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FIELD OF THE INVENTION
The invention relates to an improved torch for welding in groove joints using
Electrogas welding process (EGW).
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

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which thick plates up to 100mm (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, 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. In this context, the thickness of the EGW
torch plays an important role in decreasing the gap across the joint i.e. lesser the
thickness of torch, it will be possible to reduce the gap of joint leading to less
volume of weld metal.
EP-patent EP0326445A1 discloses a to 'Narrow gap torch" more particularly to an
internally insulated torch for making narrow groove joints. The housing is made
of rectangular section and it houses an electrode holder, including a cooling and
gas shielding arrangement to weld deep groove joints. However, this type of
construction is unsuitable for Electrogas welding, even if adapted, the torch
requires modification.
US - patent US3984652 describes a process for "butt welding of plates"
employing Electroslag and Electrogas welding processes. The welding is carried
out employing a Linde coated consumable nozzle. The details of the nozzle are
not provided.
W00151242A1 discloses a "Welding torch and stream nozzle" used for inert gas
welding process and is provided with a coating. This construction of welding
torch and nozzle is not directly adaptable to Electrogas welding process.

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W02007030720A1 describes a "welding torch having nozzle assembly with
independently removable components," which is also not suitable for electro gas
welding applications.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose an improved torch for
Electrogas welding in groove joints, which eliminates the disadvantages of prior
art.
Another object of the invention is to propose an improved torch for Electrogas
welding in groove joints which is capable to weld in square groove joints too.
Still another object of the invention is to propose an improved torch for
Electrogas welding in groove joints, which is sleek and light-weighted, and
having a simple construction.
Yet another object of the invention is to propose an improved torch for
electrogas welding, which is capable to operate in narrow grooves having 12 -15
mm gap, and joint thickness up to 75 mm.
A further object of the invention is to propose an improved torch for Electrogas
welding in groove joints, which is easily mountable on a wire feeding device.

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A still further object of the invention is to propose an improved torch for
Electrogas welding in groove joints, which has sufficient rigidity and stability in
carrying out the welding operations.
A still another object of the invention is to propose an improved torch for
Electrogas welding in groove joints, which allows easy wrapping of insulating
tape over the affected area to avoid any stray arcing during welding operation.
SUMMARY OF THE INVENTION
Accordingly, there is provided an improved torch for Electro gas welding for
groove joints comprising a shaped central member with a hole for feeding a wire
at the centre and it is curved in typical way to facilitate easy feeding of the wire;
a first solid block brazed to the central member to act as a guide; a second solid
guide block at the entry to guide the wire to be housed in the first solid block;
and means to hold a contact tip at the outlet.
The wire is fed at the outlet near vertical with respect to weld pool/plate faces so
that equal amount of heat is distributed in the solidified weld metal in single
pass. It should be made in simpler way avoiding complicated machining
operations.

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BRIEF DESCRIPTION OF THE ACCOMAPNYING DRAWINGS
Fig - 1. A schematic representation of the conventional Electrogas welding
process.
Fig-2 schematically shows the edge preparation in a prior art Electro Gas
welding.
Fig-3 shows schematic sketch of an improved torch for carrying out Electro gas
welding (EGW) in narrow groove joints according to the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
Fig. 1 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

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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 one side Electro gas
welding. The plates (1,2) to be joined are assembled to form a simple square
butt joint. The gap (X) may vary from 15 to 18 mm for conventional Electro gas
welding and 8 to 12 mm for narrow gap joints. The thickness (t) of the joint may
vary in the range of 10mm to 75mm.
As shown in Fig. 3 - the improved EGW torch (14) comprises a typically shaped
central member (15) with a center hole (15a) and suitably curved to facilitate
easy feeding of an wire (3). A first solid block (11) is brazed to the central
member (15) to act as a guide and drilled/threaded suitably to house a second
solid block (12), which guides the wire. The end of the torch (14) is provided
with an arrangement to hold a contact tip (13). The overall thickness of the torch
(14) is kept within 7 mm. The torch (14) can be insulated easily by high
temperature insulation tape to avoid any arcing during the welding.

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WE CLAIM
1. An improved torch for Electro gas welding comprising particularly in
groove joints comprising;
- a shaped central member (15) (15a) with a hole and typically
curved to facilitate easy feeding of an wire (01);
- a first solid block (11) brazed to the central member (15) to allow
guiding of the wire (1);
- a second said block (12) acting as a removable wire guide, the
second solid block (12) housed in the first solid block (11); and
- means for holding a contact tip (04).
2. An improved torch for Electro gas welding in groove joints as
substantially described herein with reference to the accompanying
drawings.

This invention relates to an improved torch for Electrogas welding in groove joints is developed which enables smooth feeding of wire to carry out welding in the grooves joint of 12-15mm gap and thickness up to 75mm. It is very sleek,
lightweight and has a very good stability during welding operation. It facilitates easy mounting and can be manufactured easily in short time.