HSS18×18×5/16 square/rectangular HSS tube

Detailing dimensions and section properties from the AISC Shapes Database, 16th Edition. Values are shown to the nearest 1/16 in. as they appear on a shop drawing.

HSS18×18×5/16 is a square tube 18 in. by 18 in. with a 5/16 in. nominal wall.

At 74.38 lb per foot it is one of the 8 HSS18×18 sizes, which run from 59.85 to 222.63 lb/ft.

For strong-axis bending its section modulus is Sx = 118 in³ and its moment of inertia Ix = 1060 in⁴, with a plastic modulus Zx = 135 in³.

Detailing dimensions

Depth (Ht)18"
Width (B)18"
Nominal wall (t)5/16"

Section properties

Weight74.38 lb/ft
Area (A)20.4 in²
Ix1060 in⁴
Sx118 in³
Zx135 in³
rx7.21 in
Iy1060 in⁴
Sy118 in³
Zy135 in³
ry7.21 in
J1630 in⁴

Other HSS18×18 sizes

Same nominal size, different weight — useful when you are checking a substitution or a lighter section.

HSS18×18×1/4HSS18×18×3/8HSS18×18×1/2HSS18×18×5/8HSS18×18×3/4HSS18×18×7/8HSS18×18×1

All HSS18×18 sizes and dimensions →

Similar weight HSS shapes

Comparable 74.38 lb/ft sections in other HSS tube sizes.

HSS24×12×5/1674.38 lb/ft · Sx 131 in³HSS22×14×5/1674.38 lb/ft · Sx 128 in³HSS20×16×5/1674.38 lb/ft · Sx 124 in³HSS11.750×0.62574.33 lb/ft · Sx 54.3 in³HSS16.000×0.43872.87 lb/ft · Sx 75.8 in³HSS12.000×0.62576 lb/ft · Sx 56.8 in³HSS20×4×1/276.07 lb/ft · Sx 83.8 in³HSS18×6×1/276.07 lb/ft · Sx 85.6 in³

Detailing values are rounded to the nearest 1/16 in. per the AISC Steel Construction Manual. Verify critical dimensions against the current Manual before fabrication. Need HSS18×18×5/16 cut, formed, or fabricated? Huntington Steel & Supply Co.

Browse more: HSS tube · Steel Beam Size Chart

Interactive drawing