Maintenance of way: Rail weld products and processes

— by Walter Weart

For the most part, North American freight and passenger railroads are spending more on infrastructure improvements this year. And they figure to keep right on investing in a pretty big way for at least the foreseeable future.

"It is a very exciting time to be in the railroad industry," says David Randolph, president and chief executive officer of Orgo-Thermit Inc., an equipment and service supplier that has been involved in thermite welding for more than a century. "Demand for innovative, high-quality products will continue to grow."

That demand certainly applies within the rail-to-rail weld product and process arena, say a range of suppliers who serve that realm.

"This is a mature business, and we will grow by expanding our comprehensive product line of Thermit® welding kits, crucibles and equipment," Randolph says.

Other suppliers of rail-weld products and processes are expanding, as well — both in terms of product lines and facilities. They're also pushing the research-and-development envelope as they pursue next-level product performance.

For example, Orgo-Thermit now is offering electronic measurement equipment, including an "electronic straight edge," says Randolph, adding that the device is designed to measure the longitudinal profile of the railhead's running and guiding surfaces on Thermit®, electric flash-butt and gas pressure welds. The device provides a documented measurement of the surface after final grinding of a weld.

Orgo-Thermit also offers the Safe Start Electronic Ignition System, a modern, easier and safer way of initiating Thermit® reactions from 25 feet away, Randolph says. The Safe Start Electronic Ignition System enables welders to stand totally clear when the Thermit® reaction is initiated.

Ensuring the weld and the rail have similar hardness is another area of focus.

"Rail hardness is being increased with hardnesses well over 400 hardness, brinell (HB), and we have developed a Head Alloyed Weld for the U.S. market, which produces a much higher running surface weld hardness — 380-plus HB — than what is currently available, thus making the weld running surface longer lasting when welding hyper-eutectoid steel metallurgy rails," Randolph says.

The high-hardness running surface welds are easy to install, as all current equipment used to install Orgo-Thermit's conventional welds can be used for installation of a Head Alloyed Weld, he says. It takes the same amount of time to install the welds as it does to install conventional Thermit® welds, Randolph says.

Advances in rail manufacturing and rail metallurgies have led to the development of rails with hardnesses well over 400 HB. As a result, Orgo-Thermit's R&D department is working to keep pace with these new trends, and the successful Thermit® welding of such metallurgy and hardness rails, Randolph says. The company recently introduced its Head Alloyed Thermit weld in North America. Research on it is being conducted at Transportation Technology Center Inc.'s Facility for Accelerated Service Testing (FAST) track in Pueblo, Colo.

"We have various Thermit® welds in test at the FAST facility, and our second-generation Thermit® Head Repair Welds, which is a process that only repairs a defect in the head of a rail, is at 140 plus million gross tons [MGT] with no failures," Randolph says.

Several Orgo-Thermit welds have been producing failure-free results at TTCI test tracks. As of mid-April, the company's Head Repair Welds installed over defective electric flash-butt welds had reached 85-plus MGT with no failures; Head Repair Welds, installed and tested over ties, reached 35-plus MGT with no failures; and Head Alloyed Welds, with a running surface hardness of more than 380 HB, had reached 60-plus MGT "without any reported problems," Randolph says.

Focus on Frogs and Diamonds

Railroads also continue to seek improvements to welding equipment used on manganese frogs and manganese crossing diamonds. For one, frog and diamond replacement is expensive. What's more, maintenance activities can put a crimp in train schedules, particularly when railroads are operating near or at capacity on certain lines. As Brian Meade, Lincoln Electric's manager of railroad technical services-global accounts, notes, there are four corners in a single track manganese insert diamond; 12 of the 16 points are impacted, requiring welding maintenance.

"We have improved productivity by increasing the machine capacity to allow for the use of larger carbon electrodes, which allows for faster arc gouging that reduces the time spent preparing the castings for repair," says Meade.

By developing a new output mode for arc gouging, and increasing the power of the welding machine, Lincoln Electric has achieved a 60 percent decrease in the time it takes to remove defective material, he says.

The company has upgraded the Air Vantage 500 with a more powerful 58-horsepower diesel, which complies with the U.S. Environmental Protection Agency's (EPA) Tier 4i emission standard. The machine still supplies power for electric grinders and air-operated equipment, offering additional uses without requiring additional hardware.

"We have improved the LN™-25 PRO wire feeder by replacing the analog display with a digital readout that allows the worker to preset the amperage without having to strike an arc, which speeds up the preparation," says Meade.

