Essential Welding Variable Methodology and Its Application in

Essential Welding Variable Methodology and Its
Application in Welding Procedure Development
for Mechanized Girth Welds of X100 Line Pipes
Yaoshan Chen and Yong-Yi Wang
Center for Reliable Energy Systems
Email: [email protected]
Phone: 614-808-4872
Scott Funderburk
Paul Spielbauer
Marie Quintana
CRC-Evans Pipeline, Houston, TX
Lincoln Electric, Cleveland, OH
March 4, 2014
Business Sensitive – No Distribution without CRES Permission
Presentation Overview
Part 1: Introduction and basics of essential
welding variable methodology (EWVM)
 Part2: How the EWVM was used in its application
to a welding procedure development for girth
welding of X100 pipes with dual-torch pulsed
GMAW

03/4/2014
Application of EWVM to Girth Welding of X100 Pipeline Steels
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2
Part 1: The Essential Welding
Variable Methodology

Why EWVM is needed
 What EWVM is
 What benefits EWVM brigns
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Introduction: The Challenge

High-strength pipeline constructions often require girth
welds with strength overmatching, low-temperature
toughness, and ductility
 For X100 pipeline welds, adequate weld metal strength requires
microstructure of mixed martensite/bainite
 The viable range of welding parameters
for such microstructure with balanced
strength and toughness (both weld metal
and HAZ) is narrower than those for
lower grade steels (X80/X70/X65)
 Applications of high-productivity welding
processes such as dual-torch GMAW-P
further complicate the relationship between
welding parameter and weld properties
03/4/2014
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Sensitivity of Weld Properties to Cooling Time

Weld properties are more sensitive to welding
parameters (cooling times of welding thermal cycles)
380
HAZ Hardness (VHN)
Pipe materials (HAZ)
X80 Pipe Steel
360
X100 Pipe Steel
340
320
300
280
450
260
LA90
240
LA100
400
200
0
10
20
30
40
50
Cooling Time T85 (s)
Weld Metal
60
Hardness (HVN)
220
NiMo80
PT01
PT02
350
300
250
200
0
03/4/2014
10
20
30
40
Cooling Times T85 (s)
Application of EWVM to Girth Welding of X100 Pipeline Steels
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50
60
5
High-Productivity Welding Processes

Dual-torch GMAW process is becoming popular in
pipeline welding
 More welding variables (torch distance, two heat inputs)
 More complex dependency of cooling time on welding parameters
 Longer cooling times T85
40
Single Torch ( Fill Pass 4)
Dual Torch-Trail Torch ( Fill Pass 1)
Cooling Time T85 (s)
30
20
10
0
0
50
100
150
200
250
Preheat/Inter-pass Temperature (oC)
03/4/2014
Application of EWVM to Girth Welding of X100 Pipeline Steels
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Essential Welding Variable Methodology


Focus: establishing essential
welding variables influencing
cooling times T85 of weld
thermal cycles
Two relationships:
 Relationship between welding
process/welding parameters and
cooling rate (time)
 Relationship between
mechanical/microstructure
response of welding materials to
cooling time

03/4/2014
The process: optimize
welding process/welding
parameters to achieve
desired weld mechanical
properties
Welding Materials
Welding Parameters
Gleeble Simulation
Thermal Analysis
Material Responses
Cooling Rate (Time)
Weld Properties
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Application of EWV Methodology
Welding Process and Parameters
Pipe Materials
Thermal Simulation (Gleeble)
T85
Cooling Time Analysis
T85
Weld Metal T85
Thermal Simulation (Gleeble) Essential Welding
Variables
CCT and Charpy Transition Curves
WM/HAZ Properties
03/4/2014
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Optimizing Welding Procedure: X100 HAZ
0
380
HAZ Hardness (VHN)
360
Viable T85 range for HAZ hardness
340
-10
Transition Temperature: X100
-20
320
300
-30
280
-40
260
240
Transition Temperature (oC)
Hardness: X100
-50
220
Viable T85 range for toughness
-60
200
0
10
20
30
40
50
60
Cooling Time (s)
03/4/2014
Application of EWVM to Girth Welding of X100 Pipeline Steels
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Optimizing Welding Procedure

