How European I-beam and channel sections are designated
European hot rolled sections are ordered by three separate items: the dimensional standard, the section designation and the steel grade. This differs from a simple "I-beam" enquiry, because the same nominal depth exists in several shapes with different flange geometry. For I and H sections the dimensional standard is EN 10365, for channels it is EN 10279. Non-alloy structural grades are ordered to EN 10025-2, and dimensional tolerances for I and H sections follow EN 10034.
IPE - I-beam with parallel flanges, designation in millimetres, so IPE 200 is 200 mm deep.
IPN - I-beam with tapered flanges and a heavier web root, used where the connection geometry requires it.
UPN - channel with tapered flanges, designation in centimetres, so UPN 200 is 200 mm deep.
UPE - channel with parallel flanges and a thinner web, efficient in strong-axis bending.
A frequent error in enquiry documents is describing UPN as a parallel flange channel. UPN channels have tapered flanges, while parallel flange channels are UPE. Mixing the two families produces the wrong connection detail and the wrong mass, so the designation must always be stated explicitly.
IPE and IPN I-beam dimensions and nominal mass
The IPE range is produced from IPE 80 up to IPE 600. Flanges are parallel and constant in thickness, which simplifies bolted end plates and shear connections. The table below gives representative sections with depth h, flange width b, web thickness tw, flange thickness tf and nominal mass.
| Designation | h (mm) | b (mm) | tw (mm) | tf (mm) | Mass (kg/m) |
|---|---|---|---|---|---|
| IPE 140 | 140 | 73 | 4.7 | 6.9 | 12.9 |
| IPE 160 | 160 | 82 | 5.0 | 7.4 | 15.8 |
| IPE 180 | 180 | 91 | 5.3 | 8.0 | 18.8 |
| IPE 200 | 200 | 100 | 5.6 | 8.5 | 22.4 |
| IPE 220 | 220 | 110 | 5.9 | 9.2 | 26.2 |
| IPE 240 | 240 | 120 | 6.2 | 9.8 | 30.7 |
| IPE 270 | 270 | 135 | 6.6 | 10.2 | 36.1 |
| IPE 300 | 300 | 150 | 7.1 | 10.7 | 42.2 |
| IPE 330 | 330 | 160 | 7.5 | 11.5 | 49.1 |
Mass values follow the nominal section tables of EN 10365, so a mill certificate may show a small variation within the tolerances of EN 10034. IPN sections cover a similar depth range but have a defined flange slope, so they are handled as a separate family and are not interchangeable with IPE in a bolted connection.
UPN and UPE channel steel
Channels are used for purlins, edge beams, bracing members and secondary framing. UPN channels have tapered flanges and are the traditional European channel, normally supplied from UPN 50 up to UPN 400. UPE channels have parallel flanges and a thinner web, which raises the section modulus per kilogram and makes them the better choice for bending members and for bolted connections that need a flat bearing surface.
| Designation | h (mm) | b (mm) | tw (mm) | tf (mm) |
|---|---|---|---|---|
| UPE 120 | 120 | 60 | 5.0 | 8.0 |
| UPE 140 | 140 | 65 | 5.0 | 9.0 |
| UPE 160 | 160 | 70 | 5.5 | 9.5 |
| UPE 180 | 180 | 75 | 5.5 | 10.5 |
| UPE 200 | 200 | 80 | 6.0 | 11.0 |
| UPE 220 | 220 | 85 | 6.5 | 12.0 |
| UPE 240 | 240 | 90 | 7.0 | 13.5 |
| UPE 270 | 270 | 90 | 7.0 | 12.5 |
Because the mass of a channel depends on both flange taper and web thickness, tender documents should quote the designation from EN 10279 together with the grade, rather than a shop description such as "200 channel".
Steel grades and mechanical properties
EN 10025-2 covers non-alloy structural steels. S235JR, S275JR and S355JR are the usual hot rolled grades. The J0, J2 and K2 suffixes indicate progressively lower Charpy test temperatures, while the NL and ML grades are normalised or thermomechanically rolled for low temperature service. Minimum yield strength and tensile range for the common grades at a thickness up to 16 mm are listed below.
| Grade | ReH min (MPa) | Rm (MPa) | Charpy impact |
|---|---|---|---|
| S235JR | 235 | 360-510 | 27 J at 20 °C |
| S275JR | 275 | 410-560 | 27 J at 20 °C |
| S355JR | 355 | 470-630 | 27 J at 20 °C |
| S355J0 | 355 | 470-630 | 27 J at 0 °C |
| S355J2 | 355 | 470-630 | 27 J at -20 °C |
| S355NL | 355 | 470-630 | 27 J at -50 °C |
S355 is the workhorse grade for primary framing, S275 suits secondary members where deflection governs, and S235 is generally reserved for light bracing and non-structural applications. Selecting the suffix is a design decision driven by the lowest service temperature and the consequence of brittle fracture, not by price alone.
Ordering and inspection notes
Quote the dimensional standard, the designation and the grade together, for example IPE 300 to EN 10365 in S355JR to EN 10025-2.
State the length, the length tolerance and whether fixed or random lengths are acceptable.
Define the delivery condition: mill finish, shot blasted and primed, or hot dip galvanised.
Request a 3.1 inspection certificate to EN 10204 so that heat number, chemistry and mechanical results can be traced.
For welded structures confirm the carbon equivalent and, where required, impact testing at the design service temperature.
Check the straightness and flange squareness tolerances of EN 10034 before accepting sections for a bolted, pre-engineered frame.
FAQ
Q: What is the difference between IPE and IPN I-beams?
IPE sections have parallel, constant-thickness flanges, while IPN sections have tapered flanges; both are dimensioned by EN 10365 but they are not interchangeable in a bolted connection.
Q: Is UPN the same as UPE channel?
No. UPN has tapered flanges and is designated in centimetres, whereas UPE has parallel flanges and a thinner web that is more efficient in bending.
Q: Which grade should be used for an outdoor European I-beam?
S355JR is common for normal service, while S355J2 or S355NL is preferred when the lowest service temperature approaches or falls below zero degrees Celsius.
Q: How is the mass of a European I-beam calculated?
The nominal mass is taken directly from the EN 10365 section table, expressed in kilograms per metre, and multiplied by the ordered length.
Q: Can IPE sections be supplied in low temperature grades?
Yes. IPE and IPN sections are regularly rolled in S355J2, S355K2 and in S355NL or S355ML for low temperature service.
Q: Which document confirms section dimensions and grade?
An EN 10204 3.1 inspection certificate, issued for the specific heat number, records chemistry, mechanical properties and the dimensional standard applied.