Sri Lanka NVQ L3 Plumber cheat sheet

Personal protective equipment for plumbing work: safety helmet, safety footwear with steel toe cap, eye protection for cutting and grinding, gloves for solvent cement and hot work, hearing protection above 85 dB(A), and respiratory protection when cutting concrete, asbestos-cement or lead pipe.

Sri Lanka's Factories Ordinance (as amended) and the Workmen's Compensation Ordinance place duties on the employer to provide a safe workplace; the employee must use guards and PPE provided and must not wilfully endanger others.

Manual handling limit rule: keep the load close to the body, avoid twisting, and use two persons or a mechanical aid for long pipe lengths, cast iron goods and cylinders; team lift is mandatory above roughly 25 kg per person.

Ladder rule: 4:1 ratio (one metre out for every four metres up), top extending about one metre above the landing point, secured at the top, and never used as a work platform for sustained work.

Trench and excavation rule: support or batter sides below 1.2 m in unstable ground, keep spoil at least 0.6 m back from the edge, and treat any confined space (manhole, sump, septic tank) as oxygen-deficient until tested.

Hot work control: clear combustibles within 10 m, use a fire blanket and extinguisher, and maintain a fire watch for at least 30 minutes after finishing soldering, brazing or grinding.

Electrical safety: use 30 mA residual current device protection on portable tools, inspect leads for damage, and never work on wet floors with unearthed equipment; treat water and electricity as a combined hazard in pump rooms.

Solvent cement and primer vapours are flammable and narcotic: ventilate the space, keep ignition sources away, and store cans closed with labels intact; lead solder and asbestos-cement dust require specific controls and disposal as hazardous waste.

Environmental controls: contain flushing water and test water, do not discharge chlorinated or cement-laden water to storm drains, segregate metal, plastic and packaging waste, and clean up spills with absorbent before they reach drains.

Pipe wrench (Stillson) sizing rule: choose a wrench whose jaw capacity matches the pipe diameter; a wrench too large for the pipe crushes thin-wall and plastic pipe, so use strap wrenches or chain tongs on finished surfaces.

Cutting methods by material: hacksaw or wheel cutter for copper and steel, ratchet or wheel cutter for PPR and PE, fine-tooth saw for PVC/UPVC with burr removal, roll grooving or threading for steel, and cast iron cut with a soil pipe cutter.

Threading: BSP pipe threads are tapered 1:16; use the correct die head size (1/2 in to 2 in typical), cut with cutting oil, and check with a thread gauge or by trial fitting a BSP female fitting about 3-4 turns by hand.

Bending copper: annealed copper can be hand-bent with a spring or lever bender; minimum bend radius is roughly 3-4 times the outside diameter, and the pipe must be re-rounded after bending to avoid flow restriction.

Material identification decisions: copper for hot water and potable supply, PPR for hot water where chlorinated water and high temperature occur, uPVC for cold supply and drainage, ABS for drainage where impact resistance matters, and galvanized steel for exposed external runs where specified.

Pressure testing equipment: hydrostatic test pump with calibrated gauge, test plugs and caps; gauge range should be about 1.5-2 times the test pressure so the reading sits in the middle of the scale.

Solvent welding rule: primer first, then cement applied to both surfaces, assemble with a quarter-turn and hold for about 30 seconds; joint strength develops fully after the manufacturer's cure time, which is longer in cold or humid conditions.

Tool care: clean and oil threading dies and pipe cutters, replace worn hacksaw blades, store levels and squares so they do not distort, and calibrate pressure gauges and test pumps periodically against a known reference.

Drawing set hierarchy: site plan, floor plans, reflected ceiling plans, riser diagrams, details and schedules; the specification and bill of quantities govern quality and quantity where drawings are silent, and the latest revision with the issue date controls.

Scale reading: 1:50 or 1:100 for floor plans, 1:20 or 1:10 for details; measure with a scale rule and verify against a written dimension because photocopies and PDFs distort scale.

Line conventions: solid thick lines for pipework, dashed for concealed or above-ceiling runs, single-line for small-bore pipework and double-line for large ducts and drains; symbols follow the legend sheet, so always read the legend before the plan.

Riser diagram logic: vertical stacks are drawn diagrammatically, not to scale; the diagram shows fixture connections, vent connections, stack offsets and the point of connection to the drain, which the plan alone cannot show.

Levels and datum: finished floor level (FFL) is the usual reference; invert level (IL) of a drain equals the pipe soffit level, and cover level minus invert level gives depth of excavation.

Gradient notation: 1 in 60 means one unit fall per 60 units run, equivalent to 1.67 percent; convert by dividing 100 by the denominator, and calculate fall as length multiplied by gradient.

Specification reading rule: check pipe material and standard (for example uPVC to a named standard), jointing method, pressure class, valve types, insulation and testing requirements before ordering any material.

Coordination checks: compare plumbing drawings with structural and electrical drawings for beam depths, sleeve positions and ceiling voids; a clash found on paper is cheaper than one found on site.

Setting out starts from a fixed datum: use the FFL and a single reference wall or gridline, then transfer levels with a water level, laser level or dumpy level and mark them permanently before any chasing.

