Checking the availability of HSS sections is easy with the Steel Tube Institute’s Capability Tool.
If you have ever opened the steel manual to find section properties for a steel HSS (hollow structural section) member, you may have been surprised by how many sizes of HSS are listed. There are hundreds of options for round, rectangular, and square tubes. Some of these sections are readily available, others are produced on demand, and some may not be available in the current market. Realizing this, the Steel Tube Institute (STI), an industry organization supported by domestic steel tube producers, has created a free Capability Tool as a resource to search which HSS sections are currently domestically produced, by whom, and whether the sections are regularly produced or produced on demand. At steeltubeinstitute.org/capability-tool, there are search fields for shape, dimension range, and grade. Three ASTM (American Society for Testing and Materials) HSS material grades are included: A500, A1085, and A1065; and one for mechanical tubing, A513. Once these fields are filled, a list of producers who provide that shape, either regularly or on demand, is generated.
ASTM A500 is the current market leader for HSS material. It is widely available in many sizes, shapes, and wall thicknesses in North American service centers. For this reason, the availability tables in this article are based on A500 material. Domestically produced A500 HSS members are dual certified as grades B/C. The B/C dual certification means that the material meets the requirements for both grades. Therefore, when utilizing A500 HSS, STI recommends specifying and designing with Grade C, which has strengths of Fy = 50 ksi and Fu = 62 ksi for squares, rectangles, and round shapes, per ASTM A500-21.
Three other material grades that are commonly specified for steel tubes have some overlap with A500 but also provide unique properties of their own. A1085 is a newer HSS material grade with tighter wall-thickness tolerances, additional Charpy V-notch requirements, and strengths of Fy = 50 ksi and Fu = 65 ksi. A1085 HSS is only produced on demand and is not readily available in the current market. A1065, another HSS material grade, provides similar strength characteristics to A500 and A1085 but is manufactured differently, allowing tapered sections, multi-sided sections (i.e., lighting poles), and larger square and rectangular sizes to be formed. Round sections are not produced using A1065. A513 is a mechanical tubing specification that is not structurally graded. It is intended for applications requiring strict dimensional tolerances, but where the member’s strength is not critical. If using A513 for structural applications (i.e., handrails), its strength MUST be verified through reports or testing.
You may have noticed the omission of a material specification, ASTM A53, often utilized for round sections. A53 is a mechanical pipe specification, not a structural specification, and there are good reasons for that. A53 focuses on producing a pipe that is rigorously tested to withstand pressurized conditions and that is coated in an exterior sealant, among other characteristics. The costs of these additional piping requirements are passed along even in non-piping structural usage. A53’s yield strength is also less than the structural grades of A500 and A1085. For these reasons, round structural tubular sections should be specified as A500 or A1085, not A53. If you find yourself asked to replace A500 round HSS with A53 pipe or vice versa, this article with a list of round HSS sizes that match common pipe sizes is helpful: steeltubeinstitute.org/resources/selecting-right-round-hss/. But remember that if A53 is ultimately used for structural applications, its strength MUST be verified through reports or testing.
The next time you are faced with hundreds of HSS choices, we encourage you to utilize the Steel Tube Institute’s free Capability Tool for the most up-to-date HSS section availability. A snapshot of production at the time this article was written is given in the included tables of commonly available square, rectangular, and round HSS A500 Grade B/C sections from multiple domestic HSS producers. A dot in Tables 1 through 4 indicates that as of August 2023, the corresponding HSS section was readily available from 2 or more STI HSS producers based on regular HSS production rolling schedules. If a section you wish to specify is not listed in the tables, it does not mean it is unavailable. Individual suppliers regularly roll sizes that are not indicated here. Ultimately, the regularly-updated Capability Tool is the best source of available sizes from each STI HSS producer, providing a more comprehensive selection beyond what is presented here.■