Water cast iron

Carbon steel heat exchangers, cast iron water boxes, screens, pump components, service water system piping, standpipes, fire protection systems, galvanized steel, engine components, and virtually all non-stainless ferrous components are subject to significant corrosion in oxygenated water. 

All these rates are, of course, quite low and the problem with corrosion of cast iron water mains is its effect on water quality rather than deterioration of the asset. 

A typical flaker , such as used in manuf of TNT and some other HE s consists of a horizontal, hollow, metallic (usually cast-iron), water-c ooled, drum, with hollow truoions mounted in bearings. It is given in Perry, pll64-L as Fig 68 and reproduced here as Fig 6. The lower part of drum dips into molten material located in a hollow, steam-... 

What is the velocity of 1000 gal/min (0.064 m3/s) of water flowing through a 10-in inside-diameter cast-iron water-main pipe What is the hydraulic radius of this pipe when it is full of water When the water depth is 8 in (0.203 m) ... 

Polycyclic aromatic hydrocarbons (PAHs) are usually only found in drinking-water as a consequence of leaching from coal-tar linings on cast-iron water mains. The PAH of greatest concern is benzo(a)pyrene, but the most commonly encountered is fluoranthene. Benzo(a)pyrene is normally only detected at significant concentrations in water when particles of coal tar are present,... 

Figure 13.12 Schematic representation of the cast iron - water interface. (Taken from Frateur et al.207)...

Figure 13.13 Equivalent circuit for a) the total impedance of the cast iron-water interface b) the anodic impedance and c) the interfacial impedance of the microporous layer.

Weston, E.B. (1896). Tables for estimating the cost of laying cast-iron water pipe of the Providence pattern . Engineering News Publishing New York. 

In other respects, corrosion in soils resembles atmospheric corrosion in that observed rates, although usually higher than in the atmosphere, vary to a marked degree with the type of soil. A metal may perform satisfactorily in some parts of the country, but not elsewhere, because of specific differences in soil composition, pH, moisture content, and so on. For example, a cast iron water pipe may last 50 years in New England soil, but only 20 years in the more corrosive soil of southern California. 

BR-10 (Russian Federation) - cast iron, water concrete... 

In some water supply areas, problems are experienced with the corrosion of old cast-iron water mains, such that iron (red-water) discolouration can become an aesthetic problem with iron concentrations exceeding several parts per million (mg/1). In such cases, the loose iron corrosion deposits can settle within a lead pipe and absorb lead it is likely that this absorption enhances lead dissolution from the lead corrosion deposit as the equilibrium concentration for the dissolved lead is given less opportunity to be realised. Any disturbance of the loose deposits, such as the scouring effect of high flow, can cause elevated concentrations of lead in the drinking water. As an approximation, lead concentrations can double as a consequence of the interaction with loose iron deposits. Particulate lead may also arise from the physical sheer of pieces of the lead corrosion deposit from within the lead pipe, as a consequence of physical damage (as can occur in partial lead pipe replacement). Vibration from heavy road traffic might also cause pieces of the lead corrosion deposit to sheer. There is some evidence (Cardew, 2009) that the lead... 

An area designated as Old Ottawa South with a four-block portion of 394 homes. This area is served by 6 inch and 8 inch diameter unlined cast-iron water main pipes installed in 1910, having poor water circulation because of the occurrence of dead-ends in the affected portion and many homes are supplied by lead service connections. 

Fitzgerald III, JH. Longevity of a graphitized cast iron water main. Materials Performance, 2007 46 30. 

The CP effectiveness at protecting steel in soils has been demonstrated in the early 1940s when CP was applied to an old natural-gas piping network that had been developing leaks at a rapidly increasing rate, enough so that abandonment was seriously considered. The observed reduction in the number of leaks immediately after the CP installation was impressive [2]. A similarly impressive reduction in the frequency of leaks on a cast iron water main was achieved at about the same period as shown in Fig. 13.1 [3]. 

Steder FE. Accelerating leak rate in cast iron water mains )rields to CP. Materials... 

Sacrificial material, such as zinc or magnesium, may be introduced into this assembly. For instance, zinc anodes are used in cast iron water boxes of copper alloy water-cooled heat exchangers. 

Graphite flakes are cathodic to iron, and corrosion is localized to iron which starts leaching (becomes a porous mass) and leaves a rich residue of graphite flakes. Graphitization is observed on gray cast iron water pipes. 

The iron content of the treated water entering supply is very low, at about 20 pg/1, but does increase to cause iron discolouration problems in some parts of the distribution network, particularly at the extremities where water stagnation times within old cast iron water mains can be more significant. Occasional spikes in iron can result in intermittent particulate lead problems at some premises. 

Municipal drinking water cannot be treated with most inhibitors because of their toxicity. Fortunately, treatment with lime to raise the pH usually affords sufficient protection to steel or cast iron water pipes. 

Sadiq, R., Rajani, B., Kleiner, Y., 2004. Probabilistic risk analysis of corrosion associated failures in cast iron water mains. Reliability Engineering and System Safety 86 (1), 1—10. 

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