NCCER Sheet Metal Worker key terms

The gear a worker wears to reduce injury risk, such as safety glasses, gloves, hard hat, hearing protection, and steel-toe boots. Employer hazard assessments determine which items are required for a given task.

A procedure that isolates energy sources on machinery or equipment and applies locks and warning tags so it cannot be started while someone services it. Only the person who applied a lock removes it under normal circumstances.

A document supplied by a product manufacturer summarizing hazards, safe handling, first aid, and protective measures for a chemical or material. Workers must be able to access SDS information for products used on the job.

Systems and practices that prevent workers from falling from elevation or arrest a fall safely, including guardrails, personal fall arrest harnesses, lanyards, and anchor points. Training and inspection of equipment are required before use.

A temporary elevated platform that supports workers and materials during construction or installation. It must be erected, inspected, and used according to the manufacturer's instructions and applicable safety regulations.

A space large enough for a worker to enter, with limited entry or exit, and not designed for continuous occupancy. Entry may require atmospheric testing, a permit, an attendant, and rescue provisions.

Standardized arm and hand movements used to direct crane or hoist operators when voice communication is impractical. Only one designated signal person should signal an operator at a time.

The slings, shackles, hooks, and hitches used to connect a load to a lifting device. Rigging must be rated for the load, inspected before use, and protected from sharp edges.

Hand-cutting tools for sheet metal. Aviation snips have compound leverage for curves and straight cuts, while tinners snips are used for straight cuts and notching. Cutting direction is indicated by color coding.

Removing sharp edges, burrs, and slivers left by cutting or shearing sheet metal. Deburring protects handlers from cuts and improves fit, finish, and coating adhesion on fabricated parts.

A tool or machine that cuts a notch or corner relief from sheet metal so adjacent bends do not interfere. Hand notchers and machine notchers are used to prepare corners for folding and seaming.

A bending machine with removable fingers that allows forming boxes and pans with return flanges. The fingers can be arranged to clear previously formed bends during a sequence of operations.

A machine with three rolls that forms curved or cylindrical shapes in sheet metal. Adjusting roll spacing and position controls the radius and the amount of curvature produced.

A powered shop machine that cuts, beads, crimps, and flanges sheet metal using interchangeable rolls or dies. It is used for edge preparation and for forming joints on duct and fittings.

A resistance welding machine that joins overlapping sheet metal at localized points by passing current through the parts under pressure. It is common in shop fabrication of galvanized and stainless duct.

The amount of material consumed in forming a bend, based on thickness, radius, and bend angle. It is used to calculate the flat pattern length before cutting and bending a part.

The process of unfolding a three-dimensional shape onto a flat sheet to create a cutting pattern. It uses geometric construction for transitions, offsets, and round-to-rectangular fittings.

A layout method that divides a surface into a series of triangles to develop patterns for irregular transitions. True lengths of triangle sides are found by projection before the flat pattern is drawn.

An orthographic drawing that shows an object as seen from the front, side, or another vertical direction. It is used with plan views to determine heights, offsets, and fitting locations.

An orthographic drawing that shows an object or layout as seen from above. It establishes horizontal dimensions, duct routing, and equipment positions relative to walls and columns.

A pictorial drawing in which three axes are shown at equal angles to represent length, width, and height. It helps visualize piping, duct, and structural routing in three dimensions.

Standardized marks on drawings that specify weld type, size, length, location, and finish. A leader line with a reference line carries the symbol and any supplementary information.

A self-locking seam formed by interlocking folded edges on duct and fittings. It is commonly used for longitudinal seams and can be sealed to limit air leakage.

A folded metal strip that slides over flanged duct edges to join two sections transversely. Cleats are often used with S-slips and are secured to resist separation and leakage.

A connection between the ends of two duct sections along the direction of airflow. Common types include slip-and-drive, flanged, and standing-seam joints, each with specific leakage and strength characteristics.

A compound applied to seams, joints, and penetrations to reduce air leakage in duct systems. Sealant class and application depend on the system pressure and the specified leakage standard.

A procedure that pressurizes a duct system or section and measures airflow needed to maintain test pressure. Results are compared with allowable leakage for the system's pressure class.

The outward force per unit area exerted by air against duct walls, expressed in inches of water column. It is used to classify duct construction and to select fans and equipment.

The pressure associated with the speed of moving air, measured in inches of water column. It is used with static pressure to determine total pressure and to select and balance air devices.

The process of measuring and adjusting airflow at terminals and dampers so each space receives its design quantity. It uses instruments such as manometers, anemometers, and flow hoods.

A movable blade or set of blades inside ductwork that regulates airflow to a branch or zone. It may be manually locked or motorized and is adjusted during air balancing.

A listed device installed in duct penetrations of fire-rated assemblies that closes on heat or fire to limit spread. Its location, rating, and inspection requirements are governed by code and listing.

A listed material or system that seals openings around ducts, pipes, and cables where they pass through rated walls or floors. It restores the fire-resistance rating of the penetrated assembly.

A metal roof in which adjacent panels are joined by raised interlocking seams. Concealed clips allow thermal movement and the seams may be mechanically seamed for weathertightness.

Sheet metal or other material installed to direct water away from joints, penetrations, and edges of a roof or wall. Correct laps and terminations prevent water entry at transitions.

The force exerted by standing water on a surface, such as a roof or wall assembly. It drives the need for proper slope, drainage, and watertight laps in architectural metal work.

Expansion and contraction of metal caused by temperature change. Design details such as clips, slots, and clearances accommodate movement without buckling, oil-canning, or fastener failure.

A model code adopted by many jurisdictions that governs mechanical systems, including duct construction, ventilation, and exhaust. Local amendments may change specific requirements, so the adopted edition must be confirmed.

Industry standards that specify duct gauges, reinforcement, joint spacing, and sealing based on pressure class. They are commonly referenced in specifications for commercial HVAC ductwork.