Claims:We claim:
1. An apparatus for protection of weld of pipe from contamination and oxidation during welding process, the apparatus (10) comprises:
a base table (1);
a height adjustment screw assembly (2) mounted on the base table (1) at one end (2a);
a guiding arrangement base frame (3) mounted at other end (2b) of the height adjustment screw assembly (2), a pair of sliding pathways (301a and 301b) mounted on the guiding arrangement base frame (3) at opposite surface of the height adjustment screw assembly (2);
a hemispherical sliding arrangement (4) slidably coupled with the pair of sliding pathways (301a and 301b);
a hemispherical purging arrangement (6) provided on the hemispherical sliding arrangement (4), the hemispherical purging arrangement (6) defines a plurality of perforations for insertion of purging gas; and
a thermal insulating material (5) provided in between the hemispherical sliding arrangement (4) and the hemispherical purging arrangement (6) to avoid contamination and oxidation during the welding process.
2. The apparatus as claimed in claim 1, wherein the screw jack assembly (2) facilitates height adjustment of the guiding arrangement base frame (3) in accordance to the degree of completion of welding and diameter of pipe that is to be welded.
3. The apparatus as claimed in claim 1, wherein the welding process is performed using Narrow Gap-Hot Wire- Gas Tungsten Arc Welding (GTAW) method.
4. The apparatus as claimed in claim 1, wherein the pair of sliding pathways (301a and 301b) facilitates sliding of the hemispherical sliding arrangement (4) over the guiding arrangement base frame (3).
5. The apparatus as claimed in claim 1, wherein the purging gases flowing through the plurality of perforations provided on the hemispherical purging arrangement (6) provides shielding blanket and protects welded zone of the pipe from oxidation.
6. The apparatus as claimed in claim 1, wherein the purging gases comprise of inert gases to provide shield to the weld of pipe from oxidation.

7. The apparatus as claimed in claim 1, wherein the thermal insulating material (5) comprises of glass wool to provide insulation and to avoid leakage of the purging gas.
, Description:An apparatus for protection of weld of pipe from contamination and oxidation during welding process
FIELD OF INVENTION
[001] The present invention in general relates to a purging apparatus for narrow gap Gas Tungsten Arc Welding (GTAW) of heat sensitive materials. In particular, the present invention relates to an apparatus for providing a shield to NG-HW-GTAW from atmosphere to avoid its contamination.
BACKGROUND OF THE INVENTION
[002] Narrow gap Hot Wire Gas Tungsten Arc Weld (NG-HW-GTAW) is an efficient process for welding of thick sections of symmetrical components with very minimal weld deposition. In HW-GTAW, the filler wire is preheated by Joule’s heating principle before feeding to the molten pool using an auxiliary welding power source at currents lower than the welding current. This can bring in advantages in terms of reduction in heat input, better productivity, reduced polluting emissions, etc.
[003] The narrow gap welding torch have a unique design with thin rectangular cross section to facilitate the reach of the torch and hence the arc along with the filler material up to the root of the weld. NG-HW-GTAW can be carried out on both flat and symmetrical components. In case of symmetrical components, the welding can be performed in 1G position by rotating the component by holding it in a rotary positioner or by moving the torch in 5G position, depending on the constraints imposed by the components in terms of shape, dimensions, accessibility, etc. In case of welding in 1G position of heat sensitive and oxide prone materials like stainless steels, nickel based super alloys, etc. due to unfavourable thermo-physical properties, the shielding provided through the torch is not sufficient to avoid oxidation of the weld.
[004] The problem is even more severe while welding smaller diameter pipes or tubes. Hence, a suitable purging set up without hindering the welding operation will be necessary to take care of the shielding.
[005] Therefore, the present invention proposes a fixture that has been designed and fabricated to provide auxiliary purging to protect the weld from oxidation in symmetrical components and the details are explained.
PRIOR ART SEARCH
[006] US patent US6410876 B1 describes the methodology for carrying out good welding of pipes with small, medium and large diameters.
[007] US patent US3560696 relates to a device which can be used for welding of butt joints in pipes. The patent describes the device that can be used for gas shielded welding with both consumable and non-consumable electrodes.
[008] US patent US4243868 relates to an apparatus for attaching tube to the side wall of the pipe for carrying out orbital welding of split construction thereby facilitating the easy removal of the welding apparatus after completion of the welding.
[009] US patent US 4331278 relates to the apparatus for welding end connections to the pipes or for attaching a flange to the existing pipe
[0010] US patent US 5428198 relates to the device for orbital welding of a cylindrical part onto a curved wall.
[0011] US patent US5837966 relates to a device for ensuring the alignment of the orbital welding head with respect to the joint by using a removable or retractable detector module in the welding head.
[0012] US patent US9770775B2 relates to a device for positioning the orbital torch in the required angle at ease for welding.
[0013] US patent US 7520538B2 relates to the method of introducing inert purge gas to the interior of the tubular component to avoid root oxidation.
[0014] US patent US 2006/0118526A1 relates to a device for automatic control of the purge gas pressure in orbital tube welding to maintain the desired pressure to ensure proper bead proper bead geometry on the root side of the welds.
[0015] US patent US 2014/0263192A1 relates to the development of a shielding cup used in connection with the welding torch to provide better shielding in deep groove orbital welding and also to provide inert gas shielding to the electrode. The cup is an attachment and uses the gas supplied through the welding torch to maintain the purity
[0016] The prior arts discussed above either discuss the apparatus for carrying out orbital pipe welding, attachment welding, etc. or about the purging set up for improving the quality in the interior side of the tubes. One prior art talks about a shielding cup which can be used as an attachment to the welding torch to protect the electrode mainly. The present invention relates to the design and fabrication of a purging arrangement for providing an auxiliary shielding during welding with NG-HW-GTAW process of heat sensitive materials to protect the solidified weld from oxidation. The various features of novelty, which characterize the invention are pointed out in the claims.

