Post on 17-Dec-2015
transcript
Enhanced Surface Tension Transfer for Pipe WeldingHarry Sadler
Manager Military and Shipbuilding Sales
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The business of The Lincoln Electric Company is manufacturing and selling The business of The Lincoln Electric Company is manufacturing and selling high quality welding equipment and consumables, and cutting equipment. Our high quality welding equipment and consumables, and cutting equipment. Our challenge is to meet the needs of our customers and to exceed their challenge is to meet the needs of our customers and to exceed their expectations. On occasion, purchasers may ask Lincoln Electric for advice or expectations. On occasion, purchasers may ask Lincoln Electric for advice or information about their use of our products. We respond to our customers information about their use of our products. We respond to our customers based on the best information in our possession at that time. Lincoln Electric based on the best information in our possession at that time. Lincoln Electric is not in a position to warrant or guarantee such advice, and assumes no is not in a position to warrant or guarantee such advice, and assumes no liability, with respect to such information or advice. We expressly disclaim any liability, with respect to such information or advice. We expressly disclaim any warranty of any kind, including any warranty of fitness for any customer’s warranty of any kind, including any warranty of fitness for any customer’s particular purpose, with respect to such information or advice. As a matter of particular purpose, with respect to such information or advice. As a matter of practical consideration, we also cannot assume any responsibility for updating practical consideration, we also cannot assume any responsibility for updating or correcting any such information or advice once it has been given, nor does or correcting any such information or advice once it has been given, nor does the provision of information or advice create, expand or alter any warranty with the provision of information or advice create, expand or alter any warranty with respect to the sale of our products.respect to the sale of our products.
Lincoln Electric is a responsive manufacturer, but the selection and use of Lincoln Electric is a responsive manufacturer, but the selection and use of specific products sold by Lincoln Electric is solely within the control of, and specific products sold by Lincoln Electric is solely within the control of, and remains the sole responsibility of, the customer.remains the sole responsibility of, the customer.
Customer Assistance Policy
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STT Process
• Purpose– Develop a semi - automatic “short
circuiting” welding process which eliminates spatter when using 100% CO2 shielding gas.
Research Began July,1985
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STT Process
• Major Achievements
– Reduced spatter in 100% CO2
– Developed capability to use larger diameter electrodes
– Reduced fumes– Ability to control the welding current
independent of the wire feed speed.
Working Prototype January,1987
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STT Process
• Results– The spatter reduction feature of the
technology also produced a very stable arc, especially at low currents. This is a big advantage when welding the open root on pipe in the 5G position
Working Prototype January,1987
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STT Process
• Background current – Arc current level prior to shorting to the
weld pool.– Contributes to the overall heat input– Keeps arc lit
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STT Process• Initial Shorting
– Response to the “arc voltage” detector sensing that the arc has shorted
– Current is reduced even further at actual ball/weld puddle contact
– Extremely low current promotes ball wetting instead of repelling
– Reason for lower spatter in STT
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STT Process• Pinch Current
– High current is applied immediately after the initial short
– Current increases, causing the molten droplet to separate from the electrode
– STT electronically calculates when droplet separation is to occur and reduces the current before this happens, eliminating the explosive spatter.
