Claims:WE CLAIM
1. A method (400) of purging on a plurality of tubes (201) (202) for butt welding (208), the method (400) comprising steps of:
providing (401) an inert gas shielding through a hose (203) mounted on an adapter (204) attached at an inlet side (205) of the first tube (201) keeping an outlet side (206) on an end of a second tube (202) open;
closing (402) the outlet side of the second tube using a cap (207); and
providing (403) the inert gas shielding again through the inlet side (205) of the first tube (201), wherein the inert gas flows to the other end of the second tube (202) and returns back to the inlet side (205) and passes out through the adaptor (204).
2. The method (400) as claimed in claim 1, wherein the inert gas passes out through a hole (301) provided on a side of the adaptor (204).
3. The method (400) as claimed in claim 1or 2, wherein the inert gas includes Argon gas and the hose (203) is made of material including polythene.
4. The method (400) as claimed in claims 1-3, wherein the outlet side (206) of the second tube (202) is remained open to eject the atmospheric air from inside the first tube (201) and the second tube (202).
5. The method (400) as claimed in claims 1-4, wherein the first tube (201) and the second tube (202) are laid side by side to each other and supported by a plurality of chucks (209, 210) for radial symmetry so that purging and welding is carried out smoothly.
6. The method (400) as claimed in claims 1-5, wherein the outlet side (206) of the second tube (202) remains open in the first step (401) to allow free flowing of the argon gas through it in order to expel the atmospheric air from inside the first tube (201) and the second tube (202).
7. The method (400) as claimed in claims 1-6, wherein the polythene hose (203) is connected to a flow meter (211) that is connected to an argon gas cylinder (212).
8. The method (400) as claimed in claims 1-7, wherein the pre gas flow duration is approximately 130 seconds for a fusion pass and approximately 150 seconds for a filler pass.
9. The method (400) as claimed in claims 1-8, wherein the post gas flow purging duration is approximately 200 seconds for the fusion pass and approximately 250 seconds for the filler pass.
10. The method (400) as claimed in claims 1-9, wherein the plurality of tubes (201, 202) are made of material including titanium.
, Description: A METHOD OF PURGING ON TITANIUM TUBES FOR BUTT WELDING

FIELD OF THE INVENTION
[0001] The present subject matter described herein relates to a method of purging on tubes for butt welding. More specifically, the present invention relates to the method of purging on titanium tubes to get defect free, oxidation free tube butt weld joints in the fabrication of pipe system (Tube bundle) used in steam generators.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] There are many steps involved in the preparation of tubes for coiling. To prepare the tubes for coiling, 18 metre length tubes are required. Whereas the tubes supplied are around 7 metre length. After taking that in account, butt welding of the tubes is essential in order to get 18 metre length tubes for coiling. The outside diameter of the tube is 18mm and thickness of the tube is 2.5mm. The material used for the tubes is titanium alloy.
[0004] The Titanium tube butt welding is the one of the important activity in the preparation of tubes for coiling. A semi-automatic Gas Tungsten Arc Welding (GTAW) machine is used for the welding of titanium tubes. Since titanium material is highly reactive with oxygen at elevated temperatures during welding, extreme care in argon gas shielding is required to evacuate the oxygen and ensure 100% inert atmosphere is present around the weld region.
[0005] In order to ensure the above requirement, three numbers of argon shielding are provided (Torch shielding, back purging and box shielding). Referring to Fig. 1, both ends of the tubes are provided with end caps an inlet cap (101) and outlet cap (102) through which argon gas is purged to make an inert atmosphere inside the tubes.
[0006] During tube butt welding, it is noticed that inner side of the tubes, nearby weld region, gets oxidised due to improper argon shielding. To overcome the above issue various methods are tried such as increasing the argon gas flow, pre flow and post flow duration etc. But all the above methods were not adequate to overcome the oxidisation of tubes. Further increase of argon gas flow caused burn through suck back and insufficient penetration during welding. Once the oxidation noticed in the weld, further production activities cannot be resumed.
[0007] After lot of trials, it is observed that there is some problem in method of argon back purging during welding. If four butt joints per shift is carried out in the earlier method and the defect is noticed, the entire material is rejected depending up on the total length of tube required.
[0008] Referring to prior art KR20140002941U, it relates to a pipe purging device, having a width adjustable connecting member at a chain connecting portion of a first blocking member and a width adjustable gas supplying portion at a chain connecting portion of a second blocking member. The gas injection unit injects the argon gas that is supplied from outside into the space between the blocking members and purging is done inside of each pipe before the welding operation.
