FIELD OF THE INVENTION
The invention relates to Electrogas Welding (EGW) process in general, and to a
simplified method for welding in groove joints from one side using Electrogas
Welding process (EGW), in particular.
BACKGROUND OF THE INVENTION
In order to improve the welding productivity several techniques are employed.
One of the important techniques of interest is the use of narrower joint grooves.
The conventional welding makes use of typical joint edge preparation e.g. V-
groove joints. As compared to this, the narrow gap welding employs near
parallel-sided edge preparation. The principal welding processes normally
employed for narrow gap welding are Submerged arc welding (SAW), Gas Metal
arc welding (GMAW), Gas Tungsten arc welding (GTAW) and Electrogas Welding
(EGW).
Electrogas Welding (EGW) is a variation of both the Gas Metal Arc Welding
(GMAW) and the Flux Cored Arc Welding (FCAW) process, in which retaining
shoes being adapted to confine the molten weld metal for vertical position

welding. Additional shielding is optionally provided by an externally supplied gas
or gas mixtures. In its mechanical aspects and application to welding practice,
EGW resembles conventional Electroslag Welding (ESW) from which it was
developed.
Electrogas Welding (EGW) is advantageously employed in many developed
countries for welding of vertical joints because of the associated overall economy
and better mechanical properties of the weld. EGW is unique among the various
arc welding processes because of the fact that it is a vertical welding process by
which thick plates up to 100 mm (max) thickness can be welded in a single pass.
Its application is widely acknowledged for shipbuilding, storage tank fabrication.,
pressure vessels, blast furnaces and steel structure fabrication including building
construction.
According to the prior art, generally square edge preparation is employed for
welding of plates using two water-cooled sliding copper shoes; one at front side
and other one at the rear side to support the weld metal. A gap of the joint at
the parallel faces is required to be maintained at 15-18 mm depending upon the
thickness of the material and the technique employed with EGW process.

However, where other side is not accessible during welding, V-groove is adopted
and welding is done from one side with one sliding copper shoe. The other side
i.e. rear side is supported by temporary backing which can be removed after
completion of welding.
One other advantage is claimed that V-groove joint can be welded by
conventional SMAW and GMAW/FCAW processes in emergency situation when
Electrogas welding machine is not available for actual welding due to non-
availability of machine owing to overload or break down of the machine.
The feeding of wire in the grooved joint is done in such a way that wire is fed at
the outlet near vertical with respect to weld pool/plate faces and at a point
located away from the face of the V-grooved joint and which is kept at a suitable
distance between root and face of the weld so that equal amount of heat is
distributed in the solidified weld metal in single pass.
US-patent US3975615 discloses a welding method and an apparatus for
practicing the process for butt welding of plated in vertical position employing
front and rear water cooling type backing shoes positioned by sliding on the
front and rear surfaces of metal plates to be butt welded. It is also mentioned
that torch is tilted to facilitate melting of the metal plates. However this type of
construction is not suitable for Electrogas welding from one side.

US-patent US3984652 discloses a process for "butt welding of plates" employing
Electroslag and Electrogas welding processes. The welding is carried out
between two plates, cutting a gap in the center leaving first weld and then
rewelding the adjoining surfaces of the first weld metal. The method has the
advantage of heat treating the heat affected zone (HAZ) of the parent metal
adjacent to the weld. The construction details of the machine are not provided.
JP-patent JP2001001169 (A) discloses a multi-layer Electrogas welding method
to a specified thickness to suppress a deterioration of quality of heat-affected
zone. In this method, welding of joint is carried out in stages in number of
layers. Each weld layer is divided in two parts and each part is completed by
multi-layer welding method by changing the configuration of water cooled copper
shoe to suit the respective shape of V-groove after welding each layer and pass.
This copper shoe is of sliding type and a fixed copper shoe is attached at the
back side of the joint. However, the details with regard to the construction of
machine are not given.
JP-patent JP2001071143 (A) discloses a Electro-gas welding method for thick
steel plates involving multi-layer welding to improve the welding efficiency
without developing lack of fusion defect by making a welding electrode oscillate
along a bevel wall and a welded bead surface of a pre-welded layer. The

