Structural steel comes in standard rolled shapes, each identified by a letter and a size designation. This chart summarizes the common shapes and how they are named.
| Shape | Example | Description | Common use |
|---|---|---|---|
| Wide flange (W) | W12x26 | I-shape, wide parallel flanges | Beams and columns |
| Standard beam (S) | S12x31.8 | I-shape, sloped inner flanges | Beams, rails |
| Channel (C) | C9x15 | C-shape with sloped flanges | Frames, purlins, supports |
| Angle (L) | L4x4x1/4 | L-shape, equal or unequal legs | Bracing, frames, lintels |
| Structural tee (WT) | WT6x20 | T-shape cut from a W beam | Truss chords, bracing |
| Hollow section (HSS) | HSS4x4x1/4 | Square, rectangular, or round tube | Columns, frames, railings |
| Pipe | Pipe 4 STD | Round hollow section | Columns, posts, handrails |
| Flat bar | FB 1/2 x 3 | Solid rectangular bar | Plates, ties, miscellaneous |
Reading a designation
A designation like W12x26 means a wide-flange shape about 12 inches deep that weighs 26 pounds per foot. The first number is the nominal depth and the second is the weight per foot, the two figures engineers use most when sizing members.
See the Steel Beam Properties Chart and the Beam Span Chart.
Reading the designations
Rolled steel shapes are named by a letter for the shape, followed by the nominal depth in inches and the weight in pounds per foot. A W12x26 is a wide flange beam about 12 inches deep that weighs 26 pounds for every foot of length. Angles list the two leg lengths and the thickness, and channels and tubes follow similar conventions.
Choosing a shape
Weight per foot is a quick guide to strength and cost, since steel is sold and priced by weight. Wide flange shapes are common for beams and columns, channels and angles for framing and bracing, and tubes for columns and frames where strength in all directions matters. Section properties and load capacity come from engineering tables, so have a structural engineer size any load bearing member.