Structural tubing per ASTM A500 is tubing produced and used for structural applications. Standard strength requirements of the tube help dictate applications for which certain tubing is most appropriate. Structural tube is often referred to as hollow structural sections or HSS. Structural Tubing, especially rectangular sections, are commonly used in welded steel frames where members experience loading in multiple directions. Square and circular HSS are very efficient shapes for this multiple-axis loading as they have uniform geometry along two or more cross-sectional axes, and thus uniform strength characteristics. This makes them good choices for columns. They also have excellent resistance to torsion. The flat square surfaces of HSS structural tubing can ease construction, and they are sometimes preferred for architectural aesthetics in exposed structures. HSS structural tubing is most commonly produced to ASTM A500 grade B standards, but can also be available in ASTM A1085 as well. Structural products are ordered to a specific outside dimension (OD) and “gauge” or wall thickness.
ASTM A500 structural tubing is welded tubing made from flat-rolled steel, formed through a roller system and welded using electric-resistance welding. Longitudinal butt joints of welded tubing shall be welded across its thickness in such a manner as to assure the structural design strength of the tubing section. Welded structural steel tubing is normally furnished without the removal of inside flash.
HSS has a high strength-to-weight ratio, excellent compression support characteristics and excellent torsional resistance.
In exposed applications, especially Architecturally Exposed Structural Steel (AESS) applications in construction, HSS provides preferred visual opportunities for the design of buildings and other structures.
HSS provides uniformity of size, shape, strength and tolerances that make its use totally predictable, especially important for demanding OEM applications.
HSS can be readily bent, formed, punched and drilled. Improvements in connection design for fastening HSS to itself or other structural materials are improving the ease of fabrication in the field as well.
Due to its higher strength ratio, especially in A1085, HSS is cost competitive with other structural materials. With improved connection and fastening methods, it often enjoys a cost advantage.
HSS is fire resistant and does not warp, twist, split, swell or shrink.
It resists dry rot and mildew.