NCCER Ironworker flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

Anchor bolt projection tolerance

Projection of anchor bolts above the base plate is typically allowed to vary ±1/4 in. from the specified dimension. Verify the structural drawings because project-specific tolerances override general practice.

Standard bolt hole size

A standard hole is punched or drilled 1/16 in. larger than the nominal bolt diameter. Oversize and slotted holes are permitted only where shown on the approved drawings.

Turn-of-nut tightening

A pretensioning method where the nut is rotated a specified fraction of a turn after snugging. The amount depends on bolt diameter, length, and whether the nut is the turned element.

DTI washer

A direct tension indicator is a hardened washer with protrusions that compress as the bolt is tensioned. A feeler gauge gap check confirms the required tension has been reached.

Column plumbness tolerance

Completed steel columns are typically limited to 1:500 of their height out of plumb, measured between working points. The contract documents may impose a tighter limit.

Stop hand signal

A raised clenched fist held overhead signals the crane operator to stop all movement immediately. This signal takes priority over any other signal being given.

Hoist hand signal

The signalman raises a thumb upward with the arm to signal the operator to raise the load. The thumb-down version of the same motion signals lower.

Dog everything signal

Both arms are extended with palms down and fingers opening and closing, signaling the operator to stop and hold all crane functions in position.

Wire rope removal criteria

Remove running wire rope from service when 12 or more randomly distributed broken wires appear in one lay, or 4 broken wires in one strand in one lay.

Prequalified WPS

A written welding procedure that meets AWS D1.1 requirements without further testing. It specifies joint detail, electrode, preheat, current, and pass sequence for the weld.

A992 minimum preheat

ASTM A992 structural steel under 3/4 in. thick requires a minimum preheat of 50°F per AWS D1.1. Thicker sections and higher-strength steels require higher preheat values.

Erection stability rule

Erect the frame in stable, self-supporting units. Never release hoisting equipment from a tier until at least two permanently connected lines of strength are in place.

Guying versus bracing

Temporary guying and bracing hold partially erected steel in alignment until permanent connections are complete. They are removed only after the structure is self-supporting.

Snug-tight condition

A bolt is snug-tight when the plies are in firm contact and the installer has applied the full effort of an ironworker with an ordinary spud wrench. It is not a tensioned condition.

Minimum bolt spacing

Center-to-center spacing of bolts is generally at least 2-2/3 times the bolt diameter, with a minimum edge distance of 1-1/2 times the bolt diameter from a sheared edge.

Load angle and sling tension

Sling tension equals load divided by the number of legs, then divided by the sine of the angle from horizontal. A 60° angle gives about 1.155 times the share per leg.

Concrete cover minimum

ACI 318 requires 1-1/2 in. cover for beams and columns, 3/4 in. for slabs and walls not exposed to weather, and 2 in. where concrete is cast against earth.

Minimum clear bar spacing

Clear spacing 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.

90-degree standard hook

A 90° hook requires a bend diameter of 6 bar diameters for No. 3 through No. 8 bars and a straight extension of 12 bar diameters beyond the bend.

180-degree standard hook

A 180° hook requires a bend diameter of 6 bar diameters for No. 3 through No. 8 bars and a straight extension of 4 bar diameters, but not less than 2-1/2 in.

Class A tension splice

A Class A lap splice requires 1.0 times the development length and is permitted where 50% or fewer of the bars are spliced within the required lap length.

Class B tension splice

A Class B lap splice requires 1.3 times the development length and applies where more than 50% of bars are spliced at one location, or where Class A conditions are not met.

Mechanical splice strength

Mechanical couplers and welded splices must develop at least 125% of the specified yield strength of the bar. They are used where lap lengths cannot be provided.

Bar placement tolerance

ACI 117 allows ±3/8 in. for bar location in members up to 8 in. deep and ±1/2 in. in members over 8 in. deep, measured from the specified position.

Bar chair spacing

Bar chairs and bolsters support the top mat of reinforcement. Typical spacing is 4 ft or less, tight enough to prevent sagging under the weight of workers and concrete.

Double tie wire

Bars larger than No. 5, or bars in heavily loaded members, are tied with double wire loops. Ties must prevent movement during concrete placement and vibration.

Development length

Development length is the embedment needed for a bar to reach its yield strength in tension. It depends on bar size, concrete strength, cover, spacing, and coating.

Bar size designation

A No. 8 bar is 1 in. in diameter and weighs 2.67 lb per foot. Bar numbers correspond to eighths of an inch of nominal diameter for No. 8 and smaller.

Stirrup spacing

Stirrups resist shear and confine concrete. Spacing is set by the structural design and is typically tighter near supports where shear forces are highest.

Reinforcement corrosion protection

Epoxy-coated bars are used in corrosive environments. Coated bars require longer development lengths and careful handling to prevent coating damage during placement.

Form tie and bar conflict

Reinforcement must not be moved to clear form ties without engineer approval. Relocating bars changes cover and effective depth, which affects structural capacity.