W8x24 is the imperial designation for a wide flange beam with a nominal depth of 8 in. and a nominal mass of 24 lb/ft. In metric terms it is a beam of roughly 203 to 210 mm depth weighing about 35.9 kg/m, and it is one of the most widely stocked rolled sections for light structural framing. Knowing the designation, the actual rolled dimensions and the grades behind it prevents costly mismatch between design drawings and delivered steel.
What the W8x24 Designation Means
In the W series the first number is the nominal depth in inches and the second is the nominal mass in pounds per linear foot. Neither figure is exact. Rolling tolerances mean the delivered depth, width and mass differ slightly from the nominal values, so engineers design against published section properties rather than the name alone.
Rolled Dimensions and Sectional Data
| Property | Value |
|---|---|
| Depth H | 203 to 210 mm |
| Flange width B | 165 to 166 mm |
| Web thickness t1 | 6.2 to 7.2 mm |
| Flange thickness t2 | 10.2 to 11.8 mm |
| Mass | about 35.9 kg/m (24 lb/ft) |
The wide, parallel flanges give the section a high major-axis moment of inertia for its weight, which is why it is chosen for floor beams, roof purlins and light crane rails.
Material Grades and Mechanical Requirements
The same profile can be rolled to several structural specifications. ASTM A36 has a minimum yield point of 250 MPa (36 ksi). ASTM A572 Grade 50 raises the minimum yield strength to 345 MPa (50 ksi) with improved atmospheric corrosion resistance. ASTM A992 is the preferred grade for building frames: minimum yield strength of 345 MPa (50 ksi), minimum tensile strength of 450 MPa (65 ksi) and a controlled yield-to-tensile ratio not exceeding 0.85, which supports ductile frame behaviour under seismic loading.
Metric Equivalents Used in Other Markets
The nearest universal column sections are UC152x152x37 at 161.8 x 154.4 x 8 x 11.5 mm and 150UC37.2 at 161.8 x 154 x 8.1 x 11.5 mm. They are close in mass but shallower and narrower than a W8x24, so connection details and bolt gauges cannot be swapped without recalculation.
Fabrication, Delivery and Inspection
Beams are cut, drilled, cambered and welded to shop drawings, with mill test certificates issued for each heat. For exposed or humid service, hot-dip galvanizing to ASTM A123/A123M is common; thin webs and flanges need even heating and cooling to limit distortion. Sections ship in strapped bundles or on wooden pallets, protected for sea freight.
Frequently Asked Questions
Q: Is a W8x24 the same as a 200 mm metric beam?
A: No. Its nearest equivalents, UC152x152x37 and 150UC37.2, are shallower and narrower, so section properties differ.
Q: What is the minimum yield strength when the beam is supplied to ASTM A36?
A: 250 MPa (36 ksi), with tensile strength of 400 to 550 MPa (58 to 80 ksi).
Q: Can the section be supplied in ASTM A992?
A: Yes. A992 requires a minimum yield of 345 MPa, a minimum tensile of 450 MPa and a yield-to-tensile ratio of 0.85 or less.
Q: How much does a W8x24 weigh per metre?
A: Approximately 35.9 kg/m, equivalent to the nominal 24 lb/ft.
Q: Can W8x24 beams be galvanized?
A: Yes, by hot-dip galvanizing to ASTM A123/A123M, with handling controls to limit distortion of the thin web.