Plumbing Pipes and Fixtures | Lesson 4: Carbon Steel Pipes and Fittings | Carbon Steel Fittings, Valves, Supports
Carbon Steel Fittings and Valves Fittings change the direction of flow in water supply and distribution systems and in drain, waste, and vent (DWV) systems. Valves regulate the flow of water in a system. They are often attached to the ends of pipe to provide access to fluid flowing through the system. Pipe fittings for steel pipes are generally made of malleable iron or cast iron. Annealing ordinary cast iron produces malleable iron. Annealing Process The annealing process consists of heating and slowly cooling the iron. This makes the iron stronger so that it can be bent or pounded to a reasonable extent without breaking. Iron pipe fittings are manufactured in two types: pressure fittings and drainage fittings, also called recessed drainage fitting. Drainage fittings have a drainage pattern design and recessed threads that should be used only in soil and waste piping systems. Pressure pipe fittings cannot be used in drainage systems because their inside surface is not smooth enough. Drainage fittings differ from pressure fittings in several ways: • The inside of drainage fittings are smooth and are shaped for easy flow. • Their shoulders are recessed so that when a pipe is screwed in the pipe fills the recessed area and forms an unbroken, internal contour. • Drainage fittings are also designed so that horizontal lines entering them will have a slope of ¼ inch per foot. Pressure Fittings The common pressure fittings used for hot and cold water distribution system, steam and hot water heating system, and gas and air piping system are listed below. Click on each pressure fittings for threaded pipes to know more: • Tees • Elbows • Unions Tees Tees are available in a number of sizes and patterns, and they are used to connect branches to a pipe at 90-degree angles. If all three outlets are the same size, the fitting is called a regular tee. If outlet sizes differ, the fitting is called a reducing tee. Elbows Elbows, or ells, are installed to change the direction of the pipe. The most common elbows, or ells, are the 90-degree ells; the 45-degree ells; the street ells (which have a male thread on one end); and the reducing ells (which have the outlet of different sizes). Unions Unions make it possible to disassemble threaded piping systems. After disconnecting the union, the length of pipe on either end of the union can be unscrewed. The two most common steel pipe unions are ground joint and flange. Couplings and Other Fittings: Couplings are used to connect two lengths of pipe and making straight runs. Couplings cannot be used in place of unions because they cannot be disassembled. Other fittings for steel pipe include nipples, crosses, plugs, caps, and bushings. Valves: The most commonly used valves for threaded pipe are the globe valve, gate valve, ball valve, and stop and waste valve. The valve used with carbon steel is not necessarily made of steel. Click on each type of valve to know more: Globe valve Globe valves are recommended for general service on steam, water, gas, and oil, where frequent operation and precise control of flow are required. Gate Valve Gate valves are designed to be fully open or fully closed and are best suited as stop valves. They can be used in lines for steam, water, gas, oil, or air. Ball Valve Ball valves are used to control the flow of gases and liquids. Stop-and Waste Valve Stop-and-waste valves are opened or closed by raising or lowering a horizontal disc using a threaded stem. Carbon Steel Supports Plumbing pipes should be properly installed and supported. Improper support can cause joints to sag, and the added stress increases the chances that the pipe will leak, break, or crack. In the case of carbon steel pipes, one or more hangers should be used for support. The basic components of hangers are pipe attachments, connectors, and structural attachments. Click on each image to know more: Pipe Attachments Pipe attachments touch or connect directly to the pipe. For horizontally supporting a pipe from a ceiling use rings, clamps, and clevises. For vertical pipes, use rise clamps. To support piping on wood-frame construction, use pipe hooks, tube straps, plumber’s tape, pipe clamps. Connectors Connectors link the pipe attachment to the structural attachment. The two main groups of connector are rods and bolts; and other rod attachments. Structural Attachments Structural attachments are the anchors and anchoring device that hold the pipe hanger assembly securely to the building structure. They include powder actuated anchor, concrete insert, beam clamps, C-clamps, beam attachments, various brackets, ceiling flanges and plates, plate washers, and lug plates.
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