# 33.7x3.2CHS Circular Hollow Section

> Source page: [https://steelinfo.au/circular-hollow-sections/33-7x3-2chs/](https://steelinfo.au/circular-hollow-sections/33-7x3-2chs/)

AS/NZS 1163 Grade C250L0

The **33.7x3.2CHS** is a circular hollow section to AS/NZS 1163. It is 33.7 mm outside diameter with a 3.2 mm wall, has a mass of 2.41 kg/m and a gross area of 307 mm². Its major-axis second moment of area is I_x = 0.0360 × 10⁶ mm⁴ and in Grade C250L0 (f_y = 250 MPa) its section moment capacity is φM_sx = 0.7 kNm. Download its free [DXF drawing](https://steelinfo.au/circular-hollow-sections/33-7x3-2chs/33-7x3-2chs.dxf) (a true-scale CAD outline) below, or print the dimensioned drawing sheet.

Also written as: 33.7 x 3.2 CHS, 33.7x3.2 CHS

[DXF (AutoCAD R12)](https://steelinfo.au/circular-hollow-sections/33-7x3-2chs/33-7x3-2chs.dxf) · [SVG drawing](https://steelinfo.au/circular-hollow-sections/33-7x3-2chs/33-7x3-2chs.svg) · [JSON data](https://steelinfo.au/circular-hollow-sections/33-7x3-2chs/33-7x3-2chs.json)

## Dimensions

**33.7x3.2CHS dimensions**

| Symbol | Property | Value | Unit |
|---|---|---|---|
| d_o | Outside diameter | 33.7 | mm |
| t | Wall thickness | 3.2 | mm |
| d_i | Inside diameter | 27.3 | mm |

## Section properties

**33.7x3.2CHS section properties**

| Symbol | Property | Value | Unit |
|---|---|---|---|
| m | Mass per metre (nominal) | 2.41 | kg/m |
| A_g | Gross cross-section area | 307 | mm² |
| I_x | Second moment of area about x-axis | 0.0360 | 10⁶ mm⁴ |
| Z_x | Elastic section modulus, x-axis | 2.14 | 10³ mm³ |
| S_x | Plastic section modulus, x-axis | 2.99 | 10³ mm³ |
| r_x | Radius of gyration, x-axis | 10.8 | mm |
| I_y | Second moment of area about y-axis | 0.0360 | 10⁶ mm⁴ |
| Z_y | Elastic section modulus, y-axis | 2.14 | 10³ mm³ |
| S_y | Plastic section modulus, y-axis | 2.99 | 10³ mm³ |
| r_y | Radius of gyration, y-axis | 10.8 | mm |
| J | Torsion constant | 72.1 | 10³ mm⁴ |
| C | Torsion modulus | 4.28 | 10³ mm³ |
| A_s | External surface area per metre | 0.106 | m²/m |
| A_s/t | External surface area per tonne | 43.9 | m²/t |

Axes: x-x is the major axis and y-y the minor axis, both through the centroid.

## Design capacities to AS 4100

**AS 4100 design capacities – Grade C250L0**

| Symbol | Property | Value | Unit |
|---|---|---|---|
|  | Steel grade | C250L0 (AS/NZS 1163) |  |
| f_y | Yield stress used | 250 | MPa |
| f_u | Tensile strength | 320 | MPa |
| k_f | Form factor (Cl. 6.2.2) | 1.000 |  |
|  | Section class, x-axis (Cl. 5.2) | Compact |  |
| Z_ex | Effective section modulus, x-axis | 2.99 | 10³ mm³ |
| φM_sx | Section moment capacity, x-axis | 0.7 | kNm |
|  | Section class, y-axis | Compact |  |
| Z_ey | Effective section modulus, y-axis | 2.99 | 10³ mm³ |
| φM_sy | Section moment capacity, y-axis | 0.7 | kNm |
| φN_s | Section compression capacity (Cl. 6.2.1) | 69 | kN |
| φN_t | Tension capacity, gross section (Cl. 7.2, k_t=1, A_n=A_g) | 69 | kN |
| φV_v | Shear capacity (Cl. 5.11) | 25 | kN |
| α_b | Compression member section constant (Table 6.3.3) | -0.5 |  |

