ASTM A 29 (Tolerances)

Width  mm Thickness  mm  Permissible variations in
Width  + mm
> 5  ≤ 6 > 6  ≤ 12 > 12  ≤ 25 > 25  ≤ 50 > 50  ≤ 75 > 75
  Permissible variations in  Thickness  +  mm >
   ≤ 25 0,18 0,20 0,25 0,50 0,50
> 25 ≤ 50 0,18 0,30 0,40 0,80 1,00 1,00
> 50 ≤ 100 0,20 0,40 0,50 0,80 1,20 1,20 1,50 1,00
> 100 ≤ 150 0,25 0,40 0,50 0,80 1,20 1,20 2,50 1,50
> 150 ≤ 200 b) 0,40 0,65 0,80 1,20 1,60 3,00 2,50
b) Flats over  150 to 200 mm in width, are not available as hot-wrougt steel bars in thickness under 6 mm.
When a square is held against a face and an edge of square edge flat bar, the edge shall not deviate by more than 3° or 5% of the thickness.
                   
Tolerances in Sectional Dimensions for Round and Square Bars and Round-Cornered Square Bars Tab. A 2.1  ASTM A 29 – 04        
Size mm   Tolerances from specified size, over and under   Out-of-round or Out-of-square section b)    
  mm or % a)   mm or % a)    
   ≤ 7   0,13 mm   0,20 mm    
> 7 ≤ 11   0,15 mm   0,22 mm    
> 11 ≤ 15   0,18 mm   0,27 mm    
> 15 ≤ 19   0,20 mm   0,30 mm    
> 19 ≤ 250   1 %       1,5 %       
a) The tolerance shall be rounded to the nearest tenth of a millimetre after calculation.    
b) Out-of-round is the difference between the maximum and the minimum diameters of the bar, measured at the same cross section.     
b) Out-of-round is the difference in the two dimensions at the same cross section of a square bar between opposite faces.    
                   
Straightness Tolerances for Hot-Wrought Bars and Bar Size Sectionsa)   Tab.  A 2.10  ASTM A 29 – 04      
Standard Tolerances   6 mm in any 1500 mm (1 mm / 250 mm) b)      
Special Tolerances   3 mm in any 1500 mm (1 mm / 500 mm) b)      
a) Because of warpage, straightness tolerances do not apply to bars if any subsequent heating operation or controlled cooling has been performed.    
b) Round to the nearest whole millimetre.