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Building a Dream: How Bel-Aire Mechanical Moved from Manual to Automated Oxy-Acetylene Pipe Cutting

By John Henderson, Group Brand Manager, Victor Technologies

You can tell an ultra-efficient company by this sign: competitors become clients.

“We can sell a pipe spool for less money than our competitors can fabricate it for themselves. Because we operate so efficiently, more and more of our clients are other mechanical contractors,” says Kevin Prevett, pipe shop superintendent, Bel-Aire Mechanical, Phoenix.

In addition to changing welding processes (from SMAW to a modified short circuit transfer GMAW and pulsed spray GMAW), Bel-Aire Mechanical increased productivity by changing pipe cutting and beveling technology. Prior to 2005, the company used standard “saddle-type”, hand-cranked beveling machines fitted with a straight oxy-acetylene torch. Operators coped pipe using manual oxy-acetylene torches.

Then in 2007, Bel-Aire Mechanical installed a two-axis microprocessor-controlled mechanized cutting system from Vernon Tool™ featuring a Victor® MT 5 machine torch. As a result of the change, man-hours dedicated to pipe cutting have been reduced from 16 to about four hours per day. However, such a productivity increase only came to fruition after intelligent planning.

Planning the Space

Bel-Aire Mechanical is a full service mechanical, HVAC and plumbing contractor. Founded in 1986, it is the largest privately-owned mechanical contracting company in Arizona. The company fabricates duct work, plumbing systems and piping for municipal work (water and gas), power plants, semiconductor manufacturers and just about anyone who needs pipe.

During the mid-2000s, President and CEO Jim Dinan realized that if the company wanted to increase its market share, it would need a new production facility. In 2006, the company purchased a four-acre industrial property with a 42,000-sq.-ft. high bay facility. Bel-Aire Mechanical completely retrofitted the building, and that included an area of the building dedicated to pipe fabrication.

To that end, Dinan charged Project Director Mike Mackintosh with finding an automated pipe machine. After flying to Louisiana and inspecting a system in operation there, Mackintosh selected a system that would bevel pipe at any angle desired, as well as cut lateral windows and saddles on pipe from 4 to 48 inches in diameter. Choosing a cutting torch was an easy decision, as the new machine torch could use the same cutting tips as the company’s manual torches, as well as the straight torch on its hand-cranked beveller.

“I’ve been in the metal trades 40 years, and there’s nothing better than Victor,” says Prevett. “I started out in the oil fields, and the standard has always been Victor. Victor torches and regulators are reliable, and they perform the task they’re designed to perform better than anybody else. When you change a tip out, the new tip performs like the old one. A lot of other brands are real finicky, and you can go crazy trying to readjust gas flow. And when a Victor torch or regulator does need service or parts, you can go to any welding shop and get it fixed and find parts by the bucketful.”

While choosing the right cutting machine may seem like the most difficult decision, there are two other critical factors. The first is space.

“If you’re buying an automated pipe system, you need to make sure the system fits your operation — literally. You have to have enough physical room. For our roll turning system, that’s about 70 feet,” says Prevett.

Pipe comes from the mill in 21-ft. lengths, which Bel-Aire Mechanical stores in its yard. When a project begins, pipe is loaded on a storage rack that feeds a 21-ft.-long entrance conveyor. Due to the climate in Phoenix, Bel-Aire Mechanical has the luxury of locating the entrance conveyor outside the building, opening a door as necessary for the operator to roll the length of pipe onto the conveyor. After that, the operator no longer needs to physically touch the pipe. A chain-driven power feed moves the pipe forward to the 22-ft.-long bed of the cutting machine.

In a turning roll machine (as opposed to a chucking system), the pipe rotates on a bed of turning rolls mounted on two parallel main shafts. The weight of the pipe secures it in the turning rolls. The two main shafts are interconnected by precision gearboxes, which are driven by a variable speed D.C. motor. Traveling along one side of the machine, a reciprocating torch carriage is synchronized with the pipe rotation to perform contouring movements. After cutting, another chain-driven power feed moves the pipe forward to an unloading conveyor and another storage rack.

“I know companies that purchased automated systems and didn’t have the 70 feet of space necessary to support them,” says Prevett. “Instead of improving productivity, they created a bottleneck because they have to unload pipe from the cutting bed instead of just sliding it over to the storage racks.”

