CHS 48.3×3.2 vs PIPE 1-1-2STD
CHS 48.3×3.2 is an CHS Hot-finished section from the UK Blue Book (SCI P363); PIPE 1-1-2STD is the closest equivalent in the American AISC Shapes Database. PIPE 1-1-2STD carries more bending: 6.899 cm³ of plastic modulus against 6.52 cm³, 5.5% more. CHS 48.3×3.2 is the lighter of the two at 3.56 kg/m against 4 kg/m, a saving of 11.0% on steel weight. Both are about 48 mm deep, so either fits the same construction zone.
| Property | CHS 48.3×3.2 CHS Hot-finished | PIPE 1-1-2STD Pipe | Difference |
|---|---|---|---|
| Mass | 3.6 kg/m | 4 kg/m | -11.0% |
| Depth | 48.3 mm | 48.3 mm | same |
| Width | 48.3 mm | 48.3 mm | same |
| Web thickness | 0 mm | 3.4 mm | -100.0% |
| Flange thickness | 0 mm | 0 mm | same |
| Area | 4.5 cm² | 4.8 cm² | -5.6% |
| Second moment, major (Iy) | 11.6 cm⁴ | 12.2 cm⁴ | -4.9% |
| Plastic modulus, major (Wpl,y) | 6.52 cm³ | 6.899 cm³ | -5.5% |
| Elastic modulus, major (Wel,y) | 4.8 cm³ | 5.064 cm³ | -5.2% |
| Second moment, minor (Iz) | 11.6 cm⁴ | 12.2 cm⁴ | -4.9% |
| Plastic modulus, minor (Wpl,z) | 6.52 cm³ | 6.899 cm³ | -5.5% |
| Radius of gyration, minor (iz) | 1.6 cm | 1.59 cm | +0.6% |
| Torsion constant (It) | 23.2 cm⁴ | 24.39 cm⁴ | -4.9% |
CHS 48.3×3.2 to BS EN 10210-2:2006; PIPE 1-1-2STD to AISC Shapes Database v16.0. Difference is expressed relative to PIPE 1-1-2STD.
How to choose between them
On stiffness, PIPE 1-1-2STD has the larger second moment of area: 12.2 cm⁴ against 11.6 cm⁴, a difference of 4.9%. 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 of steel, CHS 48.3×3.2 is the more efficient section: 1.8 against 1.7 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. 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 11.0% weight.
In short, PIPE 1-1-2STD is the stronger section and CHS 48.3×3.2 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.