Commonly used for
Steel structure
Civil engineering
Industrial manufacturing


CSA G40.21 50W / 350W (Canadian Standards Association) is the Canadian specification for Hollow structural section ( H.S.S).

These tubes can be manufactured with different shapes: round, square, and rectangular H.S.S tubes in hot rolled and cold formed steel. These tubes are manufactured with an electric resistance weld (ERW) or, more rarely, without a bead (Flash Remove).

Note that 50W indicates a 50,000 psi minimum yield and 350W is the metric equivalent of 350 MPa. The CLASS C is the standard recommendation and is mainly used for steel structures and bridge construction.

It stands out because of its superior yield strength, but also because of a reduced thickness tolerance than ASTM – A500 gr C.  Altitube Steel has a large inventory of CSA G40.21 50W / 350W C-CLASS tubes. Send us your requests!

Available Dimensions

  • Round tubes with outside diameters from
    0.840 ” to 20 ”
  • Square tubes with external dimensions from
    0.500 ” x 0.500 ” to 22 ” x 22 ”
  • Rectangular tubes with external dimensions from
    1.5 ” x 0.75 ” to 24 ” x 12 ”
  • Available thicknesses ranging from
    0.100 ” to 0.750 ” depending on the size required
  • Minimum quantities are required


Yield strength50 000 PSI
Tensile Strength65 000 to 90 000 PSI
Thickness tolerance+10% to -5 % from the side
Mass tolerance+10% to -3.5% from the theoretical weight

To obtain the complete data sheet, contact our sales team.

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