Although the automotive industry shapes people’s thought of United states manufacturing, and metal manufacturing in particular, it isn’t the nation’s largest consumer of metal-not with a long shot. It’s commercial construction.
To reduce cost, builders have trusted design strategies to reduce the level of stainless steel seamless tube a structure needs, or even reduce on-site erection time. One design avenue that is significantly more popular throughout the past two decades continues to be to utilize options to the regular wide-flange beam.
These beams have evolved into a competent building material of choice. But with regards to strength, the design in the wide-flange beam pre-sents challenging. It can span simply a certain distance (or “unbraced length”) before requiring support. From the purely strength perspective, it would be far more efficient for beams to consider a circular, square, or rectangular shape, which would extend the utmost unbraced length. The longer distance these structural members are able to span, the fewer braces and supports a building needs. Ultimately, this simply means builders may use less of what’s often their biggest expense: the structural metal itself.
Enter hollow structural sections, or HSS (see Figure 1). These round, rectangular, or square tubes have shapes that provide inherently higher strength and might span greater lengths between braces. A square steel tube by using a 3/16-in.-thick wall thickness has an allowable load of 79 kips over a column time period of 32 ft., while a similar wide flange (ASTM designation of W12 x 40) comes with an allowable load of 64 kips within the same column length (see Figure 2).
For years HSS have been useful for their dramatic effect. Builders and architects used these to make an artistic statement, not to save money, which remains true in many cases today. But because HSS are really strong, architects can design buildings with less material. HSS also spend less on finishing costs, because compared to hollow steel pipe, tubular sections have less surface to color or fireproof. Combine this with the reality that tube production costs have fallen recently, and building with HSS actually starts to make real economic sense. This is one major reason that interest in HSS is going up ever since the recession, and it’s in this environment how the tube cutting laser is commencing to open up new opportunities.
HSS represent a departure from many tube laser cutting applications that tend to work with relatively thin-walled workpieces. Shops providing HSS often must take care of workpiece weights (called “stick weights”) as much as 2,000 pounds. These workpieces are not only long, but additionally large; 14-, 16-, and 20-in. diagonal cross sections aren’t uncommon.
To make such large workpieces cost-effectively with a tube laser calls for meticulous planning. It’s far more complicated than utilizing a cutoff saw, but it also adds a lot more value on the workpiece. Modern tube lasers have load/unload functions that may handle mill-length pipe and structural material.
This capability gives designers seamless steel pipe when it comes to designing for mated sections. Mating a round tube to another one round tube seems simple, however the bevel required dexopky12 build a tight fit-up between the two sections can be extremely complicated, especially when tubes are of numerous diameters or shapes, or maybe if they intersect at unusual angles.
From an architectural engineering perspective, such angles may make the best transfer of loads and a lot efficient utilization of HSS. But to the welder and fabricator, this kind of complicated joint could be a nightmare.