Economics of Advanced Welding Techniques

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March 28, 2013

Economics of Advanced
Welding Techniques

Stephen Levesque

Director, EWI Nuclear Fabrication Center

Email:
slevesque@ewi.org


Office: 614
-
688
-
5183

Mobile: 614
-
284
-
5426

Nuclear Fabrication Consortium


Some information in this presentation was based
upon research funded by the US Department of
Energy through the Nuclear Fabrication Consortium
(operated by EWI)


The Nuclear Fabrication Consortium (NFC) was
established to independently develop fabrication
approaches and data that support the re
-
establishment of a vibrant US nuclear industry


Overview



Laser Welding


Process description (Laser and Hybrid Laser Technologies)


Potential applications


Cost benefit


Friction Stir Welding


Process description


Potential applications


Cost benefit


Cladding Technologies


Comparison of various technologies


Tandem GMAW (bonus)




Laser Welding

Laser Background


Solid
-
state laser technology is rapidly
advancing


Output powers are continuously increasing


Price per kilowatt is dropping

(~$750K for 20
-
kW)


Improved portability and electrical efficiency


Improved beam quality


fiber deliverable


Two laser technologies primarily

responsible


Fiber Laser (IPG Photonics)


Disk Laser (
Trumpf
)


ROI for laser processing is becoming

more attractive


Cost/watt, cycle time, penetration, distortion


Advantages and Challenges


The main advantages of laser

processing include:


High productivity


Low heat input


Minimal distortion


Some challenges include:


Critical joint preparation due to

limited gap bridging


Increased capital cost compared to

traditional arc
-
welding equipment


0.005
-
in
. gap

0.010
-
in.
gap

0.015
-
in.
gap

General Terminology


Autogenous Laser Welding

Shielding
gas

Laser Beam

Laser
-
Induced
Vapor
Plume

Laser
Keyhole
or
Vapor
Cavity

Liquid
Weld
Pool

Solidified
Weld Metal

General Terminology


Hybrid Laser
-
Arc Welding (Hybrid Welding)


The combination of two welding processes in the same weld
pool


Most often GMAW and Laser Welding


Laser Beam

GMAW Torch

“Arc
-
Leading” HLAW

“Laser
-
Leading” HLAW

Hybrid Terminology


The HLAW process can be used in two orientations:


High
-
level cost model built by EWI


Assumes 1 min. of arc time for GTAW and 2 sec. of laser time
per tube


Varied process efficiency to evaluate the ROI



$0
$50,000
$100,000
$150,000
$200,000
$250,000
$300,000
$350,000
$400,000
$450,000
$500,000
$550,000
0
20000
40000
60000
80000
100000
Estimated Cost

Number of Tubes

2kW Laser @ 50%
Manual GTAW @ 50%
Orbital GTAW @ 75%
Robotic GTAW @ 80%
Laser Tube Sheet Welding

Laser Tube Sheet Welding

Containment Welding


Hybrid Laser
-
GMAW welding vs.

Tandem GMAW vs.
Submerged Arc Welding

Productivity


For one
weldment

X long

"10"
50
-
in
Parts

"
10" 200
-
in
Parts

Hours

SAW

11

27

Tandem

8

18

HLAW

15

16

Includes setup time
and weld time

Cost Comparison

"10" 60
-
in
Parts

"
10" 200
-
in
Parts

Dollars

SAW

$48k

$124k

Tandem

$38k

$84k

HLAW

$69k

$72k


For one
weldment

X long

Equipment

Cost

SAW

$55k

Tandem

$150k

HLAW

$950k

Includes setup
time/weld time
(@$75/
hr
) and filler
metal cost

Combined Comparison Data

200
-
in

Other Benefits


Peak Temperature Models showing reduction in heat
input

SAW

GMAW
-
T

HLAW

Distortion and Residual Stress

SAW

Tandem

HLAW

Friction Stir Welding

Friction Stir Welding


Invented by TWI in 1991


Wayne Thomas


Solid
-
state joining process


No bulk melting of the substrate


Capable of joining


Aluminum, Magnesium, Copper, Steel, Titanium, Nickel,
many more


Non
-
consumable tool rotates and traverses along
a joint


Combination of frictional heating and strain causes
dynamic recrystallization


Adiabatic heating


Creates a very fine grain microstructure


Low distortion


Excellent weld properties


Friction Stir Welding Variables


Essential FSW variables


Vertical (Forge) force, F
z


RPM,



Travel (Traverse) speed, V
f


Process forces


Travel (Traverse) force, F
x


Cross (Transverse) force, F
y


Vertical (Forge) force, F
z

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

F
x
F
y
F
z
V
f

Ref: Arbegast, William J., "Week 2 Friction Stir Joining: Process Optimization." (2003).

