I85PREP
⌘ K
NITC Journey Level Plumber study materials
NITC Journey Level Plumber study resources

NITC Journey Level Plumber practice questions

One question at a time. Build your NITC Journey Level Plumber understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1General Plumbing Knowledge and Safety

Under the Uniform Plumbing Code, what is the minimum size of a building sewer serving a single-family dwelling?

  1. 1.5 inch
  2. 4 inch
  3. 3 inch Correct answer.
  4. 2 inch

Explanation

The UPC requires a building sewer to be not less than 3 inches in nominal diameter for a dwelling unit. A 2-inch line is acceptable only for certain fixture drains or special waste, not for the main building sewer.

Question 2General Plumbing Knowledge and Safety

What is the primary purpose of a plumbing trap in a drainage system?

  1. To increase drain velocity
  2. To filter debris from wastewater
  3. To maintain a water seal that blocks sewer gas Correct answer.
  4. To reduce noise from draining water

Explanation

A trap holds a water seal that prevents sewer gases and odors from entering the building while allowing wastewater to pass. The depth of the seal is what provides the barrier, so trap design and venting must protect that seal from siphonage.

Question 3General Plumbing Knowledge and Safety

A plumber is installing a water heater and must protect against excessive temperature and pressure. Which combination of devices satisfies standard code intent?

  1. A shutoff valve and an expansion tank only
  2. A check valve on the cold inlet and a vacuum breaker
  3. A pressure gauge and a drain valve
  4. A temperature and pressure relief valve piped to a safe discharge location Correct answer.

Explanation

A temperature and pressure relief valve (T&P valve) opens when either temperature or pressure exceeds safe limits, and its discharge must be piped to a safe point of disposal. This single device addresses both hazards on a storage water heater.

Question 4General Plumbing Knowledge and Safety

What does the term 'fixture unit' represent in plumbing sizing?

  1. The number of fixtures on a branch
  2. The rate of flow a fixture demands relative to a standard Correct answer.
  3. The physical weight of a fixture
  4. The cost of installing a fixture

Explanation

A fixture unit is a dimensionless measure of the probable rate of flow a fixture demands, used to size drains and water supply pipes. It allows different fixtures to be added together for sizing calculations.

Question 5General Plumbing Knowledge and Safety

Before entering a below-grade sewer pit to make a repair, what is the most important safety step?

  1. Notify the building owner
  2. Wear steel-toed boots
  3. Bring a flashlight
  4. Test the atmosphere for oxygen and hazardous gases and provide ventilation Correct answer.

Explanation

Confined spaces such as sewer pits can contain oxygen-deficient or toxic atmospheres, so atmospheric testing and ventilation must precede entry. Testing confirms the space is safe and is the key safeguard against asphyxiation.

Question 6General Plumbing Knowledge and Safety

What is the minimum air gap required between a fixture outlet and the flood-level rim when using an air gap as a backflow preventer?

  1. No gap is required
  2. One inch or twice the effective opening, whichever is greater Correct answer.
  3. One-quarter inch
  4. One-half the pipe diameter

Explanation

An air gap must be at least twice the diameter of the effective opening of the outlet and never less than one inch above the flood-level rim. This physical separation is the most reliable form of backflow protection.

Question 7General Plumbing Knowledge and Safety

A horizontal drain line is installed with a slope of 1/4 inch per foot. Over a 12-foot run, what is the total fall?

  1. 4 inches
  2. 2 inches
  3. 1 inch
  4. 3 inches Correct answer.

Explanation

Slope times run gives total fall: 0.25 inch per foot multiplied by 12 feet equals 3 inches. Maintaining correct slope ensures gravity drainage and helps prevent solids from settling.

Question 8General Plumbing Knowledge and Safety

A plumber must size a vent for a fixture drain. What is the primary purpose of the venting system?

  1. To filter air entering the building
  2. To supply hot water
  3. To carry wastewater away
  4. To equalize pressure and protect trap seals Correct answer.

Explanation

Vents admit air to the drainage system, equalizing pressure so trap seals are not siphoned or blown out. Proper venting also allows sewer gases to escape safely above the roof.

