W 12X170 vs HE 320 M
W 12X170 is an W section from the American AISC Shapes Database; HE 320 M is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 4506.4 cm³ against 4440 cm³ of plastic modulus, a difference of 1.5%. HE 320 M is the lighter of the two at 245 kg/m against 253 kg/m, a saving of 3.3% on steel weight. Both are about 357 mm deep, so either fits the same construction zone.
| Property | W 12X170 W | HE 320 M HE | Difference |
|---|---|---|---|
| Mass | 253 kg/m | 245 kg/m | +3.3% |
| Depth | 355.6 mm | 359 mm | -0.9% |
| Width | 320 mm | 309 mm | +3.6% |
| Web thickness | 24.4 mm | 21 mm | +16.2% |
| Flange thickness | 39.6 mm | 40 mm | -1.0% |
| Area | 322.6 cm² | 312 cm² | +3.4% |
| Second moment, major (Iy) | 68,678 cm⁴ | 68,100 cm⁴ | +0.8% |
| Plastic modulus, major (Wpl,y) | 4,506.4 cm³ | 4,440 cm³ | +1.5% |
| Elastic modulus, major (Wel,y) | 3,851 cm³ | 3,800 cm³ | +1.3% |
| Second moment, minor (Iz) | 21,519 cm⁴ | 19,700 cm⁴ | +9.2% |
| Plastic modulus, minor (Wpl,z) | 2,064.8 cm³ | 1,950 cm³ | +5.9% |
| Radius of gyration, minor (iz) | 8.18 cm | 7.95 cm | +2.9% |
| Torsion constant (It) | 1,482 cm⁴ | 1,510 cm⁴ | -1.9% |
W 12X170 to AISC Shapes Database v16.0; HE 320 M to EN 10365 · Continental Steel. Difference is expressed relative to HE 320 M.
How to choose between them
On stiffness, W 12X170 has the larger second moment of area: 68,678 cm⁴ against 68,100 cm⁴, a difference of 0.8%. 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 (17.8 against 18.1 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. W sections are specified to AISC Shapes Database v16.0 and HE to EN 10365 · 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 3.3% weight.
In short, W 12X170 is the stronger section and HE 320 M 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.