Title of Invention	AN IMPROVED METHOD OF COLD WIRE ADDITION IN LONG STEM BUTT WELDING OF PRESSURE VESSELS
Abstract	Accordingly there is provided in one aspect of the invention, an improved method of cold wire addition for pressure vessels joints in a single/tandem submerged are welding process. In a second aspect, the invention provides an improved method of cold wire addition in a welding process for hardfacing of dissimilar fillers in a two-wire submerged are welding process The invention provides a new configuration of the wire feeder, which enables feeding of multi wire simultaneously in the same wire feeder in different feed rate for different current rating. This new wire feeder substantially enhances the production rate as compared to the conventional submerged arc welding process. An integral shaft is designed and interfaced with the available DC wire feeder for coupling the additional wire feeder for feeding the cold wire in the arc cavity in SAW process. With this new wire feeder the cold wire addition can be provided in both direction of welding. This results additional weld deposit with same in-put heat energy available in the arc zone. Additional power source and control system is not required for this new design of wire feeder. This new wire feeder can be interfaced with the existing type of SAW machine. According to the invention, single weld pool is created in which the required weld chemistry is obtained by the use of three wires of same chemistry.

Title of Invention

AN IMPROVED METHOD OF COLD WIRE ADDITION IN LONG STEM BUTT WELDING OF PRESSURE VESSELS

Abstract

Accordingly there is provided in one aspect of the invention, an improved method of cold wire addition for pressure vessels joints in a single/tandem submerged are welding process. In a second aspect, the invention provides an improved method of cold wire addition in a welding process for hardfacing of dissimilar fillers in a two-wire submerged are welding process The invention provides a new configuration of the wire feeder, which enables feeding of multi wire simultaneously in the same wire feeder in different feed rate for different current rating. This new wire feeder substantially enhances the production rate as compared to the conventional submerged arc welding process. An integral shaft is designed and interfaced with the available DC wire feeder for coupling the additional wire feeder for feeding the cold wire in the arc cavity in SAW process. With this new wire feeder the cold wire addition can be provided in both direction of welding. This results additional weld deposit with same in-put heat energy available in the arc zone. Additional power source and control system is not required for this new design of wire feeder. This new wire feeder can be interfaced with the existing type of SAW machine. According to the invention, single weld pool is created in which the required weld chemistry is obtained by the use of three wires of same chemistry.

