CHS 219.1×12.5 vs PIPE 8XS
CHS 219.1×12.5 is an CHS Hot-finished section from the UK Blue Book (SCI P363); PIPE 8XS is the closest equivalent in the American AISC Shapes Database. CHS 219.1×12.5 carries more bending: 534 cm³ of plastic modulus against 508 cm³, 5.1% more. They weigh essentially the same, 63.7 kg/m and 64.6 kg/m. Both are about 219 mm deep, so either fits the same construction zone.
| Property | CHS 219.1×12.5 CHS Hot-finished | PIPE 8XS Pipe | Difference |
|---|---|---|---|
| Mass | 63.7 kg/m | 64.6 kg/m | -1.4% |
| Depth | 219.1 mm | 219.1 mm | same |
| Width | 219.1 mm | 219.1 mm | same |
| Web thickness | 0 mm | 11.8 mm | -100.0% |
| Flange thickness | 0 mm | 0 mm | same |
| Area | 81.1 cm² | 76.8 cm² | +5.6% |
| Second moment, major (Iy) | 4,350 cm⁴ | 4,162 cm⁴ | +4.5% |
| Plastic modulus, major (Wpl,y) | 534 cm³ | 508 cm³ | +5.1% |
| Elastic modulus, major (Wel,y) | 397 cm³ | 378.54 cm³ | +4.9% |
| Second moment, minor (Iz) | 4,350 cm⁴ | 4,162 cm⁴ | +4.5% |
| Plastic modulus, minor (Wpl,z) | 534 cm³ | 508 cm³ | +5.1% |
| Radius of gyration, minor (iz) | 7.32 cm | 7.34 cm | -0.3% |
| Torsion constant (It) | 8,690 cm⁴ | 8,283 cm⁴ | +4.9% |
CHS 219.1×12.5 to BS EN 10210-2:2006; PIPE 8XS to AISC Shapes Database v16.0. Difference is expressed relative to PIPE 8XS.
How to choose between them
On stiffness, CHS 219.1×12.5 has the larger second moment of area: 4,350 cm⁴ against 4,162 cm⁴, a difference of 4.5%. 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, CHS 219.1×12.5 is the more efficient section: 8.4 against 7.9 cm³ per kg/m, 6.6% 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. CHS Hot-finished sections are specified to BS EN 10210-2:2006 and Pipe 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 a marginal amount of weight.
In short, CHS 219.1×12.5 is the stronger section and CHS 219.1×12.5 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.