FIELD OF INVENTION
[001] The present subject matter described herein, relates to a welding fixture.
More particularly, to a fixture for welding titanium tubes to titanium tube plates
in shell and tube type heat exchangers.
BACKGROUND AND PRIOR ART AND PROBLEM IN PRIOR ART
[002] TIG Welding, also known as Gas Tungsten Arc Welding (GTAW), is a
process that joins metals by heating them with an arc between a tungsten
electrode (non-consumable) and the work piece. The process is used with a
shielding gas and may also be used with or without the addition of filler metal.
The weld area and electrode are protected from oxidation or other atmospheric
contamination by an inert shielding gas (argon or helium). A constant-current
welding power supply produces electrical energy, which is conducted across the
arc through, a column of highly ionized gas and metal vapours known as a
plasma. GTAW is most commonly used to weld thin sections of stainless steel
and non-ferrous metals such as aluminium, magnesium, and copper alloys. The
process grants the operator greater control over the weld than competing
processes such as shielded metal arc welding and gas metal arc welding,
allowing for stronger, higher quality welds.
[003] A shell and tube heat exchanger is a class of heat exchanger designs. It is
the most common type of heat exchanger in oil refineries and other large
chemical processes, and is suited for low and higher-pressure applications. This
type of heat exchanger consists of a shell with a bunch of tubes inside it. One
fluid runs through the tubes (tube side), and another fluid flows over the tubes
(shell side) to transfer heat between the two fluids.
[004] Tube to tube plate welding is a specialized area of TIG welding method,
whereby the arc is rotated manually through 360° with a weld overlap of 15° to
30° around a static tube to vertically placed tube plate (This tube plate will have

multiple holes drilled to the size of outer diameter of tube as per the layout of
flow path, this plate is kept vertical and the tubes are inserted in it.)
[005] The unique challenge with titanium welding is embrittlement. Difficulties
in welding Titanium and Titanium alloys originate from several basic sources,
the high reactivity of Titanium with other materials, poor cleaning of parts
before joining and inadequate protection during welding can lead to
contamination, porosity and embrittlement of the completed joints.
[006] When heated to joining temperatures Titanium and its alloys react with
air and most elements and compounds. These reactions can reduce the ductility
and toughness of welds and in addition can cause porosity, cracking and
embrittled welds or premature fracture in service, which is clearly unacceptable
in critical-use applications.
[007] The above difficulties can be avoided by shielding in and around the
weld pool with inert gas like Argon. Welder must possess a remarkable level of
hand-eye coordination to make sure their movements don't disturb the shielding
gas and create entry points for oxygen, which could corrupt the weld.
OBJECTS OF THE INVENTION
[008] It is therefore the object of the invention to overcome the aforementioned
and other drawbacks in prior art.
[009] [009] The principal objective of the present invention is to provide a
fixture for TIG welding torch to shield the surrounding metal so as to avoid
creation of entry points for oxygen.
[0010] Another object of the present invention is to provide for a welding fixture
having a high temperature resistance.
[0011] Another object of the present invention is to provide for a low weight
welding fixture.
[0012] Another object of the present invention is to provide for a fixture that is
an electrical insulator and has strong mechanical characteristics to withstand
handling wear and tear during welding.
[0013] Another object of the present invention is to ensure equal distribution of
inert gas in gas purging fixture and to cover the weld zone with inert gas.

[0014] These and other objects and advantages of the present subject matter
would be apparent to a person skilled in the art after consideration of the
following detailed description taken into consideration with accompanying
drawings in which preferred embodiments of the present subject matter are
illustrated.
SUMMARY OF THE INVENTION
[0015] One or more drawbacks of the conventional technology based on existing
apparatus and processes are overcome, and additional advantages are provided
through a novel fixture for TIG welding torch for welding titanium tubes to
titanium tube plates in shell and tube type heat exchangers. Additional features
and advantages are realized through the technicalities of the present disclosure.
Other embodiments and aspects of the disclosure are described in detail herein
and are considered to be a part of the claimed disclosure.
[0016] In an embodiment of the present subject matter, a fixture for welding
titanium tubes to titanium plates in shell and tube type heat exchangers
comprises a first member plate, a second member tube and a third member plate,
a pair of cylindrical tubular connectors (104a, 104b) connected to the third
member plate (103) and a fourth member ring (109), wherein the second member
tube (102) and the fourth member ring (109) connect the first member plate
(101) and the third member plate (103).
[0017] In another embodiment of the present subject matter, the first member
plate has a plurality of perforated holes and a central hole on the surface of the
first member plate.
[0018] In another embodiment of the present subject matter, the third member
plate has a pair of holes on each side of a central hole on the surface of the third
member plate.
[0019] In another embodiment of the present subject matter, the fixture is placed
between torch head and ceramic gas cup.
[0020] In another embodiment of the present subject matter, the diameter of the
plurality of perforated holes is 1mm.
[0021] In another embodiment of the present subject matter, the number of
plurality of holes is 150.