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STT Process
• Second Current Reduction– Current is quickly reduced before electrode
separates, eliminating spatter– STT circuitry
re-establishes the welding arc at a low current level
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STT Process
• Peak Current– High current is applied immediately after the
arc is reestablished– Arc is momentarily broadened, producing
high heating of the plate, insuring good fusion and setting the proper arc length
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STT Process
• Tailout– Current is reduced from peak
to background level– Reduces agitation of the weld puddle– This control is a coarse heat control
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STT Process
• Process Requires– Current and Voltage Sensing– High Speed Switching System– Rapid Control of Output– Rapid Response Power Source
Commercial SystemIntroduced at Essen
1993
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ReactorReactorSelects Output Selects Output
Welding CurrentWelding Current
Bridge RectifierBridge RectifierChanges AC to DCChanges AC to DC
Inductance CoilInductance CoilSmoothes / FiltersSmoothes / Filters
DC OutputDC Output
TransformerTransformerSingle Phase InputSingle Phase Input
High VoltsHigh Volts High Amps High AmpsLow AmpsLow Amps Low VoltsLow Volts
Basic Transformer Design
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AC - 50/60 HzAC - 50/60 HzHigh VoltageHigh Voltage
Low AmperageLow Amperage
DC - RippledDC - RippledHigh VoltageHigh Voltage
Low AmperageLow Amperage
DC - SmoothDC - SmoothHigh VoltageHigh Voltage
Low AmperageLow Amperage
AC - 20,000+ HzAC - 20,000+ HzHigh VoltageHigh Voltage
Low AmperageLow Amperage
AC - 20,000+ HzAC - 20,000+ HzLow VoltageLow Voltage
High AmperageHigh Amperage
DC - RippledDC - RippledLow VoltageLow Voltage
High AmperageHigh Amperage
DC - SmoothDC - SmoothLow VoltageLow Voltage
High AmperageHigh Amperage
Inverter Technology
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STT Process, Analog Control
• Controls
– Wire feed speed
Adjusts deposition rate
– Peak Current
Controls the arc length
– Background Current
Fine heat input control
– Tailout
Coarse heat input control
– Hot Start
Controls the starting heat
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STT Process, Non-Synergic Digital Control
• Controls– Wire feed speed
• Adjusts deposition rate– Peak Current
• Controls the arc length– Background Current
• Fine heat input control– Tailout
• Coarse heat input control– Hot Start
• Controls the starting heat– Start/End Options
• Preflow, Run-in, Start Time, Crater, Burnback, Postflow
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STT Process, Synergic Digital Control
• Controls– Wire feed speed
• Adjusts deposition rate– Trim
• Adjust ball size and arc energy– Weld Mode/Arc Control
• Dynamically modifies Hot Start, Peak, Background, and Tailout Current
– Start/End Options• Preflow, Run-in, Start Time,
Crater, Burnback, Postflow
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STT Process
• Benefits– Welded open root
ligament or thickness is large ~ 0.22” (5.6mm)
– Large ligament eliminates burn through on next weld pass.
Open Root Welding With STT
0.22” (5.6mm)
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STT Process
STT Replacing Short-arc
– No Lack of Fusion– Good Puddle Control– Consistent X-ray Quality Welds– Shorter Training Time– Low Fume Generation & Spatter
– 100% CO2 (on mild steel)
– Various gas mixtures
Process Advantages
STT Replacing TIG
– 4 Times Faster– Vertical Down Welding
Possible– Consistent X-ray Quality
Welds– Shorter Training Time– Welds Stainless, Nickel Alloys
and Mild Steel
– 100% CO2 (on mild steel)
– Various gas mixtures
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STT ProcessPROCESS CERTIFICATION
STT process may be used in the following variants of pipe welding:
•Root pass & basic coated electrode for other passes
•Root pass, semi-auto welding with Innershield for other passes
•For root, fill & cap passes of pipe up to 10 mm wall thickness
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Dual Process Capabilities
• Optimize Quality and Productivity by allowing process changes in same station
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U.S. Based Organizations with PUBLISHED Rules for qualification of Short Circuit Transfer Modes
• American Welding Society• American Bureau of Shipping• American Society of Mechanical Engineers• American Petroleum Institute• Any other code that references ASME SEC IX for
Procedure and Operator Qualification
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Welding Cost Analysis, Assumptions
• Labor and Overhead--$70/hr• Operating Factors
– GTAW—35%– SMAW—30%– STT—40%– FCAW—35%
• GTAW Root Pass at 1.7 ipm• SMAW Root Pass at 4.4 ipm• STT Root Pass at 5.5 ipm• Same Net Material Costs