Tee 127×152×19 vs WT 6X15
Tee 127×152×19 is an Tees (from UB) section from the UK Blue Book (SCI P363); WT 6X15 is the closest equivalent in the American AISC Shapes Database. They are close to interchangeable in bending: 77.9 cm³ against 79.15 cm³ of plastic modulus, a difference of 1.6%. Tee 127×152×19 is the lighter of the two at 18.5 kg/m against 22.3 kg/m, a saving of 17.0% on steel weight. WT 6X15 is deeper, 156.7 mm against 152.1 mm, which matters where the floor zone is tight.
| Property | Tee 127×152×19 Tees (from UB) | WT 6X15 WT | Difference |
|---|---|---|---|
| Mass | 18.5 kg/m | 22.3 kg/m | -17.0% |
| Depth | 152.1 mm | 156.7 mm | -2.9% |
| Width | 123.4 mm | 165.6 mm | -25.5% |
| Web thickness | 7.1 mm | 6.6 mm | +7.6% |
| Flange thickness | 10.7 mm | 11.2 mm | -4.5% |
| Area | 23.6 cm² | 28.4 cm² | -16.9% |
| Second moment, major (Iy) | 501 cm⁴ | 561.9 cm⁴ | -10.8% |
| Plastic modulus, major (Wpl,y) | 77.9 cm³ | 79.15 cm³ | -1.6% |
| Elastic modulus, major (Wel,y) | 43.8 cm³ | 45.064 cm³ | -2.8% |
| Second moment, minor (Iz) | 168 cm⁴ | 424.6 cm⁴ | -60.4% |
| Plastic modulus, minor (Wpl,z) | 42.7 cm³ | 78.33 cm³ | -45.5% |
| Radius of gyration, minor (iz) | 2.67 cm | 3.86 cm | -30.8% |
| Torsion constant (It) | 7.36 cm⁴ | 9.49 cm⁴ | -22.4% |
Tee 127×152×19 to BS EN 10365:2017; WT 6X15 to AISC Shapes Database v16.0. Difference is expressed relative to WT 6X15.
How to choose between them
On stiffness, WT 6X15 has the larger second moment of area: 561.9 cm⁴ against 501 cm⁴, a difference of 10.8%. 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, Tee 127×152×19 is the more efficient section: 4.2 against 3.5 cm³ per kg/m, 18.6% 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.
The two diverge much more about the minor axis: WT 6X15 has 78.33 cm³ of minor-axis plastic modulus against 42.7 cm³, 45.5% 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. Tees (from UB) sections are specified to BS EN 10365:2017 and WT 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 17.0% weight.
In short, WT 6X15 is the stronger section and Tee 127×152×19 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.