Full Text	-2- FIELD OF THE INVENTION The invention relates to a process for cold wire addition using cold wire feeder for butt joint of pressure vessels/structural/hardfacing of different combination of filler wires using single/twin/tandem wire submerged arc welding applications. More particularly, the present invention relates to an improved method of cold wire addition for long stem butt welding for pressure vessels joints in a single/tandem submerged arc welding process. BACK GROUND OF THE INVENTION The existing cold wire addition process essentially characterized by the use of one additional wire feeder with out any power source is interfaced with the existing wire feeder control system for controlling the wire feed rate. A single wire feeder along with the main wires, feeds the cold wires simultaneously. The wires in the contact nozzles are disposed tangentially in respect of the welding direction. In conventional SAW process the heat energy are distributed in such way that only 20-25% as consumed for melting the filler wire, the rest being utilized in melting the flux, super heating the molten weld pool and melting the parent plate. It is therefore a high dilution process with approximately twice as much plates are being melted as wire. This cold wire addition is one of the advanced technique to make use of excess energy available in the arc cavity for addition of filler material in the form of wire. With addition of cold wire, the excess heat energy is used efficiently for melting the wire. The addition of'cold wire* in the arc stream -3- can increase the deposition rate. Thus, the addition of cold wire ensures increased transfer efficiency compared to other method. This results in a highest usable melting rate for a given arc energy and unwanted heat which causes heavy penetration, unfavorable microstructures, high shrinkages and distortion. Thus the prior art cold wire addition technique will results in 40% increase in deposition rate and better mechanical properties over conventional single Tandem submerged arc welding process. In current practice, addition of cold wire warrants interfacing one additional wire feeder along with main wire feeder with control system to attain the required chemistry and mechanical properties. US patent 4,572,936 discloses a submerged arc multiple wire welding system in which only one or two of the plurality welding wires used constitute over or microalloyed wires. The other wires are commercially available unalloyed or low-alloyed solid wires. The process produces a weld metal which has unexpectedly high toughness values, and can be performed more economically. This multiple wire welding system is used in single or multiple-pass welding operations . This process, although constitutes a multiple wire system, the step of feeding the wires is accomplished by using different power sources and different wire feeders as mentioned in the Examples 1 to 4 of the cited prior art. According to Che disclosure, the first wire is connected to 810 A at 30 V, the second wire is connected at 790 A at 33 V, and the third wire is connected to 680 A at 34 V. The cited invention further discloses that, a similar wire combination is fed using a single wire feeder with two nozzle drawing power from a single power source with parameters of 750 A, 32 V, 0.4 m/min as the welding speed. -4-OBJECTS OF THE INVENTION It is therefore, an object of the present invention to provide an improved method of cold wire addition for long stem butt welding for pressure vessel joints in a single wire, tandem submerged arc welding process, which reduces cycle time and consumables. Another object of the present invention is to provide an improved method of cold wire addition for butt or fillet joint for, pressure vessels, in a two-wire submerged arc welding process. A further object of the present invention is to provide an improved method of cold wire addition in a welding process for hardfacing of dissimilar fillers in a two-wire submerged arc welding process which is capable of creating a common weld pool to attain required chemistry according to the code of highest quality welds, and which achieves considerable manufacturing economics. SUMMARY OF THE INVENTION Accordingly there is provided in one aspect of the invention, an improved method of cold wire addition for pressure vessels joints in a single/tandem submerged arc welding process. In a second aspect, the invention provides an improved method of cold wire addition in a welding process for hardfacing of dissimilar fillers in a two-wire submerged arc welding process The invention provides a new configuration of the wire feeder, which enables feeding of multi wire simultaneously in the same wire feeder in different feed rate for different current rating. This new wire feeder substantially enhances the -5- production rate as compared to the conventional submerged arc welding process. An integral shaft is designed and interfaced with the available DC wire feeder for coupling the additional wire feeder for feeding the cold wire in the arc cavity in SAW process. With this new wire feeder the cold wire addition can be provided in both direction of welding. This results additional weld deposit with same in-put heat energy available in the arc zone. Additional power source and control system is not required for this new design of wire feeder. This new wire feeder can be interfaced with the existing type of SAW machine. According to the invention, single weld pool is created in which the required weld chemistry is obtained by the use of three wires of same chemistry. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING Fig. 1 is prospective view of the improved method of cold wire addition in Tandem submerged arc welding for long seam butt welding of pressure vessel components according to the present invention. DETAILED DESCRIPTION OF THE INVENTION The improved method of cold wire addition technology can be adapted to conventional tandem submerged arc welding machine. By this method, a same composition (1) of filler materials and weld metal combination can be used effectively. The construction of special tandem wire feeding (2) and integral shaft -6- (3) assembly is shown in Fig. 1. A similar wire combination (1,1) is fed using a single wire feeder (2) with two nozzles (4) drawing power from a first power source (6) with a parameters of 750 A, 32 V in DC, and a third wire (5) is fed through a second power source (7) with 650A, 30V in AC and 0.4 m/min as welding speed. A single weld pool (8) is created in which the required weld chemistry is obtained by the use of three wires (1,1,5) of same chemistry. In this technique, to attain the required hardness properties including the required microstructure of the weld metal, the tandem wire with cold wire submerged arc welding is adapted, in which the common arc pool (8) is created. In the arc cavity, the fillers (1,1) with same chemical composition of same alloy wires are fed simultaneously via a single wire feeder (2) with the two nozzles (4) using the first power source (6). The direction of welding (9) is shown in Fig 1. i.e., one after another which creates the common weld pool to give the desired weld properties. This new method enables carrying out welding /surfacing in grooves having width of different sizes. The new method of tandem with cold wire addition can further be adapted for drum butt welding for long seam butt welding including cir-seam butt welding of pressure vessels components of different sizes. This method can also be used for both manual as well as for mechanized mode. The method results in savings in consumables cost and cycle time and improved mechanical properties. -7-WE CLAIM: 1. An improved method of cold wire addition for long stem butt welding for pressure vessels joints in a single/tandem submerged arc welding process, the method comprising the steps of: - providing an integral shaft (3) being interfaced with a wire feeder (2), having at least two nozzles (4); - simultaneously feeding a similar wire-combination of two wires (1,1) via the wire feeder (2), the at least two nozzles (4) of the wire feeder (2) drawing power from a first power source; - feeding a third wire (5) via a second power source (7), and; - creating a common arc pool (8) by adapting the tandem wire with cold wire submerged arc welding. 2. The method as claimed in claim 1, wherein the three wires (1,1,5) of same chemistry are used. 3. The method as claimed in claim 1, wherein the first power source (6) comprises operating parameters for example, 750A, 32V DC, and wherein the second power source (7) comprises operating parameters for example, 650A, 30V AC. 4. The method as claimed in claim 1 or 3, wherein the welding speed of the third wire (5) is about 0.4m/ min. -8- 5. The method as claimed in claim 1 wherein said weld pool is analytically neutral. 6. The method as claimed in claim 1 wherein the produced weld metal structure comprises a high proportion acicular structure. 7. The method as claimed in claim 1 wherein the surface proportions of the acicular is 100 percent. 8. The method as claimed in claim 1 wherein a single pass welding is performed. Dated this 11th day of JANUARY 2007 Accordingly there is provided in one aspect of the invention, an improved method of cold wire addition for pressure vessels joints in a single/tandem submerged arc welding process. In a second aspect, the invention provides an improved method of cold wire addition in a welding process for hardfacing of dissimilar fillers in a two-wire submerged arc welding process The invention provides a new configuration of the wire feeder, which enables feeding of multi wire simultaneously in the same wire feeder in different feed rate for different current rating. This new wire feeder substantially enhances the production rate as compared to the conventional submerged arc welding process. An integral shaft is designed and interfaced with the available DC wire feeder for coupling the additional wire feeder for feeding the cold wire in the arc cavity in SAW process. With this new wire feeder the cold wire addition can be provided in both direction of welding. This results additional weld deposit with same in-put heat energy available in the arc zone. Additional power source and control system is not required for this new design of wire feeder. This new wire feeder can be interfaced with the existing type of SAW machine. According to the invention, single weld pool is created in which the required weld chemistry is obtained by the use of three wires of same chemistry.

