Equal Versus Unequal Angle
An angle is a hot rolled L-shaped section with two legs at a right angle. In an equal angle the two legs have the same length, giving a symmetric section; in an unequal angle one leg is longer than the other, producing a non-symmetric profile. Equal angles dominate general framing because they connect easily and behave predictably, while unequal angles are specified where one leg must match a deeper beam or provide more bearing area on a particular face.
Standard Dimensions
Equal angles (GB/T 706) - from 20 x 20 x 3 mm up to 250 x 250 x 35 mm, with published mass per metre for each leg and thickness combination.
Unequal angles (GB/T 706) - from 25 x 16 x 3 mm up to 200 x 125 x 18 mm, e.g. 100 x 75 x 8 mm and 125 x 80 x 10 mm.
European series (EN 10056-1) - equal angles from 20 x 20 mm to 250 x 250 mm, unequal from 30 x 20 mm to 200 x 150 mm.
US series (ASTM A6) - L shapes with inch leg dimensions such as L4x4x1/4 and L6x4x3/8.
Section Properties and Behaviour
For the same leg length, the unequal angle offers a higher section modulus about one axis, which suits beams spanning in one direction, while the equal angle gives more balanced strength in both directions. In compression, the minimum radius of gyration governs buckling for both types; for unequal angles the weak axis is about the shorter leg. Connections are usually made on the longer leg of an unequal angle to provide more bolts in the load line.
Grades and Mechanical Properties
Q235 and Q355 (GB/T 700, GB/T 1591) - 235 MPa and 355 MPa minimum yield, the standard building grades.
A36 (ASTM A36/A36M) - 250 MPa minimum yield for US-specified projects.
S235JR, S275JR, S355JR (EN 10025-2) - European grades with 27 J impact at +20 °C.
SS400 (JIS G3101) - 245 MPa minimum yield for Asian projects.
Typical Applications
Equal angles - bracing, ties, brackets, purlins, frames and general fabrication.
Unequal angles - truss chords and webs, beam edge members, gantry rails and architectural edge trims.
Both types - tower legs, cable trays, ladders, handrails and equipment supports.
Supply and Finishing
Angles are supplied in 6 m and 12 m standard lengths, cut to exact lengths, and finished black, painted, shot blasted or hot-dip galvanized per ISO 1461. Bundles are marked with grade, size and heat number, and mill test certificates per EN 10204 type 3.1 are available for traceability.
Frequently Asked Questions
Q: When should I use an unequal angle?
When the connection or design requires a longer leg, such as matching a deeper beam face, providing more weld length, or carrying higher bending about one axis.
Q: Are equal and unequal angles made from the same steel?
Yes, both are rolled from the same structural grades; only the geometry differs.
Q: What is the most common angle size?
50 x 50 x 5 mm and 75 x 75 x 6 mm are among the most stocked equal angles worldwide.
Q: Can angles be galvanized?
Yes, hot-dip galvanizing per ISO 1461 is a standard option for outdoor use.
Q: What lengths are standard?
6 m and 12 m are standard; cut lengths from 1 m upwards are available.
Q: Do you supply mill certificates?
Yes, mill test certificates per EN 10204 type 3.1 are provided with each delivery.