It provides a sacrificial anode (zinc) to receive corrosion instead of the steel corroding.It coats the surface like paint, and under most circumstances it forms a very adherent oxide layer like aluminum and SS.Galvanizing has two methods of corrosion reduction: Galvanized steel pipe is steel pipe that is dipped into a pool of zinc (see Figure 1). However, the high rigidity of steel means that although it expands less, it exerts very high forces on anchors. Consult ANSI/MSS SP-58: Pipe Hangers and Supports – Materials, Design, Manufacture, Selection, Application, and Installation for details about hangers and hanger spacing.Ī low coefficient of thermal expansion minimizes the need for expansion loops and expansion joints. More flexible materials, however, may require hangers on as close as 4-ft centers or even continuously. Steel pipe is manufactured in 21-ft lengths, and the hangers can be spaced that widely for large-diameter pipe. Rigidity is important because it determines the distance between hangers. Some building owners do not want these chemicals in steam that may be used for humidification because of health concerns however, not using these amines might require a change to stainless steel (SS) piping or adding a separate “clean steam” system for humidification and for sterilization of medical instruments. If amines (commonly cyclohexylamine, morpholine, or diethylethanolamine (DEAE) are fed properly to neutralize condensate pipe pH, condensate pipes can last the life of the building. However, corrosion is an issue in steam-condensate pipes, and many engineers specify schedule 80 steel pipe simply because it takes about twice as long to rust through as schedule 40 pipe. ![]() It also is a good choice for steam and steam-condensate systems because it handles high temperatures and pressures well, and corrosion is normally not an issue in steam pipes. Black steel pipes tend to corrode in water and mineral of the pipe will dissolve into the water and clog the line as well.Steel often is used for closed hydronic systems because it is inexpensive, especially when compared with other materials in systems with high pressures, and corrosion is relatively easily controlled in these systems. In view of this, transport gas by galvanized pipes is dangerous so it is often used in carrying water.īlack steel pipe, on the other hand, is not suitable for water transport. Galvanized pipe has zinc on the surface so the mineral will flack off as time goes by and block the pipe. Black steel pipe is uncoated and made without steam, and therefore, it is widely used for transporting gas like propane and natural gas to residential and commercial building. ![]() The main difference between steel pipe and galvanized pipe lies in the surface. Since it has a dark color surface which is formed by iron oxide during the manufacturing process, it is called black steel pipe. Black iron pipe is also most often use in fire sprinkler systems due to its high heat resistance and for water supply lines due to its resistance to water damage. Black iron pipe is used to transport natural and propane gas in residential applications.īlack steel pipe is manufactured as seamless which makes it a better type for gas transportation and fire sprinkler systems since it can prevent fire better than galvanized pipe. Galvanized pipe fittings should not be used with gas applications.īlack pipe fittings (black malleable iron fittings) are used to make connections to black iron pipe. The main advantage of using galvanized fittings is their superior rust resistance when compared to black and copper fittings. While they work best with cold water lines, they may be used with hot water as well. Galvanized pipe and fittings may be used in most applications with the exception of underground lines. Galvanized pipe fittings are used for countless outdoor and industrial applications because of the material's ability to protect against corrosion and salt. Galvanized pipe is mainly used for carrying water to supply home and commercial buildings it may also serve as scaffolding frames because of its rust prevention. Galvanized pipe fittings are covered with a layer of zinc which makes these fittings have higher ability of corrosion protection and help to prevent the accumulation of mineral deposits that will block the pipe. ![]() For transportation, black steel pipe tend to erode more easily than galvanized pipe and therefore it is more suitable for transporting gas and galvanized pipe is fit for carrying water instead of gas. As a result galvanized pipe is more durable. Both black steel pipe and galvanized pipe are made of steel, however, galvanized pipe has a zinc coating while black pipe does not. Black steel pipe fittings and galvanized steel pipe fittings are the two most common kind of pipe applied to transport liquid and gas.
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