W 21X122 vs H-600x300x14x23-170
W 21X122 is an W section from the American AISC Shapes Database; H-600x300x14x23-170 is the closest equivalent in the European (Continental) range. They are close to interchangeable in bending: 5030.8 cm³ against 5057 cm³ of plastic modulus, a difference of 0.5%. H-600x300x14x23-170 is the lighter of the two at 170 kg/m against 181.6 kg/m, a saving of 6.8% on steel weight. H-600x300x14x23-170 is deeper, 594 mm against 551.2 mm, which matters where the floor zone is tight.
| Property | W 21X122 W | H-600x300x14x23-170 MB & MC | Difference |
|---|---|---|---|
| Mass | 181.6 kg/m | 170 kg/m | +6.8% |
| Depth | 551.2 mm | 594 mm | -7.2% |
| Width | 315 mm | 302 mm | +4.3% |
| Web thickness | 15.2 mm | 14 mm | +8.6% |
| Flange thickness | 24.4 mm | 23 mm | +6.1% |
| Area | 231.6 cm² | 217 cm² | +6.7% |
| Second moment, major (Iy) | 123,205 cm⁴ | 133,600 cm⁴ | -7.8% |
| Plastic modulus, major (Wpl,y) | 5,030.8 cm³ | 5,057 cm³ | -0.5% |
| Elastic modulus, major (Wel,y) | 4,473.7 cm³ | 4,497 cm³ | -0.5% |
| Second moment, minor (Iz) | 12,695 cm⁴ | 10,570 cm⁴ | +20.1% |
| Plastic modulus, minor (Wpl,z) | 1,238.9 cm³ | 1,077 cm³ | +15.0% |
| Radius of gyration, minor (iz) | 7.42 cm | 6.98 cm | +6.3% |
| Torsion constant (It) | 373.8 cm⁴ | 304 cm⁴ | +23.0% |
W 21X122 to AISC Shapes Database v16.0; H-600x300x14x23-170 to Continental Steel. Difference is expressed relative to H-600x300x14x23-170.
How to choose between them
On stiffness, H-600x300x14x23-170 has the larger second moment of area: 133,600 cm⁴ against 123,205 cm⁴, a difference of 7.8%. 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 of steel, H-600x300x14x23-170 is the more efficient section: 29.7 against 27.7 cm³ per kg/m, 6.9% better. Over a floor of repeated beams that difference is real tonnage, though it is often outweighed by whichever section the fabricator can actually source.
The two diverge much more about the minor axis: W 21X122 has 1238.9 cm³ of minor-axis plastic modulus against 1077 cm³, 15.0% more. If the member sees any minor-axis bending, or if it is unrestrained over a long length and lateral-torsional buckling governs, that gap decides the comparison even though the major-axis numbers looked equivalent.
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 MB & MC to 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 6.8% weight.
In short, H-600x300x14x23-170 is the stronger section and H-600x300x14x23-170 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.