Circular Hollow Sections (CHS)

CHS steel pipes have an excellent resistance to torsion and are typically used in steel frameworks where loads may be applied from multiple directions; alternatively they are often chosen more aesthetic purposes where the circular profile would be visually more appealing that square or rectangular profiles.

Our Circular Hollow Sections are sourced from Australian distributors and supplied to the Australian Standard for structural steel hollow section AS/NZS 1163 and cover steel grades C250L0 and C350L0.


15NB 21.3OD CHS (M, H, XH)
20NB 26.9OD CHS (XL, L, M, X, XH)
25NB 33.7OD CHS (XL, L, M, X, XH)
32NB 42.4OD CHS (XL, L, M, X, XH)
40NB 48.3OD CHS (XL, L, M, X, XH)
50NB 60.3OD CHS (XL, L, M, X, XH)
65NB 76.1OD CHS (XL, L, M, X, XH)
80NB 88.9OD CHS (XL, L, M, X, XH)
90NB 101.6OD CHS (XL, L, M, X)
100NB 114.3OD CHS (XL, L, M, X)
125NB 139.7OD CHS (XL, L, M, X)
150NB 165.1OD CHS (XL, L, M, X)

Please note that only the Medium sizing is readily available from most distributors. Often XL, L, H, XH can be quite difficult to source depending on whether a particular size in manufactured in Australia or not.


Nominal Bore (NB) is the European designation equivalent to the North American designation of Nominal Pipe Size (NPS). The nominal bore size categorises the CHS sizes based loosely on the internal diameter of each section. Below are some examples:

40NB CHS XL – internal diameter is 43.7mm
40NB CHS L – internal diameter is 42.5mm
40NB CHS M – internal diameter is 41.9mm
40NB CHS H – internal diameter is 40.3mm
40NB CHS XH – internal diameter is 37.5mm


Outer Diameter (OD) is the fixed overall measurement of the CHS tube. All 40NB CHS sizes are 48.3 OD.


CHS sections have a uniform thickness for the full circumference of the pipe and most CHS sizes come in a variety of thicknesses which vary depending on the pipe size selected. The thicknesses are categorized as follows:

Extra Light (XL)
Light (L)
Medium (M)
Heavy (H)
Extra Heavy (XH)