[0009] The problem with the above state of art is that it uses two separate blocking members to create a vaccum for supplying the argon gas making the device expensive and creating a hassle for the operator to insert the blocking members inside the pipe. Moreover, it does not mention about using this device to perform purging on titanium tubes/pipe.
[0010] It is therby required to develop a method of purging to obtain defect free butt joints on the titanium tubes. Hence, the present invention has been introduced.
OBJECTS OF THE DISCLOSURE
[0011] It is therefore the object of the present disclosure to overcome the aforementioned and other drawbacks in prior arts.
[0012] It is a primary object of the present disclosure to provide a method of purging to obtain defect free butt joints in tubes.
[0013] It is another object of the present disclosure to provide the adaptor on the inlet side of the first tube and the cap on the outer side of the second tube for argon back shielding on both the ends of the first tube and the second tube tubes to ensure adequate argon gas flow throughout the cross-section of the tubes.
[0014] It is yet another object of the present disclosure to establish the fusion pass time and filler pass time in the welding process.
[0015] These and other objects and advantages of the present subject matter will 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.
[0016] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION
[0017] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition and a method as claimed in the present disclosure. 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 part of the claimed disclosure.
[0018] Solution to one or more drawbacks of existing technology and additional advantages are provided through the present disclosure. 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.
[0019] The present disclosure offers a solution in the form of a method of purgin on the plurality of tubes by providing an inert gas shielding through a hose mounted on an adapter attached at an inlet side of the first tube keeping an outlet side on an end of a second tube is open. After that, closing the outlet side of the second tube using a cap and furthermore by providing the inert gas shielding again through the inlet side of the first tube, wherein the inert gas flows to the other end of a second tube and returns back to the inlet side and passes out through an adaptor.
[0020] In an aspect of the invention, the inert gas passes out through a hole provided on a side of the adaptor.
[0021] In an aspect of the invention, the inert gas includes Argon gas and the hose is made of material including polythene.
[0022] In an aspect of the invention, the outlet side of the second tube is remained open to eject the atmospheric air available inside the first tube and the second tube.
[0023] In an aspect of the invention, the first tube and the second tube are laid side by side to each other and supported by a plurality of chucks for radial symmetry that purging and welding is carried out smoothly.
[0024] In an aspect of the invention, the outlet side of the second tube remains open in the first step to allow free flowing of the argon gas through it in order to expel the atmospheric air from inside the first tube and the second tube.
[0025] In an aspect of the invention, the polythene hose is connected to a flow meter that is further connected to an argon gas cylinder.
[0026] In an aspect of the invention, the pre gas flow duration is approximately 130 seconds for a fusion pass and approximately 150 seconds for a filler pass.
[0027] In an aspect of the invention, the post gas flow purging duration is approximately 200 seconds for the fusion pass and approximately 250 seconds for the filler pass.
[0028] In an aspect of the invention, the material of the plurality of tubes are made of material including titanium.
[0029] 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.
[0030] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
[0031] 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.
[0032] 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 ACCOMPANYING DRAWINGS
[0033] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein:-
[0034] 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 present disclosure 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:
[0035] Fig. 1 illustrates the method of argon back purging according to the prior art;
[0036] Fig. 2 illustrates the components used in the method according to the present disclosure;
[0037] Fig. 3 illustrates the adaptor present on the inlet side of the first tube for purging according to the present disclosure;
[0038] Fig. 4 illustrates the method of purging the plurality of tubes using argon back purging according to the present disclosure.
[0039] The figures depict embodiments of the present subject matter for 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.
[0040] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily 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.

DETAIL DESCRIPTION OF INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS OF THE PREFERRED EMBODIMENTS:
[0041] While the embodiments of the disclosure are subject to various modifications and alternative forms, a specific embodiment thereof has been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.
[0042] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0043] The invention is related to a method for inert gas back purging for defect free welding of titanium tube butt joints using a semi-automatic GTAW tube butt welding machine. It includes an adaptor and a hose which reduce the rejection rate in tube butt welding drastically and minimise the usage of ultra-high purity argon gas grade I by making same entry and exit. The improved method changes the welding process and reduces time taken for the pre-flow and post-flow of the argon gas.
