Plumbing plays a major role in the construction of all types of residential, commercial, and industrial buildings. Of all the building trades, plumbing is most essential to the health and well-being of the community in general, and to the occupants of the buildings in particular. It is an obligation and responsibility for each and every certified plumber to uphold the vital trust placed in him or her for proper installation of plumbing materials and equipment. Each plumbing installation is governed by the rules and regulations set forth in plumbing codes that have been adopted from standards established at the local, state, and federal level. As you progress in your career, it becomes your job to ensure that codes established for the job are carried out. You may soon be the supervisor or instructor responsible for training apprentices under you.
This course introduces the different types of distribution systems used in underground and above-ground piping construction, including the wide array of materials utilized. You will also discover the functions and resources associated with water distribution, service, and storage facilities.
When you have completed this course, you will be able to:
Water is circulated from the oceans to the atmosphere by a series of processes and then to the surface of the earth and beneath it. This is known as the water cycle, or hydrologic cycle. An understanding of the occurrence of groundwater is based on a general knowledge of these processes and their relationships to each other. Basically, the cycle consists of the following processes:
The cycle usually does not progress through a regular sequence and may be interrupted or short circuited at any point. Moisture that condenses over the ocean may fall into it as rain. Rain that falls upon a heavily forested area soon may return to the atmosphere by direct evaporation or through transpiration by plants. Jungle-covered islands of the Southwest Pacific are known to produce more evaporation than adjacent areas of ocean. Water that seeps into the soil may be retained for a time by soil capillarity, or other means, before moving downward through the unsaturated zone to become a part of the groundwater.
As the rainfall and water cycle repeats itself, depending upon climatic and other conditions, a water supply is built up that can be captured and used for a multitude of purposes.
Water is vitally important to the health and welfare of all personnel. An adequate supply of safe water should be available at all times. This section will familiarize you with some of the basic components of water distribution systems.
Water distribution is the art or method of supplying water, under pressure, from a source or storage point to a user.
This section is an introduction to primary sources of drinking water
There are three main sources of water: rainwater, surface water, and underground water (Figure 1).
Figure 1 — Sectional view of water sources and relation to the earth.
Rainwater is used in some areas where water levels in the ground are very deep or nonexistent. Water runoff from roofs is collected in cisterns and used for irrigation purposes. A cistern is a holding tank for the rainwater. Although rainwater is usually relatively pure, it may be contaminated by the atmosphere or the roof.
Water that runs in streams or is found in depressions, such as lakes, reservoirs, ponds, or oceans, is called surface water. Most areas ordinarily use surface water for a potable water source. This source is the most plentiful. However, it is also the most easily contaminated. Water must be treated prior to any form of consumption. Depending on the number of contaminants, this process can be quite lengthy and costly.
The underground surface beneath which earth materials, as in soil or rock, are saturated with water is known as the water table (Figure 2).
Figure 2 — Water table location.
This level does not always remain at the same depth. Depending upon the season or amount of rainfall, it may move up or down. Underground water from a well that has been properly located and constructed is the safest. Commonly in other countries and rural America well water is generally used untreated.
Wells are by far the most common source of water. The object of a well is to make the water lying beneath the water table available for use. If the water table is close to the surface, wells are sometimes dug by hand. Dug wells are rarely deeper than 30 feet.
Hand dug wells may go dry during long rainless periods. When water is not added to the underground supply over a long period, the water table recedes. It can easily go beyond the depth of shallow wells. Hand dug wells are also more susceptible to pollution than are deeper wells.
Another kind of well is called a driven well. The driven well is used in loose, sandy, or highly permeable gravel soils. A device called a well point or drive point (Figure 3) is screwed into a length of pipe and driven down into the earth with hammer blows. It is one of the easiest methods of establishing a well. However, it is limited to depths of less than 60 feet and to soils that are not too rocky.
Figure 3 — Well points or drive points.
Bored wells are shallow (50 feet or less) and dug with a boring rig or a power driven earth auger. Like the drilled well, the bored well is typically lined with concrete tile or galvanized pipe.
Drilled wells are the deepest, (50 feet to up to 1500 feet) the most dependable, and the most pollution free. The Naval Construction Force (NCF) has well drilling capabilities of up to 1500 feet with Table of Allowance (TOA) equipment and specially trained personnel
The wells are drilled down into the water bearing strata. The well is then cased. This means that a large diameter pipe is lowered into the bore. Then, the space around the casing is filled with sand and gravel and then sealed from the surface with a grout made from betonite and cement, to a depth below the polluting effects of the surface. The well pump and draw piping itself is then placed within the casing. Screen sections of well casings allow aquifer water into the casing and the well pump then draws that water from the cased well.
Lift stations contain the pumps, valves, and electrical equipment necessary to pump water or wastewater from a low elevation to a high elevation. For example, a water lift station pumps source water uphill from a low lying collection point or well to a plumbing system or storage area. Lift stations are also used in a variety of industrial settings, including water management and treatment.
Lift station design includes pumps, level sensing probes, valves and pressure sensors, and may also include a stand-by generator. Lift stations must function in harsh and corrosive environments and are typically made of precast concrete with the pumps and valves accessible through a hatch for cleaning and maintenance.
In general, there are two types of booster pump station (BPS), open systems and closed systems.
Open BPS System
An open BPS system is one which transfers water to a higher pressure zone governed by an atmospheric storage tank (where the water surface is open to the atmosphere), basically pumping from an open air storage tank to a plumbing distribution system.
Closed BPS System
A closed BPS system is one which transfers water to a higher pressure zone closed to the atmosphere, pumping from a closed storage tank to a plumbing distribution system.
Cross connections are direct connections between a potable water supply and system carrying unsafe water.
A cross connection can cause a drastic reduction of the water pressure that could lead to back Siphonage through water pipes.
All pipelines containing unsafe water should be painted red or another color. All these pipelines will have correctly labeled valves and backflow preventers to prevent unsafe water from entering the safe water supply.
Loop system will correctly balance and maintain the desired pressure throughout the entire piping system. This system also delivers sufficient water to all use points, meeting maximum demand output.
The system is laid out in a grid or belt arrangement, which prevents dead ends and stagnated water from accumulating in piping.
In this system, piping is laid out in a one line configuration (source to fitting). There is no way to balance the load (water supply) to fixtures. If one fixture is open with full pressure, and then another fixture opens, the system will experience a pressure drop throughout. Another disadvantage with this system is that it must be flushed regularly to prevent contamination from stagnated water.
Corrosion is a constant threat to everything made of metal. It proceeds along its destructive path quietly, and in many instances, unnoticed. Corrosion is a never-ending problem.
Your job will consist of installing and maintaining plumbing systems. This includes the use of pipe, valves, fixtures, and equipment. Most of these items are metal and as such will need protection against corrosion.
Corrosion is the tendency of metal to return to its natural state. This is a result of selfinduced electric current flowing from the metal into the soil. Where current leaves a metal, it takes small particles of the metal with it, causing corrosion.
Corrosion is essentially the same in all metal; however, the rate of corrosion will vary in different environments and with different metals. Corrosion is a perpetual problem occurring in all metallic pipelines. In order for any appreciable corrosion to occur, you must have two dissimilar metals in metallic contact with one another and with an electrolyte. Moist soils and water are electrolytes. Water that is 100% pure is not a very effective electrolyte; however, most sources of water contain some degree of impurities.
All corrosion problems and resulting failures of piping systems can be associated with one or more of the basic forms of corrosion. The three types of corrosion we will discuss are galvanic, atmospheric and concentration cell.
Galvanic corrosion takes place when two dissimilar metals are connected together, commonly copper and galvanized (metal to metal) and in contact with an electrolyte such as water or moist soil. A tool scrape or a cut in the protective coating of a pipe can allow the piping to come into contact with dissimilar metals in the soil. This damage to the protective coating is called a holiday, and can result in accelerated corrosion at the point where the coating is damaged.
Atmospheric corrosion normally occurs on aboveground piping due to impurities or corrosive elements in the atmosphere. Water condenses out of the atmosphere and onto the metal. As the water condenses, it absorbs many impurities such as sulfur dioxide, hydrogen sulfide, and carbon dioxide, thus causing corrosion. Atmospheric corrosion is more of a problem in an industrial area or near the sea coast because more corrosive elements will be in the air. Corrosion only occurs while the piping is moist or wet. When the pipe surface becomes dry, atmospheric corrosion stops.
This form of corrosion is sometimes referred to as “crevice corrosion”, “gasket corrosion”, and “deposit corrosion” because it commonly occurs in localized areas where small volumes of stagnant moisture or solution are present. Normal mechanical construction can create crevices at sharp corners, spot welds, lap joints, fasteners, flanged fittings, couplings, and threaded joints. Deposits that promote concentration cell corrosion can come from a number of sources; other sites for corrosion can occur when electrolyte (moisture) absorbing materials are used for gaskets and the sealing of threaded joints. This form of corrosion can cause severe pitting of the metal surfaces and eventual penetration.
The most important element in fighting corrosion is learning to identify it. Knowing where to look and what to look for is the beginning. Start a visual inspection by looking for signs of corrosion. Check for the physical aspects of corrosion: breaks in protective coatings, dissimilar metal connections, the presence of rust or flaking metal, pitting, and any other signs of corrosion at joints and fittings. Also, look for environmental conditions, such as moisture, polluted air, chemicals and corrosive gases. Any of these conditions will trigger corrosion.
According to the Code of Federal Regulations, all metallic pipe installed after July 31, 1971 must be properly coated and have a cathodic protection system designed to protect the entire piping system or other metallic structure. Leaks in systems cause safety hazards, environmental hazards, and interruptions in service.
There are various reasons for corrosion control. Because of the hazards involved with water and wastewater, and because of environmental concerns, leak prevention is of utmost importance. Using corrosion control methods on metallic piping systems can decrease leaks.
188.8.131.52 System Life
A system will last longer with proper protection installed. Corrosion of buried metallic structures such as mains and service lines are a problem that varies in magnitude from location to location. In some areas metal piping may last more than 30 years. Uncoated or improperly coated pipe may become unserviceable after a period of a year or so depending on location.
There are two common methods of controlling corrosion: Protective coatings and cathodic protection.
The following are some of the coatings used to protect piping systems. Coatings are used as insulating material. The material isolates the pipe from its surroundings. Coatings may be applied with paint brushes, mops, rags, or at the factory. Before applying the coatings, clean the pipe all foreign matter, such as dirt and debris.
Asphalt. Asphalt coatings are the most common type of protective coating. Asphalt coatings can take considerable abrasion, impact, and temperature changes without losing effectiveness.
Coal Tar. Another type of protective coating is coal tar. Although it is less expensive than asphalt and adheres well to the pipe, wide temperature changes could cause the coating to crack.
Vinyl Coatings. Vinyl paint is a synthetic resin-base paint. This paint dries to a film that is tough, abrasion proof and highly resistant to corrosion. It is odorless, tasteless, non-toxic and nonflammable. The film is especially resistant to oils, petroleum, and solvents. Because of these characteristics, vinyl coatings are often used for gas pipelines.
Cathodic protection is the reduction or prevention of corrosion of metal surfaces by making the metal structure to be protected the cathode in the corrosion process instead of the anode. Two types of cathodic protection are (1) sacrificial anode, and (2) impressed current.
All metals possess a natural electrical potential (Voltage) and each type of metal has a specific natural voltage value. This difference determines which metal will be the anode and which will be the cathode when two dissimilar metals are in direct contact with one another. For example, copper has a natural voltage of +0.34 volts, and iron has a voltage of -0.44 volts. In any electrical system, current flows from negative to positive. When two different metals are connected together, the more positive metal will be the cathode and the more negative metal will be the anode. When these two dissimilar metals are placed in an electrolyte (such as moist soil), electrical current will begin to flow from the anode to the cathode. This electron transfer to the cathode protects the cathode from corroding and causes the anode to disintegrate (corrode).
