Plumbing NC II cheat sheet

Personal protective equipment for plumbing work: hard hat, safety glasses or goggles, face shield when cutting/grinding, hearing protection, respirator when solvent cement or lead work is present, gloves, safety shoes, and fall protection above 1.8 m.

Hierarchy of control, in order of preference: elimination, substitution, engineering controls, administrative controls, then PPE as the last line of defense.

Confined-space entry requires a permit, atmospheric testing for oxygen (19.5–23.5%), flammables, and toxics before entry, plus a standby attendant and retrieval system.

Lockout/tagout: isolate energy sources, release stored pressure and spring tension, verify zero energy, and tag before servicing pumps, water heaters, or electrically driven equipment.

Solvent cements and primers are flammable and emit VOCs; keep ignition sources away, ventilate the area, and store containers closed and upright.

Housekeeping rule: keep walkways and egress clear, coil hoses and cords off the floor, remove offcuts and metal shavings promptly, and separate scrap by material for recycling.

Fire extinguisher classes: A ordinary combustibles, B flammable liquids, C energized electrical, D combustible metals; water is never used on class B, C, or D fires.

Manual handling limit guideline: keep loads close to the body, avoid twisting, and use two-person lifts or mechanical aids for heavy pipe, cast-iron sections, or fixtures.

Incident reporting: report near misses and injuries immediately, record in the logbook, and preserve the scene until investigation is complete.

Drawing scales: 1:50, 1:100, and 1:200 are common for plans; a 1:100 drawing means 1 unit on paper equals 100 units on site.

Line conventions: solid thick lines are visible edges, dashed lines are hidden, centerlines are long-short-long, and break lines indicate omitted length.

Plan symbols: a circle with a cross is a floor drain, a circle with a diagonal line is a cleanout, an inverted triangle marks a riser, and a square with a circle is a vent terminal.

Slope notation on DWV drawings is expressed as fall per unit length (e.g., 1:50 or 1/4 in per ft); confirm direction of flow toward the drain or stack.

Specifications govern material grades, pipe schedules, jointing methods, testing pressures, and fixture types; drawings govern geometry and location. When they conflict, the specification generally prevails unless the drawing is later-issued.

Section and elevation views must be cross-checked with the plan for invert levels, ceiling heights, and pipe routing before layout.

Bill of materials is derived by scaling or dimensioning each run, adding fittings, and applying a wastage allowance (typically 5–10%).

Revision control: check the revision block and title block for issue date, drawing number, and approval stamp before starting work.

Unit conversions: 1 inch = 25.4 mm; 1 ft = 0.3048 m; 1 psi ≈ 6.895 kPa; 1 bar = 100 kPa; 1 US gallon ≈ 3.785 L.

Pipe length between fittings = center-to-center distance minus the fitting take-off (face-to-center allowance) at each end; take-offs vary by fitting type and size.

45° offset: offset = travel × 0.707; travel = offset × 1.414. For a 22½° offset, travel = offset × 2.613.

Slope calculation: fall = length × gradient. Example: 12 m run at 1:50 gives 0.24 m fall.

Marking out uses a centerline and reference datum; transfer levels with a spirit level, laser, or water level, and mark pipe with a wrap-around or saddle square for square cuts.

Cutting allowance: add threading engagement (typically 20–25 mm per threaded end for small pipe) or socket depth for solvent-welded joints before cutting.

Fixture rough-in dimensions must be measured from the finished wall and finished floor; verify against the manufacturer's rough-in sheet, not the rough structure.

Pythagorean check for square layout: 3-4-5 triangle or diagonal equality confirms right angles before setting out pipe runs.

Pipe material selection by service: PVC for cold DWV, CPVC for hot water, PEX for concealed hot/cold supply, copper for potable and hot water, galvanized steel for exposed supply, cast iron for soil stacks, and PP or HDPE for chemical waste.

Pressure ratings: schedule 40 PVC is rated for cold water; schedule 80 has thicker walls for higher pressure and is used in industrial or high-pressure service.

Fitting selection: elbows for direction change, tees for branch, wyes (Y-branch) for drainage branch with smooth flow, reducers for size change, and unions for future disassembly.

Tool selection: pipe wrench for threaded joints, strap wrench for finished surfaces, tubing cutter for copper, hacksaw or chop saw for plastic and steel, threading die for steel, and flaring or press tool for copper.

Handling: store PVC and CPVC pipe on flat supports to prevent sagging, keep out of sunlight long-term, and cap open ends to keep debris out.

Copper tube types: K (thickest, underground), L (standard supply), M (thin wall, above ground), and DWV (drainage, thinnest).

Gasket and seal selection: rubber gaskets for cast-iron hub joints, O-rings for push-fit, PTFE tape or pipe-joint compound for threaded joints (tape on male threads only).

Inspect fittings for cracks, ovality, and damaged threads before use; reject defective materials and record returns.

Cutting: use a tubing cutter for copper with a deburring tool to remove the inner burr; use a miter saw or hacksaw with a square for plastic and steel; keep the cut square to within about 1 mm.

Threading: standard pipe threads are tapered NPT (1:16 taper); use cutting oil, cut in passes, and check with a thread gauge or by engaging a fitting by hand for 2–3 turns.

