I-beam sections

Identify the profile family first

British Steel's 203 × 133 × 25 UB row lists 25.1 kg/m, so 6.0 m has an estimated mass of 150.6 kg, excluding fittings and coatings. The same nominal family contains a different depth and thickness row. Use the exact row and axis sketch for geometry, stiffness and connection checks. British Steel UB table

“I-beam” describes a cross-sectional form, not one interchangeable product. The web connects two flanges, but the flange geometry, dimensions, tolerances and available steel grades depend on the named section family. ArcelorMittal distinguishes IPE parallel-flange I sections, IPN taper-flange I sections, HE wide-flange beams, UB universal beams, and American W wide-flange and S standard-beam products. Keep the family prefix when recording or ordering a section. ArcelorMittal section families

The same producer separates dimensional standards, tolerance standards and steel-grade options. For example, its European IPE/HE/UB entries reference EN 10365 for dimensions and EN 10034 for tolerances, while IPN uses EN 10024 for tolerances. A dimensional family is not a yield-strength grade. Producer standards and grade matrix

This reference concerns stock identification and interpretation. It does not size a member for a building, lifting device or machine frame. See Stock forms and dimensions.

Read nominal names as identifiers

A section designation should lead to an exact table row. It should not be used as a substitute for the row's actual depth, flange width, thicknesses and root geometry. AISC's naming convention represents a US W-shape as nominal depth in inches followed by nominal weight in lb/ft; it separately defines a metric designation using millimeters and kg/m. Unit system and section family must travel with the identifier. AISC electronic naming convention

AISC's Shapes Database v16.0 contains dimensions and properties consistent with its Steel Construction Manual, 16th Edition, in both US customary and metric units. Its historic database is a separate resource for older shapes. A modern catalogue match is therefore not adequate identification of an undocumented existing member. AISC Shapes Database v16.0

When checking an existing section, record measured depth, flange width, web and flange thickness, flange taper and identifying marks. Measurements help narrow the candidate; they do not prove steel grade, toughness or certification. For a new order, retain the full designation, table source/version and material specification, rather than reducing the callout to “200 mm beam.”

Useful geometry and property fields

Keep the manufacturer's section sketch next to the table. An order or calculation record normally needs:

The Orange Book calculates second moments including tapers, radii and fillets. It defines radius of gyration as i = sqrt(I/A) and elastic section modulus as second moment divided by distance to the extreme fiber. It treats the torsional and warping constants separately. A simplified rectangle model can be useful for a check, but should not silently replace published properties for the actual rolled profile. ArcelorMittal property definitions

Axes and unit traps

Do not map symbols solely by letter. The Orange Book's Eurocode convention uses x along the member, y as major axis and z as minor axis, and notes that this differs from earlier UK conventions. Its dimensional values are in mm, while many calculated properties use cm; the warping constant uses dm⁶. The British Steel example below instead labels its cross-section axes x–x and y–y. Compare the sketches and physical bending direction. Orange Book axes and units

A unit conversion raises the conversion factor to the property's power: 1 cm⁴ = 10,000 mm⁴, whereas 1 cm³ = 1000 mm³. Confusing the two creates a plausible-looking number with the wrong physical meaning. Preserve units in exported spreadsheets and machine-readable records rather than depending on a heading elsewhere.

Bounded UB example

British Steel's 203 × 133 × 25 UB row lists:

The table identifies these as dimensions/properties to BS EN 10365:2017. The “25” designation is not an exact 25.0 kg/m value, and the same nominal 203×133 family includes another row with different depth and thickness. British Steel UB data sheet

Original calculations: a 6.0 m length has nominal mass 25.1 × 6.0 = 150.6 kg, excluding fittings and coatings. For an illustrative 10 kN·m pure major-axis moment, the elementary elastic stress estimate is M/W = 10,000,000 / 230,000 = 43.5 N/mm², using the rounded published modulus. About the listed minor axis, the same calculation gives 10,000,000 / 46,000 = 217.4 N/mm². This demonstrates axis sensitivity; neither result is a permitted load or complete design check.

Geometry does not establish member capacity

SteelConstruction.info's member-design guidance separates section classification and cross-section resistance from member buckling, including lateral-torsional buckling under bending, and combined axial/bending checks. Its discussion also distinguishes gross from net sections where holes and openings are present. The cited guidance identifies its basis as first-generation Eurocodes; use the code and National Annex applicable to the project. Member-design guidance

Before assigning capacity, resolve grade and thickness-dependent material properties, span, restraints, load position, connections, openings and governing limit states. A catalogue section modulus does not establish lateral restraint or connection adequacy. A mass estimate also cannot serve as a lifting plan: actual length, attached items, lifting points and equipment remain separate requirements.

Procurement and editions

Specify the complete profile and grade, dimensional/tolerance standards with editions, length and cut tolerances, inspection documents, finish and fabrication requirements. Agree deviations before cutting or drilling; preserve material identification through processing.

British Steel's PDF prints CUBD:ENG:072024 and copyright 2024, although its URL sits in a 2026 upload directory. BSI lists BS EN 10365:2026, published July 31, 2026, as current. The cited 2024 producer table's 2017 basis must not be relabeled as independently verified against every 2026 requirement. BSI's scope also excludes stainless-steel hot-rolled sections. BSI current edition and scope

The Orange Book's general notes retain a 2017 dimensional-standard basis and cite first-generation design standards. Website copyright years are not technical revisions. Confirm current producer availability and project-specific acceptance requirements rather than treating any historical stock table as a supply guarantee.