Full Text

-2-
FIELD OF THE INVENTION
The invention relates to a process for cold wire addition using cold wire feeder for butt joint of pressure vessels/structural/hardfacing of different combination of filler wires using single/twin/tandem wire submerged arc welding applications. More particularly, the present invention relates to an improved method of cold wire addition for long stem butt welding for pressure vessels joints in a single/tandem submerged arc welding process.
BACK GROUND OF THE INVENTION
The existing cold wire addition process essentially characterized by the use of one additional wire feeder with out any power source is interfaced with the existing wire feeder control system for controlling the wire feed rate. A single wire feeder along with the main wires, feeds the cold wires simultaneously. The wires in the contact nozzles are disposed tangentially in respect of the welding direction. In conventional SAW process the heat energy are distributed in such way that only 20-25% as consumed for melting the filler wire, the rest being utilized in melting the flux, super heating the molten weld pool and melting the parent plate. It is therefore a high dilution process with approximately twice as much plates are being melted as wire. This cold wire addition is one of the advanced technique to make use of excess energy available in the arc cavity for addition of filler material in the form of wire. With addition of cold wire, the excess heat energy is used efficiently for melting the wire. The addition of'cold wire* in the arc stream

-3-
can increase the deposition rate. Thus, the addition of cold wire ensures increased transfer efficiency compared to other method. This results in a highest usable melting rate for a given arc energy and unwanted heat which causes heavy penetration, unfavorable microstructures, high shrinkages and distortion. Thus the prior art cold wire addition technique will results in 40% increase in deposition rate and better mechanical properties over conventional single Tandem submerged arc welding process. In current practice, addition of cold wire warrants interfacing one additional wire feeder along with main wire feeder with control system to attain the required chemistry and mechanical properties.
US patent 4,572,936 discloses a submerged arc multiple wire welding system in which only one or two of the plurality welding wires used constitute over or microalloyed wires. The other wires are commercially available unalloyed or low-alloyed solid wires. The process produces a weld metal which has unexpectedly high toughness values, and can be performed more economically. This multiple wire welding system is used in single or multiple-pass welding operations .
This process, although constitutes a multiple wire system, the step of feeding the wires is accomplished by using different power sources and different wire feeders as mentioned in the Examples 1 to 4 of the cited prior art. According to Che disclosure, the first wire is connected to 810 A at 30 V, the second wire is connected at 790 A at 33 V, and the third wire is connected to 680 A at 34 V.
The cited invention further discloses that, a similar wire combination is fed using a single wire feeder with two nozzle drawing power from a single power source with parameters of 750 A, 32 V, 0.4 m/min as the welding speed.

