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UPMSP High School Plumbing - Code 976 study materials
UPMSP High School Plumbing - Code 976 study resources

UPMSP High School Plumbing - Code 976 practice questions

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Question 1Workshop safety, hand tools, measuring and marking out

A plumber is about to chip a galvanised iron pipe with a cold chisel and hammer in the workshop. Which item of personal protective equipment is most important for preventing injury from flying metal chips?

  1. Safety goggles Correct answer.
  2. Leather hand gloves
  3. Ear plugs
  4. Rubber gum boots

Explanation

Chipping with a cold chisel throws small, hard metal chips at high speed, and the eyes are the part of the body most exposed to them. Safety goggles with impact-resistant lenses are therefore mandatory for this operation; gloves protect the hands but do nothing for the eyes.

Question 2Workshop safety, hand tools, measuring and marking out

A plumber must cut a copper tube of about 1 mm wall thickness with a hacksaw. Which blade gives the cleanest cut without snagging the thin wall?

  1. Coarse pitch blade of 14 teeth per inch
  2. Blade with 8 teeth per inch and heavy set
  3. Any blade, since pitch does not affect thin tube
  4. Fine pitch blade of 24 teeth per inch Correct answer.

Explanation

A hacksaw works well only when at least two or three teeth are in contact with the metal at the same time. On a 1 mm wall a coarse blade lets individual teeth drop over the edge and tear or crush the tube, so a fine pitch of about 24 teeth per inch is used.

Question 3Workshop safety, hand tools, measuring and marking out

What is the main workshop use of a try square?

  1. To scribe circles on a sheet of metal
  2. To check and mark 90° angles on a workpiece Correct answer.
  3. To cut external threads on a pipe end
  4. To measure the length of a pipe to the nearest millimetre

Explanation

A try square has a stock that sits against a true edge and a blade set at exactly 90° to it, so it both checks a corner and scribes a square line across the work. It is a checking and marking tool, not a measuring or cutting tool, so the stock must be held firmly against the datum edge while marking.

Question 4Workshop safety, hand tools, measuring and marking out

When a Stillson pipe wrench is used to tighten a pipe, how should the tool be set and pulled?

  1. The pull is towards the operator and the jaws face the direction of rotation Correct answer.
  2. The wrench is used on a polished chrome surface so that the teeth grip better
  3. The pipe is gripped only at its extreme end to obtain maximum leverage
  4. The handle is pushed away from the body with the jaws facing the operator

Explanation

The pipe wrench is designed so that the harder the handle is pulled, the deeper the teeth bite into the pipe. Pulling towards the operator with the jaws facing the direction of rotation loads the frame correctly and keeps the tool under control; pushing away can cause the jaws to slip and the knuckles to strike the work.

Question 5Workshop safety, hand tools, measuring and marking out

A vernier caliper is built so that 49 divisions of the main scale equal 50 divisions of the vernier scale, and the smallest main scale division is 1 mm. What is the least count of this caliper?

  1. 0.05 mm
  2. 0.10 mm
  3. 0.01 mm
  4. 0.02 mm Correct answer.

Explanation

One vernier division equals 49/50 = 0.98 mm, and the least count is the difference between one main scale division and one vernier division, that is 1.00 − 0.98 = 0.02 mm. This is the standard metric least count of the commonly used 50-division vernier caliper.

Question 6Workshop safety, hand tools, measuring and marking out

A hole is to be drilled in a mild steel plate. Which tool is struck with a hammer to make the conical depression that stops the drill from wandering off the marked centre?

  1. Centre punch ground to 90° Correct answer.
  2. Prick punch ground to 30°
  3. Divider
  4. Scriber

Explanation

A centre punch has its point ground to about 90° so that the shallow conical impression it produces matches the drill point and guides it into the marked position. The wider angle spreads the blow and gives a seating that survives until the drill starts cutting.

Question 7Workshop safety, hand tools, measuring and marking out

Which practice is correct when a file is used at the bench?

  1. Rub the file back and forth as quickly as possible
  2. Use the file without a handle to work faster
  3. Clean the file by striking it with a hammer
  4. Fit a sound handle and cut on the forward stroke only Correct answer.

Explanation

Files are hardened and brittle, so a file used without a handle can spear the wrist if it jams; a sound handle is a safety requirement. Metal is removed on the forward stroke, so pressure is applied then and released on the return stroke, which keeps the teeth sharp and the surface flat.

Question 8Workshop safety, hand tools, measuring and marking out

A plumber needs to measure the internal bore of a pipe and transfer that size to a steel rule. Which tool is the correct choice?

  1. Odd-leg caliper
  2. Outside caliper
  3. Hermaphrodite caliper
  4. Inside caliper Correct answer.

Explanation

Inside calipers have their measuring points turned outwards so that they can be set across a bore and then compared with a rule. The legs are adjusted until they just touch the internal surface, and the setting is transferred to the rule without changing it.

Question 9Workshop safety, hand tools, measuring and marking out

A vernier caliper has a least count of 0.02 mm. With the jaws closed, the vernier zero stands 3 divisions to the right of the main scale zero. When the pipe is measured, the main scale reads 24 mm and the 20th vernier division coincides with a main scale line. What is the true diameter?

  1. 24.40 mm
  2. 24.28 mm
  3. 24.34 mm Correct answer.
  4. 24.46 mm

Explanation

The vernier reading is 20 × 0.02 = 0.40 mm, so the observed value is 24.40 mm. Because the vernier zero lies to the right of the main scale zero when closed, the zero error is positive, 3 × 0.02 = 0.06 mm, and it must be subtracted to give 24.40 − 0.06 = 24.34 mm.

Question 10Workshop safety, hand tools, measuring and marking out

A hacksaw blade repeatedly snaps near the pin holes while a 5 mm mild steel plate is being cut. The blade was tightened as far as the frame allowed and the cut was started with a heavy, jerky stroke at a steep angle. Which correction deals with the cause?

  1. Set the tension firm but not excessive and start with light, slow strokes Correct answer.
  2. Take the plate off the vice and cut it with a cold chisel on the bench
  3. Loosen the blade until it sags and bear down hard on the first stroke
  4. Fit the finest available pitch and increase the stroke rate for the whole cut

Explanation

Over-tightening puts the blade under tension that a jerky or twisted stroke converts into a crack at the pin holes, which are the weakest points. The blade should be taut enough to give a clear ring when plucked, and the groove should be started slowly and lightly with the blade flat so that the teeth cut gradually.

Question 11Workshop safety, hand tools, measuring and marking out

In the plumbing workshop, a ball pein hammer is selected rather than a claw hammer. Which task is the ball pein designed to perform?

  1. Tightening a brass compression nut on a copper tube
  2. Cutting a thread on the outside of a steel pipe
  3. Riveting a soft iron washer over a bolt end Correct answer.
  4. Pulling nails out of a wooden packing case

Explanation

The ball pein hammer has a flat face for general striking and a rounded ball face for peening, riveting and shaping soft metal. A claw hammer is a carpenter's tool for nails, while nuts and pipe threads are handled with spanners and dies.

Question 12Workshop safety, hand tools, measuring and marking out

A steel rule has a worn and rounded end. How should the plumber measure a length of copper tube with this rule?

  1. Bend the rule so the worn end grips the tube
  2. Use the worn end because only the width is affected
  3. Place the worn end at the tube end and add 2 mm
  4. Start at the 10 mm mark and subtract 10 mm Correct answer.

Explanation

A worn rule end loses its true zero, so a sound graduation such as 10 mm is used as the reference and that amount is subtracted from the final reading. Adding an estimated 2 mm or bending the rule introduces error and damages the tool.

Question 13Workshop safety, hand tools, measuring and marking out

A new hacksaw blade is being fitted into the frame. How should the teeth point?

  1. Away from the handle, cutting on the forward stroke Correct answer.
  2. Downwards only, regardless of the frame direction
  3. Alternately inwards and outwards along the blade
  4. Towards the handle, cutting on the forward stroke

Explanation

Hacksaw teeth are set to cut on the forward stroke, so the blade is fitted with the teeth pointing away from the handle. Fitting it backwards makes the saw jump and cut slowly.

Question 14Workshop safety, hand tools, measuring and marking out

A plumber needs to scribe a line parallel to the edge of a flat steel plate and also find the centre of a round bar. Which marking-out tool has legs that can be set and has one leg bent inward for these tasks?

  1. Odd-leg caliper with one bent leg Correct answer.
  2. Vernier caliper with a sliding jaw
  3. Divider with two straight pointed legs
  4. Outside caliper with two curved legs

Explanation

The odd-leg caliper, also called a jenny caliper, has one leg bent inward so it can follow an edge while the straight leg scribes a parallel line; the same tool can find the centre of a round bar. Dividers have two straight points for circles, and outside and vernier calipers are for measuring, not scribing.

Question 15Workshop safety, hand tools, measuring and marking out

Before marking out a bright steel surface, a plumber coats it with engineer's blue. What is the purpose of this coating?

  1. To lubricate the surface before drilling
  2. To make the scribed lines easier to see Correct answer.
  3. To prevent the scriber from rusting during use
  4. To harden the surface so that it can be centre-punched

Explanation

Engineer's blue is a contrasting coating applied to bright metal so that fine scribed lines stand out clearly during marking out. It is not a lubricant, a rust preventive for the scriber, or a surface-hardening treatment.

Question 16Workshop safety, hand tools, measuring and marking out

A plumber must scribe a circle of 50 mm radius on a mild steel plate. Which tool is correct for this marking-out operation?

  1. A pair of dividers set with a rule Correct answer.
  2. A micrometer adjusted to the radius
  3. A trammel bar fitted with a steel rule
  4. An odd-leg caliper set with a rule

Explanation

A pair of dividers has two straight pointed legs and is set from a steel rule to scribe circles and arcs on metal. A trammel is used for circles too large for dividers, an odd-leg caliper is for parallel lines, and a micrometer is for measuring.

Question 17Workshop safety, hand tools, measuring and marking out

A cold chisel is being ground for cutting mild steel. What point angle should the cutting edge have?

  1. 60 degrees Correct answer.
  2. 30 degrees
  3. 90 degrees
  4. 45 degrees

Explanation

A general-purpose cold chisel for mild steel is ground to about 60 degrees, which balances a keen edge with enough strength to resist chipping. Softer metals allow a sharper angle, while harder metals need a blunter angle.

Question 18Workshop safety, hand tools, measuring and marking out

A plumber must loosen a tightly rusted hexagonal nut on a pipe support without damaging the corners. Which spanner is most suitable?

  1. Ring spanner Correct answer.
  2. Open-end spanner
  3. Adjustable wrench
  4. Pipe wrench

Explanation

A ring spanner encloses all six sides of a hexagonal nut, so the load is spread over the flats and the risk of rounding the corners is reduced. Open-end and adjustable spanners bear on fewer faces, and a pipe wrench is intended for round pipes.

Question 19Workshop safety, hand tools, measuring and marking out

A metric outside micrometer has a sleeve with 0.5 mm graduations and a thimble with 50 divisions. The sleeve shows 7.5 mm and the thimble line is on 24. What is the reading?

  1. 7.74 mm Correct answer.
  2. 7.50 mm
  3. 7.98 mm
  4. 7.524 mm

Explanation

The least count is 0.01 mm because one thimble division equals 1/50 of the 0.5 mm sleeve graduation. The thimble reading is 24 × 0.01 = 0.24 mm, which is added to the sleeve reading of 7.50 mm to give 7.74 mm.

Question 20Workshop safety, hand tools, measuring and marking out

A plumber is marking out several holes on a steel plate from a single machined edge. Why is it better to measure every hole from that edge rather than from the previous hole?

  1. It removes the need to centre-punch the hole positions
  2. It avoids the build-up of errors from one hole to the next Correct answer.
  3. It makes the plate easier to hold in the bench vice
  4. It allows the scriber to be used without engineer's blue

Explanation

Measuring every hole from the same datum edge prevents errors from accumulating, because each dimension is independent and not added to the previous hole's error. Chained dimensions can drift and put the last hole out of tolerance.

Question 21Workshop safety, hand tools, measuring and marking out

A plumber is about to cut a length of steel pipe with a hacksaw. How should the pipe be held?

  1. Trapped under the plumber's foot on the floor
  2. Clamped in a bench vice close to the cut Correct answer.
  3. Gripped with a pipe wrench and left hanging
  4. Held firmly by hand at chest height

Explanation

A hacksaw cut is controlled only when the pipe is rigidly supported. A bench vice holds the pipe close to the cut, prevents rotation and keeps the hands away from the blade.

Question 22Workshop safety, hand tools, measuring and marking out

What is the purpose of a file card in the plumbing workshop?

  1. To test whether the file is hardened
  2. To measure the pitch of the file teeth
  3. To clean metal filings from the file teeth Correct answer.
  4. To record the date the file was last used

Explanation

A file card is a stiff brush used to rake out filings packed between the teeth. A clogged file scratches the work and cuts poorly, so the card is part of routine file maintenance.

Question 23Workshop safety, hand tools, measuring and marking out

Which tool should a plumber use to check that a length of horizontal pipe is level?

  1. A centre punch
  2. An outside caliper
  3. A spirit level Correct answer.
  4. A try square

Explanation

A spirit level contains a bubble in a curved vial and shows when a surface is horizontal. A try square checks squareness, while calipers and punches do not indicate level.

Question 24Workshop safety, hand tools, measuring and marking out

Why is a surface plate used when marking out a small steel bracket?

  1. It holds the bracket steady for hacksawing
  2. It cools the bracket before marking begins
  3. It measures the mass of the bracket in kilograms
  4. It provides a flat, true reference surface Correct answer.

Explanation

A surface plate is a flat, accurately machined cast iron or granite slab. It gives the workpiece a true datum so heights and lines can be marked consistently from one reference plane.

Question 25Workshop safety, hand tools, measuring and marking out

The head of a cold chisel has mushroomed after repeated hammering. What is the correct action before further use?

  1. Continue using it with lighter hammer blows
  2. Grind the mushroomed head back to a slight taper Correct answer.
  3. Wrap the head in cloth tape to contain the metal
  4. Use the chisel only for cutting wood

Explanation

Hammering work-hardens the chisel head and raises a mushroom-shaped lip that can break off. Grinding restores a slight taper and removes the dangerous overhang before the chisel is used again.

Question 26Workshop safety, hand tools, measuring and marking out

A plumber must measure the outside diameter of a copper tube to the nearest 0.01 mm. Which instrument is most suitable?

  1. A steel rule
  2. A firm-joint inside caliper
  3. An outside micrometer Correct answer.
  4. A try square

Explanation

An outside micrometer has a calibrated screw and anvils designed to contact the outside of round work. It reads to 0.01 mm, which is finer than a steel rule and is not provided by a try square or inside caliper.

Question 27Workshop safety, hand tools, measuring and marking out

A 25 mm diameter solid mild steel bar must be cut by hand. Which hacksaw blade is most suitable?

  1. 24 teeth per inch
  2. 14 teeth per inch Correct answer.
  3. 32 teeth per inch
  4. 18 teeth per inch

Explanation

A coarse blade gives enough gullet space to clear the thick chip produced by a 25 mm solid bar. A 14 teeth-per-inch blade therefore cuts freely, while finer blades clog and overheat in this section.

Question 28Workshop safety, hand tools, measuring and marking out

What is the protractor head of a combination set used for in marking out?

  1. Checking that a surface is flat
  2. Measuring the depth of a drilled hole
  3. Measuring and marking angles Correct answer.
  4. Finding the centre of a round bar

Explanation

The protractor head carries a graduated scale and can be set to any angle for measuring or scribing. The other heads of a combination set serve squareness, depth or centre-finding, not general angle work.

Question 29Workshop safety, hand tools, measuring and marking out

A portable electric drill snatches and the steel plate begins to rotate while a 10 mm hole is being drilled. What is the safest immediate action?

  1. Press harder to force the bit through the plate
  2. Grip the rotating chuck with a gloved hand
  3. Increase the drilling speed to clear the flutes
  4. Release the trigger and let the drill stop Correct answer.

Explanation

The drill can rotate the plate with great force, so the power must be removed at once. Releasing the trigger stops the spindle and allows the plate to be clamped before drilling continues.

Question 30Workshop safety, hand tools, measuring and marking out

A spirit level is placed on a surface and the bubble is centred. When the level is turned end-for-end on the same surface, the bubble moves off centre. What does this show?

  1. The surface is perfectly horizontal
  2. The surface has a slight slope
  3. The spirit level is out of adjustment Correct answer.
  4. The bubble tube is too short for the frame

Explanation

Reversing a spirit level cancels any error in the instrument itself. If the bubble shifts, the vial is not parallel to the base, so the level needs adjustment before it can be trusted.

Question 31Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

Which tool is used to cut the external thread on the end of a GI pipe?

  1. A pipe die Correct answer.
  2. A pipe reamer
  3. A pipe tap
  4. A flaring tool

Explanation

External threads on GI pipe are cut with a pipe die held in a die stock, which is rotated and advanced along the pipe end. A pipe tap cuts internal threads inside a fitting, a reamer removes burrs after cutting, and a flaring tool forms a cone on copper tube.

Question 32Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

In a solvent-cement joint for PVC pipe, what is applied before the pipe end is pushed into the fitting socket?

  1. Epoxy adhesive spread only inside the fitting socket
  2. Primer and solvent cement applied to both surfaces Correct answer.
  3. Tarred hemp gasket packed into the socket and caulked
  4. PTFE tape wound clockwise over the pipe thread

Explanation

Solvent cement works by softening the PVC surfaces so that the pipe and socket fuse into one material. The primer cleans and prepares the surface, and cement is brushed evenly on both the pipe end and the fitting socket before assembly with a slight twist.

Question 33Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

In a lead-caulked bell-and-spigot joint on a cast iron soil pipe, what is the correct sequence of work?

  1. Solvent cement is brushed on the spigot and inside the bell
  2. A rubber ring is slipped on and the joint is crimped
  3. Lead is poured first and the hemp gasket is driven in afterwards
  4. A tarred gasket is packed in, then molten lead is caulked Correct answer.

Explanation

In the traditional bell-and-spigot joint, a tarred hemp or jute gasket is first packed into the annular space to stop the molten lead. Lead is then poured and caulked tight, forming the seal while the gasket keeps lead out of the pipe bore.

Question 34Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

A GI pipe with an external BSP thread is screwed into a fitting. Which thread feature lets the joint tighten by wedging as it is screwed home?

  1. The thread is left-hand, so it resists loosening under pressure
  2. The thread is parallel, so the flanks touch along their full length
  3. The thread is cut deeper than the fitting thread, so it bottoms on the shoulder
  4. The thread is tapered 1 in 16, so it wedges tighter as it is screwed in Correct answer.

Explanation

BSPT external threads on GI pipe are cut with a 1 in 16 taper, so the thread diameter increases towards the pipe end and wedges into the fitting as it is screwed home. A jointing compound or tape is still used, but the taper produces the tightening action.

Question 35Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

A hard-drawn copper tube must be bent to a tight radius on site. Why is the tube annealed before bending?

  1. To increase its wall thickness at the bend
  2. To make the surface suitable for solvent cement
  3. To soften the metal so it bends without cracking Correct answer.
  4. To remove scale from the bore before jointing

Explanation

Hard-drawn copper is work-hardened and tends to crack when bent tightly. Annealing by heating and then cooling recrystallises the metal and restores ductility, so the tube can be bent to the required radius without splitting.

Question 36Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

Which jointing method is normally used to connect two lengths of 110 mm HDPE water pipe laid in a trench?

  1. Solvent cement applied to the spigot and socket
  2. Lead caulking in a bell-and-spigot joint
  3. Screwed GI coupling with PTFE tape
  4. Butt fusion with a heated plate Correct answer.

Explanation

HDPE cannot be reliably joined with solvent cement because polyethylene does not dissolve, and threading weakens the pipe wall. The standard field method for large HDPE mains is butt fusion, in which the squared ends are heated on a plate and pressed together to form a homogeneous joint.

Question 37Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

Which fitting is installed in a GI pipeline so that a pump can be removed without cutting any pipe?

  1. A cap
  2. A reducer
  3. A cross
  4. A union Correct answer.

Explanation

A union has two threaded ends and a central nut, so it can be undone to dismantle a section of pipe or remove a pump without cutting or unscrewing long pipe runs. Reducers change diameter, caps close a pipe end, and crosses provide four outlets.

Question 38Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

Why is CPVC specified instead of PVC for the hot-water line of a plumbing installation?

  1. CPVC has more chlorine and a higher temperature rating Correct answer.
  2. CPVC has a lower pressure rating but a much larger bore
  3. CPVC is a metal pipe and therefore conducts heat away faster
  4. CPVC is joined by lead caulking, which withstands heat

Explanation

CPVC is chlorinated polyvinyl chloride, and the extra chlorine raises its softening point so it can carry hot water at roughly 80–90°C. PVC would soften and lose strength at such temperatures, so its hot-water service is normally limited to about 60°C.

Question 39Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

A copper tube is to be connected to a GI pipe in a water line. Why is a dielectric union used at the transition?

  1. To break electrical continuity and reduce galvanic corrosion Correct answer.
  2. To provide a threaded joint that can be undone by hand
  3. To allow the copper tube to be soldered directly to the GI pipe
  4. To increase the flow velocity at the transition

Explanation

When copper and galvanised steel are in contact in water, a galvanic cell forms and the less noble metal corrodes. A dielectric union contains an insulating sleeve or washer that breaks metal-to-metal contact, so the two materials remain electrically separated.

Question 40Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

A 25 mm GI pipe is filled with dry sand and plugged at both ends before it is heated and bent. What is the purpose of the sand?

  1. It stops the wall collapsing or flattening at the bend Correct answer.
  2. It prevents the pipe from rusting inside
  3. It speeds up cooling of the heated pipe
  4. It acts as a flux for the subsequent welded joint

Explanation

Dry sand packed inside the pipe supports the wall during hot bending, so the cross-section stays round instead of flattening or kinking at the bend. The plugs keep the sand in place, and the sand is emptied out after the pipe has cooled.

Question 41Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

On a PVC water pipe, what does the marking “Schedule 40” indicate?

  1. The length of each pipe section supplied
  2. The nominal wall thickness for that pipe size Correct answer.
  3. The outside diameter of the pipe in millimetres
  4. The maximum water temperature the pipe can carry

Explanation

Schedule is a wall-thickness series: for a given nominal pipe size, a higher schedule number means a thicker wall. It does not state the outside diameter, the temperature rating, or the supplied length. The pressure rating depends on wall thickness and material, not on the schedule number alone.

Question 42Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

Which fitting is used in a straight pipeline to join two pipes of different nominal diameters?

  1. A cap
  2. A reducer Correct answer.
  3. A cross
  4. A 90° elbow

Explanation

A reducer is placed in a straight run and has one socket or end sized for the larger pipe and one for the smaller pipe. An elbow changes direction, a cap closes a pipe end, and a cross provides two branch outlets. None of those fittings is intended primarily to change diameter in a straight line.

Question 43Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

After cutting a GI pipe with a hacksaw, why is the end reamed before threading?

  1. To remove the internal burr and restore the full bore Correct answer.
  2. To soften the pipe end for bending
  3. To increase the outside diameter for the die head
  4. To remove the galvanized coating from the thread area

Explanation

Cutting leaves a sharp internal burr that reduces the bore and can disturb flow or catch debris. Reaming removes that burr and restores a smooth internal edge before the die is applied. Reaming does not enlarge the outside diameter, deliberately strip zinc, or soften the steel.

Question 44Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

Why is cutting oil applied to the pipe end and die head while threading a GI pipe?

  1. To harden the newly cut thread
  2. To lubricate and cool the die so a clean thread is cut Correct answer.
  3. To expand the pipe so the thread is deeper
  4. To wash the zinc coating away so the die cuts faster

Explanation

Threading generates heat and friction between the die and the steel. Cutting oil lubricates the cutting edges and carries heat away, which helps produce a clean thread and prolongs die life. It is not used to harden the thread, expand the pipe, or intentionally remove the zinc coating.

Question 45Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

A GI pipe has been cut and threaded on site. What should be applied to the bare steel at the cut end and on the thread before assembly?

  1. Graphite grease only
  2. A zinc-rich cold-galvanizing compound Correct answer.
  3. A layer of bitumen inside the pipe
  4. A coat of PVC solvent cement

Explanation

Cutting and threading remove the zinc layer and expose bare steel, which corrodes quickly. A zinc-rich repair compound restores sacrificial protection at these damaged areas. PVC solvent cement does not bond to steel, bitumen inside a water pipe is unsuitable, and grease alone does not replace the galvanized coating.

Question 46Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

In a soldered copper capillary joint, what draws the molten solder into the gap between the tube and the fitting?

  1. The pressure of the gas torch
  2. The thermal expansion of the copper
  3. Capillary action Correct answer.
  4. Gravity acting on the solder

Explanation

A properly cleaned and fluxed copper tube and fitting form a narrow annular gap. When the joint reaches soldering temperature, capillary action pulls molten solder into that gap and distributes it around the joint. Gravity, torch pressure, and thermal expansion are not the mechanisms that fill a capillary joint.

Question 47Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

Which joint is commonly used to connect plain-end cast iron water mains and allows slight angular deflection after assembly?

  1. Solvent-cement socket joint
  2. Butt-fusion joint
  3. Lead-caulked bell-and-spigot joint
  4. Mechanical joint with a rubber gasket and bolted gland Correct answer.

Explanation

A mechanical joint uses a rubber gasket compressed by a bolted gland, and its flexibility permits small angular deflection and movement. Lead-caulked bell-and-spigot joints are rigid, solvent cement is for PVC, and butt fusion is for thermoplastics such as HDPE.

Question 48Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

A GI pipe is marked “25 mm nominal bore”. What does the 25 mm refer to?

  1. A nominal size close to the internal diameter, not an exact dimension Correct answer.
  2. The length of the threaded end
  3. The exact inside diameter of the pipe
  4. The exact outside diameter of the pipe

Explanation

Nominal bore is a conventional size designation, not a precise measurement of either inside or outside diameter. The actual inside diameter varies with wall thickness, while the outside diameter is standardized so that threads and fittings match. Therefore 25 mm nominal bore is only approximately related to the internal diameter.

Question 49Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

An HDPE pipe is marked SDR 11. What does this mean?

  1. The pipe is rated for 11 bar working pressure
  2. The outside diameter is 11 times the wall thickness Correct answer.
  3. The wall thickness is 11 mm
  4. The pipe contains 11% recycled material

Explanation

SDR stands for standard dimension ratio, calculated as outside diameter divided by wall thickness. An SDR 11 pipe therefore has an outside diameter 11 times its wall thickness. A lower SDR indicates a thicker wall and generally a higher pressure rating; the number is not a pressure rating, a wall thickness in millimetres, or a recycled-content figure.

Question 50Pipe materials and fittings (GI, CI, PVC, CPVC, copper, HDPE) - cutting, bending, threading, jointing

In a compression fitting used on copper tube, what is the function of the olive?

  1. It filters debris from the water passing through the joint
  2. It is compressed between the tube and fitting body to form the seal Correct answer.
  3. It converts the copper tube to a solvent-weld socket
  4. It locks the nut so the joint cannot be opened

Explanation

When the compression nut is tightened, the olive is crushed against the copper tube and the fitting body. This deformation creates a mechanical grip and a sealed joint. The olive is not a filter, does not permanently lock the nut, and does not convert the fitting to a solvent-weld connection.