Claims:We claim:
1. A welding electrode for welding a spool piece of grade TX 63 on a radiant tube comprises the following composition by weight:
Carbon < 0.1 %
10 % < Chromium < 30 %
1 % < Columbium < 5 %
0.1 % < Silicon < 1 %
0.1 % < Titanium < 1 %
4 % < Tungstun < 6 %
5 % < Manganese < 10 %
Iron < 10 %
remainder being Nickel.
2. The welding electrode as claimed in claim 1, wherein the composition by weight further comprises an inbuilt austenitic stabilizer which prevent the sigma phase failure in the temperature range of 650 to 870 °C.
, Description:WELDING A SPOOL PIECE OF GRADE TX 63 ON A RADIANT TUBE

TECHNICAL FIELD
[0001] The present disclosure relates to establishing a welding process for a ruptured radiant tube used in the heat treatment furnace. More particularly the invention relates to the establishment of the welding parameters for the spool piece welding in the radiant tubes. More particularly the invention relates to the selection of proper welding electrode for joining two dissimilar alloy materials.
BACKGROUND
[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] Temperature uniformity and constant heat flux per unit length have to be maintained in heat treatment process so flame propagation inside radiant tube should be proper, ruptured radiant tubes are not suitable for maintaining the above characteristic. Apart from that while prevention of oxidation in furnace internal atmosphere charged with nitrogen but in case of ruptured radiant tube furnace atmosphere will not be inert as it is having atmospheric air which contains oxygen so scale formation rate will be high. So in order to maintain the above characteristic, we required a leak-proof radiant tube. Cost of the new radiant tube is very high as compared to the repaired cost so it is economical also. Hence it is imperative to find out a suitable method of welding a spool piece on the damaged part of the radiant tube instead of procuring new one for the replacement.

OBJECTS OF THE DISCLOSURE
[0004] Some of the objects of the present disclosure, which at least one embodiment herein satisfy, are listed hereinbelow.
[0005] It is a general object of the present disclosure to provide a specific cutting and welding process for rupture radiant tube.
[0006] Another object of the present disclosure is to propose a welding process to suit the weld material of the radiant tube and spool piece.
[0007] A still further object of the present disclosure is to select a suitable electrode for cutting process to remove uneven surfaces occurred during the puncture in the furnace.
SUMMARY
[0008] This summary is provided to introduce concepts related to an apparatus for precise positioning of welded panels. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0009] In an embodiment, the present disclosure relates to a welding electrode for welding a spool piece of grade TX 63 on a radiant tube comprises the following composition by weight:
Carbon < 0.1 %
10 % < Chromium < 30 %
1 % < Columbium < 5 %
0.1 % < Silicon < 1 %
0.1 % < Titanium < 1 %
4 % < Tungstun < 6 %
5 % < Manganese < 10 %
Iron < 10 %
remainder being Nickel.

[0010] In an aspect, the composition of the welding electrode by weight further comprises an inbuilt austenitic stabilizer which prevents the sigma phase failure in the temperature range of 650 to 870 °C.
[0011] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] 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 apparatuses, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
[0013] FIG. 1 illustrates a radiant tube assembly used in a furnace for heat treatment process;
[0014] FIG. 2 illustrates a ruptured tube cut out from a radiant tube assembly; and
[0015] FIG. 3 illustrates a spool piece in position after removal of a ruptured portion from the radiant tube assembly, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0016] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is 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 spirit and scope of the present disclosure as defined by the appended claims.
[0017] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0018] Embodiments herein describe a welding electrode for welding a spool piece of grade TX 63 on a radiant tube 01 (FIG. 1) used in a furnace for the heat treatment process. The material description of radiant tube 01 and spool pieces 03 (FIG. 3) of grade TX 63 is tabulated below:
[0019] Material spec no: ASTM A 297 Gr HP with micro addition:
limit Values in %
Cr Ni C Mo S P
MIN 24 33 0.4 - -- -
MAX 28 37 0.5 0.5 0.04 0.04

[0020] Cutting electrode specification which is used to cut the irregular shapes 02 (FIG. 2) in the radiant tube 01:
CARBON C---- 0.1-1 %
SILICON Si ---- 0.1-1 %
MANGANESE Mn --- 0.1-1 %
IRON BALANCE

[0021] By using the above cutting electrode the radiant tube 01 is made uniform circular in shape by cutting the uneven surfaces and the edge preparation is made on both ends of radiant tubes 01 using the same cutting electrode without post heating and preheating of both the radiant tube 01 and the spool piece 03 which is to be welded on the radiant tube 01.
[0022] After the trial test, the suitable welding electrode is selected and the specification is given hereunder:
CARBON C---- LESS THAN .1 %
CHROMIUM Cr---- 10-30 %
COLUMBIUM Nb--- 1-5 %
SILICON Si---- .1--1 %
TITANIUM Ti----.1-.1 %
TUNGSTON W---4-6 %
MANGANESE Mn --- 5-10 %
IRON Fe-- LESS THAN 10 %
NICKEL BALANCE

[0023] During the repair of radiant tubes 01, welding carried out without pre and post heating of job due to low wall thickness and as per the consideration was given by steel foundry society of America for ASTM A 297 HP grade material. It has been found that no defects found in the weldment and magnetic particle inspection test is carried out to find out the surface and sub-surface defects if any.
[0024] As per radiant tube material specification proposed herein, the welding electrode material composition proposed herein is tested and given a satisfactory result. While making the electrode specification, the material composition is restricted up to a specified limit within which required result can be obtained.
[0025] For instance, the material of grade TX-63 is having 0.4 to 0.5 % Carbon and this caused intergranular corrosion and the iron dilution caused the deposit ductile austenite structure to become crack sensitive and brittle martensitic structure. But the welding electrode composition proposed herein is having 60% Nickel which can withstand the considerable dilution without going out of the austenitic structure. The welding electrode proposed herein contains 1% to 5% Columbium which stabilizes the Carbon and prevents intergranular corrosion.
[0026] The high or inconsistent sulfur content of many high Nickel electrodes greatly increases their cracking tendency. So, sulfur content is restricted at 0.012% or less.
[0027] Specification of the welding electrode proposed herein is having inbuilt austenitic stabilizer which prevents the sigma phase failure in the temperature range of 650 to 870 °C. In the critical temperature range embrittling chromium-iron compound that causes complete weld failure because of the inbuilt stabilizer of its austenitic structure, it prevents the sigma phase failure in the critical range of temperature. The welding electrode composition proposed herein resists oxidation and carburization also at elevated temperature.
[0028] In contrast, in the conventional welding process, namely shielded metal arc welding, the direct current electrode positive polarity with the current range of 70-90 A is used by 3.15 mm electrode diameter selected to do the repair welding.
[0029] Furthermore, 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.
[0030] 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.
[0031] 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.
[0032] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.