Sacrificial Anode (Galvanic Anode). Use of sacrificial anodes is one method of cathodic protection. The most common type of sacrificial anode is made of magnesium. The anode is packaged in a mixture of gypsum bentonite/sodium sulphate to optimize contact with the electrolyte (soil). The anode is then connected to the pipeline with an insulated wire that is welded to the pipe surface. Electrical current will flow from the anode through the conductor (insulated copper wire) to the pipe. The current then travels along the pipeline and thereby protects it from the effects of corrosion. The anode is corroding by giving off ions that migrate into the soil. Ultimately, the anode will completely dissipate and require replacement. Refer to Figure 4.
Figure 4 — Sacrificial anode.
Sacrificial anode systems are simple and relatively inexpensive when used to protect small systems. Because they rely on the very small naturally occurring voltages between dissimilar metals, their range of protection is limited. Using this type of system on a long pipeline would require the placement of anodes every 40 or 50 feet.
Impressed Current. Impressed current is designed to protect large metallic distribution systems (such as water supply pipelines). With this method of protection, an AC power source must be available. A rectifier then changes the AC power to DC. The rectifier pulls current from the anodes, and that power flows onto the cathode (the structure to be protected, in this case the pipeline). Simultaneously, the anode is corroding by giving off ions that migrate into the soil. Ultimately, the anodes will completely dissipate and require replacement. See Figure 5.
Figure 5 — Impressed current method of cathodic protection.
The main advantage between a sacrificial anode system and an impressed current system is the range of protection afforded to the pipeline from a single location. Since a galvanic system depends upon the naturally occurring difference in potential (voltage) between the anode and the cathode, its range of protection is limited to a small area. An impressed current system, on the other hand, taps into an external source of electrical power that allows for much higher voltages, multiple anodes, and therefore a much greater range of protection (miles in some cases). In addition, a rectifier allows for greater control and monitoring of the cathodic protection process.
Most water contains minerals of one kind or another. They tend to deposit on the inside of water supply pipe, more often on galvanized steel pipe than on brass pipe with its smoother interior. So, after a number of years of use, pipe is likely to become clogged unless it is cleaned out.
Clogged piping reduces the flow of water considerably. These problems can be indicated by insufficient flow, reduced pressure, or head pressure loss. If the pipe is really badly clogged, the best advice is to replace it with new pipe, but there are methods which will clean out some material if the pipe is not too clogged. One is to attach a wire brush to a small metal rod and push it back and forth through a section of pipe, which of course has been removed from the water supply system. Flush it out now and then, and continue until you do not seem to be loosening anything more.
Another method is to take a 2-foot length of small chain that will go through the pipe you desire to clean out. Attach a piece of stout cord which is a little longer than the pipe to be cleaned to each end of the chain. Attach the free end of one cord to a piece of stiff wire and push the wire and then the cord through the pipe.
With the two cords, work the chain back and forth through the pipe several times and then flush out the pipe with water. This method will not clean out everything but it will usually dislodge some of the accumulation of deposits.
A third method is to fill the piece of pipe with diluted muriatic acid and let it stand overnight or longer. A solution of one part of muriatic acid to seven parts of water is best. Be careful not to spill any on your hands, face, or clothes for muriatic acid is both strong and poisonous. Follow all safety precautions outlined in the Material Safety Data Sheet (MSDS) and all disposal requirements outlined in local Hazardous material (HAZMAT) instructions. Screw a cap over one end of the pipe before pouring in the muriatic acid and cap the other end after the acid is in. Tilt the pipe up and down several times. Later remove the acid and flush out all accumulations it has loosened. Repeat, if necessary.
Noise in water pipes is both annoying and indicative of faulty conditions which in time might cause leaks to develop. Steps to eliminate the noise are therefore advisable. Noise in overhead pipes may be the result of lack of sufficient support. When you open a faucet, water rushes through the pipes. When you shut off the faucet suddenly, the momentum of the water is brought to a halt and the pipes vibrate. You may have to install a few pipe hangers. Pipe hangers installed every three or four feet will hold the pipe more rigidly and eliminate vibration.
In cases where pipes cannot vibrate, the momentum of water flowing through them causes what is called "water hammer," a chattering or pounding in the water system when a faucet is turned off. This can be stopped by installing a short piece of pipe next to a faucet to act as a sort of shock absorber.
The water supply line will probably come up to an elbow that turns to come through a wall. Shut off the water, and unscrew the piece of pipe that fits into the faucet. Remove the elbow and replace it with a T connection. Connect a short piece of pipe about 2 feet long with a cap on the end above the T connection, and replace the piece of pipe with the faucet on the end.
You must consider several factors when selecting the correct water supply line size. The following list will provide the minimum factors to consider:
The following pieces of information will be commonly found on specifications sheets and blueprints concerning water supply line installation:
The following table (Table 1) is a list of materials used in water supply pipe installation, along with the advantages and disadvantages of each:
Table 1 — Materials used in pipe installation.
|Cast Iron||Asbestos Cement (ACP) Transite||Steel||Plastic|
|20 feet lengths||Will not withstand vibration||Free from electrolysis||Low flexibility in small sizes||High tensile strength||Easily corrosive||Lightweight||Easy to rupture or damage|
|Mech. joints||Heavy to handle/install||Free of corrosion||Subject to impact damage||Flexible||Subject to electrolysis||Easy to use||Storage Issues|
|Very durable||Excellent flow||More difficult to locate||Withstands great pressure||Impervious to corrosion|
|Withstands impact and traffic||Lightweight||Heavy||Choice of connectors||Very flexible|
|Easily tapped||Easily tapped||Good flow||Available in several ratings|
|Corrosion resistant||Very low maint.||Withstands temperature extremes|
|Low maint.||Durable||Excellent flow|
|Withstands extreme temps|
Flexibility in the operation of a water-supply system requires the proper valves for the condition to be controlled. Valves can stop, throttle, or control the flow of water in a pipeline. Other uses include pressure and level control and proportioning flow. We use a number of different valve designs. The following is a brief description (more detailed information will be provided in later courses) of the most common valves you will encounter.
Fittings are essential to the proper operation of water-supply systems. Fittings will be covered more extensively in later courses. At this time be aware that to reduce water flow resistance, long turn fittings are preferred. When necessary, fittings will be thrust blocked (process of securing pipe bends with concrete to prevent surges in water flow from flexing the pipe or fitting loose). Always remember, the fitting must be compatible with the piping.
The following is a brief description (more detailed information will be provided in later courses) of the most common specialty or accessories you will encounter.
|Test Your Knowledge
1. What type of cleaning solution is used to clear mineral deposit build up within the water distribution piping?
- To Table of Contents -
The water supply system for a building consists of the service pipe, the distribution pipes, and the connecting pipes, as well as fittings and control valves. Water carried by the system must meet accepted standards of purity. Two major functions of a water distribution system are (1) to carry potable water for domestic use and (2) to provide a high rate of flow for fire fighting.
Occupational Safety and Health Administration (OSHA) defines a trench as a narrow excavation below the surface of the ground in which the depth is greater than the width, that width not exceeding 15 feet. The stability of soil, weather conditions, excavation depth, and the slope of the sides of a trench all affect the safety of this type of work area.
OSHA requires the use of precautionary measures in unstable work conditions for excavation of a trench that exceeds 5 feet in depth. A ladder must be provided as a means of egress when a trench is 4 feet deep or more, and the ladder must be located no more than 25 feet of lateral travel from the work area.
The slope of the sides of a trench can help ensure a safe workplace. Figures 3-6 and 3- 7 illustrate excavated trenches with stepped (benched) and sloped sides.
Figure 6 — Stepped trench.
Figure 7 — Sloped trench.
The most important factor to determine a safe trench is the soil classification and condition. Various types of soil exist, and their characteristics can change based on temperature and moisture conditions. Soils that provide the safest excavations are cohesive (consistent); if soil conditions vary within a single excavation, the least stable soil is the determining factor in establishing protective measures.
The four basic classifications of soil are described in Table 2. Each class has its own set of regulations that determines excavation and entry approach. A single type of soil, such as clay, can have several different classifications, depending on numerous factors. Use OSHA standards to train personnel to properly assess different soil classes.
Table 2 — Soil classifications.
|Class||OSHA Brief Description|
|Stable Rock||Natural solid mineral matter that can be excavated with vertical sides and remain intact while exposed|
|A||Cohesive soils with an unconfined compressive strength of 1.5 tons per square foot (tsf)|
|B||Cohesive soils with an unconfined compressive strength greater than 0.5 tsf but less than 1.5 tsf|
|C||Cohesive soil with an unconfined compressive strength of 0.5 tsf or less|
|Note: Refer to OSHA information for specific soil types and detailed determinations.|
Any weight bearing placement near a trench is known as an encumbrance, and the excavated soil is commonly referred to as spoil. Spoil placed too close to the edge of a trench can cause the trench to cave in. Place removed spoil no closer than 2 feet away from edge of a trench. The weight from excavation equipment, vehicles, stored materials, and any other load placed too close to the open edge of a trench creates a safety hazard. A safe trench can become an unsafe job site as a result of rain, temperature changes, vibrations, or other variable occurrences.
Working in any trench raises numerous safety concerns, and each excavation may bring with it unique safety issues. Water in the trench can create a muddy work environment and make it difficult to escape quickly if needed. Water can also cause electrocution if a wire is broken during the excavation phase. Additionally, a trench could potentially become explosive if a propane or natural gas line is leaking. Because of this, locate all underground utilities prior to beginning any excavation.
In trenching for waterlines, it is not necessary to set batter boards since laying water pipes to grade does not require great care because the water is under pressure. The pipes in a waterline may follow the contour of the earth’s surface in a trench that is a minimum of 2 feet deep. Minimum depth of the ditch depends upon the depth of the frost line in the area. The trench should be wide enough to permit ease of working around the pipes and to allow placing earth during backfilling. Usually, the trench is not deep enough to require bracing or shoring.
Locate the trench at least 4 feet from a previously dug ditch, or trench, to help prevent cave-ins. Lay water pipes 1 foot above and 10 feet away from nearby sewers. This helps prevent the water distribution system from becoming contaminated by leaks. Sometimes the water main and sewer lines may cross each other. In such cases, the water pipe must cross over the top of the sewer line, so be careful to make all joints tight; however, always check the local specifications and codes before installing them in this manner.
Keep the distribution system free from contamination caused by leaks, back siphonage from faulty plumbing, and cross-connections. The greatest hazard in a distribution system is cross-connection. This is one physical connection to another that is an unsafe or doubtful source of water or a connection or condition that will permit wastewater to enter the potable public supply.
An important phase in the installation of a water system is laying the underground water service pipes.
Regardless of the pipe material you use, anchor sharp bends and dead ends by rodding or concrete anchors, also referred to as thrust blocks. Where the pipe is setting in saddles, you may use metal straps. Even though the pipe is installed within a ditch, the straps help support and hold the pipe in place. Pipe should be founded on solid trench bottoms. Install automatic air-release and vacuum valves at prominent peaks on long supply mains to permit escape of air while the pipe is being filled and entrance of air when it is being drained. Elsewhere in the distribution system, air normally can be released and taken in through service lines.
Flow in water pipes may be achieved by gravity with an elevated tank or by a pumping system. When pipe must be placed in a sloping trench, make the slope as even as possible to keep the pipe from bending and breaking. After digging the trench, lay the pipe and fittings alongside it. Before you start placing the pipe; shut off the water in the main supply line. The placing should start at the main supply tee.
When you are ready to backfill a ditch, tamp the soil around the pipe by hand or use water. In backfilling, keep the pipe straight and minimize settlement. Soil used to backfill around the pipe should be as free as possible from rocks and debris. Place loose earth free from rocks, broken concrete and frozen chunks in the trench in 6 inch layers and tamp it in place until the crown of the pipe is covered by 12 inches of tamped earth. Throwing fill material directly on the exposed pipe could damage the pipe or move it out of alignment. Drop the fill material on both sides of the pipe at the same time.
When you have water available, use it instead of the tamper, especially when you have a short run to backfill. Fill the ditch completely with loose soil. Attach a piece of pipe to a water hose and push it through the loosely replaced soil until it touches the water main. Turn on the water and let it run until the water appears on the surface. This method allows all the earth to be replaced except the volume equal to that of the pipe.
Some common piping materials used in water-supply systems include cast iron pressure pipe, copper pipe, galvanized pipe, cement asbestos pipe, ductile iron pipe, concrete pipe, and PV-class water pipe. Below are some of the main characteristics of pipe made from these materials and the equipment used.
The cast iron pipe used for a water distribution system is somewhat different from that used for waste systems. Some of the major differences are in the length of the pipe, the joints, and the lining. Cast iron soil pipe for waste, as you know, comes in 5 foot and 10 foot lengths. Cast-iron pressure pipe for water mains comes in 20 foot lengths with both bell and spigot or mechanical (gland-type) joints. This pipe may be coated with coal tar pitch or be cement lined; however, uncoated pipe is available if needed for other purposes.
Measuring and Cutting
Cast iron pressure pipe is measured by the inside diameter; a ruler or tape is frequently used for measuring. With a cement lining, the lining goes beyond the inside diameter of the pipe, so you have to allow for this reduced inside dimensioning.
To cut cast iron water pipe to the desired length, use either a hand operated chain cutter or a power hacksaw. Because of the construction of this pipe, it does not need reaming after cutting; but, you can use a file to dress down the cut when necessary.
Three major types of fittings for joining cast iron pipes in water service are tees, elbows, and couplings.
In water service lines, join bell-and spigot cast iron pipe with a sulfur compound. You may also use specially prepared treated paper.
Before making a joint, first check each length of pipe for cracks or splits. After eyeing the pipe for defects, rap it with a hammer. With a little experience, you will know the difference between a good pipe and a bad (cracked or split) pipe.
A sulfur compound is melted on the job. It is then poured into a joint prepared for a cast joint. The fact that it is light in weight is its primary advantage. It requires no caulking and provides a strong joint that is unlikely to blow out. Initially, joints of sulfur compound leak or sweat slightly, but they tighten up in a short time. Since the joints are rigid, do not use them to connect a newly laid line to an old one, as the settlement of a new line can cause a crack. Use a lead joint at the connection.
Mechanical joints are made with rubber sealing rings held in place by metal follower rings bolted to the pipe. This type of joint is designed to permit expansion and contraction of the pipe without injury to the joints.
Copper pipe and tubing with soldered joints or flared-tube connectors are used for water service. Copper is highly regarded because of its corrosion resistant properties, flexibility, ease of installation, and low resistance to flow throughout its useful life.
Three types of copper, designated as Types K, L, and M, are commonly used. Type K is used for underground service and general plumbing; Type L for general plumbing; and Type M with soldered fittings only. Types K and L copper come in either straight 20 foot lengths of hard temper or in coils of 50 to 100 feet, soft temper. Type M comes in straight 20 foot lengths, hard drawn only. Vibration can also cause copper tubing to break.
The process used to soften copper is called annealing. The word “anneal” means to soften thoroughly and render less brittle. Copper is unlike steel in many respects. If copper is bent often, it could break when you try to bend it again. Should the pressure on a copper tube increase or decrease too much, the tube could break. Vibration also makes copper tubing break.
To soften steel, heat it to a cherry red and cool it very slowly. The slower it is cooled, the softer the steel becomes. With copper, the opposite is true. Heat copper uniformly to a dull red and then quench (dip) it in water (for water service). The faster it is cooled, the softer the copper becomes.
Copper, properly annealed, can be bent by hand when sharp bends are not desired. Copper partially collapses during the bending process if a tubing bender is not used or if the copper is not filled with some kind of easily removable material, such as sand. You can also make simple bends by wrapping the outside of the copper tightly with soft wire and bending the copper by hand; however, if a line must make a 45 or 90-degree bend, use a tubing bender. Hand-tubing benders are available for each size of copper. These benders assist you in making neat, accurate bends easily, quickly, and without marring or restricting the flow through the copper. It is easy to make a bend but difficult to get the bend in the correct location on the copper and to the correct degree. Be certain that you have the correct size bender for the copper you intend to bend. A bender that is either too small or too large for the copper will make a faulty bend. Figure 8 shows one type of tubing bender.
Figure 8 — Portable copper pipe and tubing bender.
Seven methods are used in measuring pipe or tubing. They are (1) end to end, (2) center to center, (3) end to center, (4) end to back, (5) center to back, (6) back to back, and (7) face to face. These measurements are also used in measuring threaded galvanized or black iron pipe.
The measurements are generally made with a ruler. Each of the seven methods mentioned above is explained in Figure 9 below.
|End to End. Indicates a pipe threaded on both
ends. The measurement is from one end of the pipe to the other end, including
Center to Center. Indicates that there is a fitting on each end of the pipe. The measurement is made from the center of the fitting on one end to the center of the fitting on the other end.
End to Center Method. applies to pipe having a fitting on one end. The measurement is made from the end of the pipe to the center of the fitting.
End to Back. Also refers to pipe with a fitting on one end. The measurement is from the back of the fitting to the other end of the pipe.
Center to Back. Indicates a pipe with a fitting on each end. The measurement is taken from the center of one fitting to the back of the other fitting.
Back to Back. Measurement refers to pipe with a fitting on each end. Here the measurement is from the back of one fitting to the back of the other fitting.
Face to Face, Measurement refers to a pipe with a fitting on each end that has an opening directly across from the pipe to which it is connected on both ends. Measure from the face of the opening to the face of the other fitting.
Figure 9 — Pipe measurements.
Cut copper with a tubing cutter, when available. Mark the copper where it is to be cut and install the cutter so the cutter wheel is over the mark and you can see the cutting wheel from the top view of the pipe, as shown in Figure 10. Now turn the adjustment wheel or handle clockwise to force the cutter wheel against the copper. Continue revolving the cutter, turning the adjustment wheel 1/4 turn per rotation until the copper is cut through and separates.
Figure 10 — Cutting copper pipe.
Copper may be cut with a hacksaw, although a tubing cutter is preferable; however, be careful to cut the copper square if it is to be flared. Be sure to use a fine-toothed hacksaw blade, 32 teeth per inch, when cutting copper.
|Test Your Knowledge
2. When laying water distribution piping underground how far above or below must the piping be from sewer piping?
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The operation of storage facilities in the distribution system is largely a matter of maintaining sufficient levels through adequate pumping and controlling water flow through appropriate valves. The two types of water storage are live storage and dead storage.
Live storage, where water is constantly circulating from the supply into the distribution system, is preferred to non-circulating storage because the latter depletes the chlorine in the water and allows tastes and odors to develop. If dead storage is necessary, the operator must maintain a close watch on chlorine residuals and the development of odors and tastes, and report conditions regularly to higher authority.
Whenever entry is required for confined spaces and storage areas, Only a certified gas free inspector is able to certify a confined space as being safe to enter without the use of respirators. However, the space still requires to be ventilated during entry to ensure adequate supply of breathable air.
Facilities for storage of water include open reservoirs, underground reservoirs, and elevated storage tanks. Ground storage reservoirs may be the same or similar to those shown in Figure 11. Three types of elevated storage tanks are pictured.
Figure 11 — Types of elevated and ground storage tanks.
You may also see standpipes used at some activities. Standpipes are, in effect, ground level storage tanks. The distinguishing characteristic of a standpipe is its relatively small diameter and extra height to provide head pressure. Under no conditions should the amount of stored water be reduced to a point below that necessary for fire fighting. Daily records maintained by the operator help ensure against such a condition (Figure 12).
Figure 12 — Standpipe.
Pneumatic water tanks are usually found in use at smaller installations and rural areas with independent wells. They consist of a pressure vessel partly filled with water, and a compressor unit that supplies air pressure to produce the desired water pressure. Pneumatic tanks may be within buildings, on outside surface locations, or underground. While the operation of these units is usually automatic, the operator is responsible for the effective operating of pressure equipment. Consult the manufacturer’s instructions for methods of starting, stopping, and operating this pressure equipment.
Here are the elements in the maintenance of storage facilities: the construction materials- concrete or steel; and the location of the tank-ground level, belowground, or elevated.
Commonly all tanks have foundations of either concrete, wood, or steel. Each material has its own maintenance procedures.
Inspect concrete foundations semiannually for settlement, cracks, spalling, and exposed reinforcing. When deterioration has set in, repair the foundation with a mixture of 1 part cement to 1 part sand.
Wood foundations and pads should be inspected for split members, rot, termite infestation, and direct soil contact of untreated wood. Make any repairs necessary to remove the undesirable condition.
Maintenance procedures for steel foundations are similar to those given later in this section for elevated storage tanks.
Concrete storage tanks may be either prestressed or nonstressed design. There is little difference in the maintenance procedures, which depend mainly on the location of the tank—aboveground or belowground.
Ground Level Storage
During early spring, inspect ground level storage facilities for water tightness and structural conditions and make repairs as necessary; at other intervals, perform the maintenance procedures set forth in the following paragraphs.
Semiannually, mark exterior walls where leakage or seepage occurs. Every spring, inspect them for seepage or leakage from cracks-breaks or cracks in the interior seal membrane. Dewater the tank and check both the interior and exterior surfaces for spalling caused by frost action, as well as settlement, cracks, and exposed reinforcing.
Remove all loose, scaly, or crumbly concrete and patch the wall with rich cement grout after wetting and painting with Portland cement slurry. Paint hardened grout with iron waterproofing compound or a similar preparation.
Chip out cracks of 1/4-inch width and l-inch depth. Moisten the cleaned crack and paint it with cement slurry. Fill the crack with a rich cement grout, dry enough to stay in place in the crack, but not dry enough to allow it to slough off. When the grout has hardened, paint it with iron waterproofing compound, or a similar preparation.
When cracks appear in pre-stressed concrete tanks, refer the problem to the erecting company for recommendations, even if the guarantee has expired or does not cover maintenance.
Every 6 months, check joints for leakage at the juncture of the floor and the walls, and for loose or missing filler, debris, or trash. Clean and repair them as necessary.
Every 6 months, inspect the roof for the condition of the covering. Are roof hatches and other covers locked? Are the screens on the overflow or at other locations in place? Clean them as necessary.
Where the tank rests on an earth embankment, check it for erosion from the lack of full sod or vegetation coverage, and for damage from burrowing animals, improper drainage, ponding water along the base, or leakage through the embankment or along the outlet piping. When leakage exists through the embankment, drain the tank and inspect the bottom for failure or cracks.
If storage tanks are constructed belowground or are surrounded by an earth embankment, the semiannual inspection and repair cover only the interior walls, roofs, accessories, and embankment. The inspection procedures and maintenance operations are the same as described above for ground level storage facilities. When the earth embankment, surrounding soil, or interior of the tank shows evidence of tank leakage, you may need to excavate the earth and make repairs on the walls.
Concrete storage tanks elevated aboveground require the same inspection and repairs as outlined above, where applicable.
Usually, outside contractors maintain and repair steel tanks. At times, though, you may have to perform various inspection and maintenance duties, such as those discussed in the following sections.
Ground Level Storage
Annually, after the winter season, inspect steel storage tanks for ice damage, water tightness, and structural conditions. Twice each year, follow the maintenance procedures set forth in the following paragraphs.
Inspect tank walls (exterior and interior) and bottom (interior) semiannually for rust corrosion, loose scale, leaky seams and rivets, and for the condition of the paint (both inside and out). Adhere to the following maintenance procedures:
- Make certain that the paint used will protect the metal against corrosion. Consult the applicable guide specifications for paint selection and application.
- Use only new coat if the previously applied coat is in fair condition. Paint bare spots of steel with a spot or patch coat before applying the finish coat. When the condition of the old paint is bad, use a complete primer coat.
Every 6 months, inspect the roof and its appurtenances, (screens on overflows, hatches, and manholes), as well as the condition of the paint. Adhere to the following maintenance procedures:
As pointed out earlier, standpipes are, in effect, ground level storage tanks. Inspection and maintenance procedures for standpipes are the same as those for ground level steel storage tanks.
When steel storage tanks are constructed belowground or are surrounded by an earth embankment, the semiannual inspection and repair include only the interior of the tank, the roof, and the accessories. The inspection and maintenance procedures are the same as those for ground storage steel tanks.
Refer to Figure 11.
Besides the inspection and maintenance procedures set forth above for ground storage steel tanks, the following specific procedures apply to elevated storage steel tanks.
