TS vs HSS
TS and HSS are two tubing designations that frequently get used interchangeably. TS tube refers to tube-shaped steel, while the latter indicates a hollow section for structural purposes. The two designations do not pose many significant dissimilarities. However, HSS is newer and, slowly, has taken over TS.
In most geographical regions, including Canada, Europe, and Asia, the preferred nomenclature for steel sections or tubes has long been HSS. The UK uses RHS, CHS, and SHS (rectangular, circular, and square hollow sections). In 1997, the AISC, or the American Institute of Steel Construction, also transitioned from TS to HSS structural steel. The purpose was to bring alignment at a global level.
The AISC has guidelines – the official Steel Construction Manual – detailing the material specifications for square HSS tubes. HSS is the standard designation for steel tubes from the second edition onwards. The HSS Connections Manual published by the AISC and the Steel Tube Institute also states it. We recommend the third edition of the Load & Resistance Factor Design manual (LRFD V3) for accurate figures.
HSS section advantages and disadvantages
Hollow structural steel (HSS) uses carbon steel, adhering to ASTM A500 specifications. It can undergo welding or be seamless. HSS sections work in numerous applications, including construction steel frames, parking lot barriers, beams, and pillars.
Advantages:
- HSS steel has a high yield strength of 46,000 psi. In contrast, the yield strength of TS steel is 35,000 psi.
- It has a lucrative strength-to-weight ratio and load-bearing capacity.
- Unlike TS steel, HSS has a surface finish that does not need a lacquered coating. So, additional processing is not required before welding, thereby saving time.
- Since HSS is a structural designation, pressure testing is not required. It makes HSS more cost-effective than a TS column.
Disadvantages:
- It can be challenging to install bolted connections since it is a closed section.
- The sizes are generally much smaller than TS – not over 10 inches.
- HSS must get manufactured to exact specifications. In tube steel vs HSS, the former can allow greater leniency.
- Not all shapes handle excessive flexure or bending; round HSS tubing works the best.
How much weight can an HSS square tube support?
Generally, an HSS square tube has excellent weight-bearing capacity and is indispensable in construction and manufacturing.
The size of these tubes gets measured by the gauge or the wall thickness and the outer diameter. These measurements assess the strength of the HSS column and the maximum weight it can bear. The load distribution, i.e., centre or uniform, also affects this calculation.
Can HSS be round, square, or rectangular?
Customers can specify the shape immediately after the HSS detailing to indicate whether they need square, rectangular, oval, or round/circular shapes. Square tubing gets favoured for applications with uniform geometries in multiple cross-sections, while HSS rectangular steel can handle multi-directional loads better.
A unique elliptical shape or custom designs are also available to address specific client requirements.
How can you check the torsion capacity of a TS tube?
Tube steel uses carbon steel and denotes a long, hollow circular section (or square). It meets ASTM A53 specifications, i.e., the tube may be seamless or welded. The diameters range from NPS 1/8 to NPS 26. Most importantly, the measurements include the outer diameter, the wall thickness, and the inner diameter. The total volume or capacity is crucial in these tubes.
The torsion capacity (Tc) can be calculated by:
Tc = (Ta x R) / I
where:
Ta = Torque applied
R = Radius of the cross-section area
I = polar moment of inertia
Tube shape works for both liquids and gases, for example, hydraulic lifts and conveyor belts. It often gets galvanized via zinc coating for corrosive environments and also encloses electrical wires. The automotive, aerospace, and medical industries also use TS steel.
Conclusion
To summarise, TS and HSS are similar, but TS is now outdated. Also, while HSS or Hollow Structural Section is a structural specification, TS steel refers to the chemical composition.
Buyers must be cautious while selecting the design properties of their tubes using HSS or TS. So, if you refer to the ASD 9th Edition, you will find the properties higher by approximately 10%. Manufacturers of HSS beams can use these metrics and remain within acceptable tolerance limits.
Another concern to watch out for is the availability of sizes listed in an older edition – they may be unavailable or not produced anymore. The available dimensions are on the official website of the AISC. Even so, some manufacturers may request a minimum order quantity to build a component.
TS Tube material & ASTM Standard
| Material | ASTM Standard |
|---|---|
| Stainless Steel | ASTM A312 |
| Carbon Steel | ASTM A106, A53, A333, A671, A672 |
| Alloy Steel | ASTM A335 |
| Inconel | ASTM B704, B163 |
| Monel | ASTM B163, B165 |
| Hastelloy | ASTM B622, B619 |
| Titanium | ASTM B338 |
HSS material & ASTM Standard
| Material | ASTM Standard |
|---|---|
| Carbon Steel | ASTM A500 |
| Stainless Steel | ASTM A554 |
| Aluminium | ASTM A847 |
| Mild Steel (MS) | ASTM A500 |