Black steel structural sections: IPE, HEA, HEB and UPN

Black steel structural sections are the beams, columns and channels that carry loads in buildings and steelwork, supplied as IPE and IPN I-beams, HEA and HEB wide-flange sections and UPN channels. ULAMEX supplies structural sections in S235JR, S275JR and S355J2, to EN 10365 dimensions and EN 10025-2 grades, with a 3.1 certificate on request. This guide covers the section types, how to choose between them, grades, standards, surface condition and how they are used.

What structural sections are

A structural section is a hot-rolled carbon steel profile with a shape chosen to carry load efficiently, an I, an H or a U, rolled from a single billet in standard sizes. The I and H shapes put most of the steel in the flanges, far from the neutral axis, so they resist bending with the least weight; the channel gives an open U for edges, supports and frames. The term black steel refers to the mill-scale surface the section leaves the rolls with, uncoated and dark, ready to be painted, galvanised or left bare in a dry enclosure.

Section types

IPE is the workhorse beam, HEB the workhorse column, and UPN the standard channel. HEA saves weight where the load allows, and HEM handles the heaviest columns.

IPE, HEA or HEB: choosing a section

The choice follows the job the section does. An IPE beam is tall and narrow, so it is efficient in bending and is the default for floor and roof beams that span between supports. An HEB is as wide as it is deep, so it resists load from any direction and is the default column and the choice for heavily loaded or short beams. An HEA is the lighter version of the HEB, used where the load allows a slimmer section and weight matters. A UPN or UPE channel is used for edges, purlins, supports and framing where an open U-shape connects more easily than a closed I. For a hollow alternative for columns and frames, see our guide to EN 10219 hollow sections.

Grades for structural sections

Sections are rolled in the non-alloy structural grades of EN 10025-2, and the grade sets the yield strength and the impact toughness.

The letter suffix is the impact grade: JR is tested at +20 C, J0 at 0 C and J2 at -20 C, so S355J2 suits structures that must stay tough in the cold. For the full grade detail see our guide to structural steel S235, S275 and S355.

Standards

Structural sections are supplied to a dimensional standard and a material grade, and the certificate ties the two together.

State the section type, size, grade and length with an enquiry, and add the 3.1 certificate requirement, so the delivered steel matches the structural design and the CE marking route.

Black steel surface and protection

Black steel leaves the mill with a dark blue-grey mill scale and no coating, which is normal and does not affect the strength. For indoor dry structures the section can be used as-rolled or primed; for exposed or damp structures the steel is protected, because bare carbon steel rusts. The usual routes are painting over a blast-cleaned and primed surface, or hot-dip galvanising for long-life outdoor protection. Where galvanising is chosen, see our guide to galvanised steel, and note that the section design and vent holes suit the dipping process.

Applications

Structural sections build the frames behind almost every kind of construction. IPE and HEB sections form the beams and columns of steel-framed buildings, industrial halls, mezzanines and platforms. HEA sections carry lighter frames and long-span roofs where weight is saved. UPN and UPE channels form purlins, edge beams, supports, machine frames and stair strings. IPN beams still serve as beams, lintels and crane rails. Across all of these the sections are drilled and welded into fabricated assemblies, then bolted or welded on site.

Fabrication and EN 1090 certification

Carbon structural steel is straightforward to fabricate: it is drilled or punched for bolted connections and welded with standard mild-steel filler. Fabrication of load-bearing steelwork for the European market is carried out to EN 1090, with the execution class set by the structure, and welding to a qualified procedure. ULAMEX holds EN 1090-1 EXC2 with welding to ISO 3834-2, so structural sections are supplied ready for certified fabrication, with a 3.1 inspection certificate to EN 10204 on request for full material traceability.

Connecting structural sections

Sections are joined into a frame by bolting or welding, and the connection type drives the fabrication. A bolted frame uses end plates, fin plates and cleats drilled or punched in the shop, then bolted on site with high-strength structural bolts, which speeds erection and simplifies inspection. A welded frame joins the sections directly with a qualified procedure, giving a stiff, clean joint used where appearance or continuity matters. Columns land on welded base plates that are bolted to the foundation with holding-down bolts. Each section is also specified by its mass per metre in kilograms, which sets both the structural capacity used in design and the weight the crane and connections must handle.

Sections versus hollow sections

Open sections and hollow sections solve different problems. An IPE or HEB open section is efficient in bending, easy to connect and easy to inspect, so it suits beams, columns and bolted frames. A hollow section resists twisting and load from any direction and has a clean closed surface, so it suits exposed architectural frames, columns and members in torsion. Many structures mix the two, open sections for the primary frame and hollow sections for bracing and exposed work. ULAMEX supplies both, so a project sources its full frame from one supplier.

Black steel structural sections from ULAMEX

ULAMEX has supplied structural steel since 1988, and sections are a core part of the range.

Need structural sections for a project? Send the section type, size, grade and length, and ULAMEX will return a non-binding quotation. See our guides to structural steel grades and EN 10219 hollow sections, and our supply capabilities, or contact the export desk at [email protected] or +48 504 424 761.

Frequently asked questions