1Fronius USA / Mike Ludwig / AWS Shipbuilding Conference 2011 / xx.xx.201x Using the Time Twin...

1 Fronius USA / Mike Ludwig / AWS Shipbuilding Conference 2011 / xx.xx.201x

Using the Time Twin Process to Improve Quality and Reduce Costs in High Deposition

Welding of Thick Section Aluminium

Mike Ludwig

Market Segment Manager Shipbuilding & Power Generation

Fronius USA - Welding Division


Outline

/ Introduction

/ Technical Requirements

/ Approach

/ Results

/ Conclusions


Acknowledgements

/ Work done by Fronius International R&D Group

/ Contributors:

/ Christoph Kammerhuber, International Shipbuilding Segment Manager

/ Stephen Egerland, International Pipeline/Offshore Segment Manager


Liquefied Natural Gas (LNG)

/ Increasing importance of Natural Gas in Energy Sector

/ Storage a/o transport over long distances

/ Significant volume reduction by liquefaction

/ Approximately 1/600 of the original volume at temperatures of approx. – 162°C

/ Different methods to transport LNG


Liquefied Natural Gas Containment Vessels (LNG)

/ Excellent method for LNG long distance transport

/ Globally applicable

/ Economically reasonable due to increasing storage capacities

/ Great engineering expertise and capital equipment for vessel construction

Source: Hyundai Heavy Industries


LNG Vessel Construction Principles

Sphere (Moss Type) Membrane

© TOSAKA


LNG Carrier – Membrane Containment Type

/ Base Material: 64FeNi (Invar 36©)/ Filler Material: NiMo28Fe4Cr (~ S

Ni1069 acc. to DIN EN ISO 18274)/ Peculiarities:/ Welding Process: Plasma Arc

Welding (PAW) and Gas Tungsten Arc Welding (GTAW)

/ ‘Difficult‘ to weld (Highly skilled welders needed)

/ Heat Input to be monitored accurately

/ Leak detection difficult to perform


SPB > Self-supporting Prismatic-shape IMO B


SPB > Self-supporting Prismatic-shape IMO B

/ Intermediate principle between Membrane and Spherical Type

/ Aluminum Alloy Construction

/ Wall Thickness: 25 mm≦

/ Benefits:/ Good Hull Stability/ Low Centre of Gravity/ Low Boil-Off Rate/ Good Maintenance Conditions


LNG Carrier – Spherical Containment Type

/ Spheres as LNG Containments

/ Construction is based on the Kvaerner-Moss Type Principle

/ Aluminum alloys are used as base materials

/ Four-Tank Design for Cargo Operation Improvement

/ Storage Capacity slightly below Membrane Containments

Source: KAWASAKI Heavy Industries

© TOSAKA


LNG Sphere Containment Construction

/ Benefits:/ Manufacturing may occur separately to

hull-construction

/ Increased use of semi-automated welding processes

/ Higher production rates

/ Improved test and repair conditions Source: KAWASAKI Heavy Industries


Outline

/ Introduction


/ Approach

/ Results

/ Conclusion


It was required to...

/ Improve welding process conditions:/ Improve weld quality/ Increase process efficiency/ Reduce production costs

/ Investigate High Performance Time Twin MIG Welding to replace manual MIG Welding and make Time Twin suitable for out-of-position welding applications in LNG Sphere Containment Manufacturing

Source: KAWASAKI Heavy Industries


Project Goals:

/ To investigate and evaluate the welding of thick section Aluminium using the MIG single wire & Twin Time (Tandem) welding process in common welding positions and under common welding process conditions

/ To develop and design a special Single & Tandem Torch for the welding in reduced weld preparation on thick section Aluminium


Outline

/ Introduction


/ Approach

/ Results

/ Conclusion


From where we got started...

/ Traditional manual MIG Welding/ Usual wire diameters (1.6 mm)/ Highly Skilled Welders

/ Push-Pull Torches required/ CV Spray Arc / Quality limitations


Equipment for single wire MIG welding trials

TPS 7200/9000 Welding System

Robacta Drive Torch

RCU 5000i


Semi-Automatic single wire MIG welding

/ Filler Wire: AA 5183 (AlMg4,5Mn) 2,0mm/ Base Material: AA 5356 (AlMg5)/ Dimension: 500 x 250 x 30mm

/ (no preheating permitted)

/ Shielding Gas: Ar70/He30/ Welding Speed: 40/45 cm/min/ Welding Position: 1 F / Two layers

/ second layer > two weld beads





/ Shielding Gas: Ar70/He30/ Welding Speed: 40/40 cm/min/ Welding Position: 1 F / Two layers

/ second layer > oscillated





/ Shielding Gas: Ar70/He30/ Welding Speed: 22,5 cm/min/ Welding Position: 2 F / One layer


Semi-Automated Single Wire MIG-Welding

/ New developed torch parts (gas nozzle, contact tip, wear parts)

/ Filler Wire: AA 5183 (AlMg4,5Mn) 2.0 mm

/ Base Material: AA 5356 (EN AW AlMg5)/ Dimensions: 500 x 250 x 35 mm

/ (no preheating permitted)/ Shielding Gas: Ar70/He30/ Welding Position: 2G / Welding Speed: 60 cm/min/ Especially developed Welding

Characteristic


Fully-Automatic single wire MIG welding



/ Shielding Gas: 100% Ar./ Welding Speed: 25cm/min/ Welding Position: 2 F / One layer > oscillated



/ Filler Wire: AA 5183 (AlMg4,5Mn) 1,6mm/ Base Material: AA 5356 (AlMg5)/ Dimension: 500 x250 x 15mm