electrode is oscillated in triangular or trapezoidal fashion depending upon the
progression of layer welding by incorporating suitable changes in the weld
parameters suitably and by changing the configuration of water cooled copper
shoe to suit the respective shape of groove after welding each pass. However,
the patent does not disclose the details with regard to construction of the
machine.
JP-patent JP10118771 (A) discloses a vertical electro-gas welding device
employing two electrodes and two nozzles to efficiently weld steel plates having
a large thickness by invading the tip of a first electrode in to beveling, and
successively, invading the tip the part of a second electrode into an opening hole
side of the beveling. The details with regard to placement of backing or copper
shoe are not disclosed.
JP-patent JP2007237263 (A) discloses a vertical electro-gas welding method
suitable for welding thick steel plates of thickness 50 mm by employing hot wire
technique to increase the deposition. The details with regard to apparatus and
placement of backing or copper shoes are not disclosed.
KR-patent KR20030057013 discloses a copper backing device capable of
adjusting thickness when performing Electro-gas welding and Electro-slag
welding. A copper plate backing device is provided to reduce processing steps for
backing material and to improve working efficiency by allowing the copper plate

backing device to be applied to plates having various thicknesses. This
construction of backing is not directly adaptable to one sided Electro-gas
welding.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a method for Electrogas
welding which eliminates the limitations of prior art.
Another object of the invention is to propose a method for Electrogas welding
which is capable to weld in V-groove joints.
Still another object of the invention is to propose a method to carry out
Electrogas welding in groove joints having a simplified construction.
Yet another object of the invention is to propose a method in such a way that
wire is fed at a location with respect to weld pool/plate face so that equal
amount of heat is distributed to achieve proper fusion in the V-grooved joint and
by selecting suitable parameters good quality weld is achieved.
A further object of the invention is to propose a simplified method so that
welding is easily performed.

A still further object of the invention is to propose innovative changes in the
present apparatus so that the above mentioned tasks can be easily
accomplished.
A still another object of the invention is to propose a simplified apparatus for
Electrogas welding in groove joints, which has sufficient rigidity and stability in
carrying out the welding operations.
SUMMARY OF THE INVENTION
Accordingly, there is provided the simplified method and apparatus to carry out
Electrogas welding in V-grooved joint to facilitate welding in single pass from one
side only.
The feeding of wire is done in such a way that equal amount of heat is
distributed in the V-grooved joint and by selecting optimum parameters to
achieve proper fusion of the joint faces.
The method of welding in V-grooved joint and apparatus are made to accomplish
the Electrogas welding in simplified way by providing adequate stability during
the welding operation.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.l - shows a schematic representation of the conventional Electrogas welding
process (EGW)
Fig.2 - shows schematically the edge preparation in a prior art for Electrogas
Welding
Fig.3 - shows schematic sketch of the apparatus in a prior art for carrying out
Electrogas welding in joints as shown in figure (2)
Fig.4 - shows schematic sketch of the apparatus after incorporating innovative
changed with regard to placement of certain components for carrying out
Electrogas welding in groove joints according to the invention
Fig.5 - shows schematically the edge preparation in simplified method for
Electrogas welding
DETAILED DESCRIPTION OF THE INVENTION
The invention will now be described with the help of accompanying drawings
which depict an exemplary embodiments of the invention. However, there can be
several other embodiments all of which are deemed to be covered by the
description.

