HSS18×18×3/8 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.

HSS18×18×3/8 is a square tube 18 in. by 18 in. with a 3/8 in. nominal wall.

At 88.73 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 = 139 in³ and its moment of inertia Ix = 1250 in⁴, with a plastic modulus Zx = 160 in³.

Detailing dimensions

Depth (Ht)18"
Width (B)18"
Nominal wall (t)3/8"

Section properties

Weight88.73 lb/ft
Area (A)24.3 in²
Ix1250 in⁴
Sx139 in³
Zx160 in³
rx7.18 in
Iy1250 in⁴
Sy139 in³
Zy160 in³
ry7.18 in
J1940 in⁴

Other HSS18×18 sizes

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

HSS18×18×1/4HSS18×18×5/16HSS18×18×1/2HSS18×18×5/8HSS18×18×3/4HSS18×18×7/8HSS18×18×1

All HSS18×18 sizes and dimensions →

Similar weight HSS shapes

Comparable 88.73 lb/ft sections in other HSS tube sizes.

HSS24×12×3/888.73 lb/ft · Sx 155 in³HSS22×14×3/888.73 lb/ft · Sx 152 in³HSS20×16×3/888.73 lb/ft · Sx 147 in³HSS14.000×0.62589.36 lb/ft · Sx 78.9 in³HSS10×10×3/489.5 lb/ft · Sx 69.4 in³HSS20×8×1/289.68 lb/ft · Sx 119 in³HSS18×10×1/289.68 lb/ft · Sx 117 in³HSS16×12×1/289.68 lb/ft · Sx 113 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 HSS18×18×3/8 cut, formed, or fabricated? Huntington Steel & Supply Co.

Browse more: HSS tube · Steel Beam Size Chart

Interactive drawing