Centre-line method: mark the centre line of each fixture and stack on the floor and wall, then offset half the pipe outside diameter to each side to get cut lines; never mark only one edge.

Gradient setting out: fall per metre equals gradient denominator divided into 1000 mm; for 1 in 60 the fall is about 16.7 mm per metre, so a 6 m run falls 100 mm.

Bracket spacing rules of thumb: copper horizontal runs about 1.2-1.5 m, uPVC soil stacks about 1.0-1.2 m with a bracket near every joint and change of direction, and vertical stacks one bracket per storey plus at the base.

Verticality check: use a plumb line or spirit level on two faces at 90 degrees; a stack must be plumb within the tolerance stated in the specification, commonly 5 mm in a storey height.

Sleeve and penetration marking: mark sleeve centres from the structural grid, set sleeves at least 50 mm larger than the pipe, and record positions before concreting so later drilling does not cut reinforcement.

Fixture setting out heights (typical): wash basin rim 750-800 mm, WC pan set out with a 150 mm waste centre from the finished wall, and shower mixer about 1000 mm above FFL; confirm against the specification because heights vary by project.

Marking discipline: use a pencil or chalk for temporary marks and a permanent marker or paint for reference lines, and record all dimensions on a marked-up drawing so the next trade can verify them.

Cut accuracy rule: cut square to the axis, then deburr and chamfer; a burr left inside a plastic pipe creates turbulence and a joint leak path, and a burr on copper prevents full socket insertion.

Copper capillary jointing: clean to bright metal, apply flux sparingly, heat the fitting body (not the pipe) until solder sweats in, then remove heat and let it set without movement; wipe excess flux to prevent corrosion.

Compression jointing: insert pipe fully past the olive seat, tighten finger-tight then about 1 to 1.25 turns with a spanner; over-tightening splits the olive and crushes the pipe.

Threaded steel jointing: apply PTFE tape in the direction of thread engagement (clockwise on a right-hand thread) or use jointing compound on male threads only; leave the first two threads bare so the fitting starts cleanly.

Solvent-welded plastic jointing: dry-fit and mark insertion depth, apply primer, apply cement to both surfaces, push fully home with a quarter turn, hold, and wipe the bead; do not disturb until cured.

Fusion jointing for PE and PPR: socket fusion uses a heated tool at the manufacturer's temperature and time; under-heating gives a cold joint, over-heating weakens the wall, so follow the pipe-diameter table.

Support and expansion rule: allow for thermal expansion of plastics (roughly 0.15 mm per metre per degree C for PPR and PE), use expansion loops or offsets on long hot runs, and never fully clamp a pipe that must slide.

Pressure and leak testing after fabrication: fill slowly, vent air, raise to test pressure, hold for the specified period, and inspect every joint; a drop in gauge with no visible leak means trapped air or a hidden joint failure.

System types: direct (mains-fed) supply suits good mains pressure; indirect (tank-fed) uses a cold water storage tank and gravity feed; pumped or pressurised systems use a booster set; the choice depends on mains pressure, building height and demand.

Storage tank rule: size cold water storage for about one day's demand, provide a lid, insect screen, overflow and warning pipe, and keep the tank at least 1 m above the highest outlet in a gravity system.

Pressure test requirement (typical): test cold and hot water pipework hydrostatically at 1.5 times the working pressure or as specified, with a minimum commonly stated as 10 bar for 1 hour, then inspect all joints; air testing is not a substitute for water testing.

Air venting and draining: install air release at high points, drain valves at low points, and fill slowly from the lowest point to push air ahead of the water; trapped air causes noisy flow and false pressure-test failures.

Hot water temperature rule: store hot water at 60 degrees C or above to control Legionella, and use a thermostatic mixing valve to deliver safe outlet temperatures at fixtures (commonly about 38-43 degrees C for bathing).

Backflow prevention: fit a check valve or air gap between the mains and any non-potable or heating circuit; a temporary connection for filling a heating system must be removed after use.

Pipe sizing logic: velocity should stay within about 1-1.5 m/s in small-bore domestic pipework to limit noise and erosion; increasing diameter reduces velocity and friction loss but raises cost and dead-leg volume.

Insulation rule: insulate all hot water pipework and any cold pipe at risk of condensation; use closed-cell insulation with wall thickness matched to pipe diameter and clip the insulation, not the pipe, where vapour sealing matters.

Commissioning record: after testing, flush the system, record test pressure and duration, note any repairs, and label valves and isolation points before handover.

Wash basin: set out the waste centre on the fixture centre line, fit the trap below the basin, seal the basin to the wall with a bead of silicone, and connect through a bottle or P trap with a water seal of at least 50 mm.

WC suite: pan spigot connects to the soil pipe with a pan connector; the cistern must be level, the flush pipe cut square, and the pan secured with corrosion-resistant screws and a sealed floor connection.

Water seal rule: every fixture must have a trap with a water seal of at least 50 mm (75 mm for some gully and floor drain applications); a shallow seal lets sewer gas through.

