Canadian HSS (hollow structural sections) are sized by outside dimensions and wall thickness in millimetres: an HSS 102x102x6.4 is a square tube 101.6 mm (4 in) on each side with a 6.4 mm (1/4 in) wall, and it weighs 18.2 kg/m. Square and rectangular HSS are listed as height x width x wall; round HSS as outside diameter x wall. The charts below list common sizes with their mass per metre, verified against the CISC section tables.
How HSS sizes are written
HSS sizes in Canada are metric names for tubes that are, in most cases, made to imperial dimensions. That's why the numbers look slightly odd:
- 102 is 4 inches (101.6 mm) rounded. 152 is 6 inches, 203 is 8 inches, and so on.
- Wall thicknesses are rounded from fractions of an inch: 3.2 (1/8 in), 4.8 (3/16 in), 6.4 (1/4 in), 7.9 (5/16 in), 9.5 (3/8 in) and 13 (1/2 in).
- Rectangular sizes put the larger dimension first: HSS 152x102x6.4 is 6 x 4 in with a 1/4 in wall.
- Round sizes use the outside diameter, which for many sizes follows pipe diameters: 88.9, 114.3, 168.3 and 219.1 mm are common examples.
The same tube can be listed several ways on drawings: HSS 102x102x6.4, HSS 4x4x1/4, or occasionally HS102x102x6.4. They describe the same section. What can differ is the material standard, which we cover below.
Square HSS size chart
Mass is per metre of length, based on nominal wall thickness. Values match the CISC structural section tables and the nominal weights in the AISC Shapes Database.
| Designation (mm) | Imperial | Mass (kg/m) |
|---|---|---|
| HSS 51x51x4.8 | 2 x 2 x 3/16 | 6.4 |
| HSS 64x64x4.8 | 2-1/2 x 2-1/2 x 3/16 | 8.3 |
| HSS 76x76x4.8 | 3 x 3 x 3/16 | 10.3 |
| HSS 76x76x6.4 | 3 x 3 x 1/4 | 13.1 |
| HSS 89x89x6.4 | 3-1/2 x 3-1/2 x 1/4 | 15.6 |
| HSS 102x102x4.8 | 4 x 4 x 3/16 | 14.1 |
| HSS 102x102x6.4 | 4 x 4 x 1/4 | 18.2 |
| HSS 102x102x7.9 | 4 x 4 x 5/16 | 22.1 |
| HSS 102x102x9.5 | 4 x 4 x 3/8 | 25.7 |
| HSS 127x127x6.4 | 5 x 5 x 1/4 | 23.2 |
| HSS 127x127x7.9 | 5 x 5 x 5/16 | 28.4 |
| HSS 152x152x6.4 | 6 x 6 x 1/4 | 28.3 |
| HSS 152x152x7.9 | 6 x 6 x 5/16 | 34.8 |
| HSS 152x152x9.5 | 6 x 6 x 3/8 | 40.9 |
| HSS 178x178x6.4 | 7 x 7 x 1/4 | 33.4 |
| HSS 203x203x6.4 | 8 x 8 x 1/4 | 38.5 |
| HSS 203x203x9.5 | 8 x 8 x 3/8 | 56.1 |
| HSS 254x254x9.5 | 10 x 10 x 3/8 | 71.4 |
Rectangular HSS size chart
| Designation (mm) | Imperial | Mass (kg/m) |
|---|---|---|
| HSS 76x51x4.8 | 3 x 2 x 3/16 | 8.3 |
| HSS 102x51x4.8 | 4 x 2 x 3/16 | 10.3 |
| HSS 102x76x6.4 | 4 x 3 x 1/4 | 15.6 |
| HSS 127x76x6.4 | 5 x 3 x 1/4 | 18.2 |
| HSS 152x76x6.4 | 6 x 3 x 1/4 | 20.7 |
| HSS 152x102x6.4 | 6 x 4 x 1/4 | 23.2 |
| HSS 152x102x9.5 | 6 x 4 x 3/8 | 33.3 |
| HSS 203x102x6.4 | 8 x 4 x 1/4 | 28.3 |
| HSS 203x152x6.4 | 8 x 6 x 1/4 | 33.4 |
| HSS 203x152x9.5 | 8 x 6 x 3/8 | 48.5 |
| HSS 254x152x9.5 | 10 x 6 x 3/8 | 56.1 |
| HSS 305x203x9.5 | 12 x 8 x 3/8 | 71.4 |
Notice that a few square and rectangular tubes weigh exactly the same. HSS 102x102x6.4 and HSS 127x76x6.4 are both 18.2 kg/m, because their perimeters are the same. Same steel, different shape: the rectangular one is stiffer about its deep axis and weaker about its shallow one.