Question 9General Plumbing Knowledge and Safety

When soldering copper tubing, what is the purpose of applying flux?

  1. To seal the pipe threads
  2. To cool the joint
  3. To remove oxidation and help solder flow Correct answer.
  4. To thicken the solder

Explanation

Flux cleans the copper surface and prevents oxidation during heating, allowing solder to flow into the joint by capillary action. Without flux, the solder may not bond properly and the joint can leak.

Question 10General Plumbing Knowledge and Safety

A water closet is installed in a public restroom and the plumber must set the tank water level. What is the typical fill level relative to the overflow tube?

  1. About one inch below the top of the overflow tube Correct answer.
  2. At the bottom of the tank
  3. Above the overflow tube
  4. Level with the top of the tank

Explanation

The fill valve should be adjusted so the water level sits roughly an inch below the overflow tube, which prevents continuous spillover into the bowl. Setting it too high wastes water; too low reduces flush volume.

Question 11General Plumbing Knowledge and Safety

What is the required minimum diameter of a water service pipe for a single-family dwelling under common code provisions?

  1. 1 inch
  2. 3/4 inch Correct answer.
  3. 1/2 inch
  4. 1-1/4 inch

Explanation

The minimum water service pipe size for a single-family dwelling is generally 3/4 inch. Smaller sizes may not deliver adequate pressure and volume to the fixtures.

Question 12General Plumbing Knowledge and Safety

A plumber is connecting a dishwasher drain to a sink drain. Which device provides an air break to prevent backflow of wastewater into the dishwasher?

  1. A pressure reducing valve
  2. An approved dishwasher drain air gap Correct answer.
  3. A cleanout
  4. A check valve only

Explanation

An approved dishwasher drain air gap provides physical air separation between the appliance's discharge and the receiving drainage system, preventing wastewater from backing into the dishwasher. A water-supply vacuum breaker protects against supply-side backsiphonage and is not a substitute for this drain separation.

Question 13General Plumbing Knowledge and Safety

What is the purpose of a cleanout in a drainage system?

  1. To vent the system
  2. To support the pipe
  3. To measure flow
  4. To provide access for clearing blockages Correct answer.

Explanation

Cleanouts provide access points so plumbers can rod or jet a drain line to remove blockages. They must be installed at specified locations such as the base of stacks and ends of building sewers.

Question 14General Plumbing Knowledge and Safety

A plumber is installing a shower valve and must limit the maximum delivered water temperature to prevent scalding. Which device accomplishes this?

  1. A check valve
  2. A tempering or mixing valve Correct answer.
  3. A backflow preventer
  4. A pressure reducing valve

Explanation

A tempering or thermostatic mixing valve blends hot and cold water to limit the maximum outlet temperature, protecting users from scalding. Pressure reducing valves control supply pressure, not temperature.

Question 15General Plumbing Knowledge and Safety

A plumber is installing a gas-fired water heater in a garage. What is the minimum required height for the ignition source above the floor?

  1. 6 inches
  2. 24 inches
  3. 18 inches Correct answer.
  4. 12 inches

Explanation

Water heaters installed in garages must have their ignition sources elevated at least 18 inches above the floor to reduce the risk of igniting flammable vapors. This is a common requirement in gas appliance installation codes.

Question 16General Plumbing Knowledge and Safety

A plumber is sizing a water supply system and must account for peak demand. What does the term 'demand' refer to in water supply sizing?

  1. The static pressure at the meter
  2. The total number of fixtures
  3. The diameter of the main
  4. The probable simultaneous flow required by fixtures Correct answer.

Explanation

Demand is the probable simultaneous flow that fixtures will require during peak use, estimated using fixture units and diversity. It is not the simple sum of all fixture flows because not all fixtures run at once.

Question 17General Plumbing Knowledge and Safety

A plumber is testing a new DWV system with water. What is the purpose of a hydrostatic test?

  1. To verify the system holds pressure without leaks Correct answer.
  2. To check vent sizing
  3. To check water quality
  4. To measure flow rate

Explanation

A hydrostatic test fills the system with water and pressurizes it to confirm joints and connections do not leak. It verifies the integrity of the installed piping before the system is placed in service.

Question 18General Plumbing Knowledge and Safety

A plumber is installing a grease interceptor for a restaurant. Where should the interceptor be located for proper function?

  1. Inside the kitchen above the floor
  2. On the roof
  3. At the end of the vent stack
  4. Outside the building downstream of the fixtures it serves Correct answer.

Explanation

A grease interceptor is typically installed outside the building, downstream of the fixtures it serves, so fats, oils, and grease cool and separate before entering the sewer. Proper location and access allow periodic cleaning.

Question 19General Plumbing Knowledge and Safety

A plumber observes that a fixture trap loses its seal after a nearby fixture drains. What is the most likely cause?

  1. The fixture is too large
  2. The vent is clogged or improperly sized, causing siphonage Correct answer.
  3. The trap is too shallow
  4. The water pressure is too high

Explanation

Loss of trap seal after a nearby fixture drains usually indicates siphonage caused by inadequate venting, such as a clogged or undersized vent. The vent equalizes pressure so the trap seal is not pulled out.

Question 20General Plumbing Knowledge and Safety

A plumber is comparing two venting arrangements for a bathroom group. Which condition would require a re-vent rather than a common vent?

  1. Fixtures with adequate trap arm length
  2. A fixture drain that cannot be vented within the allowed distance from the trap Correct answer.
  3. Fixtures on the same floor connected to a common vent
  4. Fixtures that share a horizontal branch

Explanation

When a trap arm exceeds the maximum developed length allowed for its size, it must be re-vented to protect the trap seal. Common venting applies only when the fixtures and distances meet code limits.

Question 21Piping, Fittings, and Pipe Joining

Which pipe material is joined by solvent cementing?

  1. Type L copper
  2. PVC Correct answer.
  3. Ductile iron
  4. Schedule 40 black steel

Explanation

Solvent cementing works by softening the surfaces of thermoplastic pipe and fitting so they fuse into one continuous wall. PVC and CPVC are the common plumbing thermoplastics joined this way, using primer plus cement matched to the pipe diameter and material. Metals such as steel, copper, and ductile iron cannot be solvent cemented.

Question 22Piping, Fittings, and Pipe Joining

In a nominal pipe size designation such as 1 inch Schedule 40 steel pipe, what does the schedule number represent?

  1. The thread pitch per inch
  2. The maximum working pressure in psi
  3. The wall thickness relative to the nominal size Correct answer.
  4. The outside diameter in inches

Explanation

Schedule numbers describe wall thickness for a given nominal pipe size; a higher schedule means a thicker wall. Outside diameter stays constant for a given NPS regardless of schedule, which is why fittings of the same nominal size interchange. Pressure rating is a consequence of wall thickness, not the definition of the schedule.

Question 23Piping, Fittings, and Pipe Joining

What is the purpose of applying primer before solvent cement on PVC pipe?

  1. To lubricate the joint so the pipe slides in easily
  2. To soften and clean the pipe and fitting surfaces so the cement can fuse them Correct answer.
  3. To speed the cure by cooling the plastic
  4. To seal the joint so no cement is needed

Explanation

Primer is a solvent that cleans and softens the mating surfaces, allowing the cement to dissolve and fuse the plastic into a homogeneous joint. Skipping primer on PVC reduces bond strength, especially on larger diameters. Primer is not a lubricant, a sealant, or a cooling agent.

Question 24Piping, Fittings, and Pipe Joining

Which fitting is used to connect two pipes of different nominal sizes in a straight run?

  1. Reducer Correct answer.
  2. Coupling
  3. Street elbow
  4. Union

Explanation

A reducer transitions between two different nominal pipe sizes in a straight line, either as a bell reducer or a reducing coupling. A coupling joins same-size pipe, a union allows disassembly, and a street elbow changes direction with one male end.

Question 25Piping, Fittings, and Pipe Joining

A copper tube is marked "Type L." What does this designation indicate?

  1. A thin-wall tube intended only for drainage
  2. A thick-wall tube used for underground gas service
  3. A tube with a factory-applied plastic coating
  4. A medium-wall tube commonly used for interior water lines Correct answer.

