NCCER Ironworker cheat sheet

Steel erection sequence rule: erect the frame in stable, self-supporting units; never leave a tier with fewer than two permanently connected lines of strength before releasing hoisting equipment.

Anchor bolt layout tolerance for column base plates is typically ±1/8 in. between bolt centers within a bolt group, with larger allowances for overall group location; verify against the project structural drawings.

Minimum bolt hole standards: standard holes are 1/16 in. larger than bolt diameter; oversize and slotted holes have separate diameter limits and are permitted only where the engineer of record shows them.

High-strength bolt tensioning methods: turn-of-nut (1/2 to 2/3 turn depending on bolt length and diameter), calibrated wrench, and direct tension indicator (DTI); each requires a pretension verification per the applicable RCSC specification.

A325/A490 (now F3125 Gr. A325/A490) bolts require hardened washers under the turned element when turn-of-nut is used on a surface with a slope greater than 1:20.

Plumbness tolerance for a completed structural steel column is commonly 1:500 of the height, measured between working points, unless the contract documents specify otherwise.

Crane hand signals are standardized: a raised clenched fist means stop; thumb up means hoist; thumb down means lower; arm extended with palm down and fingers opening/closing means dog everything.

Wire rope sling removal criteria: remove from service when broken wires in a running rope exceed 12 randomly distributed broken wires in one lay, or 4 broken wires in one strand in one lay.

Field welding of structural steel requires prequalified WPS per AWS D1.1; minimum preheat for ASTM A992 steel at thicknesses under 3/4 in. is 50°F.

Concrete cover minimums (ACI 318, cast-in-place, nonprestressed): 1-1/2 in. for beams and columns, 3/4 in. for slabs and walls not exposed to earth or weather (No. 11 and smaller bars), 2 in. for concrete cast against and permanently exposed to earth.

Bar spacing: clear distance between parallel bars must be at least the bar diameter, 1 in., or 4/3 times the nominal maximum coarse aggregate size, whichever is greatest.

Standard hook dimensions: 90° hook extension is 12 bar diameters; 180° hook extension is 4 bar diameters (minimum 2-1/2 in.); hook bend diameter is 6 bar diameters for No. 3 through No. 8 bars.

Tension lap splice length for Grade 60 bars in normal-weight concrete is typically 40 bar diameters for Class B splices (when more than 50% of bars are spliced at one location), and 30 bar diameters for Class A.

Mechanical couplers and welded splices are permitted where lap lengths are unavailable; they must develop at least 125% of the specified yield strength of the bar.

Tying rule: tie bars at intersections so they cannot shift during concrete placement; use double tie wire for bars larger than No. 5 or where the engineer requires it.

Placing tolerance for bar location in slabs and walls is ±3/8 in. for members up to 8 in. deep, and ±1/2 in. for members over 8 in. deep (ACI 117).

Reinforcement must be supported on bar chairs or bolsters at spacing that prevents sagging; typical spacing is 4 ft or less for slab mats.