General steps:
Determine desired weld properties: strength and toughness
(depending on, for instance, stress-based design or strainbased design)
Gleeble simulation for material responses (CCT and transition
temperatures of Charpy impact toughness for both HAZ and
weld metal) to cooling times
Determine the range of cooling times from the information of
Steps 1, 2
Identify essential welding variables that:
1.
2.
3.
4.
a)
b)
5.
6.
03/4/2014
Impact the weld properties (cooling time) the most
Can be adjusted within the ranges imposed by practical and
technical consideration on field welding
Adjust the identified essential welding variables through
changes in cooling time toward the desired weld properties
Testing of welds to verify the weld properties and qualification
of the welding procedure
Application of EWVM to Girth Welding of X100 Pipeline Steels
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Potential Benefits of Using EWVM



03/4/2014
Better weld properties and/or higher welding productivity
Reduce turn-around time for welding procedure
development
Understand the variation of weld properties with
tolerance on welding parameters
Application of EWVM to Girth Welding of X100 Pipeline Steels
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Part 2: The Application of EWVM
to Welding Procedure
Development for X100 Line Pipes

Welding procedures for an X100 pipe needed to
be developed under a tight schedule
 Previous work conducted by CRC on X100 type
materials had been on heavier wall thicknesses
03/4/2014
Application of EWVM to Girth Welding of X100 Pipeline Steels
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Application of EWVM To Girth Welding of X100

Pipe materials: X100 line pipes
 Diameter: 1219 mm, wall thickness:12.4 mm, CE=0.27

Consumables: ER110S-G and ER120S-G
 Lincoln Pipeliner 110S-G and Lincoln Pipeliner 120S-G

Welding procedure: dual-torch pulsed GMAW
 Torch distance: 127mm (4.75 in.)

WPS: Joint design and welding sequence by CRC-Evans
Cap passes
C1-DT
F3-ST
F2-DT
C2-DT
Strip pass
Dual-torch passes
F1-DT
H-ST
Hot pass
Root pass
03/4/2014
Application of EWVM to Girth Welding of X100 Pipeline Steels
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Application of EWVM To Girth Welding of X100
CRC Past Experiences
Selection of Candidate Welding Procedures
Customer and Field Welding Needs Analysis of Candidate Welding Procedures
Cooling Times of Welding Thermal Cycles
Estimated WM Hardness and UTS
Further Analysis for Changes in Bevel Angle and Hot Pass Heat Input Final Welding Procedures and Girth Welding with Process Monitoring
Small‐Scale Testing of GW
Measured Welding Parameters
Analysis of Measured Welding Parameters and Verification with Test Results
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Analysis of Candidate Welding Processes

Focus of the analysis:
 Cooling times of candidate welding procedure at different clock-
positions and under different preheat and interpass temperatures
 Estimated hardness and UTS of weld metal


The analysis tool: a predictive tool for welding thermal
cycles and cooling times with given welding parameters
The available information: weld metal CCT of two
consumables
Thermal Model
Welding Parameters
03/4/2014
Weld Metal CCT
Cooling Times
Estimated WM Hardness and UTS
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Cooling Times and Dual-Torch GMAW Characteristics
12.0
much longer than single-wire

Reheating pattern
between welding passes:
10.0
0.5
8.0
0.4
6.0
0.3
4.0
0.2
2.0
0.1
Cooling Time (s)
 Trail torch’s cooling times are
0.6
 Trail torch’s weld metal totally
0.0
0.0
re-melt the lead torch’s and
even more
 Trail torch’s cooling time
dominate the properties of WM
HP‐12
FP1‐L‐12
FP2‐T‐12
FP3‐S‐12
CP‐L‐12
CP‐T‐12
Welding Pass at 12 O'Clock Position 0.7
14.0
Heat Input
Cooling Time
Cooling Time (s)
12.0
0.6
10.0
0.5
8.0
0.4
6.0
0.3
4.0
0.2
2.0
0.1
0.0
0.0
HP‐3
FP1‐L‐3
FP2‐T‐3
FP3‐S‐3
CP‐L‐3
CP‐T‐3
Welding Pass at 3 O'Clock Position 03/4/2014
Heat Input (kJ/mm)
Cooling time feature:
Heat Input
Cooling Time
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Heat Input (kJ/mm)