Fig.l illustrates the process of Electro gas welding. A consumable electrode (3)
either solid or flux-cored is fed via a feeding roller (4) downward into a cavity
formed by the groove faces of the plates (1,2) to be welded and two water-
cooled retaining shoes (5). A sump (starting tab) is used at the beginning of the
weld to allow the process to reach stabilization before the molten metal (6)
reaches the work (1,2). Arc is initiated between the electrode (3) and the sump.
Heat from the electric arc melts the groove faces and the continuously fed
electrode (3). Melted electrode and bare metal continuously get collected in a
pool beneath the arc and solidify to form the weld metal (7). The electrode (3)
may be oscillated horizontally through the joint in thick section for uniform
distribution of heat and weld metal (7). As the cavity fills, one or both the
retaining shoes move upward with the welding head. Although the axis of the
weld is vertical, the welding position is actually flat with vertical travel. The weld
metal (WM) is deposited between the two plates (1,2). The gas supply hole (9)
and solidified slag (8) including the weld bead (10) are shown in Figure-1.
Fig-2 shows a typical edge preparation employed for Electrogas welding. The
plates (1,2) to be joined are assembled to forma simple square butt joint. The
gap (X) may vary from 15 to 18 mm for conventional Electrogas welding and 8 to
12 mm for narrow gap joints. The thickness (t) of the joint may vary in the range
of 10 mm to 75 mm.

Fig-3 shows the EGW machine developed indigenously to carry out the welding
of joints having edge preparation as shown in figure (2). It consists of frame (11)
which is moved upwards by a motorized device (part 12) on guided column (not
shown in the figure). It houses a welding torch and wire feeding device (13),
wire spool (14), oscillation arrangement (15), and water carrier assembly (16)
which is guided pneumatically. The rear copper shoe assembly (17) is attached
to this carrier assembly. The spring loaded front copper shoe assembly (18) is
attached to the frame. The wire feeding device and welding torch are attached
to oscillation assembly. The guided water carrier assembly is mounted on a cross
slide (19) which can be moved in X-Y direction and is mounted on the frame.
The plates to be welded (1,2) are kept vertically and front and rear copper shoes
(21 and 22) are provided to support the weld metal.
The innovative changes are made in the present machine to facilitate the
positioning and sliding of the front copper shoe by providing a constant
pneumatic pressure against the plates through the pneumatic cylinder. The
change is carried out to accommodate placement of pneumatic cylinder and to
facilitate its coupling to the cross slide (23). Subsequently, the rear copper shoe
assembly is eliminated to accommodate the placement of temporary backing
(24) as shown in Figure-4.

Fig-5 shows a typical edge preparation employed for one sided Electro gas
welding. The plates (1,2) to be joined are assembled to form a V-grooved butt
joint. The included angle of the joint is kept 60 degrees and root gap is
maintained in the range of 4-5 mm. The thickness (t) of the joint may vary in the
range of 10 mm to 40 mm.
SOME RELEVANT FEATURES OF THE INVENTION
• A method of one sided Electrogas welding in grooved joints
incorporating innovative changes in the placement of certain
components (Ref: fig 3 and 4) in the conventional EGW equipment
comprising:
- Change in the placement of pneumatic cylinder assembly (23) to
maintain constant pressure on front copper shoe assembly (18)
and to facilitate upward sliding movement of front copper shoe
(Fig.4)
- Elimination of rear shoe assembly (17) and water carrier
assembly (16) to accommodate temporary backing (24) on the
rear side of the V-grooved joint (Fig.4).
Possibility of using integral backing or detachable temporary
backing in the rear side of the joint.

- Feeding of consumable electrode (3) either solid or flux cored is
fed via a feeding roller (4) downward into a cavity formed by the
groove faces of the plates (1,2), front copper retaining shoe (21)
and temporary backing (24).
• Improved joint edge preparation (Ref: Fig.2 & Fig.5) to facilitate one
sided welding to achieve proper fusion with temporary backing (24).
• A method to carry out Electrogas welding by feeding of wire at a proper
location in the joint and by optimum selection of welding parameters to
achieve proper fusion of joint faces after incorporating changes as
given under points 1 and 2.

