FIELD OF INVENTION
The present invention relates to an auxiliary device for Gas Tungsten Arc Welding
(GTAW) torch to provide additional coaxial shielding with Argon gas for titanium
welding.
BACKGROUND OF THE INVENTION
In conventional GTAW torch (Fig.1) shielding of weld metal and adjacent HAZ against
the atmospheric contamination is provided through inert shielding gas flowing through a
gas cup coaxial to the Tungsten electrode. This arrangement is adequate for welding of
almost all materials except reactive materials like Titanium, Molybdenum etc.
Titanium is very reactive to atmospheric gases and for the welding of Titanium
conventional GTAW torch is not adequate to get defect free welding without
contamination of hot base material adjacent to the weld area.
To ensure contamination free base metal adjacent to the weld area normally welding of
Titanium by GTAW process is carried out either by keeping the job in an enclosure
purged with inert gas or by creating inert gas environment locally around the GTAW
2
torch normally through a trailing shield arrangement to ensure cooling of hot material
adjacent to the weld under inert atmosphere.
In the area where it is not feasible to keep the job in an inert atmosphere particularly in
case of large sized jobs, only option is to carry out GTAW of Titanium in open air using
the trailing shield approach. In restricted areas it is not convenient to provide additional
shielding required during manual GTAW welding of Titanium through conventionally
available trailing shield arrangement.
OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to propose an auxiliary device for
GTAW torch gas nozzle for co-axial shielding with argon gas for welding of titanium
which eliminates the disadvantage of existing state of arts.
Another object of the present invention is to propose an auxiliary device for GTAW torch
gas nozzle for co-axial shielding with argon gas for welding of titanium which results a
defect free sound weld.
A further object of the present invention is to propose an auxiliary device for GTAW
torch gas nozzle for co-axial shielding with argon gas for welding of titanium which
reduces fatigue to welder due to light weight of the auxiliary device.

A still further object of the present invention is to propose an auxiliary device for GTAW
torch gas nozzle for co-axial shielding with argon gas for welding of titanium which
reduces welding rework.
SUMMARY OF THE INVENTION
In order to carry out Titanium welding on large size jobs and at restricted locations
(where commercially available trailing shield arrangement does not work), a low cost
coaxial auxiliary device has been conceived and manufactured which can be fitted with
a conventional GTAW torch gas nozzle. This device is connected to a separate Argon
source to provide additional shielding coaxial to the gas nozzle to cover the hot metal
zone prone to atmospheric contamination and protect it. Thus the chances of
contamination of Titanium with atmospheric air at elevated temperature are eliminated
resulting in a sound detect free weld.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 - shows conventional GTAW Torch
Fig.2 - shows GTAW torch with the attachment assembled.
Fig.3 - shows attachment details

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
As shown in Fig.2, a compact additional shielding auxiliary device revealed fitted with
the conventional GTAW torch gas nozzle to provide the required additional shielding gas
during Titanium welding.
As shown in Fig.3, the auxiliary device comprises of a hollow cylindrical body having a
closed rear end and an open front end and having a centrally hollow passage for entry
of the GTAW torch gas nozzle to set in. The device is made of light weight aluminum
metal. A gas pipe (2) from outside is provided to the top of the body (1) to supply
secondary shielding gas for feeding the coaxial gas chamber inside the body. The open
end of the body (1) is provided with a diffuser (3) below the gas chamber for diffusing
the incoming shielding gas inside the device gas passage and a gas lens made of fine
SS wire-mesh (4) outside the diffuser (3) to supply turbulance free secondary shielding
gas. A sealing ring (5) accommodated in the top portion of the device wherein the gas
nozzle fits with auxiliary device to prevent unwanted suction of atmospheric air through
the gap between the device and GTAW torch gas nozzle which may lead to
contamination of shielding gas with atmospheric air. A locking screw (6) is provided in
the device to locate and fix the device to gas nozzle in required position.
As shown in Fig.2, the auxiliary device (1) is in assembled condition with GTAW torch
gas nozzle and fix up with a locking screw (6) for welding on large sized jobs and to

carry out welding at restricted locations. At the time of welding argon gas pipe line (2)
is in open condition and the gas enters in the device (1) and exits through the circular
opening via a diffuser (3) and a wire-mesh (4) and the gas flow covering a circular area
around the welding zone in order to protect from atmospheric air which leads to
contamination of hot base material adjacent to weld metal. A number of trials have
been carried out and satisfactory results were obtained.

WE CLAIM
1. An auxiliary device for GTAW torch gas nozzle for coaxial shielding with argon
gas for welding of Titanium comprises:
- a centrally hollow cylindrical body (1) having a close rear end and an open
front end;
- a gas pipe is provided on the top of the body to supply secondary
shielding gas for feeding the co-axial gas chamber inside the body;
- a diffuser (3) is disposed below the gas chamber for diffusing the
incoming shielding gas inside the device gas passage;
- a gas lens of fine SS wire-mesh is provided outside the diffuser to supply
turbulence free shielding gas;
characterised in that a GTAW gas nozzle is inserted in the central hollow
portion of the device through a sealing ring and co-axially fitted with a
locking screw for Arc Welding of Titanium wherein argon gas is supplied
around the welding region from the device to prevent contamination from
atmospheric air.
2. The device as claimed in claim 1, wherein the device is made of light
aluminum metal.

An auxiliary device for GTAW torch gas nozzle for additional co-axial shielding with
argon gas for welding of Titanium comprises a centrally hollow cylindrical body (1)
having a close rear end and an open front end and a gas pipe is provided on the top of
the body to supply secondary shielding gas for feeding the co-axial gas chamber inside
the body and a diffuser (3) is disposed below the gas chamber for diffusing the
incoming shielding gas inside the device gas passage and a gas lens of fine SS wire-
mesh is provided outside the diffuser to supply turbulence free shielding gas
characterised in that a GTAW gas nozzle is inserted in the central hollow portion of the
device through a sealing ring and co-axially fitted with a locking screw for Arc Welding
of Titanium wherein argon gas is supplied around the welding region from the device to
prevent contamination from atmospheric air.