Short Answer: One Shape Family, Two Different Products
H-beams and I-beams share the same I-shaped profile - two parallel flanges joined by a central web - but they are not interchangeable items. The difference is geometric: a wide-flange H-section (HW/HM/HN in the GB/T 11263 series, W shapes in ASTM practice) has a flange width close to the section depth and a comparatively thick web, while a narrow-flange I-section (IPE series, universal beam) has a flange width of roughly half the depth and a thinner web. That single proportion changes weak-axis stiffness, torsional behaviour, connection detailing and cost per metre.
A designer who swaps a narrow-flange section for a wide-flange section of the same depth typically loses more than half of the minor-axis moment of inertia, and a biaxial bending check is the fastest way to expose it.
Dimension and Mass Comparison
| Item | Wide flange HW 200x200 | Narrow flange IPE 200 |
|---|---|---|
| Depth h (mm) | 200 | 200 |
| Flange width b (mm) | 200 | 100 |
| Web thickness tw (mm) | 8 | 5.6 |
| Flange thickness tf (mm) | 12 | 8.5 |
| Mass (kg/m) | 49.9 | 22.4 |
Dimensions follow published section tables: GB/T 11263-2017 for hot-rolled H sections, EN 10365 for IPE and HE profiles, JIS G3192 for Japanese H sections, and ASTM A6/A6M for the general requirements of rolled structural shapes. Where the required depth is fixed, the load is essentially uniaxial and the frame is lightly loaded, the IPE series is the economical answer; where biaxial bending, torsion or bolted moment connections govern, the wide-flange series is the only sound choice.
Material grades are ordered separately from the section shape: ASTM A36 (yield strength 250 MPa min, tensile strength 400-550 MPa), ASTM A572 Grade 50 (yield 345 MPa min, tensile 450 MPa min), S275JR to EN 10025-2 (yield 275 MPa min for thickness up to 16 mm) and SS400 to JIS G3101 (yield 245 MPa min, tensile 400-510 MPa).
Where the Difference Drives the Design
Biaxial bending and torsion - wide flanges provide a large minor-axis section modulus and a higher torsional constant, which matters for crane runway beams, purlins under wind uplift and laterally unsupported spans.
Connections - a flange wide enough for two bolt lines allows a bolted moment end plate; a 100 mm flange rarely does, and welded stiffeners add cost.
Composite action - shear studs are welded through the flange, and stud diameter is limited by flange thickness, so narrow-flange sections accept only small connectors.
Coating and fire protection - a compact wide-flange section has a lower exposed surface area per kilogram, so intumescent paint or galvanizing consumption per metre of beam is lower for the same load capacity.
Ordering and Fabrication Notes
When an enquiry mixes the words H-beam and I-beam, three values should be confirmed before quoting: flange width, web thickness and governing material grade. Rolled lengths are normally 6 m, 9 m or 12 m; tolerances on depth, flange width, out-of-square and camber follow ASTM A6/A6M or the equivalent clause of the selected national standard. Welded built-up sections can reproduce almost any geometry where a rolled size is unavailable, but the web-to-flange welds then govern inspection and fatigue requirements, and the calculated section properties must be supplied with the mill certificate.
Frequently Asked Questions
Q: Can an I-beam replace an H-beam of the same depth?
A: No. Weak-axis stiffness, torsional resistance and available flange width are all lower in the narrow-flange section, so the substitution must be re-verified by calculation rather than assumed.
Q: How do I identify the two types from a section designation?
A: The flange width to depth ratio is the quick test. A ratio near 1.0 indicates a wide-flange H-section, while a ratio near 0.5 indicates a narrow-flange IPE or universal beam.
Q: Are H-beams always heavier than I-beams of the same depth?
A: Yes for equivalent depth. HW 200x200 weighs 49.9 kg/m against 22.4 kg/m for IPE 200, which is why narrow-flange sections are preferred for light uniaxial bending.
Q: Which section should be used for a composite floor beam?
A: Use a wide-flange section, because the wider flange accepts larger shear studs and simplifies stud welding through the flange.
Q: Do these sections have the same tolerances?
A: No. Permitted variations in depth, flange width and squareness are set by the governing standard, for example ASTM A6/A6M or the national rolling standard, and differ between section families and rolling routes.
Q: Can the two profiles be welded to each other in one frame?
A: Yes, provided the connection is designed for the forces involved and welding procedure qualification covers the thickness range of both sections, for example under AWS D1.1/D1.1M or ISO 3834 quality requirements.