Trap types: P trap for discharge through the wall or floor behind, S trap for vertical drop below, bottle trap for exposed basins, and gully trap for floor drainage; the trap must be accessible for cleaning.

Fixture heights and clearances (typical): WC centre 150 mm from the finished wall, basin rim 750-800 mm, and at least 600 mm clear space in front of a WC; confirm with the specification and accessibility requirements.

Appliance connections: washing machine and dishwasher hoses need a tap with a check valve and a standpipe with a trap; a water heater needs an expansion relief valve and a drain pipe to a safe place.

Fixing rule: use wall plugs and screws rated for the substrate (concrete, block or stud), never rely on adhesive alone for a wall-hung fixture, and check for concealed pipes before drilling.

Testing after installation: run each fixture, check for leaks at supply and waste connections, confirm trap seal retention and flush performance, and check that the overflow works before handing over.

Two-pipe vs one-pipe: a two-pipe system separates soil and waste; a one-pipe system combines them with a common stack and requires proper venting and trap design to prevent self-siphonage.

Stack sizing rule: a 100 mm soil stack typically serves a WC connection, and branch sizes must not exceed the stack capacity; the number of WCs per stack is limited by the design and must be checked against the specification.

Gradient rule: lay drainage falls at 1 in 60 to 1 in 80 for small-bore branches and about 1 in 100 for main runs, never flatter than 1 in 150; too steep a fall leaves solids behind, too flat a fall silts up.

Vent requirement: every trap must be protected by a vent; a vent stack must rise at least 150 mm above the roof or as specified, and a vent pipe must not be used as a drain.

Branch connection angle: connect branches to the stack at 45 degrees or with a swept bend, not at 90 degrees, to keep flow smooth and reduce blockage risk.

Rodding and access: provide access points at the base of each stack, at changes of direction and at intervals on long runs, and fit rodding eyes with caps that can be removed without cutting pipe.

Air admittance valve rule: an AAV can replace a vent pipe only where the manufacturer and specification allow, must be accessible, and must be installed above the flood level of the fixture it serves.

Testing drainage: carry out an air test or water test on the drainage system before covering up, check that all trap seals hold, and confirm that no cross-connection exists between soil and waste.

Support rule: support horizontal drainage runs at intervals that prevent sagging, typically about 1 m for plastic pipe, and support the stack at each storey and at the base.

Diagnostic sequence: confirm the complaint, isolate the affected section, observe the symptom (leak, noise, poor flow, backflow), test the likely cause, then repair and retest; never start by dismantling a working part.

Poor flow causes: blocked aerator or strainer, partially closed valve, scale build-up in hot pipes, undersized pipe, or air lock; check the simplest cause first, starting at the outlet.

Noise causes: water hammer from fast-closing valves (fit an arrestor), high velocity in undersized pipe, loose pipe clips, or a faulty ball valve; locate the noise source before changing parts.

Leak diagnosis: dry the surface, wrap with tissue or use a dry paper towel, and watch for the first wet point; on concealed pipework use a moisture meter or isolate sections to narrow the leak location.

Trap seal loss causes: self-siphonage, evaporation in unused fixtures, wind-induced pressure, or a blocked vent; cure the cause rather than simply refilling the trap.

Cistern and ball valve faults: constant overflow usually means a failed inlet valve washer or a mis-set float; a weak flush usually means a worn flush valve seal or a blocked rim jet.

Water heater faults: no hot water may be a failed element, thermostat, or tripped safety cut-out; a leaking relief valve may indicate a failed expansion vessel or excessive pressure, not a faulty valve alone.

Repair record rule: record the fault, the cause, the parts replaced, the test result and the date; a repair that is not recorded cannot be traced if it fails again.

Isolation before repair: close the nearest upstream valve, tag or lock it, drain the section, and confirm zero pressure at the outlet before opening any joint.

Communication chain: client instruction to supervisor, supervisor to trades, and any verbal instruction confirmed in writing (site diary or email) the same day; a verbal change with no record is a dispute waiting to happen.

Documentation set: drawings with revision numbers, specification, bill of quantities, method statements, inspection and test records, delivery notes, and the site diary; each record must be dated and signed.

Variation control: any change to scope, material or programme is recorded as a variation with cost and time impact, approved before work proceeds unless it is an emergency safety measure.

Progress reporting: report against the programme with percentage complete, materials on site, labour, delays and causes; a delay caused by another trade must be notified in writing within the contract period.

Handover documents: as-built drawings, test certificates, operation and maintenance manuals, warranties, spare parts list and training record; without them the client cannot maintain the system.

Professional conduct: keep client information confidential, do not canvass another employer's clients while employed, declare conflicts of interest, and refuse to sign off work that has not been tested.

Safety communication: toolbox talks, method statement briefings and permit-to-work for hot work or confined spaces; every worker must understand the task before starting.

Dispute prevention: agree measurements jointly, record them on a joint measurement sheet, keep photographic records of concealed work before covering, and confirm instructions in writing.

Sri Lankan practice context: work to the specification and to recognized standards, maintain statutory records for the employer, and keep your NVQ competency evidence and training records current.