Roll Cage Tube Sizes: MSA Bluebook Section K – Competitor Safety.


Roll Cage Tube Sizes

Below are the regulations set by the MSA for material choice and sizes of tubes eligible for Roll cage and safety cell construction.


1.4.1. Specifications of the tubes used: Minimum Material Cold Drawn Seamless Unalloyed Carbon Steel, containing a maximum of 0.3% of carbon.

Note: For an unalloyed carbon steel the maximum content of additives is 1.7% for manganese and 0.6% for other elements.

  • Minimum Yield Strength: 350 N/mm2


Minimum Dimensions

Mandatory tubular members

45mm x 2.5mm (1.750″ x 12swg) or 50mmx 2.0mm (2.000” x 14swg).

38mm x 2.5mm (1.500” x 12swg”) or 40mm x 2.0mm (1.6” x 0.083”).(For roll cages/bars approved prior to 1.1.95).


Optional tubular members

38mm x 2.5mm (1.5” x 0.095”) or 40mm x 2.0mm (1.6” x 0.083”).


1.4.2. In selecting the steel, attention must be paid to obtaining good elongation properties and adequate weldability.


1.4.3. The tubing must be bent by a cold working process and the centreline bend radius must be at least three times the tube diameter. If the tubing is ovalised during bending, the ratio of minor to major diameter must be 0.9 or greater.

Click here for : MSA cage design diagrams

Click here for : Roll cage tubing stock range



FIA Appendix K 2018 :  Historic Single Seater and Two Seater Racing Cars


The tubes and brace(s) must have a diameter of at least 1.375″(35mm) and at least 0.090″ (2mm) wall thickness.

(ProFormance recommend ROPT510 1.500″ (38.1mm) x 12swg (2.6mm) to retain wall thickness over the 2mm minimum requirement during the bending process) 

  • The material should be molybdenum chromium SAE 4130 or SAE 4125 (or equivalent in DIN, NF, etc.) or cold drawn low carbon seamless steel tube.
  • There must be at least one brace from the top of the bar rearwards at an angle not exceeding 60° to the horizontal fixed to the structure of the car.
  • The diameter and material of the brace must be the same as those of the rollbar itself.
  • In the case of two braces, the diameter of each of them may be
    reduced to 26/20 (ext. / int.) mm minimum (that means a diameter
    of at least 26mm and at least 3mm wall thickness)
  • These dimensions in «mm» may be replaced with the nearest imperial dimensions (that means a diameter of at least 1 inch and at least 1/8 inch wall
  • I.e  1.000 inch  x 10swg (3.2mm)




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