I-beam and H-beam describe appearance more loosely than a full section designation. RSJ is also used informally for steel beams. Those labels alone cannot identify geometry, grade or design resistance.
Compare the full designation
Ask for the section family and complete size, then look up actual depth, width, mass and section properties in the applicable manufacturer catalogue. Our British Steel UB datasheet is for selected Universal Beams. It is not an equivalence table for IPE, HE or Universal Columns.
The dimensions in a nominal name can differ from the actual dimensions. Connection geometry and available clearance should use the product data and the drawing, not a visual impression of whether the section looks like an I or an H.
Why substitutions need review
Two similarly deep sections may have different flange widths, web thicknesses, inertia and connection arrangements. Matching mass per metre alone is also insufficient. A proposed substitution requires the designer to check all relevant effects and update the issued detail where necessary.
What to send a stockholder
Specify section family, full designation, grade, cut length, quantity and fabrication revision. Include coating and delivery requirements. We removed earlier unsupported claims that one named section was automatically adequate or equivalent to another. Use the shared reference for transparent data, and obtain a project-specific design.
Structural work must be designed by a chartered structural engineer and receive the applicable Building Control approval. This article is educational and has not received an independent engineering review.