Solvent welding (PVC/CPVC): chamfer the pipe end, clean with primer, apply cement to both surfaces, insert with a quarter-turn, hold for 30 seconds, and allow full cure before pressure testing.

Copper soldering: clean to bright metal, apply flux, heat the fitting (not the solder), and feed solder until a capillary ring forms; lead-free solder is required for potable water.

Brazing uses filler with a melting point above 450 °C; soldering uses filler below 450 °C.

Bending: copper can be bent with a spring or lever bender; minimum bend radius is typically 3–5 times the pipe diameter; annealed copper is easier to bend than hard-drawn.

PEX joining: use crimp, clamp, or press fittings per the manufacturer's system; do not mix systems; keep the bend radius above the manufacturer's minimum and use bend supports.

Push-fit and press fittings must be fully inserted to the depth mark; press tools require calibration checks and the correct jaw size for the fitting.

Service entry sequence: meter, main shutoff valve, check valve or backflow preventer, pressure-reducing valve if supply exceeds about 550 kPa (80 psi), and expansion tank on a closed system.

Minimum fixture pressures: about 100 kPa (15 psi) at the fixture for most fixtures; flush valves typically need 140–210 kPa (20–30 psi).

Water supply sizing uses fixture units (FU) from a table; convert FU to probable demand in L/min or gpm, then select pipe diameter so velocity stays below about 1.5–2.4 m/s (5–8 ft/s).

Hot water: keep the hot line on the left when facing the fixture; insulate hot lines; use a recirculation line or heat-traced system to reduce wait time on long runs.

Air chambers or water hammer arrestors are installed at the end of long runs near quick-closing valves to absorb shock.

Support spacing: copper horizontal about 1.8 m, PVC horizontal about 1.2 m, and vertical support at each floor; check local code for the exact values.

Pressure testing: hydrostatic test at 1.5 times the working pressure or per code, typically 100 psi (690 kPa) for at least 1 hour with no drop.

Backflow prevention: an air gap is the highest protection, followed by an RPZ, then a double check valve; use the type required by the hazard level.

Standard DWV slopes: 100 mm (4 in) and larger pipe at 1:100 (1%); 75 mm (3 in) at 1:50 (2%); 50 mm (2 in) and smaller at 1:50 (2%); 40 mm and smaller at 1:50 or steeper per code.

A trap is required on every fixture except those with integral traps; trap seal depth is 50–100 mm (2–4 in).

Vent types: individual vent, common vent, wet vent, circuit vent, and stack vent; each fixture must have a vent unless it is wet-vented per code.

Stack rules: soil stack carries solids; waste stack carries liquid waste; a stack vent extends above the roof by at least 150 mm (6 in) or the depth of snow, whichever is greater.

Building drain slope is typically 1:50 (2%); building sewer slope is typically 1:100 (1%) or per code; check invert levels at each manhole.

Cleanouts are required at the base of each stack, at each change of direction greater than 45°, and at intervals of 15 m (50 ft) in horizontal runs.

Horizontal drainage pipe must be supported at intervals of about 1.2 m for plastic and 3 m for cast iron; vertical stacks are supported at each floor.

Air admittance valves (AAV) may substitute for a vent only where the code allows and where the valve is accessible and above the fixture flood level.

Fixture setting: verify rough-in dimensions, level the fixture, secure with closet bolts or anchors, and seal the base with caulk or grout per specification.

Water closet rough-in is typically 300 mm (12 in) from the finished wall to the closet flange centerline; confirm the actual fixture.

Flush valve installation: install a vacuum breaker at least 150 mm (6 in) above the fixture rim; check the flush volume setting.

Fixture testing: fill and drain each fixture, check for leaks at supply and drain connections, and verify trap seal and vent function.

Drain test: plug the fixture drain, fill the fixture to overflow, and observe for leaks; then remove the plug and confirm free flow.

Appliance connections: water heaters require a T&P relief valve piped to a safe discharge point and a drain pan where required; dishwashers need an air gap or high loop.

Accessories: install shutoff valves at each fixture, escutcheons at wall penetrations, and flexible connectors only where permitted.

Commissioning: record test pressures, flush volumes, and any adjustments in the handover documentation.

Leak diagnosis: isolate by closing shutoffs progressively; check joints, valves, and fixture connections; use a pressure gauge on a capped line to detect hidden leaks.

Low pressure causes: partially closed valve, clogged aerator, undersized pipe, high demand, or a failing pressure-reducing valve.

Slow drain causes: partial blockage, improper slope, bellied pipe, or a blocked vent; check the vent first if gurgling occurs.

Water hammer causes: loose pipe supports, failed air chambers, or quick-closing valves; fix by adding arrestors and securing supports.

No hot water: check the power or gas supply, thermostat, heating element, dip tube, or mixing valve; for tankless units check the flow sensor and descaling.

Sewer odors: dry trap, broken vent, or a failed wax ring; refill traps and check vent termination above the roof.

Frozen pipe thawing: open the faucet, apply gentle heat with a hair dryer or warm cloth, never an open flame; insulate and heat-trace exposed runs.

Repair documentation: record the fault, root cause, parts replaced, and test result in the maintenance log for trend analysis.