-4-OBJECTS OF THE INVENTION
It is therefore, an object of the present invention to provide an improved method of cold wire addition for long stem butt welding for pressure vessel joints in a single wire, tandem submerged arc welding process, which reduces cycle time and consumables.
Another object of the present invention is to provide an improved method of cold wire addition for butt or fillet joint for, pressure vessels, in a two-wire submerged arc welding process.
A further object of the present invention is to provide an improved method of cold wire addition in a welding process for hardfacing of dissimilar fillers in a two-wire submerged arc welding process which is capable of creating a common weld pool to attain required chemistry according to the code of highest quality welds, and which achieves considerable manufacturing economics.
SUMMARY OF THE INVENTION
Accordingly there is provided in one aspect of the invention, an improved method of cold wire addition for pressure vessels joints in a single/tandem submerged arc welding process. In a second aspect, the invention provides an improved method of cold wire addition in a welding process for hardfacing of dissimilar fillers in a two-wire submerged arc welding process
The invention provides a new configuration of the wire feeder, which enables feeding of multi wire simultaneously in the same wire feeder in different feed rate for different current rating. This new wire feeder substantially enhances the

-5-
production rate as compared to the conventional submerged arc welding process. An integral shaft is designed and interfaced with the available DC wire feeder for coupling the additional wire feeder for feeding the cold wire in the arc cavity in SAW process. With this new wire feeder the cold wire addition can be provided in both direction of welding. This results additional weld deposit with same in-put heat energy available in the arc zone. Additional power source and control system is not required for this new design of wire feeder. This new wire feeder can be interfaced with the existing type of SAW machine.
According to the invention, single weld pool is created in which the required weld chemistry is obtained by the use of three wires of same chemistry.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
Fig. 1 is prospective view of the improved method of cold wire addition in Tandem submerged arc welding for long seam butt welding of pressure vessel components according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The improved method of cold wire addition technology can be adapted to conventional tandem submerged arc welding machine. By this method, a same composition (1) of filler materials and weld metal combination can be used effectively. The construction of special tandem wire feeding (2) and integral shaft

-6-
(3) assembly is shown in Fig. 1. A similar wire combination (1,1) is fed using a single wire feeder (2) with two nozzles (4) drawing power from a first power source (6) with a parameters of 750 A, 32 V in DC, and a third wire (5) is fed through a second power source (7) with 650A, 30V in AC and 0.4 m/min as welding speed. A single weld pool (8) is created in which the required weld chemistry is obtained by the use of three wires (1,1,5) of same chemistry. In this technique, to attain the required hardness properties including the required microstructure of the weld metal, the tandem wire with cold wire submerged arc welding is adapted, in which the common arc pool (8) is created. In the arc cavity, the fillers (1,1) with same chemical composition of same alloy wires are fed simultaneously via a single wire feeder (2) with the two nozzles (4) using the first power source (6). The direction of welding (9) is shown in Fig 1. i.e., one after another which creates the common weld pool to give the desired weld properties.
This new method enables carrying out welding /surfacing in grooves having width of different sizes. The new method of tandem with cold wire addition can further be adapted for drum butt welding for long seam butt welding including cir-seam butt welding of pressure vessels components of different sizes. This method can also be used for both manual as well as for mechanized mode. The method results in savings in consumables cost and cycle time and improved mechanical properties.

-7-WE CLAIM:
1. An improved method of cold wire addition for long stem butt welding for
pressure vessels joints in a single/tandem submerged arc welding process,
the method comprising the steps of:
- providing an integral shaft (3) being interfaced with a wire feeder
(2), having at least two nozzles (4);
- simultaneously feeding a similar wire-combination of two wires
(1,1) via the wire feeder (2), the at least two nozzles (4) of the
wire feeder (2) drawing power from a first power source;
- feeding a third wire (5) via a second power source (7), and;
- creating a common arc pool (8) by adapting the tandem wire with
cold wire submerged arc welding.

2. The method as claimed in claim 1, wherein the three wires (1,1,5) of
same chemistry are used.
3. The method as claimed in claim 1, wherein the first power source (6)
comprises operating parameters for example, 750A, 32V DC, and wherein
the second power source (7) comprises operating parameters for
example, 650A, 30V AC.
4. The method as claimed in claim 1 or 3, wherein the welding speed of the third wire (5) is about 0.4m/ min.