Friction Stir Welding

Local Clamp

FSW Tool

Main Spindle

Fixturing

FSW Economics


FSW of Aluminum


15% reduction in man
-
hour per ton rate in aluminum panel
fabrication


Hydro Aluminum


Total fabrication savings of 10% in shipbuilding
-

Fjellstrand


60% cost savings on Delta II and IV rockets


Boeing


400% improvement in cycle time for fabricating 25mm thick
plates


General Dynamics Land Systems


FSW of Steel Pipeline


Estimated cost savings


Onshore construction, 7%


Offshore construction (J
-
Lay), 25%

-
Kallee
, S. W. (2010). Industrial Applications of Friction Stir Welding. In D.
Lohwasser
, & Z. Chen,
Friction Stir Welding From Basics to

Applications

(pp. 118
-
163). Boca Raton: CRC Press.

-
Kumar, A., Fairchild, D. P.,
Macia
, M., Anderson, T. D., Jin, H. W., Ayer, R., . . . Mueller, R. R. (2011). Evaluation of Economic

Incentives and Weld Properties for Welding Steel Pipelines Using Friction Stir
Welding.
Proceedings

of the Twenty
-
first (2011)

INternational

Offshore and Polar Engineering Conference

(pp. 460
-
467). Maui: ISOPE.


FSW of Steel Cost Model


Assumptions


Plain carbon steel


Simple butt joint configuration


Use of EWI
DuraStir
™ tools


Machine and
fixturing

purpose built for assumed application


Range of thicknesses


3, 6, 9, 12, 16, 19 mm


Broken down in terms of cost/meter based upon weld length
achievable each month

FSW Cost Summary

Cost Summary



















Thickness



3.00 (mm)

6.00 (mm)

9.00 (mm)

12.00 (mm)

16.00 (mm)

19.00 (mm)



















Production Costs:



$246.31/m

$307.24/m

$373.45/m

$444.94/m

$531.46/m

$613.51/m

Fixed Costs:



$18.12/m

$21.44/m

$27.94/m

$28.31/m

$40.52/m

$53.20/m

Variable Costs:



$36.46/m

$41.32/m

$62.65/m

$83.29/m

$127.46/m

$306.23/m



















Total Cost Per Meter:

$300.88/m

$370.00/m

$464.05/m

$556.55/m

$699.44/m

$972.94/m

Cladding

Introduction


Many process options exist for weld cladding

and
hardfacing



A number of factors should be considered when
selecting a process:


Desired deposition rate


Required dilution level


Welding position


Component size/geometry


Method of application


Manual/semi
-
automatic


Mechanized


Automated


Welder/operator skill


Alloy/material to be

deposited


Equipment cost

Available Processes for
Surfacing Include



Thermal spray


Resistance
cladding


Laser
cladding


Gas
tungsten arc welding (GTAW
)


Plasma
arc
welding (PAW)


Gas metal arc welding (GMAW)


Submerged arc welding (SAW)


Single and multi
-
wire SAW


Submerged arc strip cladding


Electroslag strip cladding


Explosion
welding


Resistance Cladding


Uses Simple off the shelf sheet material and may use
interlayers to make a fusion type weld between CRA
and Pipe


Can make the clad weld in one pass


Uses sheet metal consumables which are much
lower cost than wire consumables


Post weld surface finish should meet customer
requirements


No dilution of base metal into CRA surface


Resistance Cladding

Current Cladding Techiques


Explosive Welding $$$$


Requires post cladding longitudinal seam weld which impacts
fatigue


Roll Bonding


Requires post clad longitudinal seam weld


GMAW / GTAW / SAW welding


Processing time intensive with
inspectability

issues


Liner Expansion (lowest cost)


Risk of liner buckling is concerning to customers during
installation or dynamic lines


Resistance Cladding


Cost comparison

0
20
40
60
80
100
120
CRA Piping
Expanded Liner Pipe
Roll Bonded Pipe
RSEW Pipe
Normalized Price Per Unit

Tandem GMAW

Bonus Material

Why Use Tandem GMAW?


Improve Productivity and
Quality


Increased deposition rates


Faster travel speeds


Maintain or improve overall
weld quality, gap filling
capability



Deposition rate (lbs/hr)

Image courtesy of Lincoln Electric

Example


5.25
-
in.
-
thick test joint


0.5
-
in.wide groove


2
°

included angle


Travel speed: 15 ipm


Heat input: 46 kJ/in.


Single bead per layer


27 passes required to fill
4.5 in.


Fill height per pass ≈ 0.17 in.


Clean UT results