 182 minutes 68 minutes 31 minutes
Costs (only an example)
Manpower 34 Euro/hour
Electrodes 5 Euro/kg
Wire 3 Euro/kg + 0,5 Euro/kg gas
Manpower cost 102 Euro 38 Euro 17 euro
Welding weight 2 kg 1,6 kg 1,2 kg
Consumables cost 11 Euro 6 Euro 4 Euro
Total weld cost 113 Euro 44 Euro 21 Euro
12°
R: 3,2 mm
1 mm
1,5 mm
12°
30°
1,5 mm
~ 5 mm
30°
1,5 mm
The bevel =
volume
reduction
The finished
weld

63
Hollow bead
The x-ray shows how a hollow channel inside the first
bead may be caused by the presence of dirt inside the
pipe, by inaccurate grinding of the internal wall of the
pipe near the bevel, by bad weather conditions which
make water or steam reach the weld while the first
bead is being carried out or by incorrect welding
parameters (too much current, too much gas).
Remedies
Check internal cleaning of the pipe, all the circumference,
by means of manual grinding (brushing is not sufficient)
for a section of at least 2 cm from the bevel.
In bad weather conditions, manual cleaning with cloths
of the internal wall of both the pipes to be joined even
before carrying out the first bead and before the
overhead section (6:00) as it is that most likely to
convey water or steam.
Periodic check of welding parameters
Lack of penetration
This presents itself as an interruption, perhaps of
considerable length or with sections of the inside weld
seam, which should instead be uniform after the first
bead. In pipes with a sufficiently large diameter to
permit internal accessibility it is visible to the naked eye
and, in some cases, the intact bevel is visible (a
welding process for instantaneous repair of the fault
from the inside) is recommended. It may be caused by
incorrect geometrical dimensions of the bevel, incorrect
welding parameters, bad fit up (excessive
misalignments) or poor operator skill.
Remedies
Check bevel, check welding parameters, pipe rotation
(always compatible with the position of the longitudinal
welds which must be spaced a certain length) or
application of shims on the internal clamp expanders to
reduce misalignments.
We will not dwell on the skill of the operators; the most
expert should be chosen and reserved for the first bead
(a delay in execution stops the whole “welding train”).
Lack of fusion
The main defect of wire processes. In x-ray it appears
as a continuous or short dashed line on one or both
sides of the joint; by assessing its position as regards
the first bead (whiter seam at the centre of the film),
you can assume its depth.
The main causes are: incorrect bevel dimensions,
incorrect welding parameters or operator negligence.
Remedies
Constant check of all process geometrical and
functional parameters and informed operators.
A second case exists. Less common than the lack of
fusion called INTERPASS, caused by the dropping of the
weld pool in the vertical section of the pipe (2:00-5:00)
due to incorrect welding parameters; it appears in the x-
ray as a darker veil between two successive beads.
Porosity
In a coated electrode process, the weld pool is
protected from external oxidation by combustion of the
coating, but in a wire process it is protected by a
protective gas, introduced into the arc zone by a torch;
the lack of gas causes porosity.
Remedies
Check the good state of maintenance of coverages for
protection from the wind, check the good state of
maintenance of sleeves, connections, gas diffusers and,
more as recommendation than a technical remedy,
substitute gas cylinders before they finish completely.
Slag inclusion
Defect found only in the mixed (electrode+wire) technique,
it presents itself in the slab as an elongated, cracked
inclusion of a certain thickness, usually positioned on one
side of the bevel. It is caused by bad slag cleaning in the
second bead, which remains imprisoned and does not
melt in the successive wire bead.
A sporadic case, mentioned for comprehensiveness, is
slag inclusion due to its entrapment in the hollow
created between the second bead and the bevel wall if
this, in the section at 30°, has not been completely filled.
To be more clear, if you start to weld with wire before
filling the bevel section at 30° with the electrode, this
could cause defects (even lack of fusion).
Remedies
Thorough cleaning of the second bead
External defects (undercuts and excess
weld metal)
These cannot be considered real welding defects which
cause joint seal problems, but are “to be repaired” due
to the possibility of the start of corrosion or fatigue
failure (cuts) or to facilitate subsequent operations of
coating and installation (excess weld material)
Remedies
Good preparation of the joint before executing the
finishing bead: the underlying bead must be uniform,
perfectly clean and leave 1mm from the pipe surface to
permit the voluminous pool of the last bead to rest
smoothly and create a 1-1.5mm seam for the widest part
of the joint.
At the end of the “welding train”, it is advisable to
provide a tractor, even of small size for the manual
repair of defects on the external bead.
Defects and remedies

Pipelines welding handbook_welding_techn

More Related Content

What's hot (20)

Similar to Pipelines welding handbook_welding_techn (20)

Recently uploaded (20)

Pipelines welding handbook_welding_techn