Plumbing and Pipefitting - Ch3

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CHAPTER 3

BASIC PLUMBING REPAIRS AND MAINTENANCE

This chapter covers step-by-step repair procedures for leaky pipes, frozen pipes, andfixture and drain-line stoppages. (Repairing leaky valves and faucets is covered in Chapter7.) Preventive maintenance, covered in this chapter, can help reduce corrosion and scale,which can cause leaky pipes and a sharply reduced water flow, respectively.

3-1. Leaks.

a. Pipe Corrosion. Corrosion is the thinning of the wall of a metal pipe, caused byelectrolysis (chemical breakdown by electric current), rust, or acidity of the water. Galvaniccorrosion (resulting from a direct current of electricity) occurs in a plumbing installationsystem that includes two different kinds of metal pipe, such as galvanized pipe and copperpipe.

The first sign of corrosion may be a leak in the system occurring within the walls or

floors of the building. Water may show up several levels below the leak. To help locatethe leak, use a strip of wood as a resonator to detect and magnify the sound of the leak. Placeone end of the wood against your car and other end against the pipe and trace the sound.Sound will increase as you get closer to the leak.

(1) Repairing Corrosion. After locating the leak, cut out and replace the corroded pipeas follows:

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(2) Reducing Corrosion. The two ways to reduce corrosion in in plumbing systems are

Dielectric unions. Dielectric unions placed in the cold-and hot-water takeoffsfrom the tank can control gallvanic corrosion of water tanks. A dielectric unionhas a fiber washer, which insulates the tank from the rest of the plumbinginstallations, preventing the flow of current from the tank to the system.

Magnesium rods. Magnesium rods are used in some water healers, such as thegas-operated type, to protect against rust and corrosion. They act as elctrolyticcells in which the magnesium particles go into solution, flow through the water,and are deposited on the metal to be protected. The electrolytic action(electrolysis) dissolves the rods. Eighteen months is considered the maximumlife of the rods; then they must be replaced.

b. Valve Repair. All valves should be checked regularly for leaks. Most leaks are fromleaky washers or bonnets. Refer to Chapter 7, paragraph 7-2 (pages 7-3 through 7-6) forrepairs.

c. Faucet Repair. Refer to Chapter 7, paragraph 7-5 (pages 7-9 through 7-15) for faucetrepairs.

d. Temporary Repairs for Small Leaks. Small leaks in a system require temporary oremergency repairs. Before making any repairs, shut off the water and relieve the pressurefrom the system. Pipes can be temporarily repaired with one of the following methods:

3-2. Frozen Pipes. Water supply lines may freeze when exposed to temperatures below32 F (0C). Outside pipes must be buried below the frost line. In northern zones, this is 4feet or more. If building temperature falls below freezing, inside pipes may also freeze,causing the pipe to break at the weakest point. Use the procedures in Figure 3-1 for thawingabove- and below-ground pipes.

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3-3. Scale. Scale can sharply reduce the flow of water to fixtures. Scale is a result of hardwater. Hard water contains a large amount of calcium and magnesium compounds whichprevent soap from lathering. This forms a scum, which slows down the flow of water. Thescum deposits harden and from scale.

a. Reducing Scale. In localities where the water is unusually hard, a water softner isused to reduce the hardness. The softner normally contains zeolite, which must berecharged regularly. The recharge is done by adding sodium chloride (table salt) to thewaler. Water softners are programmed to recharge at a set time each day. The softened wateris then piped into the distribution system.

b. Removing Scale. To remove scum that has formed on the inside of a pipe, do oneof the following

Flush with hot water.

Use lye or lye mixed with a small quantity of aluminum shavings. Only coldwater should be used with lye.

For a sharp reduction of water flow, you may have to replace the entire pipe.

NOTE:Chemical cleaners should not be used in pipes that are completely stopped upbecause the cleaners must contact the stoppage directly.

3-4. Waste-System Stoppages. A common problem in waste systems is a stoppage. Astoppage can occur in a fixture drain, floor drain, branch line, or main line. The cause canbe hair, grease, or other foreign matter that holds back the flow of waste disposal. Use theproper clearing tool to clear the stoppage. These tools (Figure 3-2) are designed to clearstoppages in different areas of the waste system. These areas are

a. Water Closets. Use the procedures in Figure 3-3.

b. Lavatories and Sinks. Use the procedures in Figure 3-4 (pages 3-6 and 3-7).

c. Urinals. A stoppage in a urinal with an exposed P-trap is cleared the same as alavatory (using a plunger and a 1/4- to l/2-inch snake). A urinal with a waler seal is clearedthe same as a water closed (using a plunger and a 1/4- to l/2-inch snake).

d. Bathtubs. Use the procedures in Figure 3-5 (pages 3-8 and 3-9).

e. Shower Drains. Use the procedures in Figure 3-6 (page 3-10).

f. Branch and Main Waste Lines. Stoppages that occur in a branch or main waste linein a building are cleared through a cleanout. Use the procedures in Figure 3-7 (page 3-11).

g. Grease Traps. All work is done on the principle that grease is lighter than water andwill rise to the top of the water. To clear a grease-trap stoppage

Step 1. Remove the top cover and dip out the grease with a ladle.

Step 2. After the grease is scooped out, scrape the walls and bottom.

Step 3. Flush with clear water.

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Plumbing and Pipefitting - Ch3