WELDING FOR NEW POWER
Soaring gas prices have started a national dialogue on new, domestic and renewable forms of supplying power. One of the leading sources discussed is wind power. Wind power generation increased five-fold globally in the last seven years, but production in the U.S. lagged.
Germany receives 12 percent of their energy from wind, for example, while the U.S. receives less than 1 percent. But America does have capacity to harness this resource. According to a Department of Energy study, wind could provide as much as 20 percent of the U.S. power supply by 2030.
THE CHALLENGES
Essential to wind power generation is the fabrication of wind towers capable of enduring the extreme conditions in which they are placed. Environmental exposure and high quality material requirements are two of the many challenges presented in wind tower fabrication. Many U.S. companies seek to position themselves as leaders in this field and are partnering with suppliers to meet these challenges.
One such company is T Bailey, Inc. (Anacortes, WA), which has been in business for more than 15 years and, in 2004, decided to bring their experience in heavy civil and industrial general contracting to this rapidly growing industry. "When it comes to renewable energy sources, wind power is growing by leaps and bounds, especially here in the Pacific Northwest," says weld manager Kris Morse of T Bailey. "With our construction experience and manufacturing facilities, it was a natural strategic decision for us to get in the business of building towers."
The biggest literal challenge is the actual construction of the tower. Measuring 180-240 feet, with larger designs always coming, the assembled tower can be straight or conical and consists of three or more sections, each made up of six or more "cans."
The can starts as flat steel that is cut and rolled into the desired shape. To do this, manufacturers must start with quality materials and ensure precise cutting, beveling and fit-up procedures. The cans are then submerged arc welded longitudinally before being circumferentially welded together to form the sections. Lastly, heavy flanges are attached to either end of each section to provide for assembly in the field. All these steps require quality welds able to meet exacting test standards. And with demand growing, you've got to be able to do it fast.
A STRATEGY FOR GROWTH
With this in mind, T Bailey began an aggressive expansion plan and a competitive analysis of their available options in manufacturing and, in particular, submerged arc welding. "Simply expanding our facilities wasn't enough to keep up with customer demand," Morse explains. "We needed a way to build towers faster. So we took a hard look at our welding operations, because every seam on every tower that rolls out our front door is welded."
In order to fully optimize their welding process, T Bailey examined many factors. Electrodes need to have an optimized ratio of manganese to silicon to produce the required low temperature impact results. Fluxes must be suitable for multi-pass welding, while not hindering the performance of flux recovery systems. Welding power sources and consumables must provide high deposition rates and increase overall productivity while producing consistent welds, since all welds need to pass rigorous ultrasonic testing. Any failure demands costly and time-consuming rework.
The company tested a number of systems before choosing one comprised of a Lincoln Electric Power Wave® AC/DC 1000? inverter power source and Lincoln's P223 flux and Lincolnweld® L-S3 electrode.
THE SYSTEM
Lincolnweld® P223 flux is a neutral flux, making it suitable for the multiple-pass welding T Bailey performs. Morse discovered that this flux does not easily break down or have small particles – both factors that can contribute to weld defects and the decreased performance of flux recovery systems, requiring filters to be changed more frequently.
Additionally, the flux has a low bead profile with straight edges, and minimum undercutting, with fast-freezing slag, all attributes that T Bailey found beneficial.
The L-S3 electrode is a low carbon, high manganese, medium silicon wire designed with an optimized ratio of manganese to silicon and low residual tramp elements to produce high low temperature impact toughness at the higher deposition rates used for multiple-pass wind tower construction.
The Power Wave® AC/DC 1000? is rated at 1000 amps for AC or DC. This equipment produces a variable AC output, as well as straight DC+ or DC- output. No hardware configuration changes are required.
The machine's patented Waveform Control Technology? and variable AC/DC frequency allows for higher deposition rates at lower amperages compared to other available machines. It also provides a more stable arc for a consistent penetration pattern along the length of the weld, which is necessary in order for the welds to pass ultrasonic testing.
The Nextweld® Waveform Control Technology uses electronic regulation circuitry to control and shape the output waveform and tailor welding waveform parameters to the application. The AC waveform operates at any frequency between 0 and 200 Hz with a single knob.
Dialing in the frequency aids in stabilizing the arc. The amplitude and duration of the positive and negative cycles are independently adjustable to deliver greater control of bead shape, higher deposition rates and lower heat inputs.
Parameters can be controlled and regulated automatically so synergic adjustments can be made by the machine while welding. A variety of operating modes can be used to favor high deposition or high travel speeds.
For multiple arc set ups, any phase relationship can be achieved between the output waveforms regardless of the input connection – to reduce arc blow and virtually eliminate Scott connections.
THE RESULTS
Today, T Bailey produces 475 to 550 towers annually. Due to its strategic decision to get into the wind tower fabrication market and their choice of Lincoln Electric, they are poised and ready to help the U.S. meet its' growing need for domestically produced energy.
The company has a 40,000 sq ft fabrication plant, located on five acres in Anacortes, that includes a 25,000 sq ft steel fabrication facility and a 14,000 sq ft state-of-the-art wheelabrating and painting facility. The fabrication shop performs custom fabrication of heavy structural and plate products meeting API, AWWA, AWS, UL, and ASME codes.
Equipment in the plant includes two four-roll plate rollers. The larger set rolls to 1-3/4 in x 10 ft and the smaller set rolls to ¾ in x 10 ft. A CNC-controlled plasma cutting machine features a 40 ft x 11 ft water table and has AutoCAD downloading capability. Other equipment includes tank and vessel turning rolls, ironworkers, band saws and overhead cranes. The company employs 30 people in the shop and 15 in the office.
The company also operates a 50,000 sq ft facility located on 20 acres in Ephrata, with further expansion plans for an additional 70,000 sq ft building that will eventually employ about 80 people.
T Bailey, Inc., 12441 Bartholomew Road, Anacortes, WA 98221, 360-293-0682, Fax: 360-293-3893, www.tbailey.com.
The Lincoln Electric Company, 22801 St. Clair Avenue, Cleveland, OH 44117, 216-481-8100, Fax: 216-486-1751, www.lincolnelectric.com.