OBJECTIVE
[0017] A main objective of the present invention is to provide an arrangement for providing auxiliary shielding for NG-HW-GTAW of symmetrical components
[0018] Yet another objective of the present invention is to provide for an apparatus that protects NG-HW-GTAW welds from contamination.
[0019] Yet another objective of the present invention is to provide for a purging arrangement for welding of heat sensitive materials like stainless steels, Cr-Mo steels, etc.
[0020] Still another objective of the present invention is to provide for an apparatus for carrying out welding of pipe component made of nickel based super alloys.

SUMMARY OF THE INVENTION:
[0021] The present invention relates to an apparatus for protection of weld of pipe from contamination and oxidation during welding process. The apparatus disclosed in the present invention comprises of a base table on which a height adjustment screw assembly is mounted. The apparatus also has a guiding arrangement base frame that is mounted at other end of the height adjustment screw assembly and a pair of sliding pathways mounted on the guiding arrangement base frame at opposite surface of the height adjustment screw assembly (2). The apparatus further comprises of a hemispherical sliding arrangement that is slidably coupled with the pair of sliding pathways. The apparatus consists of a hemispherical purging arrangement that is provided on the hemispherical sliding arrangement and it defines a plurality of perforations for insertion of purging gas. A thermal insulating material is also provided in between the hemispherical sliding arrangement and the hemispherical purging arrangement to avoid contamination and oxidation during the welding process.
[0022] In an aspect, the height adjustment screw assembly facilitates height adjustment of the guiding arrangement base frame in accordance to the degree of completion of welding and diameter of pipe that is to be welded.
[0023] In an aspect, the welding process is performed using Narrow Gap-Hot Wire- Gas Tungsten Arc Welding (GTAW) method.
[0024] In an aspect, the pair of sliding pathways facilitates sliding of the hemispherical sliding arrangement over the guiding arrangement base frame.
[0025] In an aspect, the purging gases flowing through the plurality of perforations provided on the hemispherical purging arrangement provides shielding blanket and protects welded zone of the pipe from oxidation.
[0026] In an aspect, the purging gases comprise of inert gas to provide shield to the weld of pipe from oxidation.
[0027] In an aspect, the thermal insulating material comprises of glass wool to provide insulation and to avoid leakage of the purging gas.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0028] 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, the left-most digit(s) of 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 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:
[0029] Fig. 1 schematically illustrates adjustable purging apparatus for protection of NG-HW-GTAW from contamination.

