Describing Sizing of Plumbing Piping

Sizing of Plumbing Piping

Plumbing must he sized enough to allow fixtures to operate properly and for proper draining and venting. The size of water supply piping is based on these conditions:

Amount of water needed.

Supply pressure.

Pipe length.

Number of stories to be supplied.

Flow pressure needed at the farthest point from the source.

The size of drainage piping is based on standards established for the type of fixture and the average amount of waste that can be discharged through the fixture in a given amount of time. The size of vent pipes is based on the number of drainage fixture units that drain into the waste portion of the vent stack.

American National Standard taper pipe threads are the standard thread used on pipes and pipe fittings. These threads are designed to provide pressure tight joints or not, depending on the intended function and materials used. American pipe threads are measured by the nominal pipe size, which is the inside pipe diameter. For example, a 1/2" pipe size has an outside diameter of Bier. Pipe threads are identified using a thread note such as 3/4 I4NPT, where the 3/4 is the nominal inside diameter of the pipe. 14 is the number of threads per inch. and S: r stands for National Pipe Thread.

Define Piping Practices..........!!!

Piping Practices

The piping system must be installed correctly so that the system has the best chance of operating correctly. Factors such as expansion and contraction of the pipe when the system is heated and cooled must be taken into consideration before the installation is started. All piping expands when the system is heated from room temperature to the temperature of the circulating water. Copper pipe has a much higher coefficient of expansion than iron or steel pipe does. According to the IBR 100 Guide, a 100-foot length of steel pipe expands I inch when heated from room temperature to 200°F, whereas a 100-foot length of copper pipe expands 1.5 inch under the same conditions. Long piping runs expand so much that leaks can occur if expansion joints are not provided. Expansion and contraction also cause noise as the system warms up to temperature and cools down. Room for expansion can be provided in piping runs with expansion loops or expansion joints. Baseboard convectors are limited to length because of expansion. Manufacturers' recommendations must be followed when you select baseboard radiation because these systems may have long runs of units. Expansion joints may be recommended at intervals. The pipe must be reamed at all connections where it was cut during installation. The burr made by the pipe cutter restricts flow by causing turbulence and must be eliminated. A complete piping system will have many of these restrictions if good piping practices are not followed. Thread seal should be applied only to external threaded connections, as depicted in. If it is applied to the internal threaded connections, the thread seal will turn loose and be carried through the piping and cause problems such as plugged heat exchangers and strainers. Water pipes in the system should be exactly level or rise in the direction of the flow so that air that enters the system can move with the water. If the pipes are pitched downward in the direction of the water flow, air will trap in the high spots and restrict the water flow.

Each water system must have a method for draining the complete system in case of freezing weather when the heating & drain cleaning system may not be functioning. For example, if a building will be vacant for a long time, the complete system must be drained. Drain valves at all low points with a method of breaking the vacuum while draining will ensure that the system is empty. The vacuum break must be at the high point in the system. When a valve on the bottom of a system is opened to drain the system, a vacuum forms at the high points in the system as the water tries to drain. It is possible that all the water will not drain; some may be suspended in the system. These places where water remains will freeze in cold weather. Automatic air bleed valves can provide the necessary vacuum break. If there are no automatic bleed valves, the technician must open all manual bleed valves in order to drain the system completely. After a system is installed, the inside of the piping must be cleaned. Construction dirt, oil from threading the pipe, and pipe dope will be inside the piping. The boiler will have an oil coating on the inside that must be removed. It is recommended that the system be operated for several days after it is filled and leak tested. Then a special detergent should be added and circulated in the system for several more days. The system should then be drained and refilled several times to clean out the detergent and suspended oil. Finally, the system should be filled with water and water treatment provided by a company that specializes in water treatment. The water treatment contains additives for preventing rust and corrosion.

Room for pipe expansion

a pipe cutting burr

external portion of the threads

construction dirt will be in the pipe of a new job