Permissible variations for structural shapes and plates as received from the mill are established in ASTM A6/A6M 21 Section 12. These historically developed standard tolerances define the acceptable limits of variation from theoretical dimension for the cross-sectional area, flatness, straightness, camber, and sweep for rolled sections. Many of these tolerances are repeated in the Steel Construction Manual Part 1.

Generally, standard fabrication practice accommodates these structurally acceptable variations. In special cases, mill tolerances may require consideration in design by the Structural Engineer of Record [SER]. If more restrictive tolerances are required they must be specified in the contract documents.

last modified 09 June 2022