-8-
5. The method as claimed in claim 1 wherein said weld pool is analytically
neutral.
6. The method as claimed in claim 1 wherein the produced weld metal structure
comprises a high proportion acicular structure.
7. The method as claimed in claim 1 wherein the surface proportions of the
acicular is 100 percent.
8. The method as claimed in claim 1 wherein a single pass welding is performed.
Dated this 11th day of JANUARY 2007

Accordingly there is provided in one aspect of the invention, an improved method of cold wire addition for pressure vessels joints in a single/tandem submerged arc welding process. In a second aspect, the invention provides an improved method of cold wire addition in a welding process for hardfacing of dissimilar fillers in a two-wire submerged arc welding process
The invention provides a new configuration of the wire feeder, which enables feeding of multi wire simultaneously in the same wire feeder in different feed rate for different current rating. This new wire feeder substantially enhances the

production rate as compared to the conventional submerged arc welding process. An integral shaft is designed and interfaced with the available DC wire feeder for coupling the additional wire feeder for feeding the cold wire in the arc cavity in SAW process. With this new wire feeder the cold wire addition can be provided in both direction of welding. This results additional weld deposit with same in-put heat energy available in the arc zone. Additional power source and control system is not required for this new design of wire feeder. This new wire feeder can be interfaced with the existing type of SAW machine.
According to the invention, single weld pool is created in which the required weld chemistry is obtained by the use of three wires of same chemistry.

Documents:

00039-kol-2007 correspondence.pdf

00039-kol-2007 form-18.pdf

0039-kol-2007 abstract.pdf

0039-kol-2007 assignment.pdf

0039-kol-2007 claims.pdf

0039-kol-2007 correspondence others.pdf

0039-kol-2007 description(complete).pdf

0039-kol-2007 drawings.pdf

0039-kol-2007 form-1.pdf

0039-kol-2007 form-2.pdf

0039-kol-2007 form-3.pdf

39-KOL-2007-(26-03-2012)-AMANDED CLAIMS.pdf

39-KOL-2007-(26-03-2012)-CORRESPONDENCE.pdf

39-KOL-2007-(28-09-2011)-ABSTRACT.pdf

39-KOL-2007-(28-09-2011)-AMANDED CLAIMS.pdf

39-KOL-2007-(28-09-2011)-DESCRIPTION(COMPLETE).pdf

39-KOL-2007-(28-09-2011)-DRAWINGS.pdf

39-KOL-2007-(28-09-2011)-EXAMINATIONREPORTREPLYRECIEVED.pdf

39-KOL-2007-(28-09-2011)-FORM 1.pdf

39-KOL-2007-(28-09-2011)-FORM 2.pdf

39-KOL-2007-(28-09-2011)-FORM 3.pdf

39-KOL-2007-(28-09-2011)-OTHERS.pdf

39-KOL-2007-(29-02-2012)-CORRESPONDENCE.pdf

abstract-00039-kol-2007.jpg

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Patent Number

256510

Indian Patent Application Number

39/KOL/2007

PG Journal Number

26/2013

Publication Date

28-Jun-2013

Grant Date

26-Jun-2013

Date of Filing

11-Jan-2007

Name of Patentee

BHARAT HEAVY ELECTRICALS LIMITED

Applicant Address

REGIONAL OFFICE- REGIONAL OPERATIONS DIVISION(ROD), PLOT NO: 9/1, DJ BLOCK, 3RD FLOOR, KARUNAMOYEE, SALT LAKE CITY, KOLKATA-700091 REGISTERED OFFICE- BHEL HOUSE, SIRI FORT, NEW DELHI-110049

Inventors:

#	Inventor's Name	Inventor's Address
1	MANNAR SAMY RAMAKRISHNAN	WELDING RESEARCH INSTITUTE, BHARAT HEAVY ELECTRICALS LIMITED, TIRUCHIRAPPALLI-620014
2	GANAPATHY UMASHANKER	WELDING RESEARCH INSTITUTE, BHARAT HEAVY ELECTRICALS LIMITED, TIRUCHIRAPPALLI-620014
3	KRISHNA SAMY PADMANABAN	WELDING RESEARCH INSTITUTE, BHARAT HEAVY ELECTRICALS LIMITED, TIRUCHIRAPPALLI-620014

PCT International Classification Number

B21K1/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA