Maharashtra HSC NSQF Plumber General II cheat sheet

Personal protective equipment sequence for plumbing work: helmet, safety goggles or face shield, ear plugs, gloves, safety shoes, and a dust or vapour respirator before entering any trench, shaft, or confined space.

A confined space is any space with limited entry and exit that is not designed for continuous occupancy; manholes, septic tanks, and sumps qualify. Test for oxygen (19.5–23.5 percent), then flammable gas, then toxic gas before entry.

A trench deeper than 1.5 m needs shoring, benching, or a trench box; spoil and materials are kept at least 0.6 m back from the edge; ladders must extend 1 m above the top.

Use the emergency sequence: raise alarm, isolate the supply or machine, rescue only with breathing apparatus and a harness plus lifeline; never enter a manhole to rescue a collapsed worker without respiratory protection.

Colour codes for gas cylinders and pipelines: oxygen is black with a white shoulder in India, acetylene is maroon, LPG is red; never use oil or grease on oxygen fittings.

Hand tool safety rules: carry pipe wrenches with jaws closed, never use a wrench as a hammer, cut away from the body, and keep the work area dry when using portable electric tools with a three-pin earthed plug.

Health hazards of plumbing: lead exposure from old solder and lead pipes, sewer gas (hydrogen sulphide) exposure, leptospirosis from rat urine in drains, and cement dermatitis; wash hands before eating and change out of contaminated clothing.

Fire safety in plumbing: hot work permit before brazing or soldering, a fire extinguisher rated for electrical and gas fires nearby, and a minimum 3 m clearance from flammable material before using a blowtorch.

Pipe wrench sizes are marked by the nominal length of the handle in mm or inches; a 350 mm (14 inch) wrench suits pipes up to 40 mm; a stillson wrench grips in one direction only, so reverse the jaw to back off a joint.

Pipe vice, chain vice, and bench yoke hold pipe for cutting and threading; the die head of a pipe threading set is sized in mm or inch nominal bore, and cutting oil is applied during threading to protect the dies.

Pipe cutters: wheel-type cutter for GI and copper, hacksaw with 18–24 TPI blade for PVC and CI, and a soil pipe cutter for cast iron; always ream the burr after cutting so flow area is not reduced.

Materials by application: GI (galvanised iron) for exposed cold water lines, copper for hot water and medical gas, CPVC or PPR for hot water, uPVC for soil and waste, SWR PVC for drainage, and CI for underground sewer lines.

Standard pipe sizes: 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150 mm nominal bore; the nominal bore is not the exact outside diameter, so always measure OD before selecting a fitting.

Pressure ratings: uPVC plumbing pipe is commonly rated 6 kg/cm² or 10 kg/cm²; CPVC SDR 11 handles hot water at about 93 °C; copper type L is used for domestic water and type K for underground burial.

Leveling and alignment tools: spirit level, plumb bob, and laser level; a fall of 1 in 40 to 1 in 60 is typical for 100 mm soil pipe and 1 in 80 to 1 in 100 for 50 mm waste pipe.

Solvent cement for PVC is applied to both socket and spigot with a twist of a quarter turn on assembly and held for 30 seconds; the joint must be left undisturbed for at least 24 hours before pressure testing.

Thread standards for GI pipe are BSP (British Standard Pipe) parallel or taper; a taper thread seals on the thread flanks with jointing compound, while a parallel thread seals on a gasket or O-ring.

Jointing methods and their use: lead-tin solder for copper capillary joints, compression fittings for accessible copper repairs, solvent cement for PVC, push-fit for quick repairs, and flanged joints for pumps and valves.

Support spacing for horizontal pipe: 15–20 mm bore at about 1 m, 25–50 mm at 1.8–2.4 m, 80–100 mm at 3 m; vertical stacks are supported at each floor level with a riser clamp.

An air chamber or water hammer arrestor, installed close to the tap on the discharge side, absorbs the pressure surge that causes banging when a quick-closing valve shuts.

A bypass or jumper line around a water meter, pump, or PRV allows servicing without cutting off supply; a gate valve isolates and a globe valve regulates flow.

Bending copper tube: annealed copper can be hand-bent with a spring or lever bender; the minimum bend radius is about 3 to 4 times the outside diameter; hard-drawn tube needs an annealing heat before bending.

Testing a new installation: cap all openings, fill with water, apply test pressure of 1.5 times working pressure (minimum 10 bar for domestic lines), hold for at least 1 hour, and check for pressure drop or visible leaks.

Expansion allowance: a 10 m steel pipe heated through 50 °C expands about 6 mm; use an expansion loop, a slip joint, or a flexible connector to absorb movement on long hot water runs.

A direct supply system feeds fixtures from the mains; an indirect system feeds a storage tank first, then distributes by gravity; indirect is used where mains pressure is intermittent or low.

A storage tank must be sized to hold at least 24 hours of demand; the float valve inlet is set 25 mm above the overflow level and the overflow pipe discharges visibly above ground.

A one-pipe system uses a single stack for soil and waste with a vent; a two-pipe system separates soil and waste; a single-stack system with a vent valve is common in multi-storey buildings.

Vent pipe requirements: the vent stack rises full bore above the roof, at least 300 mm above the roof surface and 900 mm away from any opening window or air intake.

Trap seal depth must be 25–75 mm; the trap prevents sewer gas entry; a vent pipe or anti-siphon valve protects the seal from being siphoned out by the flow in the stack.