/ Shielding Gas: 100% Ar./ Welding Speed: 22,5 cm/min/ Welding Position: 3 F Vertical up/ One layer > oscillated



/ Filler Wire: AA 5183 (AlMg4,5Mn) 2,4mm/ Base Material: AA 5083 (AlMg4,5Mn)/ Dimension: 500 x 150 x 25mm


/ Shielding Gas: Ar70/He30/ Welding Speed: 60/40 cm/min/ Welding Position: 1 F / four layers > 8 weld beads



/ Filler Wire: AA 5183 (AlMg4,5Mn) 2,4mm/ Base Material: AA 5083 (AlMg4,5Mn)/ Dimension: 500 x 150 x 25mm


/ Shielding Gas: Ar70/He30/ Welding Speed: 38 cm/min/ Welding Position: 1 G / Two layers > oscillated

/ one layer from each side





/ Shielding Gas: Ar70/He30/ Welding Speed: 60/40 cm/min/ Welding Position: 1 G / Two layers

/ second layer > oscillated


Metallographic Results of Single Wire MIG Welding Trials

Position 2G Position 3G


Single Wire MIG Welding Procedure: 3G-Position


2006 – The very first humble steps in Single-Wire MIG Welding / Manual welding torch on ‘quasi-similar‘ joint

geometry/ Wire diameter: AA 5183 ( 1.6 mm)/ Base material: AA 6061 (AlMgSi) / Thickness: 15 mm


... and the results


Next Step – Fundamental Investigations on Manual MIG


The Tool and the Outcome


Outline

/ Introduction


/ Approach

/ Twin Welding

/ Conclusion


Time Twin – Tandem High Performance MIG Welding

LHSBLHSB

*LHSB = Local High Speed Bus

/ Fully Synchronised welding system.

/ 2 digital power sources/ 2 wire feeders/ 2 separate electrode potentials/ 1 high duty cycle welding torch / All linked by a high speed bus


Equipment

Oscillation Unit

Tripod Unit

Time Twin Welding System

Time Twin Torch

RCU 5000i


Time Twin High Performance Tandem Welding System

/ Commercially available Tandem Welding System

/ Especially shaped gas nozzle / Varying arc-gaps during the weld trial

series/ Column and Boom System for

mechanized torch motion/ Implementation of weaving motion / Trials started under using regular welding

characteristic


Specific LNG Containment Narrow Gap Weld Sequence

/ Specifically developed for LNG sphere containment heavy wall applications

/ Considerable reduction of weld metal deposition rate

/ Considerable reduction of operation time

/ Limited suitability for semi-automated welding processes


Modified Narrow Gap Design

Diagram with permission of Norrish, J. – ‘Advanced Welding Processes‘, © IOP Publishing 1992


Tandem Welding – Electromagnetic Interferences

Source: UEYAMA, T., ‘Occurrence of Arc Interference andInterruption in Tandem Pulsed GMA Welding‘ IIW Doc. No. XII-1883-06


Electromagnetic Interference – A Closer View...


Improved Tandem MIG Welding Characteristic


Advanced State of Research and Development

/ Specifically modified narrow gap gas nozzle, contact tips and wear parts

/ Excellent narrow gap root access/ Adjusted tip or arc gap assures high

process stability/ Stable and sound weld pool

controllability/ Appropriate nozzle cooling yields good

resistance against thermal impact


New Developed Narrow Gap Tandem Torch


Time Twin Welding in 3G Position


Reducing the number of layers...

/ Total number of weld layers was required to be reduced from 8 (workshop-condition) down to 6

/ 7 front side + 2 rear side layers were achieved at the trials beginning using Time Twin High Performance welding in 3G-position

/ Continuous reduction of layer number could be obtained by improving welding conditions and -sequence

7 front side layer trial


Final Weld Joint Configuration …


Final Weld Sequence …

60


Variables

/ Filler Wire: AA 5356 (AlMg5) 1,6mm/ Base Material: AA 5356 (AlMg5)/ Dimension: 1000 x 350 x 60mm / Preheating > 60°, interpass temperature 60°/ Shielding Gas: Ar70/He30/ Welding Speed: Target 7.5 ipm/ Welding Position: 3 G / six layers > oscillated


…Pictorial Results

Metallographic Result

Front View Cap Layer1

2

3

4

5

6

Back face


Weld Deposition Rates – 3G-Position Narrow Gap Time Twin Aluminum Welding

Number of Layer/ Weld

Deposition Rate lb/h

Leading ElectrodeWire Feed Speed

m/min

Trailing ElectrodeWire Feed Speed

in/min

Welding Speedin/min

1 / ~ 14.0 433 334 8.6

2 / ~ 10.4 334 236 7.1

3 / ~ 10.8 334 256 7.9

4 / ~ 6.5 197 157 7.1

5 / ~ 10.0 315 236 7.1

6 / ~ 8.6 275 197 7.1


Conclusion

/ LNG aluminum alloy sphere manufacturing requires highest weld quality levels

/ Continuous increase in production rates requires a rise in welding process efficiency

/ Out-of-position single wire MIG GMAW has reached physical limits

/ Time Twin Tandem Welding was shifted towards being usable for out-of-position welding

/ Project requirements to improve quality and efficiency could be met entirely

/ Tailor-made welding power supply welding characteristics were used to cover the complete process range

/ Sophisticated welding torch engineering resolved joint design restrictions

/ Time Twin Process with narrow groove torch equipment proved excellent suitability for similar aluminum welding applications

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1Fronius USA / Mike Ludwig / AWS Shipbuilding Conference 2011 / xx.xx.201x Using the Time Twin...

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