[0022] In another embodiment of the present subject matter, the central hole has
a diameter of 17.5mm.
[0023] In another embodiment of the present subject matter, the diameter of the
central hole is 30mm.
[0024] It is to be understood that the aspects and embodiments of the disclosure
described above may be used in any combination with each other. Several of the
aspects and embodiments may be combined to form a further embodiment of the
disclosure.
[0025] The foregoing summary is illustrative only and is not intended to be in
any way limiting. In addition to the illustrative aspects, embodiments, and
features described above, further aspects, embodiments, and features will
become apparent by reference to the drawings and the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] It is to be noted, however, that the appended drawings illustrate only
typical embodiments of the present subject matter, and are therefore not to be
considered for limiting of its scope, for the invention may admit to other equally
effective embodiments. The detailed description is described with reference to
the accompanying figures. In the figures, a reference number identifies the figure
in which the reference number first appears. The same numbers are used
throughout the figures to reference like features and components. Some
embodiments of system or methods or structure in accordance with embodiments
of the present subject matter are now described, by way of example, and with
reference to the accompanying figures, in which:
[0027] Figure 1a, Figure 1b and Figure 1c illustrates a schematic view of the
fixture and the components of the fixture in accordance with an embodiment of
the present disclosure;
[0028] Figure 2a and Figure 2b illustrate a schematic view of the welding torch
with the fixture in accordance with an embodiment of the present disclosure;
[0029] The figures depict embodiments of the present subject matter for the
purposes of illustration only. A person skilled in the art will easily recognize
from the following description that alternative embodiments of the structures and

methods illustrated herein may be employed without departing from the
principles of the disclosure described herein.
DETAILED DESCRIPTION
[0030] The detailed description of various exemplary embodiments of the
disclosure is described herein with reference to the accompanying drawings. It
should be noted that the embodiments are described herein in such details as to
clearly communicate the disclosure. However, the amount of details provided
herein are not intended to limit the anticipated variations of embodiments; on the
contrary, the intention is to cover all modifications, equivalents, and alternatives
falling within the scope of the present disclosure as defined by the appended
claims.
[0031] It is also to be understood that various arrangements may be devised that,
although not explicitly described or shown herein, embody the principles of the
present disclosure. Moreover, all statements herein reciting principles, aspects,
and embodiments of the present disclosure, as well as specific examples, are
intended to encompass equivalents thereof.
[0032] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of example embodiments.
As used herein, the singular forms “a",” “an” and “the” are intended to include
the plural forms as well, unless the context clearly indicates otherwise. It will be
further understood that the terms “comprises,” “comprising,” “includes” and/or
“including,” when used herein, specify the presence of stated features, integers,
steps, operations, elements and/or components, but do not preclude the presence
or addition of one or more other features, integers, steps, operations, elements,
components and/or groups thereof.
[0033] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For
example, two figures shown in succession may, in fact, be executed concurrently
or may sometimes be executed in the reverse order, depending upon the
functionality/acts involved.
[0034] Unless otherwise defined, all terms (including technical and scientific
terms) used herein have the same meaning as commonly understood by one of

ordinary skill in the art to which example embodiments belong. It will be further
understood that terms, e.g., those defined in commonly used dictionaries, should
be interpreted as having a meaning that is consistent with their meaning in the
context of the relevant art and will not be interpreted in an idealized or overly
formal sense unless expressly so defined herein.
[0035] The present disclosure discloses a fixture for a welding torch for welding
titanium tubes to titanium plates in a shell and tube type heat exchanger. The
fixture is made of high heat resistant material, electrical insulating and has high
strength. The fixture is able to maintain a uniform supply of inert gas around the
weld zone. The fixture is compact having a low weight and thus easy to
assemble and attach with the welding torch.
[0036] These and other advantages of the present subject matter would be
described in greater detail with reference to the following figures. It should be
noted that the description merely illustrates the principles of the present subject
matter. It will thus be appreciated that those skilled in the art will be able to
devise various arrangements that, although not explicitly described herein,
embody the principles of the present subject matter and are included within its
scope.
[0037] As illustrated in Figure 1a, the present subject matter discloses a fixture
100 for welding titanium tubes to titanium plates in shell and tube type heat
exchangers. The fixture 100 is attached to a welding torch used during the
welding process. The fixture 100 is clamped to the welding torch as illustrated in
Figure 2b.
[0038] A fixture 100 for welding titanium tubes to titanium plates in shell and
tube type heat exchangers, the fixture 100 comprises a first member plate 101, a
second member tube 102, a third member plate 103, a pair of cylindrical tubular
connectors 104a, 104b connected to the third member plate 103 and a fourth
member ring 109, wherein the second member tube 102 and the fourth member
ring 109 connect the first member plate 101 and the third member plate 103. The
first member plate 101 has a plurality of perforated holes 105 of diameter 1mm
and a central hole 106 of diameter 30mm on the surface of the first member plate
101. The third member plate 103 has a pair of holes 107a, 107b of diameter 3mm

