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Extreme metalworking

By Meghan Boyer

It takes experienced workers able to troubleshoot challenges to fabricate in the field

September 2011 - It’s difficult for some fabricators who work in the field to imagine what projects they will handle from one day to the next. From fixing pipeline welds on the side of a mountain to cutting an access hole in a nuclear waste storage tank, the constant changes and challenges keep their attention focused and ensure no two days (and sometimes no two projects) are the same.

Every day is different, says Carl Franson, vice president of operations with AK Services Inc., an Everett, Mass.-based waterjet contractor. “We do just about any mobile application you can do with a waterjet system,” he says, noting there’s “a new project every time you turn around.”

With the different variables and unique situations that can occur, fabricators who work in the field need to be able to adapt to changing factors, troubleshoot when problems occur and sometimes perform within strict criteria and timelines.

An important lesson to learn in the field is to “be prepared,” says Bruce Kivisto, general manager at Chukar Waterjet Inc., St. Michael, Minn. “In terms of a learning experience, being prepared is probably the very biggest lesson.”

Facing the elements
Fabricating in an enclosed facility results in a fairly typical environment in which to work day-to-day. Metalworkers and their equipment are protected from the elements, while those who work in the field must work around Mother Nature. Garry Allison, a member of Pipeliners Local Union 798, routinely battles wind, dirt, heat and cold as he repairs pipeline welds across the country.

Working recently in western Wyoming on the Ruby Pipeline project, a 680-mile, 42-in. natural gas transmission pipeline that runs from Wyoming to Oregon, Allison experienced a range of challenges. He was working on the side of a mountain with a steep grade, and “the higher the elevation, the more wind,” says Allison. “You are out there in the elements: the wind, it might snow, it might rain. Making repairs, your hands get cold, you get cold. There’s the possibility of welding machines going down, equipment failing. You wonder why in the world you do this,” he says.

To fix a pipeline weld, Allison gouges out the defective weld using carbon arc gouging to remove the defect. He then cleans and preps the area before preheating it and beginning to weld. The depth and length of the defect affect the time required to complete the repair, says Allison, noting it can take two to three hours for one weld if it’s a long defect. “If there is a lot of wind blowing that day, you may have a lot of wind going down the pipeline, and that affects the welding process,” says Allison. Wind inside the pipe can make it difficult to put the root bead in because it wants to blow out, he says.

Kivisto encountered a challenging environment when he contributed to helping stop the Deepwater Horizon oil leak in the Gulf of Mexico. Chukar and Jet Edge Inc., St. Michael, Minn., provided ultra-high-pressure waterjet equipment to blast away hydrate ice crystals that had formed inside a containment cap at the spill site. The crystals were clogging the containment system.

“The environment is harsh in terms of the salt water. It’s very corrosive,” says Kivisto. “We were asked to be able to pump sea water directly, which means all of our seals and internal parts see that sea water.” The seals also had to withstand the ambient pressure of the ocean water as the 36,000 psi waterjet intensifier pump descended to 5,000 ft. below the surface, he says.

Ultimately, the seals held up well against the harsh conditions. “We actually ran the unit subsea for 30 hours submerged, and it was in the water for longer than that, and the seals are intact and functioning fine,” says Kivisto.

Tommy Maldonado, senior supervisor for mine maintenance at Tyrone FMI in New Mexico, works with challenging, dirty conditions repairing ground-engaging equipment required for work in copper mines. A track dozer that weighs between 50 tons and 75 tons uses a moldboard to engage and push dirt. Over time, the liner on the moldboard wears out and needs to be rebuilt so no damage occurs to the parent metal skin of the moldboard.

Maldonado’s crews use plasma arc equipment from Hypertherm Inc., Hanover, N.H., to cut and gouge the welds of the liners to remove them from the moldboard. The moldboards, which can measure roughly 20 ft. across and 8 ft. to 10 ft. high, are in different stages of wear, and all of them are dirty from working in the mine. “We have to do a lot more cleaning, so that makes it harder to gouge out,” says Maldonado. From start to finish, depending on the condition of the moldboard, the process can take up to a month to remove the liners and rebuild a moldboard.

