Red Seal Sheet Metal Worker flashcards

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

Lockout/Tagout

Procedure to isolate and secure energy sources before maintenance; prevents accidental startup. Use locks and tags on disconnects and valves.

Hazard Communication

Requires labeling and Safety Data Sheets for hazardous chemicals; workers must be trained on risks and safe handling.

Fall Protection Threshold

In general industry, fall protection is required at heights of 3 m (10 ft) or more; use guardrails, nets, or personal fall arrest.

Third-Angle Projection

Orthographic projection where top view is above front view and right side view is to the right; common in North American drawings.

Hidden Lines

Short dashed lines representing edges not visible in the current view; help interpret internal features.

Title Block

Drawing area containing project name, drawing number, revision, scale, date, and approvals; always verify latest revision.

True Length

Actual length of a line in space, found by rotating it parallel to a reference plane in an auxiliary view; used in pattern development.

Parallel Line Development

Pattern development method for prisms and cylinders; stretch-out length equals circumference or perimeter of base.

Bend Allowance

Length of neutral axis arc in a bend; formula BA = (π/180) × angle × (inside radius + K × thickness), where K is K-factor.

Bend Deduction

Amount subtracted from sum of flange lengths to obtain flat pattern; BD = 2 × OSSB − BA, where OSSB is outside setback.

Galvanized Steel

Steel coated with zinc for corrosion resistance; coating weight measured in g/m² or oz/ft²; avoid welding without removing zinc and ventilation.

Stainless Steel Contamination

Carbon steel particles embedded in stainless cause rust; use dedicated tools and non-contaminating brushes.

Sheet Metal Gauge

Standard thickness measure; U.S. Standard Gauge for steel (e.g., 24 ga = 0.024 in); aluminum uses Brown & Sharpe gauge.

Aviation Snips

Hand shears with compound leverage; color-coded: left (red), right (green), straight (yellow); used for cutting curves and straight lines.

Shear Blade Clearance

Gap between blades; typically 5–10% of material thickness; too much clearance causes burrs and edge cracking.

Springback

Elastic recovery of metal after bending; compensate by overbending; increases with higher yield strength and thinner material.

Minimum Bend Radius

Smallest inside radius that can be bent without cracking; depends on material and temper; for mild steel typically 1× thickness.

Deburring

Removing sharp edges and burrs after cutting or shearing; use file, deburring tool, or grinder to prevent injury and improve fit.

Rivet Diameter Selection

Rivet diameter should be at least 3 times the thickness of the thickest sheet; hole size matches rivet diameter; grip length covers total thickness.

Pittsburgh Seam

Interlocking seam used for rectangular duct; formed by folding edges and locking together; provides strength and air tightness.

Self-Drilling Screws

Fasteners with drill point that tap their own hole; select length for at least 3 full threads engagement; avoid overdriving.

Galvanic Corrosion

Corrosion when dissimilar metals contact in presence of electrolyte; isolate with tape or gasket, especially aluminum and steel.

Flashing Lap

Minimum overlap for roof flashing is 75 mm (3 in); lap joints in direction of water flow and seal laps.

Rain Screen Principle

Building envelope design with drainage plane, air barrier, and ventilation behind cladding to manage moisture and improve durability.

Thermal Movement

Expansion and contraction due to temperature changes; allow with slotted holes or clips; typical 1 mm/m for steel, 2.4 mm/m for aluminum over 100°C range.

Duct Seal Class

SMACNA classification for duct leakage; Seal Class A is highest, requiring sealing of all joints and seams.

Duct Hanger Spacing

Support spacing per SMACNA: 2.4 m (8 ft) for rectangular duct, 3 m (10 ft) for round duct; support at joints.

Fire Damper Installation

Installed at fire-rated penetrations to prevent spread of fire; must be inspected and tested after installation.

Pitot Tube Traverse

Method to measure airflow: measure velocity pressure at points across duct; average and convert to velocity using V = 1096 × √VP (ft/min).

Air Balancing Tolerance

Adjust dampers to achieve design airflow within ±10%; measure with anemometer or pitot tube.

Duct Leakage Test

Pressurize duct and measure leakage per SMACNA; allowable leakage depends on seal class; ensures energy efficiency.

Commissioning Report

Document verifying installation against design, test results, and equipment operation; required for building handover.