Plumbing NC I cheat sheet

Hierarchy of hazard control, in order of preference: elimination, substitution, engineering controls, administrative controls, then PPE. PPE is the last line of defence.

Personal protective equipment for plumbing work: safety helmet, safety footwear, eye/face protection, hearing protection above 85 dB(A), gloves matched to the chemical, and respiratory protection for dust, solvent vapour, or sewage aerosols.

A confined space is any space not designed for continuous occupancy with restricted entry or exit; entry requires a permit, atmospheric testing (oxygen 19.5-23.5%), a standby person, and rescue arrangements.

Hydrogen sulfide (H2S) is heavier than air and deadens the sense of smell at higher concentrations; never rely on odour as a warning in sewers or pits.

Isolation before work on piping: lockout/tagout, depressurize, drain, vent, and verify zero energy. Water at 1 bar exerts roughly 100 kPa; trapped thermal expansion can raise pressure many times higher.

Manual handling rule of thumb: keep the load close to the body, bend the knees, avoid twisting; two-person lift or mechanical aid for loads above about 25 kg.

Emergency response sequence: raise the alarm, make the area safe if it is safe to do so, give first aid within your training, then report and record the incident.

Communication on site: take and confirm instructions back, use a permit-to-work for hot work and confined spaces, and record verbal changes in writing.

Hand signals and tag lines for crane or excavator lifts: one designated signaller only; stop signal is valid from anyone at any time.

Pipe wrench: place the jaws so that pulling force drives the teeth into the pipe; the hook jaw adjusts to the work direction. Never use a cheater bar or hammer on the handle.

Stilson-type wrench capacity is marked on the handle; a wrench that is too large will slip and round the pipe.

Hacksaw blade selection: 18 teeth per inch for thick-wall steel and copper, 24-32 TPI for thin-wall tube and plastic; at least three teeth must be in contact with the work.

Files cut on the forward stroke; a bastard cut removes material fast, a smooth cut finishes. Clean the file with a card file, never by striking it.

Power drill safety: clamp the work, use the correct bit for the material, let the bit cool, and never wear loose gloves or sleeves near a rotating chuck.

Threading machine and power bender: check the guard and the emergency stop before use, keep hands clear of the die head and the bending shoe, and support long stock at both ends.

Pressure testing equipment: a hand pump with a calibrated gauge; test gauges must be within their valid calibration period and rated above the test pressure.

Soldering and brazing gear: use a lead-free solder for potable water, keep flux off skin, and ventilate; brazing filler melts above 450 degrees C, soldering below it.

Tool inspection before use: check insulation on portable electric tools, test RCD/GFCI protection, and remove damaged tools from service with a tag.

Drawing scales: 1:50 means one unit on the drawing equals 50 units on site; measure with the stated scale bar, not an assumed one.

Plan, elevation, and section views work together; a plan shows layout in the horizontal plane, an elevation shows heights, a section shows concealed construction.

Line conventions: solid lines are visible work, dashed lines are hidden, centre lines are long-short-long, and a break line shows omitted length.

Sanitary and drainage drawings use gravity-flow slopes, expressed as a ratio (1:60) or as a fall in mm per metre; confirm the slope on the drawing before setting out.

Riser diagrams are schematic, not to scale; they show pipe sizes, fixture connections, vents, and floor levels, not horizontal distances.

Specifications govern material, jointing method, testing, and standards; where a drawing and a specification conflict, raise a request for information rather than choosing one.

Title block and revision table: check the drawing number, revision letter, date, and approval status before setting out or cutting.

Isometric drawings show a single pipe route in three dimensions with true lengths along each axis; they are used for fabrication and material take-off.

Symbols to recognize: gate valve, check valve, pressure-reducing valve, floor drain, trap, vent stack, water heater, and stopcock; a legend on the sheet defines the project symbols.

Unit conversions: 1 inch = 25.4 mm; 1 foot = 0.3048 m; 1 gallon (US) = 3.785 L; 1 psi is approximately 6.895 kPa; 1 bar = 100 kPa.

Pipe sizes are nominal; the outside diameter of steel pipe is fixed for a given nominal size, while the inside diameter changes with wall thickness (schedule).

Take-off quantity = measured length plus allowance for fittings, offsets, and waste. Add a waste allowance of about 5 percent for straight runs and 10 percent for complex fabrication.

True length of an offset: for a 45-degree offset, the travel equals the offset multiplied by 1.414, and the fitting allowance is subtracted for each 45-degree elbow.

