essential variables in GTAW- - ASM Hou
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By Nathan Sumrall Welding Engineer [email protected] (972) 533-5664 Superior Cladding, LLC. 11505 Todd St. Houston TX 77055 “The potential impact of non- essential variables in GTAW- Hotwire overlays”
Transcript of essential variables in GTAW- - ASM Hou
By Nathan Sumrall
Welding Engineer
[email protected] (972) 533-5664
Superior Cladding, LLC.
11505 Todd St. Houston TX 77055
“The potential impact of non-essential variables in GTAW-
Hotwire overlays”
OUTLINE
1. Introduction to Overlays
2. Problem Statement
3. Hypothesis
4. Corrective Action and Methodology
5. Results and Observations
6. Conclusions and Going Forward
1. Introduction to Overlays
Manufacturing Process
Rough Machine
Pre-weld NDE
Weld Overlay
Final Machine
Final NDE
Part in
Service
2. Problem Statement
Isolated Event: Part rejections!
1. 25% parts were LP Rejected at Final NDE / Inspection (API 6A PSL3)• 85% in weld metal.• 15% on fusion-line.• All rejections in API Ring-Type-Joints. AISI 4130 BM.
2. High profile projects
Rough Machine
Weld Overlay
Final Machine
Final NDE
Part in
Service
3. Hypothesis
If the welding procedures were followed, and they were previously qualified with excellent track records, then a non-essential variable may have affected weld quality.
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Topic Aside
The goal: Forming perfect welds?
4. Corrective Action
What is the LP detecting?
“There is a correlation between LP test results and the oxide content of a weld.” – Dave Hebble
4. Corrective Action
4. Corrective Action
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4. Corrective Action
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4. Corrective Action
Fish Bone Diagram
4. Corrective Action
The topic Impact (Scoring: 1 thru 3)
Gas Quality 1. Gas coverage1. Weld Contamination2. Wettability
Grinding Techniques 1. Compounding Oxides2. Weld Contamination3. Wettability
Wire Cleanliness 1. Wettability1. Weld Contamination1. Compounding Oxides
The Arc 1. Weld quality1. Oxide formation3. Weld profile
Referencing: ASME IX QW-256 and 256.1, 2015
4. Corrective Action
The topic Action Items
Gas Quality P: Production to use Vertical Liquid Gas (VGL) supply per machine. 1. Compare gas delivery methods (Argon Manifold Gas [MG] vs VGL)2. Test gas manifold for contamination (oxygen)
Grinding Techniques
P: Production to Grind every layer (L1) until corrective action is complete. 1. Compare grinding intervals
Filler’s Cleanliness
P. Production to use secondary vendor for Ring Grooves1. SEM Evaluation2. Compare Primary (P) and Secondary filler wires (S)
The Arc 1. Compare background currents (pulse)
4. Methodology
Controls• Single Heat of Base Metal
• Liquid Argon
• Matched heat inputs
• Single Machine
• Inconel 625
Source BM,
4130, single heat.
(NACE MR0175)
Rough Machine BX-
154
(API 6A)
Receiving Inspection /
NDE
Weld Overlay
Inconel 625
(ASME IX)
PWHT
1175F
4 HRS
(ASME VIII)
Final Machine
BX-154
(API 6A)
Final NDE
(API 6A)
Blind Selection
Analysis
(Corrective
Action)
Variables• 2 Wire Suppliers (P/S)
• 2 Gas delivery methods (MG / VGL)
• 2 Grinding intervals (L1 / L3)
• 2 Pulsed currents (50%/75%)
4. Methodology
Test Matrix
Sample ID Wire Brand Gas DeliveryGrinding Interval
Background Current
-01 P MG L3 50-02 P MG L3 50
-03 P MG L3 50-04 P MG L3 50
-05 S MG L3 50-06 S VGL L3 75
-07 P VGL L3 50-08 P VGL L2 50-09 S VGL L1 50
-10 S VGL L1 75-11 P MG L1 50
-12 P MG L1 75
P Primary Wire Supply S Secondary Wire Vendor
MG Manifold Gas VGL Vertical Gas Liquid Cylinder
L3 Every 3 layers L1 Every Layer
50 50% current output 75 75% current output
5. Results and Observations
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Sample ID Wire Brand Gas DeliveryGrinding Interval
Background Current
LPPass/Fail
-01 P MG L3 50 P
-02 P MG L3 50 F-03 P MG L3 50 N/A
-04 P MG L3 50 P-05 S MG L3 50 F
-06 S VGL L3 75 F-07 P VGL L3 50 P-08 P VGL L2 50 P-09 S VGL L1 50 P-10 S VGL L1 75 F
-11 P MG L1 50 F-12 P MG L1 75 F
5. Results and Observations
Test Matrix with Results
Sample ID Wire Brand Gas DeliveryGrinding Interval
Background Current
LPPass/Fail
-02 P MG L3 50 F
-05 S MG L3 50 F-06 S VGL L3 75 F
-10 S VGL L1 75 F-11 P MG L1 50 F
-12 P MG L1 75 F
5. Results and Observations
Test Matrix with Results
P Primary Wire Supply S Secondary Wire Vendor
MG Manifold Gas VGL Vertical Gas Liquid Cylinder
L3 Every 3 layers L1 Every Layer
50 50% current output 75 75% current output
Sample ID Wire Brand Gas DeliveryGrinding Intervals
Background Current
LPPass/Fail
-01 P MG L3 50 P
-04 P MG L3 50 P-07 P VGL L3 50 P
-08 P VGL L2 50 P-09 S VGL L1 50 P
5. Results and Observations
Test Matrix with Results
P Primary Wire Supply S Secondary Wire Vendor
MG Manifold Gas VGL Vertical Gas Liquid Cylinder
L3 Every 3 layers L1 Every Layer
50 50% current output 75 75% current output
6. Conclusions
Most significant variable?• Gas Delivery, the piping.• Contaminated gas
1. Argon Bulk tank: 2 ppm OxygenArgon drops in the shop:2. 43.5 ppm3. 60.1 ppm4. 85.6 ppm(Aspiration)
6. Conclusions
Short Term Actions taken:
• Follow the WPS and best practices as verified in ring groove study (document with training per API Q1).
• Use VGL liquid argon at each station.
• Update customers on results.
Long Term Actions
• Replace Bulk piping and test for contamination before use.
6. Going Forward
• Identify elements in select oxide inclusions / LP rejects.
• Research methods to prevent or reduce oxide formations.
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Open Discussion
By Nathan Sumrall
Welding Engineer
(972) 533-5664
Superior Cladding, LLC.
11505 Todd St. Houston TX 77055
.125 in3.17 mm
.125 in3.17 mm
