PFC 180×90×26 vs MC 7X19.1
PFC 180×90×26 is an PFC section from the UK Blue Book (SCI P363); MC 7X19.1 is the closest equivalent in the American AISC Shapes Database. MC 7X19.1 carries more bending: 237.61 cm³ of plastic modulus against 232 cm³, 2.4% more. PFC 180×90×26 is the lighter of the two at 26.1 kg/m against 28.4 kg/m, a saving of 8.1% on steel weight. Both are about 179 mm deep, so either fits the same construction zone.
| Property | PFC 180×90×26 PFC | MC 7X19.1 MC | Difference |
|---|---|---|---|
| Mass | 26.1 kg/m | 28.4 kg/m | -8.1% |
| Depth | 180 mm | 177.8 mm | +1.2% |
| Width | 90 mm | 87.6 mm | +2.7% |
| Web thickness | 6.5 mm | 8.9 mm | -27.0% |
| Flange thickness | 12.5 mm | 12.7 mm | -1.6% |
| Area | 33.2 cm² | 36.2 cm² | -8.3% |
| Second moment, major (Iy) | 1,820 cm⁴ | 1,794 cm⁴ | +1.4% |
| Plastic modulus, major (Wpl,y) | 232 cm³ | 237.61 cm³ | -2.4% |
| Elastic modulus, major (Wel,y) | 202 cm³ | 201.56 cm³ | +0.2% |
| Second moment, minor (Iz) | 277 cm⁴ | 252.2 cm⁴ | +9.8% |
| Plastic modulus, minor (Wpl,z) | 83.5 cm³ | 79.477 cm³ | +5.1% |
| Radius of gyration, minor (iz) | 2.89 cm | 2.64 cm | +9.5% |
| Torsion constant (It) | 13.3 cm⁴ | 16.94 cm⁴ | -21.5% |
PFC 180×90×26 to BS EN 1993-1-1:2005 / BS 4-1:2005; MC 7X19.1 to AISC Shapes Database v16.0. Difference is expressed relative to MC 7X19.1.
How to choose between them
On stiffness, PFC 180×90×26 has the larger second moment of area: 1,820 cm⁴ against 1,794 cm⁴, a difference of 1.4%. 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, PFC 180×90×26 is the more efficient section: 8.9 against 8.4 cm³ per kg/m, 6.2% 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. PFC sections are specified to BS EN 1993-1-1:2005 / BS 4-1:2005 and MC to AISC Shapes Database v16.0; 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 8.1% weight.
In short, MC 7X19.1 is the stronger section and PFC 180×90×26 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.