Direct Answer
AISC Code of Standard Practice (CoSP) Chapter 6 specifies fabrication tolerances for structural steel members — column straightness (L/1000), beam sweep and camber, connection plate location (±3/16"), bolt hole location within a group (±1/32"), and overall member length (±1/8" to ±3/16" depending on member type and length). These are the baseline; project specifications may impose tighter tolerances for special conditions.
Full Explanation
Key AISC CoSP tolerances: (1) Column straightness: maximum deviation from straight = L/1000 (a 20-foot column can bow no more than 0.24"). (2) Beam sweep (lateral): maximum = L/1000. (3) Overall length (beams): ±3/16" for beams up to 30 feet, increasing slightly for longer members. (4) Connection plate location: ±3/16" in plan, ±3/16" in elevation relative to the member end or work point. (5) Bolt hole location within a group: ±1/32". These tolerances stack — a member at the limit of every tolerance simultaneously still meets code but may create fit-up challenges.
What This Means for Your Shop
Tighter-than-AISC tolerances cost money and time. If the engineer specifies 'within ±1/16" for member length' where AISC allows ±3/16", you should price the additional QC effort in your bid. Non-standard tolerances are also grounds for a change order when they apply to a portion of scope not identified at bid time.
Common Mistakes
Accepting tight tolerance requirements in the general notes without pricing them. A specification that requires all members within ±1/16" instead of ±3/16" means 100% dimensional inspection and potentially more rework — that has a cost.
Recommended Process
At bid review, compare the project specification's tolerance requirements to AISC CoSP defaults. Identify any areas where the project specification is tighter. Price the additional QC effort and flag the deviation in your bid clarifications.