Semiannually, check tower structures for rust and corrosion, loose, missing, bowed, bent, or broken members; loose sway bracing; misalignment of tower legs; and evidence of unstableness. The following items must be covered:
Besides general roof inspection and repair, as described for ground storage steel tanks, inspect obstruction and navigation and relamp them if necessary. Additional items that should be covered are as follows:
In cold climates, potable water storage tanks (with small riser pipes) and elevated storage tanks (for fire protection only) usually have heating equipment to prevent freezing in severe low temperatures. Conduct the following checks:
Cathodic Protection Equipment
Only impressed current cathodic protection systems are used for protecting steel water storage tanks against corrosion. This system of protection may be applied to all types of steel water tanks-ground level standpipe, underground, and elevated. Other applicable procedures are as follows:
Make certain that the connections to the rectifier are not reversed. Reversed connections will result in tank damage.
Tanks As pneumatic tanks are usually on smaller installations, they may be too small for interior inspection, except for observations through a removable hand plate. The size, therefore, determines the inspection procedures to follow. Standard inspection procedures are as follows:
Every 6 months, ladders, walkways, guardrails, handrails, stairways, and risers should be inspected for rust, corrosion, poor anchorage, loose or missing pieces, or other deterioration or damage. Standard inspection procedures include the following:
At semiannual intervals, remove all accumulations of dirt, trash, debris, and excess foliage in the area surrounding the storage tank.
|Test Your Knowledge
3. Water storage tanks are made of what two materials?
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Water may be obtained from several sources, such as lakes, rivers, streams, and reservoirs. Since water is constantly subject to pollution from the natural environment, it must be treated to make it safe for human consumption. Private wells are another source of supply if public water service is not available. Well water must be analyzed by a recognized water-testing laboratory and certified by health authorities before it is used.
Pumps convey water under pressure from the source to the point of use. Pumps may be classified as primary, booster, or emergency. Primary pumps are those which provide movement of the water through the system. They are located at the source and treatment plant. Booster pumps may be installed at various points in the system to increase and maintain water pressure. They may be used at pumping stations when water must be moved a long way from the source to the treatment plant. They may also be used to lift water to storage tanks. Emergency pumps are used in case of breakdown or to satisfy fire-fighting requirements. Pumps are available in an incredible variety of designs and sizes. They can also be driven by a variety of power sources and prime movers.
Water is pumped from a source to a water treatment facility. After going through the treatment process, the water is potable (fit to drink), and is usually palatable (tastes good).
The piping system consists of feeder mains (large pipes that supply water), distribution mains, and service lines. Distribution mains are the pipes that distribute the water throughout a base or community. They include any lateral or branch lines. Service lines transport water from the distribution mains to the various buildings and facilities. The two standard designs used for exterior water distribution systems are the tree design and loop design. Rarely will you find a system that does not incorporate some features of both designs.
In a tree design system, smaller lines branch off the main line and come to a dead end. When the system must be worked on, the entire "branch" of the system must be isolated, stopping water service to many facilities in that area ( Figure 13).
Figure 13 — Tree design networks.
In the loop system, the lines branch off but return to the main line forming an integrated grid or loop. The loop design is preferred over the tree design because if one line breaks in a loop system, it can be isolated without interrupting the flow of water to the majority of users within that area.
Control valves are installed throughout the distribution piping and are used to start and stop flow. They may vary by type and design, but the majority of them will be gate valves. Many of these valves are located below the ground surface in valve boxes. The valves are placed at strategic points in order to isolate the system for maintenance or repair. See Figure 14.
Figure 14 — Curb stop.
Fire hydrants must be placed in all areas where there is a need for fire protection. Proper operation and use of hydrants is essential to water distribution, economy, and safety. Every fire hydrant should have its own isolation valve for maintenance or repair of the hydrant. Refer to Figure 15.
Figure 15 — Types of fire hydrants.
The quantity of water needed on a military installation depends on several factors. They include the number of military personnel living on base, the number of civilian employees, fire-fighting needs, irrigation, and industrial use.
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Taps made in water mains are also the point where water service lines begin. The selftapping machine, shown in Figure 16, is a specialized tool for tapping a water main that is under operational pressure.
Figure 16 — Water main self tapping machine.
It consists of a tubular body strapped to the pipe to be tapped. An intermediate tubular section contains a check (flop) valve that can be opened or closed as necessary, and an upper portion with a handle that is turned to tap the pipe. By using this tool, it is possible to tap a hole in an operating water main as shown in Figure 16, and install a corporation stop while the main is under operating pressure.
Excavate the area around the water main. Clear away enough soil from around the main to provide sufficient working space. Thoroughly clean the part of the main where the tapping machine will be installed. Attach the self-tapping machine to the main. Start the tapping process.
Many manufacturers produce different types of tapping machines to tap water mains that are under pressure. Their basic principle of operation is the same; however, their operating procedures may vary. For this reason you should always follow the operating instructions provided by the individual manufacturers.
After the combination drill/tap has penetrated through the main, reverse the ratchet to remove the drill bit. Install corporation stop. Remove the tapping machine and check for leaks. Flush the main to remove any debris that may be in the system.
The maximum size of a tap will be determined by the material that the main is made of and the size (diameter) of the main. Water mains are generally made of cast iron, Polyvinyl chloride (PVC), Chlorinated polyvinyl chloride (CPVC), or asbestos cement.
Tapping Cast Iron
When tapping cast iron pipe that is 8 inches in diameter or less, the largest tap you should make is 2 inches. A general rule to go by is; the tap should not be larger than one quarter (1/4) the diameter of the pipe. This rule applies to cast iron and PVC mains.
Tapping Asbestos Cement Pipe
When tapping asbestos cement pipe 6 inches or less in diameter, the largest tap you can make is 3/4 inch. Use a 1 inch tap for larger pipe.
When larger taps are required, build a manifold or install a tee in the line. Build a manifold by making a series of taps in the main and connecting them. Space the taps at least 10 inches apart (Figure 17).
Figure 17 — Service line manifold.
A tapping saddle is installed around the pipe to be drilled. The saddle has a leak proof gasket. A strap is placed around the pipe and tightened to clamp the saddle and gasket in place. The drilling machine is then attached securely to the tapping saddle and used to drill a hole into the main. The corporation stop is screwed into the saddle. See Figure 18.
Figure 18 — Tapping saddle.
The tapping saddle and drilling machine are used to drill holes from 1/8 inch to 2 1/8 inches under normal conditions.
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The water service line, commonly referred to as a “building service line”, begins at the distribution main and extends into the building. A typical water service line is illustrated in Figure 19. This line is comprised of a corporation stop, a flexible connector, a curb stop, a stop and waste valve, and a meter stop or gate valve.
Figure 19 — Water service from main to the building.
The corporation stop is the first component in a water service line. It is a valve that is joined directly to the distribution main when the main is initially tapped. It is a quick opening valve that is buried in the open position and not accessible from ground level. Flexible connections protect the corporation stop from damage. See Figure 20 for examples of corporation stops.
Figure 20 — Corporation stops.
The flexible connection protects the corporation stop from strain or damage that might result from any movement of the water main or service line due to settling, earth movement, and expansion or contraction. There are several types of flexible connectors. The type of connector to be used will depend upon the type of piping material used for the water service line.
The swing joint is a type of flexible connection commonly used with a galvanized steel service line (Figure 21). The connection consists of two elbows separated by a short section of pipe or a nipple. A nipple is a short piece of pipe with threads on each end, used for joining valves. The flexibility of the threaded joints at the two elbows will protect the corporation stop from strain or damage in the event of any movement of the pipe after the trench is backfilled.
Figure 21 — Typical swing joint.
When copper tubing is used to fabricate the service line, form an expansion loop in the line near the connection to the corporation stop. The expansion loop is a short length of soft drawn copper tubing that has been formed into a loop. The loop provides lateral or vertical flexibility depending on which way the line is installed.
The curb stop (Figure 22) is a valve that provides an accessible shut-off to a service line. It is located underground on the service line outside the building. Curb stops allow isolation of the service line for repair or maintenance. They are normally gate or ball valves. The curb stop should be installed with a valve box for ease of access and maintenance.
Figure 22 — Curb stop.
A building service line should be equipped with a stop and waste valve (Figure 23), which may be used for draining purposes. The stop and waste valve is designed with a drilled passage through the disc on the side of the valve body that provides a way to relieve system pressure or to drain the system. When the valve is closed, the water at the inlet side stops flowing. The water on the outlet or building side of the valve drains through the drilled passage in the valve body.
Figure 23 — Stop and waste valve.
Curb boxes, often referred to as valve boxes, are installed when underground valves must be accessible for on/off operations at ground level (Figure 24). This is often the case when the components of the water distribution system require maintenance or repair. Curb stops and meter stops are some of the buried valves that require valve boxes.
Figure 24 — Curb box.
Valve boxes are normally made of cast iron, plastic, or concrete. The yoke (or base) must be centered over the valve to provide sufficient space to engage the operating handle. The valve box must then extend upright to ground level. Many manufacturers make valve boxes with extension tubes that can be adjusted by sliding or screwing the extension tube up or down. It is important that the weight of the box does not rest directly on the valve or the piping. You can accomplish this by placing bricks or stone supports under the bottom edges of the valve box. This will prevent the box from settling, which could damage the valve or piping. Valve boxes are often covered with a cap to prevent access by unauthorized personnel and to prevent debris from entering the valve box. It is important to periodically clean and maintain valve boxes so that they fulfill their function of providing protected access to valves.
Water pressure is important to consider when sizing a service line. The types of flushing devices in a facility are an important factor in determining water supply pressure. Flushometers require more water pressure than a gravity tank flushing system can provide. The length of the building service line also needs to be considered. The longer it is, the more pressure it will take to transport the water to the building. You must know what type of fixtures and how many there are in order to supply enough water for all of them. You must determine how often the fixtures might be used and the height of the building. Each fixture that is installed must have adequate water supply pressure. Pipe diameters for rough-in of various fixtures are shown in the International Plumbing Code (IPC) Handbook, Table 604.5 and Table 3 below.
Table 3 — Minimum pipe size for plumbing fixtures.
|Water closet tank||3/8|
|Water closet with flushometer valve||1|
|Water closet with flush valve||1|
|Water closet, one piece||1/2|
|Urinal with flushometer valve||3/4|
|Urinal with flush tank||1/2|
|Water heater (domestic)||3/4|
|Bathtub (all sizes)||1/2|
|Combination sink and tray||1/2|
As water flows through pipe and fittings there is a resistance. The higher the flow and the smaller the pipe, the higher the resistance. In addition to calculating for head loss you also need to consider friction loss. Determine size of the pipe and the number and type of fittings used along with the distance of the run. Friction loss is also experienced when water needs to be pumped above the service line water level. As the level or height increases, as does friction loss. Booster pump and pressure tanks are used where the normal system pressure is low and needs to be increased. The stream of water in the pipe can be pictured as a series of layers of water traveling at different speeds with the center moving the fastest. The resistance to flow caused by these layers is called pipe friction. In a small pipe, this friction loss may be overcome by supplying water at a higher pressure than otherwise would be required. In a location where higher water pressure is not available, friction loss may be reduced by increasing the size of the pipe.
|Test Your Knowledge
4. Which of the following flexible connections is commonly used with a galvanized steel service line?
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The building water distribution system includes all the hot and cold water piping needed to supply installed fixtures. A shutoff valve, commonly a stop and waste valve, is installed just inside the building. The piping extending from this point becomes the cold water distribution main. Water is thus conveyed to various points throughout the building. Most of the piping is installed when the framework of the building is under construction. It is done at this time because it is easy to run the piping to the desired points in the wall for the various fixtures. For this fact it is imperative that you work with Builders (BUs), Steelworkers (SWs) and crew leaders to develop rough-in, installation, test and finishing schedules to maintain the projects critical timelines.
Galvanized steel piping is used extensively in interior water distribution systems. Swing joints are constructed to allow for flexibility in the water lines. Piping is screwed together with threaded fittings. Galvanized steel piping comes in 21 feet lengths.
Copper pipe or tubing is also used for interior water distribution systems. It is an easy material to work with, which makes it very popular. However, it costs more than other piping materials. Hard drawn copper is the most commonly used; however, soft drawn copper can also be installed.
CPVC is the only plastic pipe used for interior plumbing. It is commonly used for interior distribution systems because it is easy to install, will not rust, rot or corrode, and is very inexpensive. CPVC is a plastic pipe made to withstand temperatures of 180° and 100 psi of pressure.
Cross-linked polyethylene (PEX) is a high-temperature, flexible plastic (polymer) pipe. The cross-linking raises the thermal stability of the material under load. Thus, the resistance to environmental stress cracking, creep, and slow crack growth are greatly improved over polyethylene. PEX pipe is approved for potable hot and cold water plumbing systems. PEX tubing is light weight, and it can withstand operating temperatures of up to 200° F. It is flexible and can easily be bent around corners and obstacles, and through floor systems. Sizes of PEX tubing range from 3/8-inch to over 2 inches.
Buildings will have a cold water distribution system. As you can see in Figure 25, branch lines are connected to the distribution main by using a reducing tee, nipple, and a 90° elbow. This arrangement is called a swing joint. The fixture supply risers are vertical pipes connected to the branch lines by means of a 90° elbow. Risers should be supported at each floor level and at joints. It is also necessary to support these risers near fixture outlets (Figure 26). These headers and braces will hold the pipe in position.
Figure 25 — Water supply branch line.
Figure 26 — Water distribution pipelines.
The hot water distribution system begins at the water heater. Figure 26 shows both hot and cold supply lines. Branch lines are installed to run horizontally at a slight grade toward the shutoff valve or stop and waste valve (This allows you to drain the system). Install a gate valve at the base of a riser that supplies a large number of fixtures, such as those in a multistory building. With this arrangement, you can shut off the water supply in any given section without turning off the water supply to other portions of the building.
In accordance with the IPC, Article 604.3, the water distribution system shall be designed, and pipe sizes shall be selected such that under conditions of peak demand, the capacities at the fixture supply pipe outlets shall not be less than shown in Table 4 below and Table 604.3 of the IPC.
Table 4 — Water distribution system design criteria.
|Bathtub, balanced-pressure, thermostatic or combination balanced-pressure/thermostatic mixing valve||4||20|
|Bidet, thermostatic mixing valve||2||20|
|Shower, balanced-pressure thermostatic or combination balanced-pressure/thermostatic mixing valve||3||20|
|Sillcock, hose bibb||5||8|
|Water closet, blow out, flushometer valve||25||45|
|Water closet, flushometer tank||1.6||20|
|Water closet, siphonic, flushometer valve||25||35|
|Water closet, tank, close coupled||3||20|
|Water closet, tank, one piece||6||20|
The minimum size of a fixture supply pipe is shown in Table 3. The fixture supply pipe shall not terminate more than 30 inches from the point of connection to the fixture. A reduced size flexible water connector installed between the supply pipe and fixture must be of an approved types, as detailed by the IPC. The supply pipe shall extend to the floor or wall adjacent to the fixture.
|Test Your Knowledge
5. When installing a service sink, what is the minimum flow pressure value needed?
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All fixtures have different rough-in (piping that is installed in walls, floors, and ceilings during construction phase before wallboard is installed) requirements. In this section we will discuss the water supply rough-in requirements to fixtures.
If you install a lavatory, it may be a wall hung, pedestal, counter top, or trough type. Therefore, it is important for you to have the manufacturer’s rough-in specifications for the installation. You will probably be given a sheet like the one shown in Figure 27. It will give you the rough-in dimensions you will need to do the job correctly.
Figure 27 — Lavatory specifications.
When roughing-in a lavatory, you must install both the hot and cold water supply lines. Install the hot water line on the left side of the lavatory and the cold water on the right. The left and right side are determined while facing the lavatory. The minimum sized pipe used to supply water to a lavatory is 1/2 inch.
A 2 inch x 6 inch mounting board (hereafter referred to as a backing board) is used to support a wall hung lavatory. The backing board must be nailed between the studs (Figure 28) before the sheet rock is installed. This board serves as an anchor for the bracket screws because sheet rock is not strong enough to support the weight of the fixture.
Figure 28 — Mounting board.
There are four basic types of urinals; wall hung, pedestal, trough, and stall. Each type is different and the water supply rough-ins to them will also be different.
To obtain rough-in measurements for a urinal, consult the manufacturer's rough-in specification sheet (see Figure 29). As you can see, this sheet shows two views of the unit and indicates the measurements you need for rough-in purposes.
Figure 29 — Flush type wall hung urinal.
The urinal requires only a cold water supply line.
The minimum size pipe used to supply water to a flushometer type urinal is 3/4 inches.
In the United States, tank type urinals are rarely found, these types of fixtures however are still common in many European Countries. The minimum size supply line for a tank type urinal is 1/2 inch.
Use a 2 inch X 6 inch backing board to support a wall hung urinal. Use only brass screws and bolts when installing a urinal because of their resistance to corrosion.
Water closets require a considerable flow of water to maintain necessary sanitation. The greatest possibility of contamination exists at these fixtures because of the quick growth of bacteria. Piping systems for water closets must be installed according to the manufacturer’s specifications to increase their efficiency and minimize maintenance costs.
Refer to the manufacturer’s specification sheet prior to roughing-in a water closet.
Water closets require only a cold water supply.
The minimum size pipe used to supply a tank type water closet is 1/2 inch. The rough-in will extend approximately 1 1/2 inch through the wall. Once the wall is “finished”, screw an angle stop valve onto the rough-in nipple. Figure 30 shows the specifications of a tank type water closet.
Figure 30 — Tank type water closet.
A flushometer type water closet requires a 1inch supply because of the large volume of water needed for flushing action.
Before roughing-in water supplies to a fixture, you must know the type of fixture to be installed. The type of fixture is identified on the blueprints for the particular job. Refer to the manufacturer’s rough-in specifications for the rough-in piping measurements.
Figure 31 shows an example of a manufacturer’s rough-in specifications for a bathtub and shower combination. The rough-in sheet gives two views and the necessary measurements for correct location and installation of rough-in piping for the fixture.
Figure 31 — Rough-in specifications for a shower and bathtub combination.
The hot and cold water supply risers are connected to the branch by means of a 90° elbow. It will extend above the finished floor to the heights given for that particular fixture indicated in the manufacturer's rough-in specifications. Both hot and cold water supply lines are 1/2 inch in diameter and are installed 8 inches apart.
Mixing valves can have three handles, two handles, or only one which can be used to adjust the temperature of the water and control flow. Installation of the mixing valve, the riser for the shower head, and the piping for the tub spout are all part of the rough-in of the fixture.
A 2 inch x 4 inch header board is cut to fit snugly between the studs. The header has two holes drilled through it 8 inches apart. They should be drilled only large enough to accommodate the piping. The header will support and align the risers (Figure 32).
Figure 32 — Header installation.
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Among the pipe materials installed underground are cast-iron soil pipe, vitrified clay pipe, concrete pipe, and plastic pipe.
Cast-iron soil pipe and fittings are composed of gray cast iron made of compact, closegrained pig iron, scrap iron and steel, metallurgical coke, and limestone. Cast-iron soil pipe is commonly used in and under buildings, protruding from 2 to 10 feet from the building. (The IPC recommends at least 3 feet.) Here it connects into a concrete, plastic, or clay house sewer line. Cast-iron soil pipe is also used under roads or other places of heavy traffic.
When the soil is unstable, it is better to use cast iron soil pipe; however, do not use cast-iron soil pipe in soil containing cinders or ashes; the reason is that the soil may contain sulfuric acids, which cause the pipe to corrode and to deteriorate rapidly.
When the soil contains cinders and ashes, use vitrified clay or plastic pipe instead of cast-iron soil pipe.
The cast-iron soil pipe used in plumbing installations comes in 5- and 10-foot lengths. Sizes of cast-iron soil pipe are 2, 3, 4, 6, 8, 10, 12, and 15 inches nominal inside diameter. It is available as single hub or double hub in design, as shown in Figure 33.
Figure 33 — Single hub and double hub cast iron soil pipe.
Note that single-hub pipe has a hub at one end and a spigot at the other. The double hub pipe has a hub at both ends. Hubs, or bells, of cast-iron soil pipe are enlarged sleeve-like fittings. In previous common plumbing practices they were cast as a part of the pipe and were used to make a water and pressure-tight joint with oakum and lead. This is particularly important to know when working on, rehabbing or demoing older plumbing services. These joints were made with a lead compound and are significant lead hazards as such they should be handled with care and reported to your crew leader and safety petty officer immediately.
Cast-iron soil pipe is generally available in two weights: standard or service (SV) and extra heavy (XH). The extra heavy pipe is used where superior strength is required, for example, under roadways, where the pipe may vibrate or settle slightly, and tall stacks. Standard or service weight pipe is adequate for most construction.
Cast-iron soil pipe sections are generally 5 and 10 feet in length, but strictly speaking, this is not true. The reference to a 5-foot length of pipe applies to the laying length, not the overall dimensions. For clarity, first note that cast-iron soil pipe in 2, 3, 4, and 6 inch (inside) diameter sizes are in common use. The length of the bell for the 3 inch diameter pipe is 2 3/4 inches; and for the 4 and 6 inch diameter sizes, the length is 3 inches. Now note that while the laying length of a 4 inch diameter cast-iron soil pipe is 5 feet, the overall length is 5 feet 3 inches.
The most common measurement of cast-iron soil pipe, for a shorter length than 5 feet, is the overall measurement. When making this measurement for 4 inch pipe, take the desired length of pipe for the installation and add 3 inches to it for the bell.
Before joining cast-iron pipe, you often have to cut the pipe to provide the desired length. Cast-iron soil pipe can be cut with an abrasive cutter, a band saw, a hydraulic manual snap or ratchet cutter (Figure 34, Views A and B), or a hammer and chisel. The hammer and chisel method is slow and used only when other cutting tools are not available. Here is a step-by-step procedure for cutting with a hammer and chisel.
Figure 34 — Ratchet cutter and squeeze cutter.
Figure 35 — Supporting soil pipe for cutting.
Another means of cutting a short piece, 1 or 2 inches, is with a hacksaw and an adjustable wrench. Cut a groove with the hacksaw around the pipe to a depth equal to one half of the wall thickness of the pipe. Break away the section of pipe using an adjustable wrench as a lever, as shown in Figure 36.
Figure 36 — Cutting cast iron pipe with hacksaw and adjustable wrench.
A good point to remember is that if you must cut a short piece of CISP, cut it from a piece of double hub pipe. Thus the remaining pipe still has a hub and can be used.
CISP fittings are used for making branch connections or changes in the direction of a line. Both CISP and fittings are brittle, so exercise care to avoid dropping them on a hard surface. Some of the CISP fittings you may use in your work are described below.
A number of different types of bends are generally used on jobs involving CISP. Some of the common types are the 1/16, 1/8, short sweep 1/4, long sweep 1/4, and reducing 1/4 bend. Look at Figure 37 to get an idea of the shape and appearance of each of these types of bends.
Figure 37 — Types of CISP bends.
The 1/16 bend is used to change the direction of a cast-iron soil pipeline 22 1/2 degrees. A 1/8 bend is used to change the direction of a cast-iron soil pipeline 45 degrees. The SHORT SWEEP 1/4 bend is a fitting used to change the direction of a castiron soil pipeline 90 degrees in a short space. The LONG SWEEP 1/4 bend is used to change the direction of a cast-iron soil pipeline 90 degrees, but more gradually than the short sweep 1/4 bend. The REDUCING 1/4 bend gradually changes the direction of the pipe 90 degrees, and in the sweep portion, it reduces nearly one size. A 4 by 3 reducing long sweep 1/4 bend has a 4-inch SPIGOT on one end, reducing 90 degrees to a 3 1/4- inch HUB on the other end. Note that for all CISP fittings, the spigot end is always listed first.
Tees connect branches to continuous lines. Learn to recognize the four designs of tees shown in Figure 38. For connecting lines of different sizes, REDUCING tees are often suitable.
Figure 38 —CISP tees.
The TAPPED tee is frequently used in the venting system; it is called the main vent tee. The SANITARY tee is commonly used in a main stack to allow the takeoff of a CISP branch.
