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New MIG Technology Improves Pipe Fabrication
- Faster travel speeds
- Reduced training time
- Potential to eliminate the hot pass
- Potentially no backing gas for some of the 300 series stainless steel grades.
- Superior quality welds
- Reduced rework costs (which can cost up to $500 to fix a serious flaw)
- Exceptional tolerance for high-low misalignment between pipe sections
- Minimal clean-up time (no slag to chip, little or no spatter)
Customer Testimonial
“You actually have to experience the new modified short circuit transfer RMD process to believe how easily an operator can learn it and how easily it creates a quality root bead. Hopefully, the 100 to 400 percent productivity improvements will be enough of an incentive for stainless pipe fabricators to re-examine their processes.”
— Jim Cuhel, welding engineer, Miller Electric Mfg. Co.
Application
- Root pass welding on pipe in shop fabrication applications; the pipe can be made from carbon steel, stainless steel and other alloyed metals.
Key Business Issue
- Improving productivity and/or meeting customer deadlines without hiring additional operators.
Challenge
- Improving welding speed
- Maintaining welding quality
- Finding qualified new operators or re-training existing operators
Previous System & Process
- Stick and TIG welding, as well as conventional short circuit transfer MIG.
New Solution
- A modified short circuit transfer process, patented by Miller, called Regulated Metal Deposition (RMD).
- With RMD, the welding system anticipates and controls the short circuit, then reduces available welding current to create a consistent metal transfer. Precisely controlled metal transfer provides uniform droplet deposition, making it easier for the welder to control the puddle.
Results
- Faster travel speeds compared to Stick or TIG. RMD provides welding travel speeds of 6 to 12 inches per minute, which is 100 to 400% faster than Stick welding travel speeds of 3 to 8 ipm or TIG speeds of 3 - 5 ipm.
- Simplified operator training. As a result of a stable and more controllable weld puddle, apprentice operators can quickly and easily learn to create uniform, high quality welds within a few days. Experienced operators master RMD in as little as two hours!
- Excellent weld quality. High-speed video proves that a stable short circuit process [RMD] creates only small ripples in the weld puddle, which in turn allows consistent tie-in to the sidewall. Thus, RMD addresses the cold lap and lack of fusion issues pipe fabricators had with conventional MIG welding.
- Potential to eliminate backing gas in stainless steel applications. The stable RMD process pushes enough shielding through the root opening to prevent sugaring (oxidation) on the backside of the weld. Fabricators have qualified procedures to weld some of the 300 series stainless steels without a backing gas, improving productivity by up to 400 percent (large diameter pipes take a long time to purge, and the gas is costly).
- Significant cost savings. The RMD process creates a root pass weld with a 1/8- to 1/4-in. throat. In many instances, the amount of root pass metal deposited will be sufficient to support the heat input requirements of the first pulsed MIG or flux cored fill pass. Fabricators can eliminate the TIG hot pass, saving about $15 on a 12-in., schedule 40 pipe.
