Guidelines for Cutting Structural Tube in Your Fabrication Shop

August 10, 2015 / , , , , , , , ,

As reported in our recent Metal-Cutting Industry Report on Non-Residential Construction, the use of industrial and structural steel tube and pipe is growing. According to a market tracker from Metal Bulletin Research (MBR), the category is growing at the fastest rate since the recession, mostly due to economic growth and falling oil prices.

“Construction demand for structural tubing is now growing at a steady pace in most regions of the USA,” the MBR report states. “There has been some concern among market participants that the drop in oil prices and the associated hit to the local energy-centered economies would be detrimental to their construction outlook, especially since these were some of the initial drivers of growth in the recovery. So far, construction continues unabated, as contracts, financing and permitting have already been settled.”

Industry players are also optimistic. HGG, a supplier of tube-processing machinery, told MetalForming magazine it expects the category to grow by about 15 percent in North America alone. (You can read the full MetalForming article here.)

This is good news for fabricators that serve the industrial and commercial construction industries or that cut structural tube for other applications. In either case, most shops are working with hollow structural steel (HSS) tube specified to ASTM A500 (the standard specification for cold-formed welded and seamless carbon steel structural tubing in round, square and rectangular shapes). Although most shops wouldn’t categorize HSS as difficult to cut, it does have some unique characteristics operators need to understand to ensure proper cutting.

Unlike solid tubing, which only requires one cut, HSS tube requires the blade to cut through two thin solids with a space in between. These types of cuts—known as interrupted cuts—are best suited for bi-metal band saw blades because they are designed to withstand the vibration. Carbide band saw blades, on the other hand, have strong, durable teeth, but they are not shock resistant. Therefore, bi-metal blades that reduce harmonics are the best choice.

HSS tubes also aren’t ideal for bundle cutting. While cutting tubing in bundles can allow shops to increase the number of parts per shift, it can substantially reduce blade life. In fact, some experts say that any increased part volume efficiency is offset by a 20 to 25 percent reduction in band life.

A recent article from highlights several other best practices for sawing structural tube. The following are a few of the industry publication’s tips:

For more guidelines on cutting HSS tube, including a discussion on circular saw blade options, you can read the full article here.