RBSE SS Voc Plumbing key terms

A pointed metal weight hung on a cord to establish a true vertical line. Plumbers use it to align vertical pipes and risers when a spirit level cannot be placed against the work.

A tool containing a liquid-filled vial with an air bubble that shows whether a surface is horizontal or vertical. It is used to check pipe gradients and fixture alignment.

An adjustable wrench with serrated jaws that grip round pipe and fittings for turning. Its jaw teeth bite in one direction, so the handle must be pulled toward the user.

A wrench using a fabric or rubber strap to grip polished pipe and chrome fittings without scratching. It is preferred for visible fixture work and for loosening plastic unions.

A second wrench held on one fitting to stop it turning while a mating fitting is tightened. Using two wrenches prevents strain on the pipe and avoids loosening joints elsewhere.

A tool with a cutting wheel that is rotated around copper or plastic tube and tightened progressively to score through the wall. It produces a square end with minimal burr.

Removing the raised inner and outer edge left after cutting metal pipe. Deburring restores full bore, prevents turbulence and erosion, and lets solder or push-fit seals seat properly.

A bench-mounted clamp with shaped jaws that hold pipe firmly during cutting and threading. Correct clamping prevents the pipe rotating and keeps cuts square to the axis.

Cutting a tapered screw thread on the end of steel pipe so it accepts screwed fittings. The taper ensures the joint tightens and seals as it is made up.

Wearable gear such as safety glasses, gloves, hearing protection and safety footwear that reduces injury exposure. It is the last line of defence after elimination, substitution and engineering controls.

A written authorisation required before soldering, brazing, grinding or any operation producing flame, sparks or heat. It confirms fire precautions, a fire watch and clearance of combustibles before work starts.

Deterioration caused when two dissimilar metals contact each other in the presence of an electrolyte, so the less noble metal corrodes. It is why copper must not connect directly to galvanised steel.

A fitting with an insulating sleeve or washer that separates two dissimilar metals in a piping joint. It interrupts the electrical path and prevents galvanic corrosion at copper-to-steel connections.

Steel pipe coated with a zinc layer to resist rust in water and drainage service. Threads cut on site expose bare steel, so cut ends need protection against corrosion.

Unplasticised polyvinyl chloride pipe, rigid and chemically resistant, widely used for soil, waste and vent drainage and for cold water. It is joined by solvent cement or push-fit ring seals.

Chlorinated polyvinyl chloride, a rigid plastic pipe with higher temperature tolerance than uPVC. It is used for hot water distribution and is joined with solvent cement made for CPVC.

Cross-linked polyethylene flexible tubing supplied in coils and used for hot and cold water distribution. It bends around obstacles, needs fewer joints, and connects with crimp or push-fit fittings.

A glued plastic joint made by applying solvent cement that softens both surfaces so they fuse. The pipe must be cut square, deburred, cleaned and primed for a sound seal.

A copper or bronze fitting sized so solder is drawn into the gap between tube and socket by capillary action when heated. Clean surfaces and flux are essential for a leak-free joint.

A paste or liquid applied to metal before soldering that removes oxides and stops new oxidation during heating. It lets solder flow and wet the joint evenly.

A mechanical joint where a nut tightens an olive or ferrule against the pipe to form a seal. It needs no heat or solder and can be dismantled for maintenance.

A fitting with a threaded ring that joins two pipe ends and can be undone to separate them without cutting. It allows fittings and fixtures to be removed for repair or replacement.

A banging noise and pressure surge caused by water stopping abruptly when a tap or valve closes quickly. It is controlled by correctly sized pipes, slow-closing valves and shock arrestors.

A capped vertical length of pipe holding trapped air that cushions pressure surges in supply lines. It absorbs the shock wave that causes water hammer when flow stops suddenly.

A valve used to shut off water to a fixture, appliance or section of pipe for repair. Isolation valves limit the area drained and let maintenance proceed without shutting the whole building.

A valve with a sliding gate that opens fully to give straight-through flow with little pressure loss. It is used for isolation rather than throttling, which would wear the gate and seat.

A one-way valve that allows flow in one direction and closes automatically against reverse flow. It protects supply systems from backflow and pumps from running backwards.

Measures such as air gaps, check valves and reduced-pressure zone assemblies that stop contaminated water being drawn or pushed into a potable supply. It protects drinking water from cross-connection hazards.

A physical unobstructed vertical space between a water outlet and the flood level of a fixture or vessel. It is the most reliable form of backflow protection because no mechanical part can fail.

A toilet fixture that receives soil and discharges it through a trap to the drainage system. It must be securely fixed, have a water seal, and be flushed from a cistern or flush valve.

A U-shaped pipe section holding water that blocks sewer gases from entering the building. It must keep a designed seal depth and be protected from siphonage by venting.

The highest level to which water rises in a fixture before it overflows onto the floor. It sets the minimum height for air gaps and the level to which fittings must resist backflow.

A pipe that admits air to the drainage system and releases gases above the roof. It equalises pressure so trap seals are not siphoned out and allows foul air to escape safely.

The main vertical drainage pipe carrying discharge from water closets (soil) and other fixtures (waste) down to the drain. It is normally extended upward as the main vent.

The downward slope of a drain or horizontal pipe expressed as a ratio or in millimetres per metre. Correct fall keeps solids moving and prevents blockage from silting.

The lowest point of the internal bore of a drain or pipe at a given section. Invert levels are recorded on drawings to confirm gradients and connection depths.

A covered chamber giving access to a drain or sewer for inspection, rodding and clearing blockages. It is placed at changes of direction, junctions and intervals along long runs.

A vertical pipe carrying water or drainage between floors of a building, often grouped in a duct. Risers appear on drawings as circles or short vertical lines with labels.

A three-dimensional pipe layout drawn on three axes at 30 degrees, showing pipe runs, fittings and sizes without perspective distortion. It is the standard working drawing for plumbing installations.

A priced schedule listing quantities of pipes, fittings, fixtures and labour needed for a job. It is built from measured drawing take-offs and forms the basis of the tender price.

An allowance added to an estimate for unforeseen work, price changes and minor variations. It is not a hidden profit margin and is drawn down only when justified.

The cost per hour or per day of a tradesperson's time, including wages and on-costs such as insurance and supervision. It is multiplied by estimated hours to price the work.

Finding the source of water loss using methods such as isolating sections, metering, listening for flow noise and inspecting for damp. Early detection prevents structural damage and water waste.

Clearing a blocked drain by feeding flexible rods or a drain snake through a manhole or access point. Correct technique avoids damaging pipe joints and trap seals.

An enclosed or partly enclosed area with restricted entry, poor natural ventilation and potential for hazardous atmosphere, such as a pit or large tank. Entry needs assessment, permits and rescue arrangements.

A distribution fitting with several outlets fed from one supply, used in PEX and underfloor heating systems. It allows each circuit to be isolated and balanced separately.