The angle at each corner of a tube must measure 90o + 1o.
Outside Corner Radius
The outside corner radius of each corner must not exceed 2.5 times the wall thickness.
The twist of a square or rectangular section must not exceed 2mm plus 0.5mm per metre length of tube i.e. the maximum twist in a 6.0m length may be 1mm + 6mm = 18mm.
Concavity / Convexity
The concavity / convexity must not exceed 0.8% of the outside dimension H (Height) or B (Breadth), with a minimum of 0,5mm.
The straightness tolerance for mechanical and structural round tubing is 2mm/metre length.