Direct Answer
Bolt callouts on shop drawings specify diameter (e.g., 3/4"), grade (A325 or A490), and installation method (snug-tight, pretensioned, or slip-critical). They also show hole type (standard, oversized, short-slot, long-slot), bolt spacing, and edge distance. All of this information must match the connection design and the AISC Specification requirements for the joint.
Full Explanation
AISC 360 Chapter J governs bolt design. A325 bolts (now ASTM F3125 Grade A325) are the standard for most structural connections. A490 (now F3125 Grade A490) bolts are used for high-strength connections. Snug-tight installation (tightened to the point that plies are in firm contact) is acceptable for most static-load connections. Pretensioned installation (tightened to a minimum specified tension) is required for connections subject to tension, shear reversal, or slip-critical requirements. Slip-critical connections require full pretension and a Class A or B faying surface.
What This Means for Your Shop
Bolt installation method affects both your shop cost and field cost. Pretensioned bolts require turn-of-nut, twist-off (TC bolt), or direct tension indicator methods — each requires trained inspection. Specify and procure the correct bolt type before fabrication.
Common Mistakes
Installing snug-tight where pretensioned is required, or using A325 bolts where A490 is specified. Both are structural deficiencies that may require costly replacement.
Recommended Process
Mark the installation method on your shop floor drawing set. Brief your bolting crews on which bays or connections require pretensioning. Document bolt lot numbers and certifications as part of your QC package.