Centre-to-centre measurement between fittings is converted to cut length by subtracting the fitting take-out (centre-to-face dimension) at each end.

Fall calculation: fall = length multiplied by gradient. A 12 m run at 1:60 falls 12 divided by 60 = 0.2 m, or 200 mm.

Volume of a pipe or tank: volume = cross-sectional area multiplied by length; for a cylinder, area = pi multiplied by radius squared.

Setting out: establish a datum level and a reference line first, transfer levels with a water level or laser, and check square with the 3-4-5 method.

Marking: use a wrap-around or a pipe square for square cuts on round pipe; a freehand line will produce an out-of-square end and a failed joint.

Copper tube cutting: use a wheel cutter and deburr both inside and outside; a burr left inside disturbs flow and can cause erosion-corrosion.

Solder joint sequence: clean to bright metal, apply flux thinly, assemble with a capillary gap, heat the fitting evenly, and feed solder until a full ring appears at the joint.

Brazing uses filler melting above 450 degrees C with a flux or a self-fluxing alloy; it produces a stronger joint than soft soldering and is used for higher temperatures and pressures.

Threaded steel pipe: standard taper is 1:16 (about 1.8 degrees), giving roughly 3 threads engagement by hand and 5 to 6 threads when tightened with a wrench.

Cut threads must be lubricated with cutting oil, cleaned, and protected with jointing compound or PTFE tape applied in the direction of thread engagement.

Solvent-welded plastic pipe: cut square, chamfer, clean with primer, apply cement to both surfaces, assemble with a quarter turn, and hold until set; cure time depends on diameter and temperature.

Push-fit and compression fittings: the pipe must be cut square, inserted to the marked depth, and the compression nut tightened by hand then about one turn with a wrench.

Pipe bending: minimum bend radius depends on the material and the bender; for a 90-degree bend, the gain equals twice the radius minus the developed arc, and must be allowed for in the cut length.

Grooved and mechanical couplings allow jointing without heat or thread; the pipe end must be cut square and the groove rolled to the coupling manufacturer's dimension.

Direct water supply feeds from the mains; indirect supply feeds from a storage tank. Many codes require indirect supply where backflow risk or interruption is a concern.

Backflow prevention: an air gap is the highest protection, followed by a reduced-pressure zone assembly, then a double check valve; a simple check valve is not adequate for high hazard.

Water hammer is controlled with air chambers, surge arrestors, or slow-closing valves; it is caused by sudden velocity change in the line.

Drainage is gravity flow with a continuous air path: every fixture trap is protected by a vent, and the vent stack terminates above the roof.

Trap seal depth is typically 50-75 mm; a shallow seal evaporates and a deep seal is hard to clear. Trap arms have a maximum developed length that depends on pipe size.

Drainage pipe slope: 1:60 to 1:40 for small-bore branch drains is common; too little slope causes solids deposition, too much slope leaves liquids behind the solids.

A building drain carries waste to the building sewer; a soil pipe carries sewage, a waste pipe carries other discharge, and a vent pipe carries air only.

Testing: water supply is pressure tested at typically 1.5 times working pressure for a set period; drainage is tested by water test or air test before concealment.

Pipe support spacing depends on material and diameter; plastic pipe needs more supports than steel because of thermal expansion, and expansion loops or offsets are provided.

Fixture setting: check the rough-in dimensions on the drawing, set the fixture level, secure to framing or floor, and connect with a trap that is accessible for cleaning.

Water closet types: close-coupled, washdown, siphon, and flush valve; flush valve installations need a minimum supply pressure and flow stated by the manufacturer.

Faucets and mixers: install with the hot on the left and cold on the right; a thermostatic mixing valve limits delivery temperature at the outlet.

A pressure-reducing valve is set to the required downstream pressure, typically about 300-500 kPa; install a strainer upstream and an expansion relief downstream where the system is closed.

Floor drains require a trap primer where the trap would otherwise dry out; a trap that has lost its seal allows sewer gas into the building.

Water heaters: fit a temperature and pressure relief valve, discharge it to a safe place, and provide an expansion vessel or relief on a closed system.

Fixture maintenance: replace washers and cartridges with the correct size, clean aerators and strainers, and test for leaks at the supply and waste connections after reassembly.

Accessibility: grab bars must be anchored into structure or blocking, not into drywall alone; accessible fixtures have specified mounting heights and clear floor space.

Commissioning: flush the lines, check flow and temperature at each outlet, verify no leaks at traps and valves, and record test results before handover.