FIA APPENDIX J ARTICLE 253/A16.2 and MSUK K2.2.2/DRAWING K64

We are often asked for the 35mm x 35mm x 2.5mm box section for seat rails

The regulations stipulate the cross member must be a square extruded section.

Steel is not produced by the extruding method so are unable to supply a box section that meets that rule.

As Standard, the only box sections available in the market place is a welded rolled section which can be refered to as ERW (electric resistance welded) or CFS /HFS (Cold formed section / hot formed section) which starts life as a sheet metal, formed, and welded to box section shape, the weld line will show on one face of the section and by it’s very nature of production, it does not meet the ruling.

It is also possesses a considerably lower yield / tensile strength than the rest of the Roll Cage construction (350N/mm2 Min Yield)

For example :

E220 = 220 N/mm2 Min

S235 = Yield 235 N/mm2 min

CR4 = Yield 180 N/mm2 Max

We, as a major supplier to the motorsports world have completed a costing excersise for producing a Seamless Box Section in the dimensions required by way of cold drawing and have submitted a request of change of terminolgy to the MSUK and FIA in order to supply material that would meet this rule requirement, however, we are yet to receive a response at time of writing.

As an alternative we supply the ROPT510 and BS4 T45 seamless tubes in the 38.1mmod x 2.64mm dimensions to ensure this regulation can still be met in the meantime.