Explanation

Copper tube types are graded by wall thickness: Type K is heaviest, Type L is medium, and Type M is light. Type L is widely used for interior domestic water piping and is accepted in many buried applications. Type K is the heavy-wall choice for underground and service lines, and Type M is the lightest.

Question 26Piping, Fittings, and Pipe Joining

Which joining method is standard for connecting threaded galvanized steel water pipe?

  1. Solvent welding
  2. Brazing with silver alloy
  3. Press fitting with elastomer seal
  4. Threading with tapered pipe threads and fittings Correct answer.

Explanation

Galvanized steel water pipe is joined with tapered pipe threads cut to the NPT standard, sealed with thread compound or tape, and assembled with threaded fittings. The taper produces an interference fit that seals as the joint is tightened. Solvent welding applies to thermoplastics, and brazing is a copper method.

Question 27Piping, Fittings, and Pipe Joining

What is the primary reason for deburring the inside of a cut plastic or copper pipe end before assembly?

  1. To expose a clean surface for thread cutting
  2. To create a chamfer that holds solvent cement
  3. To prevent turbulence and erosion and to allow full insertion of the pipe Correct answer.
  4. To remove material so the pipe fits deeper into the fitting

Explanation

A burr left on the inside of a cut end creates turbulence, noise, and erosion of the pipe wall, and on plastic pipe it can also scrape cement or damage the socket. Reaming or deburring also allows the pipe to seat fully in the fitting. It is not done to create clearance or to prepare for threading.

Question 28Piping, Fittings, and Pipe Joining

Which hanger is designed to support a horizontal pipe while allowing it to move axially as it expands and contracts?

  1. Riser clamp
  2. Roller hanger Correct answer.
  3. Clevis hanger with a fixed bolt
  4. Anchor

Explanation

A roller hanger supports the pipe's weight while permitting longitudinal movement, which is needed where thermal expansion must be guided rather than restrained. A fixed clevis hanger grips the pipe and resists axial movement, and an anchor restrains movement entirely. Riser clamps carry vertical pipe at floor penetrations.

Question 29Piping, Fittings, and Pipe Joining

A plumber is joining 2 inch PVC drain pipe in cold weather. Which practice best supports a sound solvent-cemented joint?

  1. Assemble the joint and then apply cement around the outside
  2. Apply cement and assemble immediately with a quick quarter turn, then hold Correct answer.
  3. Use primer only, since cold slows the cure
  4. Coat only the fitting socket and push the pipe in

Explanation

Cement is applied to both the pipe end and the fitting socket, and the parts are assembled promptly with a slight quarter turn to spread the cement evenly. The joint is then held briefly to resist push-out while the cement sets. Cement must never be relied on from the outside or omitted.

Question 30Piping, Fittings, and Pipe Joining

When making a soldered copper joint, what is the purpose of applying flux?

  1. To chemically clean the surfaces and prevent oxidation so solder can flow Correct answer.
  2. To fill the gap in place of solder
  3. To act as a permanent sealant after the joint cools
  4. To raise the melting point of the solder

Explanation

Flux removes oxides and shields the heated copper from further oxidation so capillary action can draw solder into the joint clearance. Without flux, solder beads on the surface instead of flowing into the fitting. Flux does not change the solder's melting point or substitute for solder fill.

Question 31Piping, Fittings, and Pipe Joining

Which condition most commonly causes a failed soldered copper joint that leaks under pressure?

  1. Solder applied to a joint cleaned and fluxed immediately before heating
  2. Solder applied with the flame moved continuously around the fitting
  3. Solder applied until a ring appears at the fitting mouth
  4. Solder applied to an overheated, oxidized joint Correct answer.

Explanation

Overheating burns the flux and oxidizes the copper, so the solder cannot wet or flow into the joint, leaving voids that leak. Proper technique uses a soft, bushy flame, even heating, and solder applied only when the joint reaches temperature. A visible ring of solder at the mouth indicates adequate fill.

Question 32Piping, Fittings, and Pipe Joining

A plumber must join copper tube to a threaded steel pipe in a domestic water line. Which fitting arrangement best limits galvanic corrosion at the connection?

  1. A steel coupling threaded onto the copper tube
  2. Direct threading of the copper tube into the steel fitting
  3. A PVC nipple between the copper and steel
  4. A brass or dielectric union between the dissimilar metals Correct answer.

Explanation

Copper and steel are dissimilar metals, and direct contact in the presence of water creates a galvanic cell that corrodes the steel. A dielectric union or a brass adapter separates the metals and interrupts the conductive path. Direct threading of copper into steel accelerates corrosion at the joint.

Question 33Piping, Fittings, and Pipe Joining

Which pipe thread form is standard for plumbing joints on steel pipe?

  1. Tapered thread that seals by interference as it is tightened Correct answer.
  2. Buttress thread
  3. Straight thread with an O-ring
  4. Square thread

Explanation

Plumbing steel pipe uses tapered pipe threads, commonly NPT, where the diameter decreases along the thread so the joint tightens into an interference fit. Thread compound or tape fills the remaining spiral clearance. Straight threads rely on a gasket or O-ring and are used for other applications.

Question 34Piping, Fittings, and Pipe Joining

A plumber is installing a press-fit copper joint. Which step is essential before pressing?

  1. Thread the fitting onto the pipe
  2. Heat the fitting with a torch to soften the seal
  3. Verify the pipe is fully inserted to the depth mark and the fitting is aligned Correct answer.
  4. Apply flux to the fitting

Explanation

Press fittings rely on an elastomer seal compressed by the press tool, so the pipe must be fully inserted to the marked depth and the fitting aligned before pressing. Pressing a partly inserted pipe leaves an incomplete seal and a weak joint. Flux and heat are not used with press fittings.

Question 35Piping, Fittings, and Pipe Joining

What is the main function of a dielectric union in a plumbing system?

  1. To reduce the pipe size at a connection
  2. To absorb thermal expansion in a long run
  3. To allow a pipe run to be taken apart for service
  4. To electrically isolate two piping sections and prevent galvanic corrosion Correct answer.

Explanation

A dielectric union uses an insulating sleeve or gasket to break electrical continuity between two piping sections, which prevents galvanic current between dissimilar metals. It also happens to be a union that can be disassembled, but isolation is its defining purpose. Size reduction and expansion absorption are handled by other fittings.

Question 36Piping, Fittings, and Pipe Joining

A drain line must change direction by 90 degrees in a horizontal run while keeping the flow turning smoothly. Which fitting best serves this purpose?

  1. Vent tee
  2. Test tee
  3. Long-sweep quarter bend Correct answer.
  4. Sanitary tee

Explanation

A long-sweep quarter bend has a generous radius that guides flow smoothly through a 90 degree turn in a horizontal drain, reducing the chance of solids settling. A sanitary tee is intended for a vertical branch into a horizontal drain, and a vent tee is for venting. A test tee provides a cleanout for testing.

Question 37Piping, Fittings, and Pipe Joining

Which factor most directly determines the minimum support spacing for a horizontal run of plastic drain pipe?

  1. The water pressure at the fixture
  2. The pipe diameter and the manufacturer's published spacing tables Correct answer.
  3. The color of the pipe
  4. The number of fittings in the run

Explanation

Support spacing for plastic drain pipe depends on pipe diameter, temperature, and the manufacturer's published tables, which account for the material's stiffness and expansion behavior. Larger diameters generally require closer spacing. Color, fitting count, and fixture pressure do not set the spacing.

Question 38Piping, Fittings, and Pipe Joining

A plumber is assembling a large-diameter PVC joint and finds the pipe will not seat fully in the fitting socket. What is the most likely cause?

  1. The pipe was cut square but not deburred or chamfered, and interference prevents full insertion Correct answer.
  2. The primer was applied with a natural-bristle brush
  3. The pipe end was not chamfered and the socket is full of cement
  4. The cement was applied too thinly

Explanation

A square cut with a burr or without a slight chamfer can catch on the socket wall and prevent full insertion, leaving too little bond area. The pipe end should be chamfered and deburred and the dry fit checked before cementing. Cement thickness and brush type do not prevent seating.

Question 39Piping, Fittings, and Pipe Joining

What is the purpose of a mechanical joint on ductile iron water main?

  1. To seal and restrain the joint using a gasket compressed by a follower gland Correct answer.
  2. To solvent-weld the pipe to a fitting
  3. To fuse the pipe by melting the iron
  4. To provide a threaded connection to copper

Explanation

A mechanical joint uses an elastomer gasket seated in the bell, compressed by a follower gland and bolts to seal against the spigot end. It accommodates some deflection and is common on buried water mains. It does not fuse metal, weld plastic, or adapt to copper threads.

Question 40Piping, Fittings, and Pipe Joining

A plumber must connect a new copper water line to an existing galvanized steel line in a basement. Which approach best limits corrosion at the transition?

  1. Install a brass or dielectric transition fitting between the metals Correct answer.
  2. Thread the copper directly into the steel tee
  3. Use a lead-free solder bridge between the pipes
  4. Wrap the joint with tape and connect directly

Explanation

Copper and galvanized steel form a galvanic couple when joined directly in a wet system, and the steel at the joint corrodes preferentially. A brass or dielectric transition fitting separates the metals and interrupts the current path. Tape or solder does not stop galvanic action.

Question 41Piping, Fittings, and Pipe Joining

A soldered copper joint on a hot water line fails repeatedly at the same location. Which cause is most consistent with a joint that shows a porous, grainy appearance with dark oxidation inside?

  1. The solder was applied with the flame directed away from the fitting
  2. The joint was overheated and the flux burned before solder was applied Correct answer.
  3. The tube was cut with a tubing cutter and reamed
  4. The fitting was cleaned with an abrasive cloth

Explanation

Overheating burns the flux and oxidizes the copper, so solder cannot wet the surface and the joint fills with voids and inclusions, giving a grainy, oxidized appearance. The remedy is a softer flame, even heating, and solder applied as soon as the joint reaches temperature. Proper cutting, reaming, and cleaning are correct practices.

Question 42Piping, Fittings, and Pipe Joining

A long straight run of CPVC hot water pipe is installed between two fixed anchors with no allowance for expansion. What is the most likely result?

  1. The pipe will contract and pull the anchors loose
  2. The anchors will absorb the movement through their threads
  3. The pipe will expand against the anchors and may bow, crack, or pull joints apart Correct answer.
  4. The pipe will absorb the movement without effect because CPVC does not expand

Explanation

Thermoplastic pipe expands significantly with temperature rise, and restraining both ends of a straight run without an offset, loop, or expansion joint concentrates stress in the pipe and joints. The run can bow, crack, or fail at cemented joints. Anchors do not absorb axial movement.

Question 43Piping, Fittings, and Pipe Joining

A plumber is joining 4 inch PVC sewer pipe in a trench. Which sequence best follows accepted solvent-cementing practice?

  1. Cut square, deburr and chamfer, dry fit, clean, prime both surfaces, apply cement to both, assemble with a quarter turn, hold, then wipe excess Correct answer.
  2. Cut square, apply cement to both surfaces, assemble, and test under pressure before the joint sets
  3. Cut square, prime the pipe only, apply cement to the fitting only, and assemble without turning
  4. Cut square, apply cement to the pipe only, assemble, and backfill immediately

Explanation

Accepted practice is a square cut, deburring and chamfering, a dry fit to check depth, cleaning, priming both surfaces, cement on both surfaces, prompt assembly with a quarter turn, a brief hold, and wiping the excess bead. Pressure testing is done after the joint has cured, not while it is setting.

Question 44Piping, Fittings, and Pipe Joining

A threaded steel joint leaks at the threads despite being tightened firmly. Which cause is most consistent with a leak that appears along the thread spiral rather than at the pipe wall?

  1. The pipe was reamed after cutting
  2. Too little or damaged thread sealant left the spiral clearance unsealed Correct answer.
  3. The pipe was cut too long for the run
  4. The fitting was made of brass rather than steel

Explanation

Tapered pipe threads seal by interference, but a spiral clearance remains that must be filled with thread compound or tape. Insufficient, damaged, or improperly applied sealant leaves a leak path along the thread spiral. Reaming and correct cut length do not create this leak pattern.

