Enhanced Surface Tension Transfer for Pipe Welding

1. Enhanced Surface Tension Transfer for Pipe Welding Harry Sadler Manager Military and Shipbuilding Sales

2. Customer Assistance Policy The business of The Lincoln Electric Company is manufacturing and selling high quality welding equipment and consumables, and cutting equipment. Our challenge is to meet the needs of our customers and to exceed their expectations. On occasion, purchasers may ask Lincoln Electric for advice or 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 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 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 practical consideration, we also cannot assume any responsibility for updating 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 respect to the sale of our products. 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 remains the sole responsibility of, the customer.

3. Conventional Short Circuit Transfer

4. Traditional Short Circuit Transfer click on picture to run video

5. STT Process Research Began July,1985 • Purpose • Develop a semi - automatic “short circuiting” welding process which eliminates spatter when using 100% CO2 shielding gas.

6. STT Process Working Prototype January,1987 • 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.

7. STT Process Working Prototype January,1987 • 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

8. STT Process STT Welding Arc

9. STT Process • Background current • Arc current level prior to shorting to the weld pool. • Contributes to the overall heat input • Keeps arc lit

10. 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

11. 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.

12. 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

13. 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

14. STT Process • Tailout • Current is reduced from peak to background level • Reduces agitation of the weld puddle • This control is a coarse heat control

15. Surface Tension Transfer

16. STT Process • High speed video of STT arc • click on picture to run video

17. STT Process • High speed video of STT arc • click on picture to run video

18. STT Process Sheet Metal Welding With STT Traditional CV Short Arc Welding Welding with STT

19. STT Process Commercial SystemIntroduced at Essen1993 • Process Requires • Current and Voltage Sensing • High Speed Switching System • Rapid Control of Output • Rapid Response Power Source

20. Basic Transformer Design Reactor Selects Output Welding Current Inductance Coil Smoothes / Filters DC Output Transformer Single Phase Input High Volts High Amps Low Amps Low Volts Bridge Rectifier Changes AC to DC

21. Inverter Technology DC - Smooth Low Voltage High Amperage AC - 20,000+ Hz High Voltage Low Amperage DC - Smooth High Voltage Low Amperage AC - 50/60 Hz High Voltage Low Amperage DC - Rippled High Voltage Low Amperage AC - 20,000+ Hz Low Voltage High Amperage DC - Rippled Low Voltage High Amperage

22. Analog Power Source with Analog Feeder

23. Digital Power Source and Digital Feeder, Software Controlled

24. Build it Yourself

25. 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

26. 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

27. 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

28. STT Process STT open root (viewed from inside of pipe) • click on picture to run video

29. STT Process Open Root Welding With STT • Benefits • Welded open root ligament or thickness is large ~ 0.22” (5.6mm) • Large ligament eliminates burn through on next weld pass. 0.22” (5.6mm)

30. STT on Pipe

31. With Good Root Fusion

32. Process Advantages 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 • 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

33. STT Process Open Root Welding With STT Single-sided welding

34. STT Process Open Root Welding With STT

35. PROCESS CERTIFICATION STT Process • 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

36. Dual Process Capabilities • Optimize Quality and Productivity by allowing process changes in same station

37. 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

38. 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

39. Eight Inch Schedule 40 A106B Pipe, 5G Position