WE CLAIM
1. An apparatus of one sided Electrogas welding (EGW) in groove joints
consisting:
- a frame (11) comprising a welding torch and wire feeding device
(13), wire spool (14) and oscillation arrangement (15);
- a front copper shoe (21) which is spring loaded and attached to
the frame (11);
- a welding torch and wire feeding device (13) which are attached
to oscillation arrangement (15);
- a pneumatic cylinder assembly (23) to facilitate coupling to the
cross slide (23) which is mounted on the frame (11); and
- two plates (1,2) which are to be welded, kept vertically
Characterized in that placement of pneumatic cylinder assembly (23) to
maintain a constant pneumatic pressure on front copper shoe assembly (18)
and to facilitate upward sliding movement of front copper shoe (21)
eliminates rear shoe assembly (17) and water carrier assembly (16) of the
prior art to accommodate temporary backing in the rear side of the V-
grooved butt joint, wherein both backing and V-groove are the modifications
employed in the invention.

2. The apparatus as claimed in claim l, wherein the front copper shoe (21)
is provided to support the weld metal.
3. The apparatus as claimed in claim 1, wherein the frame (11) moves
upwards by a motorized device (Part 12) on guided column.
4. A method carried out with the apparatus as claimed in claim 1 for one
sided Electrogas welding (EGW) in groove joints comprising steps of:

- edge preparation of the plates (1,2) to be welded;
- feeding of consumable electrode (3) via a feeding roller (4)
downward into a cavity formed by the groove faces of the plates
(1,2), front copper retaining shoe (21) and temporary backing
(24);
- providing a sump (starting tab) at the beginning of the process
before the molten metal (6) reaches the work (1,2);
- initiation of arc between the electrode (3) and the sump;
- continuous collection of melted electrode and resulting molten
metal in a pool beneath the arc, where these being solidified to
form the weld metal (7);
- oscillation of electrode (3) done horizontally through the joint in
thick section;

- starting of movement of the front retaining shoe upward with
welding head as the cavity fills; and
- deposition of weld metal (WM) between two plates (1,2).

5. The method as claimed in claim 4, wherein said edge preparation of the
plates (1,2) to be joined is done to form a V-grooved butt joint when
assembled.
6. The method as claimed in claim 4, wherein the sump allows the process
to reach stabilization before molten metal (6) reaches the work (1,2) at
the beginning.
7. The method as claimed in claim 4, wherein said oscillation is done for
uniform distribution of heat and weld metal (7).
8. The method as claimed in claim 4, wherein the V-groove having an
included angle 60 degrees of the joint, root gap maintained in the range
4-5 mm and thickness (t) of the joint varies in the range of 10 mm to 40
mm.

9. The method as claimed in claim 4, wherein the edge preparation in the
form of V-grooved butt joint facilitates in single pass from one sided
welding to achieve proper fusion with temporary backing (24).
10. The method as claimed in claim 4, wherein the feeding of consumable
electrode (3) either solid or flux-cored is done, so that equal amount of
heat is distributed in the V-grooved joints and the heat from the electric
arc melts the grooved faces and continuous fed electrode (3).

An apparatus of one sided Electrogas welding (EGW) in groove joints consisting a
frame (11) comprising a welding torch and wire feeding device (13), wire spool (14) and oscillation arrangement (15); a front copper shoe (21) which is spring loaded and attached to the frame (11); a welding torch and wire feeding device (13) which are attached to oscillation arrangement (15); a pneumatic cylinder
assembly (23) to facilitate coupling to the cross slide (23) which is mounted on
the frame (11); and two plates (1,2) which are to be welded, kept vertically
characterized in that placement of pneumatic cylinder assembly (23) to maintain
a constant pneumatic pressure on front copper shoe assembly (18) and to
facilitate upward sliding movement of front copper shoe (21) eliminates rear
shoe assembly (17) and water carrier assembly (16) of the prior art to
accommodate temporary backing in the ear side of the V-grooved butt joint,
wherein both backing and V-groove are the modifications employed in the
invention.
The invention relates to a method also for one sided Electrogas welding (EGW) in
groove joints.