Although orbital welding technology is not new, it continues to evolve, becoming more powerful and versatile, especially for pipe welding. An interview with Tom Hammer, an experienced welder at Axenics in Middleton, Massachusetts, reveals the many ways this technique can be used to solve complex welding problems. Image courtesy of Axenics
Orbital welding has been around for about 60 years, adding automation to the GMAW process. It is a reliable and practical method for making multiple welds, although some OEMs and manufacturers have yet to exploit the capabilities of orbital welders, relying on hand welding or other metal pipe joining strategies.
The principles of orbital welding have been around for decades, but the capabilities of the new orbital welders make them a more powerful tool in a welder’s toolbox, as many of them now have “smart” features that make programming and handling easier before the actual welding. ● Start with quick and precise settings to ensure consistent, clean and reliable welds.
The Axenics Welding Team in Middleton, Massachusetts, a contract component manufacturer, helps many of its customers get orbital welded if the right item for the job exists.
“Wherever possible, we wanted to eliminate the human factor in welding, as orbital welders usually produce better quality welds,” says Tom Hammer, qualified welder at Axenics.
Although the earliest welding was performed 2000 years ago, modern welding is an extremely advanced process that is an integral part of other modern technologies and processes. For example, orbital welding can be used to create the high-purity piping systems used to produce semiconductor wafers, which are used in virtually all electronics today.
One of Axenics’ clients is part of this supply chain. The company was looking for a contract manufacturer to help expand its manufacturing capacity, specifically to create and install clean stainless steel channels that allow gases to flow through the plate manufacturing process.
While orbital welders and torch clamp turntables are available for most pipe work at Axenics, they do not preclude hand welding from time to time.
Hammer and the welding team reviewed the customer’s requirements and asked cost and time questions:
Hammer uses Swagelok M200 and Arc Machines Model 207A rotating enclosed orbital welders. They can hold tubes from 1/16″ to 4″.
“Microheads allow us to get into very hard to reach places,” he said. “One of the limitations of orbital welding is whether or not we have the right head for a particular joint. But today, you can also wrap the chain around the pipe you are welding. Welders can walk the chain and there is virtually no limit to the size of the welds you You can do it. I’ve seen several machines weld 20″ pipes. What these machines can do today is impressive.”
Considering the cleanliness requirements, the number of welds required and the low wall thickness, orbital welding is a reasonable choice for this type of project. When working with airflow control piping, Hammer often welds 316L stainless steel.
“Then things get very thin. We’re talking about welding thin metal. With manual welding, the slightest adjustment can cause the weld to break. That’s why we prefer to use orbital welding heads, where we can drill through each section of the weld tube and make it perfect, before we put the part in. We reduce the power to a certain amount so we know when we put the part in it it will be perfect. Manually, the change is done by eye, and if we pedal too much, it can go right through the material.”
The job consists of hundreds of welds that must be identical. The orbital welder used for this job completes the weld in three minutes; when the Hammer is running at maximum speed, it can manually weld the same stainless steel pipe in about a minute.
“However, the car doesn’t slow down. You run it at top speed first thing in the morning and by the end of the day it’s still running at top speed,” Hammer said. “I first run it at maximum speed in the morning, but in the end, it doesn’t.”
Preventing contaminants from entering stainless steel tubing is critical, which is why high-purity soldering in the semiconductor industry is often done in a clean room, controlled environment that prevents contaminants from entering the soldering area.
Hammer uses the same pre-sharpened tungsten in his flashlights as the Orbiter. While pure argon provides external and internal purge for manual and orbital welding, orbital welding also benefits from being performed in a confined space. When the tungsten is released, the sheath fills with gas and protects the weld from oxidation. When using a manual torch, gas is supplied to only one side of the pipe to be welded.
Orbital welds are generally cleaner because the gas coats the pipe longer. Once welding has begun, argon provides protection until the welder is satisfied that the weld is cold enough.
Axenics works with a number of alternative energy customers who manufacture hydrogen fuel cells for a variety of vehicles. For example, some indoor forklifts use hydrogen fuel cells to prevent chemical by-products from destroying food supplies. The only by-product of a hydrogen fuel cell is water.
One of the customers had the same requirements as a semiconductor manufacturer, such as weld cleanliness and uniformity. He wants to use 321 stainless steel for thin wall welding. However, the work involved building a prototype manifold with multiple valve banks, each protruding in a different direction, leaving little room for welding.
An orbital welder suitable for this job will cost about $2,000 and will be used to make a small number of parts, with an estimated cost of $250. It doesn’t make financial sense. However, Hammer has a solution that combines manual and orbital welding.
“In this case, I would use a turntable,” says Hammer. “It’s actually the same as orbital welding, but you rotate the tube, not the tungsten electrode around the tube. I use my hand torch, but I can clamp it in a vise in the right position to keep my hands…free, so human hands can’t damage the weld due to shaking or shaking. This eliminates most of the human error factor. It’s not that ideal, like orbital welding because it is not indoors, but this type of welding can be done in a clean room environment to eliminate contaminants.”
While orbital welding technology ensures cleanliness and repeatability, Hammer and his fellow welders know that weld integrity is critical to preventing downtime due to welding defects. The company uses non-destructive testing (ND) and sometimes destructive testing for all orbital welds.
“Every weld we make is visually verified,” Hammer says. “After that, the welds are checked with a helium spectrometer. Depending on the specification or customer requirements, some welds are checked by radiography. Destructive testing is also possible.”
Destructive testing may include tensile strength tests to determine the ultimate tensile strength of the weld. To measure the maximum stress that a weld on a material such as 316L stainless steel can withstand before failure, the test stretches and stretches the metal to the breaking point.
Alternative energy consumer welds are sometimes subjected to ultrasonic non-destructive testing on the welds of triple heat exchanger hydrogen fuel cell components used in alternative energy machines and vehicles.
“This is a critical test because most of the components we ship contain potentially hazardous gases. It is very important to us and our customers that the stainless steel is flawless and does not leak,” says Hammer.
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Post time: Aug-24-2022