The TEST tee is used in stack and waste installations where the vertical stack joins the horizontal sanitary sewer (Figure 39). It is installed at this point, so you can insert a test plug and fill the system with water in testing for tightness. The test tee is also used in multistory construction.
Figure 39 — Typical stack and vent installation.
Four types of CISP 90-degree Y-branches are in general use, as shown in Figure 40. These are normally referred to as combination Y and 1/8 bends.
Figure 40 — Types of CISP, 90° Y-branch.
The STRAIGHT type of 90-degree Y-branch has one section that is straight through and a takeoff on one side. The side takeoff starts out as a 45-degree takeoff and bends into a 90-degree takeoff. This type of branch is used in sanitary sewer systems where a branch feeds into the main, and it is desirable for the incoming branch to feed into the main as nearly as possible in a line parallel to the main flow. Refer to Figure 40.
The REDUCING 90-degree Y-branch is similar to the straight type; however, as shown in Figure 38, the branch takeoff of the 90-degree Y-branch is smaller than the main straight-through portion. It is generally used in the same way as the straight type, except the branch coming into the main is a smaller pipe than the main.
The DOUBLE 90-degree Y-branch (or DOUBLE COMBINATION Y and 1/8 BEND) is easy to recognize since there is a 45-degree takeoff bending into a 90-degree takeoff on both sides of the fitting, as shown in Figure 38. It is very useful as an individual vent.
The BOX type of 90-degree Y-branch has two takeoffs. It is designed for each takeoff to form a 90-degree angle with the main pipe. The two takeoffs are spaced 90 degrees apart.
The increaser is used to increase the size (diameter) of a straight-through line. It is often used at the top of a main stack and vent.
A closet bend is a special fitting inserted into a soil branch. This enables the soil branch to be fitted to the water closet. It may be untapped or have either one or two side taps for waste to vent use. Closet bends are made in different styles to fit different types of closet flanges (rims for attachment). One type has a spigot end for caulking into the branch line and a scored end (marked with lines) to fit into the closet flange. The scoring makes it easier to cut the bend to the desired length for a given connection. Another type has a hub connected to the closet flange with a sleeve or short length of pipe. The end attached into the soil line is scored for cutting to size. Still other types may be scored for cutting at both ends or may be of the regular hub-and-spigot pattern.
Regular offsets are used to carry the soil or waste lines past an obstruction, such as a part of the building.
There are various methods for joining pipe. This means that you must know the procedure to make various types of joints required for the kind of pipe to be joined. Compression joints and no-hub joints are means for connecting pipes. Figure 45 shows these types of joints.
Figure 45 — Various joints used to connect CISP fittings.
In making attached joints, you need various types of equipment. Because of the importance of this equipment, this section will discuss the common types of attaching equipment and safety procedures to observe when making attached joints.
In making a compression joint, be sure to clean the internal surface of the hub and the external surface of the pipe and/or fitting to be joined. When using a cut pipe, remove the sharp edge by peening or by lightly filing the rough edge to permit the pipe to slide and NOT gouge into the gasket. Insert the gasket into the hub, and make sure the retaining flange or collar of the gasket is next to the face of the hub. Be sure to use the recommended lubricants available (normally soap or an adhesive type). Apply them to the inside of the gasket. Align the spigot and hub to be joined, keeping the spigot and hub in a straight line. The spigot end of the pipe or fitting can be forced into the gasket with an assembly tool.
To join CISP as a no-hub joint, place a neoprene or an elastomeric gasket on the end of one pipe and the stainless steel shield and clamp assembly, commonly referred to as a no hub coupling, as shown in Figure 46, on the end of the other pipe.
Figure 46 — No hub pipe and fittings.
Firmly seat the pipe ends against the integrally molded shoulder inside the gasket. Slide the shield and clamps into position over the gasket and tighten the stainless steel clamps alternately and firmly to about 60 inch-pounds of torque. No Hub fittings are NOT to be used under slab and must be accessible.
Vitrified clay pipe is made of moistened powdered clay. It is available in laying lengths of 2, 2 1/2, and 3 feet and in diameters ranging from 4 to 42 inches. Like CISP, it has a bell end and a spigot end to make joining easy. After the pipe is taken from the casting, it is glazed and fired in large kilns to create a moisture proof baked finish. It is used for house sewer lines, sanitary sewer mains, and storm drains. The types of fittings for clay pipe are primarily bends, tees, and Y-branches. You may have to use plain precast concrete pipe for sewers in the smaller sizes (less than 24 inches). This pipe is not reinforced with steel. This concrete pipe is similar to vitrified clay pipe in measuring, cutting, joining, and handling.
Handling and Storing Clay Pipe
Be careful when you store and handle clay pipe because it is very fragile and cracks easily. Never drop clay pipe or roll it down an embankment without control. Do not drop heavy objects on clay pipe. When backfilling a trench, do not use fill with rocks or other heavy debris in it. Tamp by hand or by pneumatic tampers, bearing in mind the density of the backfill. Lay clay pipe in a trench and bed it evenly and firmly. The more perfect the bedding, the greater the load the pipe can sustain. Common sense can save a lot of time by eliminating rework.
Vitrified clay and concrete pipe, both available in short lengths, seldom need cutting except for manholes and inlets. If, after measurement, you have to cut vitrified clay or concrete pipe, score it with a chisel, deepening the cut gradually until the pipe breaks cleanly at the desired point. Vitrified clay and concrete pipes may also be cut with CISP “snap-off’ or “chain” cutters.
Figure 47 shows some common fittings used with vitrified clay and concrete pipes. Note that these types of pipes are used outside the building. This greatly reduces the number of different types of fittings required.
Figure 47 — Gross section of clay or concrete fittings.
Joints on vitrified clay and concrete pipe may be made of cement or bituminous compounds. Cement joints may be made of grout, which is a mixture of cement, sand, and water. The following procedure may be used as a guide in joining pipe with grout. The procedure for joining pipe with bituminous compounds is very similar.
Note that a regular swab, with some additional rags tied to the end to compensate for larger size pipe, is ideal for dragging through each length to remove the excess mortar.
The use of “speed seal joints” (rubber rings) in joining vitrified clay pipe has become widespread. Speed seal joints eliminate the use of oakum and mortar joints for sewer mains. This speed seal is made a part of the vitrified pipe joint when manufactured. It is made of permanent polyvinyl chloride and called a “plastisol joint connection.” This type of joint helps to ensure tight joints that are root-proof and flexible.
One person can quickly and easily install the speed seal, or mechanical seal. To make the joint, first insert the spigot end into the bell or hub.
Then give the pipe a strong push, so the spigot locks into the hub seal. A solution of liquid soap spread on the joint will help it slip into place easily. Other types of mechanical seal joints are also available. They all use about the same method of installation. Special mechanical seal adapters are made to join vitrified clay pipe with CISP or CISP to vitrified clay pipe.
At first, plastic was used for lawn sprinklers, farm water systems, and acid drainage from mines. Now plastic pipe is used for all kinds of applications, from shipboard installations to municipal water treatment and domestic water uses.
The advantages of plastic pipe or as it is commonly referred to, Polyvinylchloride (PVC), include resistance to nearly all acids, caustics, salt solutions, and other corrosive liquids. It does not scale, pit, corrode, or rust. Bacteria do not grow well, and it is also nontoxic. PVC piping has very low-friction resistance because of its smooth, inner surface. Being nonconductive, it is not subject to electrolytic corrosion. PVC piping can be used underground in acid, alkaline, wet, or dry soil without a protective coating. It is strong and can handle operating pressures in most moderate service processes within the temperature range of that particular material. PVC piping is light in comparison to metal. Finally, it can be easily joined in a wide variety of methods. Each method has a certain advantage.
Handling and Storing of PVC Piping
When unloading PVC piping, do not drop it on the ground. Remember, scratches and gouges from dragging it on rough surfaces tend to reduce the pressure-carrying capacity. Store PVC piping on racks to prevent sagging. Remove burrs and sharp edges on storage racks before storing the pipe. Store PVC piping in a shaded area away from any source of heat that could cause damage to the pipe. During prolonged storage, do not stack it more than 2 feet high because the weight causes it to flatten or go out of round. Before installing PVC piping, inspect all pipe and fittings for cuts, scratches, buckling, and kinks that should be cut out. Also, store piping out of direct sunlight, as it breaks down the chemical compound makes it brittle and unserviceable.
When cutting PVC piping, use a miter box, when utilizing the following types of saws: fine-toothed hacksaw, circular saw, band saw, or reciprocating saw with carbide-tipped blades. Pipe and tube cutters can be used when adapted with a deeper cutting blade made for cutting PVC piping. DO NOT USE a tubing cutter. The cutting wheel will not cut deep enough, and the outside diameter (OD) of the pipe will become larger. Use a miter box or hold-down rig to help cut the pipe square. Remove all burrs and chips from both the inside diameter (ID) and OD of the pipe. Level the end of the pipe to approximately 1/16 inch to 3/32 inch at a 10-degree to 15-degree angle. This minimizes the wiping of solvent from the ID of the fitting, as the pipe is put into the socket. You can bevel the end of the pipe with a coarse file or special beveling tool.
Plastic flanges and flange fittings (Figure 48) are available in a full range of sizes and may be attached to the pipe. Soft rubber gaskets are preferred with plastic flanges. When tightening flange bolts, pull them down gradually to a uniform tightness and in a diametrical manner, as shown in Figure 49.
Figure 48 — PVC piping fittings. Figure
3-49 — Diametric order of tightening flange bolts.
There are four methods of joining PVC piping: solvent welding, fusion welding, fillet welding, and threading. These types are mentioned here and explained in detail in course 4 of this manual.
Placing PVC Piping in the Ground
On hot days, after the plastic pipe has been cement solvent welded, it is a good idea to snake the pipe beside the ditch or if the ditch is wide enough, in the ditch during its required drying time. DO NOT APPLY STRESS TO or DISTURB A JOINT THAT IS DRYING. Snaking gives added length to the pipeline to compensate for thermal contraction as the pipe cools. When the temperature change is less than 30°F, snaking is not necessary. When cement solvent welding on a hot, summer day during the late afternoon, be sure to snake the line. Since the pipe dries during the cool of the night, the thermal contraction of the pipe could stress the joint and pull the pipe apart due to inadequate time for the cement to cure.
Testing should be done in two intervals:
Assemble small pipes and join them in sections on top of the ground and lay them in the trench by hand. Large, heavy pipes are usually laid in the trench and then joined. These pipes may be lowered into the trench by rope, cable, or chain. Larger pipe may require the use of machinery operated by an Equipment Operator (EO) or licensed individual.
When assembling and joining pipes outside the trench, make sure you are a safe distance from the edge of the trench to prevent cave-ins. Also, do not leave tools or materials near the edge of a trench where workers may knock them off and injure themselves or lose their footing and fall into the trench.
Lay sewer pipes on a compacted bed of sand, gravel, or material taken from the trench excavation, if suitable, to provide a slightly yielding and uniform bearing. This step assures safe support for the pipe, the fill, and the surface loads. When pipes are laid on sand, gravel, or similar material, the weight of the pipe usually provides a suitable equalizing bed.
Embed pipelines carefully, so they do not settle at any point. Settling causes suspended matter to collect in the lower portion of the pipe, restricting the flow and reducing the handling capacity of the line.
After you have laid the pipes, your next step is to check the grade and align the pipeline. This is very important in installing an underground sewer system. Remember, sewage does not flow uphill, unless of course you are using forced main or a pump, as a lift station does. Lay the pipe so the flow of the sanitary waste in each length of pipe flows from the hub end to the spigot end or we could say the hub end is upstream. Place each length of pipe starting at the lowest elevation and working up the grade; therefore, the spigot is inserted into the hub of the length laid previously. Check each length for grade and alignment before placing the next length.
When you are grading for the proper pitch per foot, use the method shown in Figure 50 as a guide. This figure shows a ditch with batter boards used in transferring line and grade to trench and also shows a stick for checking grade.
Figure 50 — Laying sewer pipe to line and grade.
