SHS 140×140×6.3 vs SHS 140×140×6
SHS 140×140×6.3 is an SHS Hot-finished section from the UK Blue Book (SCI P363); SHS 140×140×6 is the closest equivalent in the European (Continental) range. SHS 140×140×6.3 carries more bending: 166 cm³ of plastic modulus against 159 cm³, 4.4% more. SHS 140×140×6 is the lighter of the two at 25.1 kg/m against 26.1 kg/m, a saving of 4.0% on steel weight. Both are about 140 mm deep, so either fits the same construction zone.
| Property | SHS 140×140×6.3 SHS Hot-finished | SHS 140×140×6 SHS | Difference |
|---|---|---|---|
| Mass | 26.1 kg/m | 25.1 kg/m | +4.0% |
| Depth | 140 mm | 140 mm | same |
| Width | 140 mm | 140 mm | same |
| Web thickness | 0 mm | 0 mm | same |
| Flange thickness | 0 mm | 0 mm | same |
| Area | 33.3 cm² | 31.8 cm² | +4.7% |
| Second moment, major (Iy) | 984 cm⁴ | 944 cm⁴ | +4.2% |
| Plastic modulus, major (Wpl,y) | 166 cm³ | 159 cm³ | +4.4% |
| Elastic modulus, major (Wel,y) | 141 cm³ | 135 cm³ | +4.4% |
| Second moment, minor (Iz) | 984 cm⁴ | 944 cm⁴ | +4.2% |
| Plastic modulus, minor (Wpl,z) | 166 cm³ | 159 cm³ | +4.4% |
| Radius of gyration, minor (iz) | 5.44 cm | 5.45 cm | -0.2% |
| Torsion constant (It) | 1,540 cm⁴ | 1,475 cm⁴ | +4.4% |
SHS 140×140×6.3 to BS EN 10210-2:2006; SHS 140×140×6 to EN 10219 · Continental Steel. Difference is expressed relative to SHS 140×140×6.
How to choose between them
On stiffness, SHS 140×140×6.3 has the larger second moment of area: 984 cm⁴ against 944 cm⁴, a difference of 4.2%. This matters more often than the strength comparison, because on normal floor spans deflection rather than bending capacity sets the beam size - so if the two are close on modulus but apart on inertia, the stiffer one is usually the better answer even when it is not the stronger one.
Measured as bending capacity per kilogram, the two are equally efficient (6.4 against 6.3 cm³ per kg/m), so on a pure steel-tonnage basis there is nothing to choose between them. The decision comes down to availability, connection detailing and what the rest of the frame uses.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. SHS Hot-finished sections are specified to BS EN 10210-2:2006 and SHS to EN 10219 · Continental Steel; the steel grades, tolerances and available lengths differ, connection details and bolt gauges are set out differently, and the two are rarely both stocked in the same market. Check availability before changing a section on a drawing to save 4.0% weight.
In short, SHS 140×140×6.3 is the stronger section and SHS 140×140×6 is the lighter one; where those are the same section, it is the clear choice, and where they are not, decide on whether your design is governed by capacity or by tonnage.