0.7
14.0
Responses of WM Strength to Cooling Times

ER110S-G was expected to achieve X100 strength and higher over
a range of welding condition defined by T85 <13 s, at very low heat
inputs
 ER120S-G was expected to achieve X100 strength and higher over
a wider range of welding conditions defined by T85<20 s;
Should guard against too rapid a cooling rate to avoid excessively
high strength and hardness, T85 >7s
Pipeliner 110S-G
03/4/2014
Pipeliner 120S-G
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Optimizing Welding Procedure

The welding procedures were finalized after:
 Inputs from multiple project stakeholders
 A single joint design with 10º bevel angle to be utilized for other
project materials: significant benefit to installation contractor
 Replacing pulsed GMAW with short-circuit process for the hot
pass (change of heat input):
Reduced complexity of field training
Minimizing potential errors in field welding
 More adjustment of heat inputs to make the welding procedure
more robust and field-ready

All were done before any mechanical testing:
 reduced the time required to complete the welding procedure
qualification and
 reduced mechanical testing cost
03/4/2014
Application of EWVM to Girth Welding of X100 Pipeline Steels
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Weld Production and Process Monitoring

Welds were made with monitoring and recording of:
 welding amperage, wire feed speed, voltage and travel speed
every 25 mm.
 bevel dimensions of pipe ends in six locations around the
circumference prior to clamping with the Internal Welding Machine
 Alignment (hi-lo) at six circumference locations
 Preheat and interpass temperatures


03/4/2014
After welding, data were processed to calculate average
heat input for each pass at different circumference
locations
The recorded data were used for the calculation of
cooling times and weld properties
Application of EWVM to Girth Welding of X100 Pipeline Steels
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Test Results and Verification with Prediction



Cooling time prediction with measured welding parameters
Estimates of weld metal hardness and weld metal UTS for
each pass
Predicted weld metal total UTS (volume-average)
Example: Predicted cooling times, hardness, and weld metal
UTS for ER110S-G at 12 O’clock position:
Avg. Heat
Preheat/Interpass
Input (kJ/mm) Temperature ( C )
Cooling Time Hardness
Average Total Weld
T85 (s)
(HV)
UTS (MPa) UTS (MPa)
Weld Pass
Pass Name
1
Single-torch hot pass
0.29
102
1.38
404
1110
2
Dual-torch lead pass
0.64
105
4.15
N/A
N/A
3
Dual-torch trail pass
0.66
N/A
12.70
278
792
4
Single-torch pass
0.49
123
3.42
361
1029
5
Dual-torch cap lead pass
0.53
115
2.88
N/A
N/A
6
Dual-torch cap trail pass
0.54
N/A
7.89
304
867
910
03/4/2014
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Test Results and Versification with Prediction

Summary of measured and predicted weld metal UTS
1200
Measured
Tensile Strength (MPa)
1000
Predicted
800
600
400
200
0
110S-G-12
110S-G-3
110S-G-6
120S-G-12
120S-G-3
120S-G-6
Weld-Clock-Position
03/4/2014
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Further Work

03/4/2014
X100 pipe steel is being evaluated; tested weld HAZ
properties will compared to predicted results
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Summary

The essential welding variable methodology can be used
to optimize welding procedure with the following
components:
 A predictive tool for cooling times of welding thermal cycles from welding
parameters
 Material responses of pipe steels and weld metals to cooling times with
CCT and transition temperatures of Charpy impact toughness


The methodology is generic. It has shown that it can be
applied to lower grade pipeline steels (X80). We believe
it can be equally effective on other welding processes
such as SMAW, FCAW, and SAW
Its application to the welding procedure development for
X100 pipes demonstrated:
 It reduced development time and
 It saved cost for mechanical testing
 Enable contractors to meeting right project time.
03/4/2014
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