An engineering aid is responsible for setting the batter boards at the proper level for the job at hand. Batter boards are placed across the trench at about 25 to 50-foot intervals. Elevations are run by an EA, and a mark is placed on the stakes at some even-foot distance above the invert (the lowest point on the inside of the pipe) of the sewer. A nail is then driven in the top of the batter boards, and a cord is stretched from board to board. The center line for the pipe is then transferred from the cord to the bottom of the trench by means of a plumb bob. Grade is transferred by means of a stick, marked in even-foot marks, having a short piece fastened at a right angle to its lower end. Grade is checked by placing the short piece on the invert of each length of sewer pipe and aligning the proper mark on the grade rod to the cord.
After completing the rough-in piping of a project, test and inspect all the piping for leaks. The purpose of testing the pipeline is to make sure the joints are tight enough to withstand working pressure.
Before covering the pipe, test it for leakage. There are several methods of effecting this test. The most widely used is the water test, although you may use an air test or odor test.
Here are the main steps in making a water test, commonly referred to as a Stack test. At the lowest point of the section to be tested, insert a test plug in the open end of the pipe or a test tee, like those shown in Figure 51, and plug other openings. Fill the pipe to its highest level with water; an IO-foot head is required. Leave the water in the pipe for at least 15 minutes before starting the test. This allows the oakum to soak up some water before you look for leaks. If necessary, refill the pipe to overflow and check each joint for leaks.
Figure 51 — Test plugs and test tees.
Before making an air test, fill the system with water and allow it to stand. Drain the water from the lines and reinsert the test plug. Close all openings and apply air pressure of at least 5 pounds per square inch (psi). In a satisfactory test, the line should hold 5 pounds psi for 15 minutes. If it does not, cover the joints with a soapy water solution and check for bubbles at the leak.
Before making an odor test, plug all openings in the sewer and the branches. After sealing the openings, pour 2 ounces of oil of peppermint in each line or stack. Then pour approximately 1 gallon of boiling water into the stack and seal it. The odor of peppermint at any point in the installation indicates a leak. The inspector, checking the installation for leaks, should not be near the oil of peppermint at any time before the inspection. Such exposure rapidly dulls his or her sensitivity to the odor of peppermint. The peppermint test is not as conclusive as the water and air tests described above, since there is no pressure on the pipe.
Repeat tests as necessary until all the leaks are located and repaired. Where a system of pipelines has been installed using gaskets, test one floor at a time. Should there be more than one floor to be tested, be sure all bends, changes of direction, and ends of runs are restrained (limited).
Normally, it is not your responsibility to construct manholes. They are made of concrete or brick; however, you may be working with the Builders (BU) in spotting the location for the manholes. Figure 52 shows a typical drop manhole.
Figure 52 — Standard drop manhole for sanitary or storm drainage system.
Watertight manholes are made of brick or concrete, 4 feet in diameter at sewer level. Place them at junctions and bends in the line. Space them preferably 300 feet apart for 8 inch pipe, 400 feet apart for 10 to 15 inch pipe, 500 feet apart for 18 to 48 inch pipe, and 600 feet apart for larger sizes. Lay sewers straight to line and grade between manholes; changes in the size of sewer lines must take place only at the manholes. The crown of the outlet pipe from a manhole should be on a line with or below the crown of the inlet pipe. When the invert of the inlet pipe is more than 2 feet above that of the outlet pipe, provide a drop manhole to conduct the sewage to a lower level with minimum turbulence.
After all pipelines have been laid and tested, they are ready to be covered; this process is known as backfilling and tamping. Use the method described below for sewer lines.
Tamp fine material, free from stones and other debris, in uniform layers, that are commonly 6 inch lifts, with a small hand or air operated tamper under, around, and over the pipe. Use a hand shovel to backfill the ditch until the pipe has a 2 foot covering. Place this fill in the ditch and tamp it in 4 inch layers or less. It should proceed evenly on each side of the pipe, so injurious side pressure cannot occur. Make sure you do NOT walk on the pipe until you have at least 1 foot of soil tamped over the pipe. Until 2 feet of fill has been placed over the pipe, the filling should be done carefully with hand shovels; after that, machinery may be used for faster backfilling. However, do not let the machinery run over the line.
Puddling, or flooding, with water to consolidate the backfill should NOT be done for a sewer line. The sections of pipe are in short lengths and tend to settle very rapidly to form pockets or low spots in the line.
|Test Your Knowledge
6. Which of the following tees are used in stack and waste installations?
- To Table of Contents -
After the underground piping is installed for a sewer system, the next phase is to install the aboveground piping. The following sections provide information on materials applicable to the installation of aboveground sewage piping. Installation procedures are the same for aboveground and underground sewer pipe.
The sanitary waste system collects wastewater from plumbing fixtures such as water closets, sinks, tubs, showers, and lavatories and allows it to flow by gravity through the piping to a treatment plant. Waste piping systems are installed to allow the waste to gravity flow through the piping as much as possible. Therefore, horizontal piping in the sanitary waste system is generally sloped at 1/4 inch per foot. Large diameter pipe may be sloped slightly less.
Knowledge of these systems are important for two fundamental reasons: (1) During residential construction, detailed drawings of waste systems are not usually available, therefore, you may have to design the system yourself (based on your knowledge of the function and purpose of system components) and, (2) During commercial construction jobs, knowledge of system design and function is required to install more complicated systems within the requirements of the plumbing code.
Pipes that carry fecal matter and discharges from water closets.
Pipes that carry liquid waste, free of fecal matter and discharges, from fixtures other than water closets.
Vertical systems of soil, waste, or vent piping extending through one or more stories.
Any part of the piping system other than a main, riser, or a stack; normally any horizontal pipe in a waste system is generally referred to as a branch.
Piping sizes are defined by the length of sections, and by the inside diameter (ID).
The building drain is the lowest part of a building’s drainage system that receives the discharge from soil, waste, and other drainage pipes inside the building, and conveys it to the building sewer, which begins two feet outside the building wall.
The horizontal piping of the drainage system, which extends from the end of the building drain (2 feet outside the building), is called the building sewer. It conveys the discharge it receives from the building drain to a public sewer, private sewer, individual disposal system, or other point of disposal.
Refer to Figure 53 for locations of above terms.
Figure 53 — Basic sanitary waste system components.
A number of different types of pipes are used in the aboveground and interior parts of a plumbing system. Some of the common types of pipes are discussed briefly below.
Excellent material for aboveground plumbing, it is costly. It is available in lengths from 18 to 22 feet. Galvanized wrought iron pipe is constructed of wrought iron dipped in molten zinc to protect it from corrosion and provide high resistance to acid waste.
Composed of an alloy of cast iron and silicon. It is used to serve chemical laboratories and other installations through which acid waste flows. In handling acid resistant pipe, such as Durion™, be careful because it is very brittle and cracks easily. It is cast in 5 foot lengths and comes in single and double hubs.
The types of joints made with cast iron soil pipe are: bell and spigot pipe, which uses a compression gasket; and no hub pipe, which uses no hub couplings. Disadvantages of using cast iron pipe are that it is heavy (which requires more supports) and subject to corrosion. In addition, cast iron piping is difficult to cut and fit.
Brass pipe consists of an alloy of zinc and copper. It has a smooth interior and can resist most acids; however, it is expensive. It is available in 20 foot lengths; because it tends to bend, it must be supported at intervals of 8 to 10 feet.
Used to carry distilled water for batteries; however, tin lined, block tin, glass, or some types of plastic pipe must be used where no impurities are acceptable. Because it bends easily, lead pipe must be well supported. It is available in three weights: (1) standard, (2) common, and (3) extra heavy. The standard weight is most commonly used.
Galvanized steel pipe may be used for small drains and vent piping. It should not be used for drains attached to urinals because it will quickly corrode and leak. Most galvanized pipe is standard weight and will be joined by threaded joints.
Suitable for use in waste, vent, and water installations. Remember that ammonia and water corrode copper and bronze lines. Also, when you use copper for waste pipe installations, always make sure it is rigid to overcome sagging. You can obtain the pipe in convenient lengths, then cut it to size for the job at hand.
Suitable for use aboveground for sewage, venting, and water.
Plastic pipe is commonly used on interior drainage systems. Plastic piping is lightweight, easy to install and will not rust, rot, or corrode. PVC and Acrylonitrile-butadiene-styrene (ABS) are the most commonly used piping for constructing interior Drainage Waste and Venting (DWV) systems. They will be of either Schedule 40 or DWV thickness and can be joined by specifically formulated solvent glue. PVC is by far the most commonly used plastic pipe material.
There are waste fittings designed for virtually any situation that you may encounter during the installation of a sanitary waste system. The text below addresses only the most commonly used.
Bends are used for making turns in a run of waste piping. The degree of turn a bend provides may be expressed in terms of degrees or fractions. For example, a bend that makes a 45 degree turn is called a 1/8 bend and a bend that makes a 90 degree turn is called a 1/4 (quarter) bend. See Figure 54.
Figure 54 — Types of bends.
The closet bend is a 90° or 1/4 bend with a long branch designed specifically for making a connection between a closet flange and a soil stack. See Figure 55.
Figure 55 — Closet bend.
A wye is used to change the direction of flow less than 90%. It usually branches off a pipe at a 45% angle. See Figure 56.
Figure 56 — Wye connection.
A sanitary tee is used for branching off of a pipe at a 90 degree angle. See Figure 57.
Figure 57 — Sanitary tee.
Most often the sanitary tee is used to change the direction of flow from a branch or horizontal drain to a stack. The branch opening of the fitting is gradually sloped to gently guide the wastewater from the branch into the vertical piping of the stack. Branch openings of the sanitary tee may or may not be tapped. The term “tapped” indicates that the opening of the fitting has female pipe threads. A sanitary tee cannot be laid on its back or side because when a sewer auger is used for unclogging, the auger can go in either direction in the line. To avoid this situation a wye or wye and 1/8 (Figure 56) bend should be used.
The primary purpose of the test tee is to test the system. It is normally the first fitting on top of the stack base. A plug is threaded into the branch opening to seal the system. The plug stays in place except when performing leak tests. If no provisions have been made for cleaning the sanitary sewer system, the test tee can be used as a clean out because it is shaped similar to a sanitary tee. Ensure that you do not damage the threads of the test tee with the auger cable. See Figure 58.
Figure3-58 — Test tee.
This fitting is commonly used as a stack base. It is normally installed at the base of soil or waste stacks. Its design allows for use in branches or the building drain to allow for change of direction from a vertical pipe to horizontal pipe. This fitting allows for a 90- degree change of direction off of a run of horizontal pipe. The branch of the fitting is long, sweeping, and provides a more gradual change of direction than a sanitary tee. A combo wye and 1/8 bend can be used either laying on its back or side. See Figure 59.
Figure 59 — Combination wye and 1/8 bend.
Used to connect piping from four different directions. This fitting would be used to connect two fixtures to a single soil or waste stack. See Figure 60.
Figure 60 Double tee.
A four way fitting similar to a combo but with two opposing branch connections. See Figure 61.
Figure3-61 — Double wye and 1/8 bend.
A cleanout fitting consists of a threaded opening and cap. It is designed to allow the utilities worker access to the piping system for removing stoppages. It is common to install a cleanout on the stack base of the building drain during residential construction. Multiple cleanouts are generally installed during commercial construction. See Figure 62.
Figure 62 — Cleanout.
A trap is a device or fitting used to provide a water seal, which if properly vented, will prevent sewer gases from entering the building. Sewer gases formed by decomposing organic material in wastewater are potentially explosive and/or combustible. These gases, besides being obnoxious, may also be harmful if inhaled. For these reasons, a trap should be installed on every plumbing fixture. Traps are generally installed at the piping connection between the plumbing fixture and the waste system piping. There are several types of traps that may be installed to protect buildings and their occupants from sewer gases. Note the parts of a trap are labeled in Figure 63.
Figure 63 — Parts of a trap.
A P-trap is the most commonly used trap on plumbing fixtures. It gets its name from its design. It is used mainly on lavatories, sinks, tubs, and shower units. It contains a two inch water seal. See Figure 64.
Figure 64 — P-Trap.