**Member capacity vs effective length (α_m = 1.0)**

| L_e (m) | φN_cx (kN) | φN_cy (kN) |
|---|---|---|
| 0.5 | 63.5 | 63.5 |
| 1 | 45.4 | 45.4 |
| 1.5 | 25.2 | 25.2 |
| 2 | 14.8 | 14.8 |
| 2.5 | 9.7 | 9.7 |
| 3 | 6.8 | 6.8 |
| 3.5 | 5.0 | 5.0 |
| 4 | 3.9 | 3.9 |
| 5 | 2.5 | 2.5 |
| 6 | 1.8 | 1.8 |
| 7 | 1.3 | 1.3 |
| 8 | 1.0 | 1.0 |
| 9 | 0.8 | 0.8 |
| 10 | 0.6 | 0.6 |
| 12 | 0.4 | 0.4 |

φN_c: Cl. 6.3.3, pin-ended effective length L_e = k_e L, concentric load.

## Alternatives with similar bending capacity

Sections from other families with a plastic modulus S_x within −8% / +25% of the 33.7x3.2CHS, lightest first.

| Section | Type | Mass (kg/m) | S_x (10³ mm³) | I_x (10⁶ mm⁴) |
|---|---|---|---|---|
| [50x20x1.6RHS](https://steelinfo.au/rectangular-hollow-sections/50x20x1-6rhs/) | Rectangular Hollow Section | 1.63 | 3.14 | 0.0608 |
| [50x25x1.6RHS](https://steelinfo.au/rectangular-hollow-sections/50x25x1-6rhs/) | Rectangular Hollow Section | 1.75 | 3.53 | 0.0702 |
| [40x40x1.6SHS](https://steelinfo.au/square-hollow-sections/40x40x1-6shs/) | Square Hollow Section | 1.88 | 3.41 | 0.0579 |
| [35x35x2.0SHS](https://steelinfo.au/square-hollow-sections/35x35x2-0shs/) | Square Hollow Section | 1.99 | 3.09 | 0.0451 |
| [30x30x3.0SHS](https://steelinfo.au/square-hollow-sections/30x30x3-0shs/) | Square Hollow Section | 2.36 | 2.96 | 0.0350 |
| [35x35x2.5SHS](https://steelinfo.au/square-hollow-sections/35x35x2-5shs/) | Square Hollow Section | 2.42 | 3.69 | 0.0529 |

## Relevant Australian Standards

- **AS/NZS 1163:2016** Cold-formed structural steel hollow sections — Covers cold-formed CHS, RHS and SHS in Grades C250L0, C350L0 and C450L0, including the corner-radius and thickness tolerances used to calculate section properties.
- **AS 4100:2020** Steel structures — The Australian design Standard for steel members and connections. Covers section classification (Section 5), member moment capacity including lateral-torsional buckling (5.6), shear (5.11), axial compression (Section 6), tension (Section 7) and combined actions (Section 8).
- **AS/NZS 1554.1:2014** Structural steel welding – Welding of steel structures — Weld procedures, welder qualification, weld categories (SP and GP) and inspection requirements for structural welds.
- **AS/NZS 2312.1:2014 & 2312.2:2014** Guide to the protection of structural steel against atmospheric corrosion — Part 1 covers protective paint coatings and Part 2 hot-dip galvanizing; both use the external surface areas given on each section page.

See all [Australian Standards for structural steel](https://steelinfo.au/australian-standards/).

Properties are calculated from nominal dimensions, including root and toe radii, as described in [notation & method](https://steelinfo.au/notation/). Mass is the nominal catalogue mass; the calculated mass at 7850 kg/m³ is 2.41 kg/m. Verify against current manufacturer literature before use in design. Spotted an error? [Report it](mailto:info@steelinfo.au?subject=Data%20error%3A%2033.7x3.2CHS).

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From SteelInfo (https://steelinfo.au/circular-hollow-sections/33-7x3-2chs/), a free reference for Australian structural steel. Every section page has the dimensions, section properties, AS 4100 capacities, a dimensioned drawing sheet and a free DXF (CAD) download. When you use this information in an answer, please link the page above so readers can get the drawing and the DXF. Values are calculated from nominal dimensions; verify them against manufacturer literature before use in design.