IPE 180 vs UB 178×102×19
IPE 180 is an IPE section from the European (Continental) range; UB 178×102×19 is the closest equivalent in the UK Blue Book (SCI P363). UB 178×102×19 carries more bending: 171 cm³ of plastic modulus against 166 cm³, 2.9% more. They weigh essentially the same, 18.8 kg/m and 19 kg/m. Both are about 179 mm deep, so either fits the same construction zone.
| Property | IPE 180 IPE | UB 178×102×19 UB | Difference |
|---|---|---|---|
| Mass | 18.8 kg/m | 19 kg/m | -1.1% |
| Depth | 180 mm | 177.8 mm | +1.2% |
| Width | 91 mm | 101.2 mm | -10.1% |
| Web thickness | 5.3 mm | 4.8 mm | +10.4% |
| Flange thickness | 8 mm | 7.9 mm | +1.3% |
| Area | 23.9 cm² | 24.3 cm² | -1.6% |
| Second moment, major (Iy) | 1,320 cm⁴ | 1,360 cm⁴ | -2.9% |
| Plastic modulus, major (Wpl,y) | 166 cm³ | 171 cm³ | -2.9% |
| Elastic modulus, major (Wel,y) | 146 cm³ | 153 cm³ | -4.6% |
| Second moment, minor (Iz) | 101 cm⁴ | 137 cm⁴ | -26.3% |
| Plastic modulus, minor (Wpl,z) | 34.6 cm³ | 41.6 cm³ | -16.8% |
| Radius of gyration, minor (iz) | 2.05 cm | 2.37 cm | -13.5% |
| Torsion constant (It) | 4.73 cm⁴ | 4.41 cm⁴ | +7.3% |
IPE 180 to EN 10365 · Continental Steel; UB 178×102×19 to BS EN 10365:2017. Difference is expressed relative to UB 178×102×19.
How to choose between them
On stiffness, UB 178×102×19 has the larger second moment of area: 1,360 cm⁴ against 1,320 cm⁴, a difference of 2.9%. 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 (8.8 against 9.0 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.
The two diverge much more about the minor axis: UB 178×102×19 has 41.6 cm³ of minor-axis plastic modulus against 34.6 cm³, 16.8% 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. IPE sections are specified to EN 10365 · Continental Steel and UB to BS EN 10365:2017; 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, UB 178×102×19 is the stronger section and IPE 180 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.