Various types of P-traps are available, so designs may differ from one manufacturer to another. The P-trap is usually made of nickel or chrome-plated brass, malleable galvanized; cast iron, other metal alloys, and plastic.
The P-trap is used for fixtures suspended from the walls or supported on pedestals, for instance, lavatories, sinks, and urinals. At times the P-trap may also be suitable in showers, baths, and installations that do not waste large amounts of water.
When using a P-trap for fixtures suspended from the wall, install it as close to the fixture as possible. Be careful not to install a vertical leg that is too long between the trap and the fixture. It is also important for the horizontal leg connection to the waste system to be short for ventilation purposes.
Deep P-traps are very similar to P-traps. The only physical difference is that the Deep P-trap has 4 inch water seal as opposed to the P-trap’s 2 inch water seal. Deep P-traps are generally installed on fixtures that are seldom used, such as a deep sink in a janitor's closet or a floor drain in a remote location. The Deep P-trap will not evaporate as quickly during periods of non-use and therefore will continue to protect building occupants from sewer gases. See Figure 65.
Figure 65 — Deep P-Trap.
Many plumbing fixtures may be manufactured with a trap as an internal part of the fixture. This type of trap is called an integral trap. A good example of a fixture with an integral trap is the water closet. See Figure 66. Some urinals are also manufactured with an integral trap.
Figure 66 — Integral trap.
There are several ways the water seal in a trap may be depleted or lost. Again, lack of a sufficient water seal within a trap is dangerous due to the sewer gases that form in a waste system. Therefore, you should be aware of how trap seal loss may occur. In the four paragraphs that follow, you will find a description of ways by which trap seals are lost.
Direct siphonage commonly occurs in unvented or improperly vented traps. Direct siphonage starts when water in a fixture exits the fixture abruptly. The water leaving the fixture creates unequal atmospheric pressure on the inlet and outlet sides of the trap seal. The higher pressure on the inlet side pushes the water out of the trap. The result is most of the water in the trap discharges into the vertical pipe that serves as a drain for the fixture. If trap seal loss occurs, sewer gases can then enter the structure, thereby creating a fire or explosion hazard and also offensive odors. The way to prevent direct siphonage is to ensure all traps are adequately vented during installation of the waste system. See Figure 67.
Figure 67 — Direct siphonage.
Siphonage by Momentum
Siphonage by momentum is the loss of a trap's water seal due to the momentum of water passing the trap outlet, which creates a negative pressure on the outlet side of the trap. Consequently, the water is drawn out of the trap and discharged into the vertical pipe that serves as a drain for the fixture. This type of trap seal loss normally occurs in buildings with more than one floor. Water is discharged from the fixture at the upper floor level, and as the water drops in the vertical pipe, it gains momentum. As the water passes the opening of the trap on the fixture at a lower floor level, the water is drawn out of the trap of the lower fixture. Improper venting of fixtures further aggravates this condition. It can be avoided by individually venting each fixture.
This type of trap seal loss is caused by some foreign object lodged in the trap. The object acts as acts as a wick, absorbing water from the trap and dripping the water down the waste piping. Rags, lint, string, hair, and mop strings are common objects that cause this problem.
Trap seals can be lost due to evaporation when fixtures are not used for long periods of time. This is especially true in warm or hot climates. When a trap seal evaporates, you can replenish the water seal by running water into the fixture. If this is not possible or convenient, then the drain opening may be sealed with a cap to prevent sewer gases from entering the structure.
Vertical main of soil, waste, or vent piping extending through one or more stories. Each type of stack is further defined by the function it performs.
Portion of vertical piping that receives wastewater containing fecal matter, or urine from fixtures such as water closets, urinals, or similar fixtures. See Figure 68.
Figure 68 — Soil stack.
A waste stack is vertical piping that receives wastewater discharges from fixtures such as lavatories, sinks, tubs, showers, washing machines, and dishwashers. These fixtures do not normally contain fecal matter or urine. See Figure 69.
Figure 69 — Waste stack.
A soil stack can receive discharges from soil and waste pipes, however, a waste stack can only receive discharges from waste pipes.
A vent is a pipe that allows air into a waste piping system to protect trap seals and allow sewer gases to escape. By allowing atmospheric pressure into a waste piping system, equal pressure is provided on both sides of a trap seal. Allowing sewer gases to escape from the piping systems reduces the chance of explosions, fire, and offensive odors inside a structure.
A stack vent is an extension of a soil or waste stack above the highest horizontal drain connected to the stack. It is important to note that stack vents are a part of a soil or waste stack. Remember, each stack is defined by the function it performs. A stack vent is nothing more than a vent for a stack.
Vertical pipe installed primarily for the purpose of providing circulation of air to and from any part of the drainage system. Absolutely no fixtures drain into a vent stack. A vent stack could be one lone stack that provides circulation of air through the drainage system, or it could be in the form of a main vent. See Figure 70.
Figure 70 — Main vent.
A main vent is a vent stack. It is the principle artery of a venting system to which vent branches are connected. It connects full size at the base of the soil or waste stack below the lowest fixture drain. It extends full size through the roof or connects above the highest fixture branch to a main vent tee. Absolutely NO fixtures drain into a main vent!
A pipe installed specifically to vent one fixture trap and which connects with the vent system above the fixture served, or terminates in the open air. See Figure 71.
Figure 71 — Individual vent.
A section of pipe that ventilates two fixtures that are back to back or side by side at the same elevation is called a dual vent. See Figure 72.
Figure 72 — Dual vent.
A wet vent (See Figure 73) is a section of vent pipe that also serves as a drain for another fixture. When connecting a wet vent to the drain piping of another fixture, both fixtures must be on the same floor. The advantage of wet venting is that fewer vents will have to be projected through the roof. Although wet venting is permissible, it is not recommended.
Figure 73 — Wet vent.
This vent is used primarily in single story buildings but may be used on the top floor of multiple story buildings. Loop vents are used to ventilate a battery of fixtures that drain into a common branch pipe. A battery of fixtures is a group of two or more fixtures that share a common drain. A loop vent ties into the branch between the two fixtures that are furthest from the soil or waste stack and “loops” back and ties back into the soil or waste stack. Loop vents may also be used where no adjacent wall is available to house the vent pipe. Refer to Figure 74.
Figure 74 — Loop, Circuit, and Relief vents.
The circuit is basically the same as a loop vent, with the exception that a circuit vent connects back to a main vent and not a soil or waste stack. In multiple story buildings (with the exception of the top floor), circuit vents are used to ventilate a battery of fixtures. Refer to Figure 74.
The primary function of relief vents is to provide circulation of air between drainage and vent systems. An example of the use of relief vents would be between branch lines and the loop or circuit vents that serve these lines. This type of vent is used to provide additional venting to fixtures located closer to the stack. Refer to Figure 74.
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Water distribution is vital to the success of any mission you will encounter. Having knowledge of water sources and storage, water well construction, pump placement, and water distribution system selection will enable the safe conduct and completion of your job. Another important aspect of your job is the establishment of water service, including trenching, placement of pipes, and backfilling requirement. The selection and correct measurement of water supply piping and fittings is crucial for the continuous supply of water.
Exterior and interior water distribution systems were covered, including material and component selection, the building of service lines, sizing requirements, and installation of water supply lines to the various fixtures. Above ground and underground sewage drainage systems were discussed, including material selection, joining of components, and the testing requirements unique to each system.
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1. Drinking water is also known as what?
2. Water for consumption is obtained from how many different sources?
3. What is the most common source of water?
4. How deep is a dug well excavated to?
5. What type of well is constructed in loose, sandy, or gravelly soil?
6. What is the maximum depth of a driven well?
7. Which of the following wells is the most pollution free well?
8. What is the maximum depth of a bored well?
9. What is the lift limit of a shallow well pump?
10. What is the most commonly used shallow well type pump referred to as?
11. What is the minimum depth that a deep well pump is utilized?
12. What is utilized to transfer water from a low elevation to a higher elevation?
13. Which of the following BPS systems is used to transfer water to a higher pressure zone closed to the atmosphere?
14. Pipelines containing unsafe water are painted what color?
15. What type of system is used to prevent stagnated water from accumulating in the piping?
16. When self induced electric current flows from the metal into the soil, this is known as what condition?
17. How many different types of corrosion are associated with water systems?
18. Atmospheric corrosion normally occurs in which type of piping systems?
19. Which of the following terms is NOT a term used to refer to concentration cell corrosion?
20. What is the most common type of protective coating used in corrosion control?
21. Which of the following corrosion control protective coating is often used for gas pipelines?
22. What are the two types of cathodic protection process?
23. When utilizing the sacrificial anode system on a long pipeline, what is the minimum distance between anodes?
24. The impressed current system is designed to protect what type of system?
25. Noise in water pipes is indicative of what faulty condition?
26. What is the minimum size diameter of a water main line?
27. Which type of valve is used to control water by throttling?
28. How many different soil classifications are used to determine excavation and entry approaches for trenching?
29. What is the minimum distance that water pipes are placed from sewer piping?
30. Cast iron pressure pipe for water main come in what lengths?
31. Which of the following types of copper piping is utilized for general piping projects?
32. How many methods are utilized to measure piping or tubing?
33. Which measuring method is taken from the end of the pipe to the center of the fitting?
34. Which measuring method is taken from the back of one fitting to the back of the other?
35. Water that is constantly circulating from the supply point into the distribution system is known as what type of storage?
36. At what intervals should ground level storage tank roofs be inspected?
37. During the conduct of an inspection of elevated storage tank, the heating system needs to run prior to the start of the winter season, how long is the heater run to verify proper operation?
38. Which type of cathodic protection systems are used for protecting steel water storage tanks against corrosion?
39. Which type of pump is used to increase water pressure?
40. Which of the following water mains distributes water throughout a community?
41. What are the two types of standard design systems used for exterior water distribution?
42. What determines the maximum size of a tap when tapping a main line?
43. The tap should NOT be larger than 1/4 the diameter of the pipe.
44. A service line consists of all the following EXCEPT what component?
45. Which of the following is the first component in a service line?
46. When copper tubing is used to fabricate the service line, what type of flexible connection is used?
47. In a small pipe, friction loss may overcome by what means?
48. CPVC piping can withstand temperatures as high as what?
49. Risers should be supported at every other floor level and at joints.
50. What is the maximum distance that a fixture supply pipe can terminate from the point of connection to the fixture?
51. Which of the following pipe sizes is the minimum size to utilize when connecting supply water to a lavatory?
52. How many types of urinals are there currently in use?
53. What is the minimum size utilized in water supply piping for a flushometer type urinal?
54. How far apart are cold and hot water lines installed from each ofter?
55. What type of piping is used under roads or other places of heavy traffic?
56. When excavating you realize that the soil contains cinders and ashes; which type of piping would be utilized?
57. Which of the following fittings is used to change the direction of a CISP 22 1/2 degree?
58. Which fitting is used mostly in venting systems?
59. Which fitting is useful as an individual vent?
60. Which fitting is utilized to join two sanitary sewer branches at a 45 degree angle?
61. Vitrified piping is typically used in what location?
62. During prolonged storage, PVC piping should NOT be stacked more than how many feet high?
63. How many different ways are there to join plastic piping?
64. When testing plastic piping, which test is performed first?
65. When conducting the water test after sanitary drainage installation, how long is the water to remain in the pipe?
66. 15 inch sewer drainage piping has been installed, what is distance required between manholes?
67. When performing backfill operations on a trench, how much soil should be placed on the piping before walking on the pipe is authorized?
68. Which type of pipe carries fecal matter and discharges from urinals?
69. Which of the following components is the vertical portion of vent piping?
70. Lead pipe is available in how many weight classifications?
71. Which fitting is designed for making a connection between a closet flange and a soil stack?
72. Which fitting is commonly used as a stack base?
73. Which CISP fitting is also known as which of the following?
74. A device or fitting used to provide a water seal in a waste water system is known as what?
75. What pressure, if any, is caused by siphonage by momentum trap loss?
76. Which type of vent or stack receives waste water that contains fecal matter?
77. Which type of vent or stack receives waste water discharge from dishwashers?
78. What type of vertical piping is utilized to provide circulation of air to any part of a drainage system?
79. What fitting can also serve as a drain for another fixture?
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