Varying challenges
The environment is not the only factor that leads to challenges in the field. Franson battled not only freezing temperatures but the difficulty of running ultra-high-pressure waterjet equipment from a 300-ft. distance. AK Services cut a 55-in.-diameter hole in a nuclear waste storage tank to aid in cleanup of 240,000 gal. of radioactive and chemical waste with a robotic system.

The task required more than one year of work and planning before Franson and his team made a single cut. An initial challenge was to determine the rate of advance for the abrasive jet cutting head that would allow the team to cut through 15 in. of concrete and layers of steel rebar.

The crew had to operate from 300 ft. away from the tank because of the risk associated with the hazardous material. Franson’s crew stayed outside the radiological area and watched what was happening at the tank using cameras. They also had to limit the amount of water and garnet that passed into the tank, because whatever enters the tank becomes radioactive and eventually must be cleaned out and decontaminated.

“We could have moved the equipment inside, but then we would have had to scan everything out [to ensure it was not contaminated],” says Franson. Four people rotated through the work during a more than 30-hour time period. At times, Franson had to rely on a support group working by the tank that he had trained during a mock-up phase of the project’s development. “It was definitely a challenge,” he says.

For those working in the military, unexpected damage to a vehicle or weapon could have serious consequences, which is why fabricating replacement parts in the field—even on the front lines—is an asset. Omax Corp., Kent, Wash., recently supplied a mobile abrasive waterjet system to the Department of Defense for use in Afghanistan by the U.S. military. The JetMachining Center “is repairing tank and gun parts so they don’t have to bring them back to the U.S.,” says Steve Brown, major account sales manager with Omax. The military uses the system inside a transportable structure to cut mild steel, stainless and some titanium.

“Since this is a forward base, it’s important to keep their machinery operating. If they run over a land mine or IED, rather than send that piece of equipment back to the states, they are able to repair it in the field using reverse engineering,” says Brown. The turnaround time if they fabricate in the field is typically hours instead of weeks or months, he notes. Because the system is portable, the military is able to move it as necessary. “It’s just temporary, because they never know when they will have to evacuate and move to another position.”

A learning experience
Successfully overcoming the challenges that may arise in the field “comes from experience,” says Allison. Using quality tools also is beneficial, because it can make a job easier, he says. “I use Miller products, so I have state-of-the-art tools,” says Allison, noting a wireless remote hand control from Miller Electric Mfg. Co., Appleton, Wis., has helped him combat some of the challenging factors involved in welding in the field.

The stakes can be high: If a weld is not fixed properly, it can cost thousands of dollars to cut out the problem area and reweld it, says Allison. Additionally, “you’ve got to have experienced people in every part of the job to have a safe job,” he says. “It’s very easy for a man to lose his life.”

A job sometimes can require equipment that is adapted specially for it. AK Services spent multiple months developing the waterjet cutting system Franson would use to cut into the nuclear waste holding tank. The company engineered a three-piece stainless steel motion system with two circles separated by guide bushings with a ring gear in the middle. “We built a motion device with a ring gear that was driven by a drive gear that ran off a pneumatic motor, and we fashioned it around so that it would accept the Jet Edge high-flow cutting head,” says Franson. Redundant aspects, such as four Jet Edge cutting heads, were included in case of failure, but the crew was able to complete the entire cut using the one lead cutting head, he says.

For his work in the Gulf of Mexico, Kivisto began with standard equipment and then began to modify it to meet the project’s needs. This method ensured Kivisto and his team could be prepared for the project quickly. “From the day they called until we shipped equipment was about one week,” he says. “That was in early June [2010], and during the rest of June, we put in a few more modifications and made it into a workable system that could be launched from a boat.”

No matter what challenges and requirements are involved, every project is a learning experience. “After we get done with it, we kind of sit back and try to decide how we could have done it quicker and more efficiently,” says Franson. “There’s a lot of different things that you learn when you are on a job for nine months.” FFJ

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