NCCER Boilermaker flashcards

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

Lockout/Tagout Zero Energy

Lockout/tagout isolates and locks every energy source, then verifies a zero-energy state before work begins, preventing accidental startup or release of stored hydraulic, pneumatic, or steam energy.

Confined Space Oxygen Range

Acceptable entry atmosphere requires oxygen between 19.5 and 23.5 percent; levels below or above that range create asphyxiation or flammability hazards and require ventilation or supplied air.

OSHA Trench Spoils Rule

Spoil piles, tools, and materials must be kept at least two feet back from the trench edge; trenches five feet deep or more require a protective system such as sloping, shoring, or a trench box.

Grinding Wheel RPM Rating

A grinding wheel's marked maximum speed must equal or exceed the grinder spindle speed; overspeed can burst the wheel, so the guard must be in place and the tool rest set close.

Fire Watch Duration

A fire watch is maintained during hot work and for at least 30 minutes after the work ends, checking for smoldering sparks and hidden fires in adjacent combustibles.

Ladder 4-to-1 Rule

For every four feet of working height, the ladder base sits one foot from the wall, giving roughly a 75 degree angle that keeps the ladder from tipping backward.

Neutral Flame

A neutral flame shows one distinct inner cone and is used for cutting steel and welding mild steel; excess oxygen gives a short sharp cone and excess acetylene a feathered three-part flame.

Acetylene 15 psi Limit

Free acetylene is unstable and can decompose explosively above about 15 psi gauge, so regulators and manifolds are never set higher and copper tubing is never used with acetylene.

Oxygen Hose Fittings

Oxygen hose is green with right-hand threads and fuel gas hose is red with left-hand threads, so the fittings cannot be cross-connected; oil and grease must never contact oxygen equipment.

E7018 Electrode Meaning

E marks an electrode, 70 means 70,000 psi minimum tensile strength, 1 means all positions, and 8 means a low-hydrogen iron-powder coating that must be kept in a heated rod oven.

Standard V-Groove Bevel

A standard single-V groove uses a 37.5 degree bevel on each plate, producing a 75 degree included angle, usually with a small root face and root opening.

Cutting Oxygen Purity

Oxyfuel cutting needs oxygen of at least 99.5 percent purity; lower purity slows the oxidation reaction, leaves ragged kerf edges, and increases slag and cutting time.

Backfire Versus Flashback

A backfire is a momentary pop as the flame goes out at the tip; a flashback is flame traveling back into the hose or regulator and requires shutting off the oxygen valve first.

Third-Angle Projection

In third-angle projection the top view sits above the front view and the right-side view sits to the right of the front view, matching projection onto a glass box.

Drawing Scale 1/4 Inch

A quarter inch equals one foot scale means one quarter inch on the print represents twelve inches actual, so any measured length is multiplied by 48 to get real size.

Circumference Formula

Circumference equals pi times diameter, C = 3.1416 D; it gives the flat pattern length when a shell is rolled from plate using the mean diameter.

Mean Diameter Rolling

Rolling layout uses the mean diameter, outside diameter minus one plate thickness, so a rolled ring finishes at the specified outside diameter after the ends are welded.

Hidden Line Convention

Hidden edges are drawn as medium-weight short dashes, center lines as thin long-short-long lines, and visible outlines as heavy solid lines so the drawing reads consistently.

Bend Allowance Formula

Bend allowance equals 0.01745 times the bend angle in degrees times the sum of the inside radius plus half the plate thickness, giving the neutral-axis arc length.

Sling Leg Tension Formula

For a two-leg sling, tension per leg equals the load divided by twice the sine of the leg angle from horizontal, so flatter slings carry far more tension.

Sling Angle Factor

At 60 degrees from horizontal each leg carries about 0.577 times the load, at 45 degrees about 0.707 times, and at 30 degrees a full 1.0 times the load.

Wire Rope Safety Factor

Wire rope slings use a 5-to-1 design factor, so the working load limit is one fifth of the nominal breaking strength of the assembly.

Shackle Side Loading

Shackles must be loaded along the centerline from bow to pin; side loading cuts capacity sharply, and screw pins must be fully seated and secured against backing out.

Hook Removal Criteria

Remove a hook from service when its throat opening has increased more than 15 percent, wear exceeds 10 percent of the original dimension, or cracks or twists are found.

Center of Gravity Below Hook

The hook must hang directly above the load's center of gravity so the load hangs level; an off-center hook causes swinging and uneven loading of the sling legs.

Chain Sling Design Factor

Alloy chain slings are designed with a 4-to-1 factor; grade 80 or grade 100 chain is standard, and stretched, gouged, or worn links require removal from service.

Fire-Tube Boiler

In a fire-tube boiler hot combustion gases pass through tubes surrounded by water, giving a large water volume and steady low-pressure heating service.

Water-Tube Boiler

In a water-tube boiler water circulates inside tubes surrounded by hot gases, permitting higher pressures and much faster steam response than fire-tube designs.

Hydrostatic Test Pressure

New power boiler construction is hydrostatically tested at one and one-half times the maximum allowable working pressure while the shell, tubes, and all joints are inspected for leaks.

ASME Section VIII

ASME Section VIII governs pressure vessel design and fabrication, Section I covers power boilers, and Section IX covers welding procedure and welder performance qualification.

Counterflow Heat Exchanger

Counterflow exchangers pass the hot and cold fluids in opposite directions, producing the largest mean temperature difference and the highest effectiveness per unit of surface area.

Economizer Function

An economizer uses flue gas leaving the boiler to preheat incoming feedwater, lowering stack temperature and recovering sensible heat to raise overall boiler efficiency.