Question 45Piping, Fittings, and Pipe Joining

Which statement correctly describes the relationship between nominal pipe size and actual dimensions for steel pipe?

  1. Nominal size equals the inside diameter for all schedules
  2. Nominal size is a designation; outside diameter is fixed per size while inside diameter varies with schedule Correct answer.
  3. Nominal size equals the outside diameter for all sizes
  4. Nominal size equals the outside diameter only for sizes above 12 inches

Explanation

Nominal pipe size is a standardized label, not a direct dimension. For a given NPS the outside diameter is fixed so fittings interchange, while the inside diameter changes with wall thickness or schedule. This is why a 2 inch Schedule 40 and a 2 inch Schedule 80 pipe have different bores but the same outside diameter.

Question 46Piping, Fittings, and Pipe Joining

A plumber is selecting fittings for a drainage system and wants a fitting that provides a smooth, sweeping change of direction rather than a sharp turn. Which fitting type is intended for this purpose?

  1. Long-sweep elbow Correct answer.
  2. Street 45
  3. Test tee
  4. Sanitary tee

Explanation

Long-sweep elbows have an extended radius that lets flow change direction with less turbulence and less chance of solids settling. This is why they are required in drainage where the flow turns from horizontal to vertical or through tight bends.

Question 47Piping, Fittings, and Pipe Joining

When solvent-cementing PVC pipe, the plumber applies cement to the pipe end and the fitting socket and then pushes the pipe home. Why must the pipe be given a quarter turn and held in place briefly after insertion?

  1. To cool the cement so it cures faster
  2. To squeeze out excess cement so the socket stays clean
  3. To line up the manufacturer's print on the pipe with the fitting
  4. To spread cement evenly and allow the joint to set before it can push apart Correct answer.

Explanation

Solvent cement softens both surfaces and the joint can back out under the force of insertion if it is not held. A quarter turn distributes cement around the full circumference and the brief hold lets the joint grab and set in the fully seated position.

Question 48Piping, Fittings, and Pipe Joining

A plumber is brazing copper refrigerant lines and must decide how much clearance to leave between the tube and the fitting cup for the filler metal to draw in. Which condition best allows capillary action to pull the brazing filler into the joint?

  1. An interference fit that requires driving the tube in
  2. A loose fit with visible gaps at the cup
  3. A slightly oversized cup packed with flux
  4. A close, uniform clearance between tube and fitting Correct answer.

Explanation

Capillary attraction depends on a small, uniform gap so the molten filler is drawn along the entire overlap by surface tension. Clearances that are too large let the filler run through, while an interference fit prevents filler from entering at all.

Question 49Piping, Fittings, and Pipe Joining

A plumber is making up a threaded joint on black steel gas piping and wants to control how far the pipe engages the fitting. Which practice best supports a sound threaded joint?

  1. Apply thread sealant to the male threads, leaving the first two threads bare Correct answer.
  2. Tighten until the pipe end contacts the fitting stop
  3. Wrap the entire pipe end including the bare threads with tape
  4. Thread the pipe so the threads bottom out tightly in the fitting

Explanation

Sealant belongs on the male threads, with the first couple of threads left bare so the sealant is not pushed into the pipe bore. Engagement is controlled by proper threading and fitting makeup, not by forcing the pipe against a stop.

Question 50Piping, Fittings, and Pipe Joining

A plumber is installing a flanged joint on a large-diameter steel water main and notices the two flange faces are not parallel. Which condition most directly explains why the joint may leak even after the bolts are fully tightened?

  1. The bolts were tightened in a crossing pattern
  2. The gasket was lubricated before installation
  3. The pipe was cut with a wheel cutter rather than a saw
  4. The flanges are misaligned, so the gasket cannot seat evenly Correct answer.

Explanation

A gasket seals only when it is compressed uniformly between parallel flange faces. Angular or parallel misalignment concentrates the bolt load on one area, leaving part of the gasket under-compressed and prone to leakage under pressure.