Evaluating the Impact

In addition to planning facility layout, Prevett notes that companies need to evaluate how moving from manual to mechanized cutting will change logistics.

“The move requires management to shift its way of thinking about production planning,” he says. “In fact, that’s probably the hardest thing. It takes a different mindset, and it takes time to change established habits.”

While slower, manual oxy-fuel cutting (like manual or semi-automatic welding) maximizes flexibility. For example, operators can easily shift from cutting thin to thick wall pipe and cutting different pieces of pipe.

“The objective is different in a mechanized operation,” says Prevett. “If we put a 21-ft. length of pipe on the bed, we want to maximize the number of cuts on that pipe so we don’t have to handle it more than once. Also, we’ll want to maximize the number of cuts on pipe with the same wall thickness so we don’t have to change cutting tips and re-set oxygen and fuel gas pressure and flow rates. You can cut much faster with a machine, but you only increase productivity with good planning.”

A Quality Cut

Mechanized cutting speed varies with thickness, but, as an example, a 24-in. diameter pipe with a wall thickness of 0.375 in. takes approximately three minutes to cut. This equates to a travel speed of about 25 ipm using a size 0, general-purpose “101 style” cutting tip.

“With a machine, you get a straight cut with a well prepared finish. There’s no grinding involved and a minimal amount of buffing. Clean up time is perhaps 30 seconds for a 24-in. diameter piece,” says Prevett. “By way of comparison, a cut made by a highly skilled operator with a hand beveling machine typically requires three to four minutes of clean-up time, and of course about twice the cutting time.”

After installing the mechanized cutting system, a single operator working a handful of hours can accomplish the same volume of work as two operators working an eight-hour shift.

Oxy-Acetylene Advantages

Bel-Aire Mechanical does have a plasma power source with a 180-degree machine torch it can connect to its automated cutting system. Plasma is mainly used for cutting low purity stainless steel and other special alloy materials. To start, the company primarily cuts mild carbon steel or black iron pipe. Much of this pipe has a coating, and the oxy-acetylene flame cleanly burns away the coating. The plasma arc does not, and it creates more smoke. Any speed gains offered by plasma on thinner wall pipe are offset by the need to remove the coating.

When Bel-Aire Mechanical does cut stainless steel pipe, it’s often for high-purity applications such as semiconductor manufacturing. In this case, the company uses a mechanical cutting machine, as they are concerned about spatter from the plasma arc getting inside the pipe.

Cut accuracy is not an issue, as the oxy-acetylene process can actually create a more precise cut than a plasma system. Because the plasma gas swirls, one side of the cut always has some degree of bevel (and note that the bevel is more of an issue on thinner materials than on thicker material). Conversely, the cutting oxygen stream produces a cut with straight walls, and the cut is highly repeatable.

Lastly, Prevett likes the simplicity of oxy-acetylene consumables. The mechanized system uses the exact same cutting tips as the company’s manual torches, and such tips are available at every welding supply store.

The Vision for Investment

Moving from manual to automated cutting requires more than just evaluating cutting machines or cutting processes. For a company cutting high volumes of non-ferrous pipe, evaluating plasma cutting processes further complicates the matter.

However, Bel-Aire Mechanical demonstrates that choosing equipment is only half the battle. Without forethought on how an automated system will affect facility layout and radically change work planning, a seven-figure investment could produce a monumental headache. Fortunately, Bel-Aire Mechanical’s key managers knew how to build their future.

Automated cutting torch systems require about 70 feet of space for the entrance conveyor and cutting bed (shown here), as well as the unloading conveyor.

 

Bel-Aire Mechanical uses an automated oxy-acetylene torch to make repeatable bevels on mild carbon steel (shown here) and black iron pipe. Note the general purpose cutting tip and cleanliness of the cut.

 

Successfully implementing an automated cutting system requires a different mindset, such as cutting as much of the same type of pipe as possible without a consumable swap out.

 

The automated torch requires very little operator involvement after entering the program. Here, the operator makes a small manual adjustment to correctly position the pre-heat flames.

 

Automated oxy-acetylene cutting produces a clean cut that requires about 30 seconds of buffing. The slag shown here will drop off at the end of the cut.