on each side of a central hole 108 of diameter 17. 5mm on the surface of the
third member plate 103. The fixture 100 is placed between torch head 201 and
ceramic gas cup 202.
[0039] The inert gas supply is given to the fixture 100 connection for shielding
the surrounding metal of weld pool and the facet of the fixture 100 is designed
such that flow of inert gas is laminar and uniform surrounding the weld pool.
[0040] The material selection of the fixture 100 is decided based on the low
material density, weight of the fixture 100 is as minimum as possible, as it has to
be clamped to the welding torch. The fixture 100 remains stable at high
temperatures arising out of welding radiation. The fixture 100 is easy in handling
and prevents creation of any additional burden during handling of welding torch
by a user.
[0041] It will be understood by those within the art that, in general, terms used
herein, and especially in the appended claims (e.g., bodies of the appended
claims) are generally intended as “open” terms (e.g., the term “including” should
be interpreted as “including but not limited to,” the term “having” should be
interpreted as “having at least,” the term “includes” should be interpreted as
“includes but is not limited to,” etc.). It will be further understood by those
within the art that if a specific number of an introduced claim recitation is
intended, such an intent will be explicitly recited in the claim, and in the absence
of such recitation no such intent is present. For example, as an aid to
understanding, the following appended claims may contain usage of the
introductory phrases “at least one” and “one or more” to introduce claim
recitations. However, the use of such phrases should not be construed to imply
that the introduction of a claim recitation by the indefinite articles “a” or “an”
limits any particular claim containing such introduced claim recitation to
inventions containing only one such recitation, even when the same claim
includes the introductory phrases “one or more” or “at least one” and indefinite
articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted
to mean “at least one” or “one or more”); the same holds true for the use of
definite articles used to introduce claim recitations. In addition, even if a specific
number of an introduced claim recitation is explicitly recited, those skilled in the

art will recognize that such recitation should typically be interpreted to mean at
least the recited number (e.g., the bare recitation of “two recitations,” without
other modifiers, typically means at least two recitations, or two or more
recitations). It will be further understood by those within the art that virtually
any disjunctive word and/or phrase presenting two or more alternative terms,
whether in the description, claims, or drawings, should be understood to
contemplate the possibilities of including one of the terms, either of the terms, or
both terms. For example, the phrase “A or B” will be understood to include the
possibilities of “A” or “B” or “A and B.”
[0042] It will be further appreciated that functions or structures of a plurality of
components or steps may be combined into a single component or step, or the
functions or structures of one-step or component may be split among plural steps
or components. The present invention contemplates all of these combinations.
Unless stated otherwise, dimensions and geometries of the various structures
depicted herein are not intended to be restrictive of the invention, and other
dimensions or geometries are possible. In addition, while a feature of the present
invention may have been described in the context of only one of the illustrated
embodiments, such feature may be combined with one or more other features of
other embodiments, for any given application. It will also be appreciated from
the above that the fabrication of the unique structures herein and the operation
thereof also constitute methods in accordance with the present invention. The
present invention also encompasses intermediate and end products resulting from
the practice of the methods herein. The use of “comprising” or “including” also
contemplates embodiments that “consist essentially of” or “consist of” the
recited feature.
[0043] Although embodiments for the present subject matter have been
described in language specific to structural features, it is to be understood that
the present subject matter is not necessarily limited to the specific features
described. Rather, the specific features and methods are disclosed as
embodiments for the present subject matter. Numerous modifications and
adaptations of the system/component of the present invention will be apparent to
those skilled in the art, and thus it is intended by the appended claims to cover all

such modifications and adaptations, which fall within the scope of the present
subject matter

We Claim:
1. A fixture (100) for welding titanium tubes to titanium plates in shell and tube
type heat exchangers, the fixture (101) comprises:
a first member plate (101);
a second member tube (102);
a third member plate (103);
a pair of cylindrical tubular connectors (104a, 104b) connected to the third
member plate (103); and
a fourth member ring (109), wherein
the second member tube (102) and the fourth member ring (109) connect the first
member plate (101) and the third member plate (103).
2. The fixture (100) as claimed claim 1, wherein the first member plate (101)
has a plurality of perforated holes (105) and a central hole (106) having a
diameter of 30mm on the surface of the first member plate (101).
3. The fixture (100) as claimed in claim 1, wherein the third member plate (103)
has a pair of holes (107a, 107b) having diameter 3mm on each side of a central
hole (108) on the surface of the third member plate (103).
4. The fixture (100) as claimed in claim 1, wherein the fixture (100) is placed
between torch head (201) and ceramic gas cup (202).
5. The fixture (100) as claimed in claim 1, wherein the diameter of the plurality
of perforated holes (105) is 1mm.
6. The fixture (100) as claimed in claim 1, wherein the number of plurality of
holes is 150.
7. The fixture (100) as claimed in claim 1, wherein the central hole (108) has a
diameter of 17.5mm.

8. The fixture (100) as claimed in claim 1, wherein the diameter of the central
hole (106) is 30mm.