Practical readiness: Kentucky Journeyman Plumber (UPC) Practice Questions

What is the correct order for making a PVC solvent-cement joint?

Preparation comes first (square cut, deburr and chamfer, clean, dry fit), then primer and cement while the primer is still wet, then a quarter turn and a hold so the pipe does not push back out.

Why is a slight bevel (chamfer) put on the outside edge of a PVC pipe end before cementing?

A square sharp edge wipes the cement out of the socket as the pipe goes in; a small chamfer keeps the cement in the joint.

After pushing a cemented PVC pipe into its fitting, why give it a quarter turn and hold it?

The quarter turn spreads the cement around the joint; holding it for about 30 seconds keeps the tapered socket from pushing the pipe back out.

How long must a new PVC DWV joint cure before the system is tested?

Cure time depends on pipe size, temperature and humidity; follow the cement manufacturer's cure chart before pressure or water testing.

When soldering a copper joint, where should the torch flame be aimed?

Heating the fitting lets capillary action pull molten solder into the joint; solder should melt on contact with the hot joint, not in the flame.

Why must the inside burr be reamed from a cut copper tube?

A tube cutter rolls a burr inward. Left in place, it makes turbulence that wears through the tube (erosion corrosion) and reduces flow.

A copper joint was overheated until the flux turned black. What is the likely result?

Burned flux and oxidized copper keep solder from wetting the surfaces. The joint should be taken apart, cleaned and redone.

When brazing copper-to-copper joints with a copper-phosphorus (BCuP) filler, what is true about flux?

Copper-phosphorus alloys are self-fluxing on copper; flux is needed when brazing copper to brass or bronze. Medical gas brazing also uses a nitrogen purge.

After cutting and threading steel pipe, what must be done to the pipe end before assembly?

Reaming removes the burr that would restrict flow and catch debris; threads are cleaned of chips and oil before joint compound goes on the male threads.

When threading steel pipe with a die, how far should the threads be cut?

Standard pipe threads are tapered; cutting until the pipe end is about flush with the die gives the right length. Over-threading leaves weak, exposed threads.

What is the correct way to install a no-hub coupling on cast iron soil pipe?

Both pipe ends must butt against the gasket's center stop; the stainless shield goes over the gasket and the bands are tightened to the maker's torque, alternating sides.

What tool is usually used to cut cast iron soil pipe on the job?

A chain-type snap cutter scores and breaks cast iron cleanly and square; abrasive saws are also used.

Use the 45-degree constant 1.414. A stack must jog 16 inches. What is the center-to-center travel between the two 45-degree fittings?

Multiply the offset by 1.414 for 45-degree fittings.

In a 45-degree offset, how does the run (setback) compare with the offset?

A 45-degree offset makes an isosceles right triangle: the run equals the offset, and the travel is 1.414 times either.

Use the 22-1/2-degree constant 2.613. A drain must offset 10 inches with 22-1/2-degree fittings. What is the travel?

Flatter fittings need a longer travel: 2.613 for 22-1/2 degrees versus 1.414 for 45 degrees.