Drainage gradients: 100 mm soil pipe laid at 1 in 40 to 1 in 60, 150 mm at 1 in 60 to 1 in 100; too flat causes solids to settle, too steep lets water run ahead of solids.

Water demand: domestic consumption is commonly taken as 135 litres per head per day for design; peak flow is estimated by fixture units or by the number of outlets served.

A sump and pump set with a non-return valve lifts drainage from a basement to the sewer level; the non-return valve prevents backflow when the pump stops.

A water closet is set with the outlet connected to a 100 mm soil pipe; the P-trap or S-trap is built into the pan or fitted below; the flush cistern delivers about 5 to 10 litres per flush.

Wash basin and sink wastes are 32 mm or 40 mm; a bottle trap is used where the waste cannot be trapped below the fixture, and the trap seal must still be 25–75 mm.

A floor trap (nahani trap) with a 50 mm outlet and a removable grating is set in the floor of bathrooms and kitchens; the grating must be flush with the finished floor and the trap below is accessible.

A bib cock is a wall-mounted tap; a pillar cock sits on a basin; a stop cock isolates a branch; a float valve controls tank filling; a flush valve is used on urinals and WCs.

A geyser or electric water heater needs a pressure relief valve on the hot outlet, a non-return valve on the cold inlet, and an earthing connection; the thermostat setting is typically 60–65 °C.

A water meter is installed on the incoming line with the flow arrow in the direction of flow; a strainer or filter is fitted upstream to protect the meter and the valves.

A urinal with a flush valve or sensor flush needs a 15 mm supply and a 40 mm waste; the trap must be accessible for cleaning, and the spreader or sparge pipe distributes water over the bowl.

Accessibility fitting: a grab bar is fixed into a wall stud or a solid anchor at 700–900 mm height; an accessible WC has a clear space beside the pan for a wheelchair transfer.

Isometric drawings show the pipe run in three dimensions with pipe sizes written along each line; a single-line diagram shows the schematic with symbols and is used for estimating.

Standard plumbing symbols: circle with a cross for a floor drain, circle with a dot for a gate valve, a triangle for a bib cock, and a rectangle with a diagonal for a water meter.

Scale: a 1:50 drawing means 1 mm on paper equals 50 mm on site; measure the drawing in mm and multiply by the scale factor to get the real length.

Estimation method: take off pipe lengths by diameter from the drawing, add 5–10 percent for wastage, then list fittings, valves, fixtures, and supports with their counts.

Rate analysis for a pipe run: cost of pipe per metre plus fittings plus labour plus wastage plus contractor profit and overheads; a typical overhead and profit allowance is 10–15 percent.

Labour constants: a plumber can install roughly 10–15 m of GI pipe per day in a domestic installation, and about 8–12 fixtures per day in a simple bathroom fit-out; use published schedule rates for the exam.

A bar bending schedule or a material take-off sheet lists item, description, unit, quantity, rate, and amount; the total is the estimated cost before taxes.

A bill of quantities uses units: metre for pipe, each for fittings and fixtures, square metre for waterproofing, and cubic metre for excavation and concrete.

Leak repair sequence: shut off the isolating valve, drain the line, cut out the damaged section, fit a coupling or a new length, remake the joint, then refill and test.

A pressure test uses a hydraulic pump with a calibrated gauge; the gauge range should be about twice the test pressure, and the reading is taken after the pipe has been filled and air expelled.

A smoke test or a water test on a drainage line checks for leaks; a smoke test is used for a completed drainage system where water cannot be filled to the top.

A leak on a copper joint is usually remade by heating the fitting, wiping away old solder, cleaning with emery cloth, applying flux, and re-soldering; never solder a wet joint.

A blocked drain is cleared with a plunger, a drain auger or snake, or a high-pressure jetting machine; a CCTV survey locates a collapsed pipe or root intrusion.

A water hammer or banging noise is cured by fitting an air chamber, a water hammer arrestor, or a pressure-reducing valve if the supply pressure is above about 3.5 bar.

A dripping tap is repaired by replacing the washer on a compression tap or the ceramic cartridge on a quarter-turn tap; the water must be shut off first.

A pump that loses prime or a tank that overflows points to a faulty float valve, a worn foot valve, or an air leak on the suction side; check the suction line joints before replacing the pump.

A quotation states scope of work, materials with brand and specification, rates, taxes, payment terms, and validity period; an estimate is an internal calculation, while a quotation is a formal offer to the client.

GST on plumbing works is charged at the applicable rate on the invoice; a registered business must show the GSTIN, invoice number, date, and HSN or SAC code on the bill.

A work order or contract should record the site address, start and completion dates, price, retention or security deposit, and a defect liability period, typically 12 months.

Statutory registrations for a plumbing enterprise include Udyam (MSME) registration, GST registration, a trade licence from the local body, and a current account in the firm's name.

Effective communication on site: confirm the work instruction in writing, report a delay or extra work before it is done, and record a joint measurement signed by the client's representative.

A safety and quality checklist for handover includes a pressure test record, a leak-free check of every fixture, correct fall on drains, and a demonstration to the client on valve locations.

Costing for profit: price = direct material + direct labour + overheads + contingency + profit margin; track wastage and idle labour to protect the margin.

Digital tools for a plumbing business: a mobile quotation template, a photo record of before and after work, and a simple accounts sheet for material, labour, and payment tracking.