Round HSS size chart
Round HSS outside diameters in this table follow the AISC metric listing; Canadian section tables designate them by rounded diameter and wall (for example, a 168.3 mm tube with a 6.4 mm wall).
| Outside diameter (mm) | Outside diameter (in) | Wall (mm) | Mass (kg/m) |
|---|---|---|---|
| 73.0 | 2.875 | 4.8 | 8.0 |
| 88.9 | 3.5 | 6.4 | 12.9 |
| 101.6 | 4.0 | 6.4 | 14.9 |
| 114.3 | 4.5 | 4.8 | 12.9 |
| 141.3 | 5.563 | 6.6 | 21.8 |
| 168.3 | 6.625 | 6.4 | 25.4 |
| 219.1 | 8.625 | 6.4 | 33.3 |
| 273.1 | 10.75 | 6.4 | 41.8 |
| 323.9 | 12.75 | 9.5 | 73.8 |
Round HSS is less commonly stocked in small quantities than square and rectangular, and the wall thicknesses on offer vary more between producers. Confirm the exact diameter and wall your supplier can get before detailing connections around it.
These charts are a representative selection, not a full list. Availability varies by region, by supplier and over time, so always ask for stock sizes. For design properties (area, moment of inertia, section modulus, radius of gyration) use the CISC Handbook of Steel Construction or the producer's published tables.
Material: CSA G40.21 350W, Class C and Class H
Canadian HSS is commonly produced to CSA G40.20/G40.21, grade 350W, which has a minimum yield strength of 350 MPa. The standard defines two classes:
- Class C: cold-formed and left as formed. This is the everyday product for posts, frames and bracing.
- Class H: either hot-formed, or cold-formed and then stress-relieved by heating. The heat treatment reduces the residual stresses left by forming, and CSA S16 assigns Class H columns a higher compressive resistance than Class C. That can allow a lighter column, but Class H is not stocked as widely.
Some tube is also made to the US standard ASTM A500. Be aware that US design tables (AISC) use a reduced "design wall thickness" for many tubes made to ASTM A500, so they list a smaller area and lower properties than Canadian tables for the same nominal tube. For HSS 102x102x6.4, the AISC metric area is 2,170 mm² against 2,320 mm² in the CISC table. Your engineer must use the properties that match the material actually specified, and the fabricator must supply that material with mill certificates.
Where HSS gets used
HSS is popular because it is equally strong in both directions (square and round), resists twisting well and looks clean when left exposed:
- Basement and garage posts. A square HSS post with a welded base plate and cap plate is a common replacement for an adjustable steel column. Whether a telepost can stay is a separate question, covered in adjustable steel columns: can they be permanent?
- Columns and frames in commercial buildings, canopies and mezzanines.
- Bracing and trusses, where round or square tubes keep members light.
- Railings, guards and stair framing, using smaller sizes.
- Lintels and headers in some details, where a rectangular tube suits the wall.
For beams carrying floor loads over long spans, a wide-flange beam is usually more efficient than a tube of similar weight. See our Canadian W-shape beam chart to compare.
HSS lengths and ordering
Length. Mills cut HSS to length as it is produced and can supply long lengths to order. Service centres stock common sizes in standard imperial lengths, and those vary from one supplier to the next. For posts and frames, ordering cut to length avoids waste and site cutting.
Weight. Multiply the length in metres by the mass per metre. Four posts of HSS 102x102x6.4 at 2.4 m each come to 9.6 m, and 9.6 x 18.2 = about 175 kg before plates.
What to send when you order:
- Size in metric or imperial, exactly as on the drawing, including wall thickness.
- Material standard and class (for example CSA G40.21 350W Class C).
- Cut lengths and quantities.
- Base plates, cap plates, holes and any welded clips, with dimensions.
- Finish: mill finish, primer or galvanizing. Galvanized tubes need vent and drain holes, which the galvanizer and designer should agree on.
Getting HSS posts and frames fabricated
We supply HSS posts for basements and framing with base and cap plates welded on, and fabricate HSS frames and members to shop drawings with CWB-certified shop welding. The size, wall and plate details come from your drawings or your engineer; we cut, weld and mark each piece to match.
Send us your drawings for a quote, or see our steel products for posts, beams, plates and channels.
Frequently asked questions
How are HSS sizes written in Canada?
Square and rectangular HSS are written as outside height x width x wall thickness in millimetres, for example HSS 102x102x6.4. Round HSS are written as outside diameter x wall thickness. The numbers are rounded from imperial sizes, so HSS 102x102x6.4 is the same tube as a 4 x 4 x 1/4 inch HSS.
Is HSS structural steel?
Yes. Hollow structural sections are structural steel members, produced in Canada to CSA G40.20/G40.21 (commonly grade 350W) and designed under CSA S16 like beams and other shapes.
What is the difference between Class C and Class H HSS?
Class C HSS is cold-formed and left as formed. Class H is hot-formed, or cold-formed and then stress-relieved by heating. Class H has lower residual stresses, which CSA S16 recognizes with higher compressive resistance for columns.
What lengths does HSS come in?
Mills can produce HSS in long cut lengths, and service centres stock common sizes in standard imperial lengths. Stock lengths vary by supplier and size, so ask, or order the HSS cut to length.