DETAILED DESCRIPTION OF THE CURRENT INVESTIGATION
[0030] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
[0031] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments and detailed in the following description. Descriptions of well-known components and processing techniques are omitted to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0032] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0033] 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. Narrow Gap-Hot Weld-Gas Tungsten Arc Weld is a gas shielded process used for carrying out welding of heavy gauge components. The welding can be performed on both flat and symmetrical components. In case of welding symmetrical components made of heat sensitive materials like nickel based super alloys especially of smaller diameters in 1G position with component rotated using a rotary positioner, the shielding provided through the torch head will not be sufficient to avoid oxidation of weld bead at the outer side. The issue is prominent while welding heavy gauges, as the number of passes required to complete the weld will also be large. The oxides in these grade of materials are tenacious and difficult to be removed and hence can lead to defects like inter pass lack of fusion, inclusions, etc.in the weld.
[0034] Hence, a purging apparatus has been developed to provide auxiliary inert shielding to the weld to avoid contamination. The apparatus protects the weld by providing inert shield to the weld by using inert gas. The inert gas provides a shielding blanket and helps in avoiding contamination of weld by preventing oxidation of a heat sensitive material during welding process.
[0035] The present invention provides for an apparatus for protection of weld of pipe from oxidation and contamination during welding process of the pipe. In reference to Fig. 1, the present invention provides for a height adjustable apparatus which can be adjusted according to the degree of completion of weld as well as according to the diameter of pipe that is to be welded. The apparatus comprises of a base table 1 that supports whole structure of the apparatus. Over the base table 1, a height adjusting screw assembly 2 is provided that facilitates adjusting of height of the apparatus in accordance with the degree of completion of weld. The height adjustment screw assembly 2 is mounted from its one end 2a to the base table 1.
[0036] Further, a guiding base frame 3 is mounted at the other end 2b of the height adjustment screw assembly 2 along with a pair of sliding pathways (301a and 301b). Then a hemispherical sliding arrangement 4 is slidably coupled with the pair of sliding pathways (301a and 302b). The sliding pathways 301a and 302b facilitates sliding movement of the hemispherical sliding arrangement 4 that allows shielding of completed weld part of pipe that is to be welded.
[0037] Further, the apparatus 10 comprises of a hemispherical purging arrangement 6 that is provided on the hemispherical sliding arrangement 4. The hemispherical purging arrangement 6 defines a plurality of perforations for insertion of purging gas. In the present invention, inert gases are used as purging gas to avoid contamination and oxidation of weld. The inert gases flows through the plurality of perforations defined by the hemispherical purging arrangement and used as a medium to provide shield to the weld from oxygen present in the atmosphere.
[0038] Also a thermal insulating material 5 provided in between the hemispherical sliding arrangement 4 and the hemispherical purging arrangement 6 to avoid escaping of heat from the apparatus and leakage of purging gases. Glass wools are provided as the thermal insulating material 5 to insure thermal insulation of the apparatus.

[0039] Reference numerals:
1- Base table
2- Height adjustment screw assembly
2a and 2b- Ends of height adjustment screw assembly (2)
3- Guiding arrangement base frame
301a and 301 b- Pair of sliding pathways
4- hemispherical sliding arrangement
5- Thermal insulation
6- Hemispherical purging arrangement
10- Apparatus for protection of weld of pipe from oxidation