[0044] Referring to Fig. 2, the complete set up of machine after fixing an adaptor and a cap (207) on a plurality of tubes (201, 202) is disclosed to purge the tubes (201, 202) for butt welding (208). The adapter (204) is attached on the first tube (201) and the cap (207) is attached on the second tube (202).
[0045] The adapter (204) has a space for taking in a polythene hose (203) to insert argon gas shielding in the first tube (201) and the second tube (202). The polythene hose (203) is connected to a gas regulator (211) of the argon gas cylinder (212). The user is able to change the flow of the argon gas according to the requirement by using the gas regulator (211).
[0046] The first tube (201) and the second tube (202) are laid side by side to each other and both of the tubes are supported by a plurality of chucks (209, 210). The chucks (209, 210) are used to hold the first tube (201) and the second tube (202) for radial symmetry so that purging and welding is done smoothly.
[0047] The cap (207) is connected on the second tube (202). The cap (207) is removed and put on again according to the need as provided in the method (400).
[0048] Referring to Fig. 3, the adapter (204) has an a hole (301) provided on one end of the adapter (204). The hole (301) is located near to the first tube (201) to pass the supplied argon gas through it. The adaptor has a side hole (302) that provides a space to pass the argon gas through it. The side hole (302) is in direct connection with the inlet side (205) of the first tube (201).
[0049] Referring to Fig. 4, a method (400) of purging on the plurality of tubes (201) (202) for butt welding (208) is disclosed. In the first step (401), before the argon welding is initiated, the adapter (204) is fixed on the tube inlet of the first tube (201). The adapter (204) is attached to the polythene hose (203) for supplying the argon gas shielding through it. At this time, the outlet side (206) of the second tube (202) remains open to allow free flowing of argon gas through it in order to expel all the atmospheric air available inside the plurality of tubes (201, 202).
[0050] In the second step (402), the outlet side (206) is closed using the cap (207). The cap (207) is then applied on the outlet end of the second tube (202) to stop the flow of argon gas to flow outside from the tubes (201, 202).
[0051] In the third step (403), the argon gas shielding is provided through the inlet side (205) and gas flows up to the other end of the second tube (202). Since the other end of the second tube (202) is closed with the cap (207) as disclosed in the second step (402), the supplied argon gas returns back to the inlet side (205) and passes out through the hole (301) provided on the adapter (204).
[0052] This forward and return flow of argon gas ensures complete inert atmosphere inside the tubes (201, 202) and also ensures non-ingression of atmospheric air inside the tubes (201, 202), leading to defect free welding. The Pre gas flow duration is 130 seconds for fusion pass and 150 seconds for filler pass. Similarly post gas flow purging duration is 200 seconds for fusion pass and 250 seconds for filler pass.
[0049] The gas, material are given as example without restricting scope of the invention to the same. Thus, other materials, gas readily apparent to a person skilled in the art are understood to be within purview of the invention.
TEST RESULTS
[0053] The table below shows that the method (400) disclosed in the present invention for inside gas shielding is effective by reducing the pre flow and post flow durations considerably.
Description Pre flow Post flow
Earlier method of purging Present method of purging Earlier method of purging New method of purging
Gas flow duration during Fusion pass (Time in seconds) 180 130 250 200
Gas flow duration during Filler pass (sec) 200 150 350 250

[0054] The above table shows that the time taken in all the stages is dramatically reduced for each butt joint. Considering the number of joints per shift and number of tubes required to make one assembly, the method (400) of purging as provided in the present disclosure paves the way for substantial saving in time and also saving of money because of defect free joint is obtained as the repairing cost and the material cost are high for the titanium tubes.
TECHNICAL ADVANTAGES
[0055] With the help of the solution as proposed herein in the context of the present disclosure, defect free joint is obtained using the present method.
[0056] The present disclosure also provides that the set of connectors and the polythene purging hose, reduces the rejection rate in tube butt welding drastically and minimise the usage of ultra-high purity argon gas grade I by making the same entry and exit instead of single inlet and single outlet used in the conventional purging process.
[0057] The present disclosure further provides that the inside gas shielding is so effective that pre flow and post flow durations are reduced considerably.
[0058] The invention is cost effective.
[0059] 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 disclosures 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. Also, 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). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general, such construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general, such construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). 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.”
[0060] 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 disclosure 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 disclosure, and other dimensions or geometries are possible. Also, while a feature of the present disclosure 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 disclosure. The present disclosure 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.
[0061] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0062] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
[0063] 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 particulars 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). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). 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”.
[0064] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[0065] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0066] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0067] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.