UC 203×203×71 vs HE 220 B
UC 203×203×71 is an UC section from the UK Blue Book (SCI P363); HE 220 B is the closest equivalent in the European (Continental) range. HE 220 B carries more bending: 827 cm³ of plastic modulus against 799 cm³, 3.4% more. They weigh essentially the same, 71 kg/m and 71.5 kg/m. Both are about 218 mm deep, so either fits the same construction zone.
| Property | UC 203×203×71 UC | HE 220 B HE | Difference |
|---|---|---|---|
| Mass | 71 kg/m | 71.5 kg/m | -0.7% |
| Depth | 215.8 mm | 220 mm | -1.9% |
| Width | 206.4 mm | 220 mm | -6.2% |
| Web thickness | 10 mm | 9.5 mm | +5.3% |
| Flange thickness | 17.3 mm | 16 mm | +8.1% |
| Area | 90.4 cm² | 91 cm² | -0.7% |
| Second moment, major (Iy) | 7,620 cm⁴ | 8,090 cm⁴ | -5.8% |
| Plastic modulus, major (Wpl,y) | 799 cm³ | 827 cm³ | -3.4% |
| Elastic modulus, major (Wel,y) | 706 cm³ | 736 cm³ | -4.1% |
| Second moment, minor (Iz) | 2,540 cm⁴ | 2,840 cm⁴ | -10.6% |
| Plastic modulus, minor (Wpl,z) | 374 cm³ | 394 cm³ | -5.1% |
| Radius of gyration, minor (iz) | 5.3 cm | 5.59 cm | -5.2% |
| Torsion constant (It) | 80.2 cm⁴ | 77 cm⁴ | +4.2% |
UC 203×203×71 to BS EN 10365:2017; HE 220 B to EN 10365 · Continental Steel. Difference is expressed relative to HE 220 B.
How to choose between them
On stiffness, HE 220 B has the larger second moment of area: 8,090 cm⁴ against 7,620 cm⁴, a difference of 5.8%. 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, HE 220 B is the more efficient section: 11.6 against 11.3 cm³ per kg/m, 2.7% 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.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. UC sections are specified to BS EN 10365:2017 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 a marginal amount of weight.
In short, HE 220 B is the stronger section and UC 203×203×71 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.