Lincoln also increased the power of the feed, with the Maxtrac® drive roll system, which includes a wire guide to straighten the wire. The improved technology on the newer machines, feeders and welding wire enables welders to establish much better gouging and arc control, resulting in faster defect removal and heavier weld build-up with less heat input, Meade says.

Other suppliers have been busy on several fronts, as well. The American Recovery and Reinvestment Act has fast-tracked a number of projects during the past 18 months, enabling Railtech Boutet Inc. to add jobs and expand its Napoleon, Ohio, plant, says Oliver Dolder, executive vice president and chief operating officer.

Along the way, the company is working to simplify the welding process, cut time required to be on the track, and reduce operator error and failure rates.

"We began offering the Head Wash Repair (HWR) system in April, and this can be used to repair transverse and corner gauge defects," says Dolder, adding that several railroads have tried the HWR repair successfully in a range of weather conditions. "As the rail is not being cut, defection is not a problem, new joints are not being created and the required FRA paperwork is reduced."

Railtech Boutet, too, is responding to the increases in rail hardness.

"New high strength rail is as hard as 400 brinell, but the old welds were in the 315 to 330 range, and we are working on welds for this type of rail," Dolder says.

The challenge: ensuring the weld isn't brittle.

"This will be closer to the metallurgical properties of those types of special rails, which will accommodate those railroads that are currently using these types of rails in mainline track and/or tangents and curves," says Dolder.

From Problem to Solution

Progress Rail Services Inc. also continues to add capacity to meet growing demand for electric flash-butt welding, which remains the preferred method of joining rails, said Mark McLean, sales manager, rail welding, in an e-mail. In addition to adding more welded rail trains and unloaders, the company has increased its contract service fleet of in-track welders.

Progress Rail also has expanded its mobile welding services to accommodate customer demand for rail preparation and finish grinding after welding. The company's Chemetron Rail Welding division also has added lower-consumption welds, increased pulling power on closure welds and improved clamping designs that are intended to provide consistent alignment and improved productivity, McLean said.

Meanwhile, Holland Co. L.P.'s welding division continues to monitor customer needs. Railroads remain focused on "joint elimination," as one of the smaller Class Is created 15,000 new joints last year, says Kevin Flaherty, Holland's vice president of maintenance-of-way sales and marketing. Flash-butt welding with the use of a "wedge" can eliminate replacing the defect with a rail plug, avoiding two additional joints, he says.

Holland also has teamed up with the Edison Welding Institute to develop a Head Defect Repair Weld. In this process, the rail head defect is removed and, utilizing flash-butt welding technology, a replacement rail wedge is installed. So far, the process has passed all American Railway Engineering and Maintenance-of-Way Association weld tests and rolling load tests, Flaherty says.

During the past 10 years, Holland has invested "considerable time and money" to improve the weld quality, matching weld schedules to new rail steels and increasing productivity of installing its flash-butt weld. "Innovations enabled by the Holland Intelliweld Control System, combined with the Holland Puller Lite and Low Consumption Weld have enabled lower-cost installations and opened new opportunities to utilize a flash-butt weld," Flaherty says.

Focusing on R&D

Meanwhile, the testing continues. Railroads still need high-performance welds that are faster and easier to make, said TTCI Senior Engineer Daniel Gutscher and TTCI Principal Investigator Joseph LoPresti in an e-mail.

TTCI currently is testing several weld products in the track at the FAST facility. Under the Association of American Railroads' Strategic Research Initiative, TTCI researchers are testing thermite railhead repair welds (Railtech Boutet's, in addition to the previously mentioned Orgo-Thermit weld), which collectively had accumulated 141 MGT with no failures as of mid-April. TTCI also is testing the new electric flash railhead repair weld developed by Edison Welding Institute and Holland. The welds had accumulated 61 MGT with no failures.

Although rail hardness now can exceed 400 brinell, the hardness of weld heat-affected-zones (HAZ) drops to around 260 brinell — the same HAZ hardness the softer rails have, Gutscher and LoPresti said. The drastic change in hardness results in a greater difference in wear and batter around welds, which creates a high-stress environment that may cause the weld to degrade and fail. TTCI researchers are exploring ways to mitigate the problem by focusing on reducing the overall width of the HAZ and reducing the amount of softening at the running surface.

TTCI also continues to develop a thermite weld that uses an engineered bottom feed process to reduce weld metal splash and corresponding oxide formation, Gutscher and LoPresti said. The modeling has been completed; now, TTCI is working with North American thermite weld vendors to produce prototype sand molds for laboratory and track testing.

Walter Weart is a Denver-based free-lance writer.