Ductile cast-iron pipes

Figure 2. Cross section of a 155 mm-inside diameter ductile cast iron pipe buried for 567 Ms.

Gerhold, W. F., "Corrosion Behavior of Ductile Cast Iron Pipe in Soil Environment, Journal AWWA, December 1976, pp. 674-678. 

Because of the disadvantages described, the thin coating of tar pitch was replaced by a cement mortar lining [26], Ductile cast iron pipes [27] with a cement mortar lining (CM lining) have since been used exclusively in Germany since the midseventies. 

Thermal resistance The thermal resistance specified in DIN EN 476 of 318 K (45 °C) for nominal diameters up to DN 350 and 308 K (35 °C) for nominal diameters greater than DN 400 was fulfilled by the ductile cast-iron pipe. 

Maintenance suitability Investigations with respect to the influence of high-pressure water sprays on the cement mortar lining of the ductile cast-iron pipes showed that there was no damage caused by commonly used nozzle heads and flushing pressures up to 170 bar. 

Rohre aus duktilem GuKeisen in der Abwasserentsorgung (Ductile cast-iron pipes in waste-water disposal) (in German)... 

Mruk and Palermo and Hunt, W. J., The Design of Grey and Ductile Cast Iron Pipe, Cast Iron Pipe News, March/Apiil 1970. 

Agent same as anolyte circuit. Energetics piping to be PFA-lined carbon steel pumps to be titanium valves to be PFA-lined ductile cast iron agitators to be PTFE-coated stainless steel seals and gaskets to be Kalrez, PTFE, or PTFE-clad. Heat exchangers to be 304L stainless steel. Catholyte evaporator to be Inconel 690/625 hydrocyclones to be titanium. 

The corrosion rate of ductile iron pipes in soils was in the range 0.62-2.5 mm/yr with an average of 1.11 mm/yr which is twice the rate of cast iron pipe. Failure of ductile iron pipe was solely due to localized pitting corrosion leading to pipe wall perforation. 

There was no indication of pipe failure due to the defects of the pipe material. With the exception of one example corrosion of both ductile iron and cast iron pipes from the water side was negligible. 

Thin bituminous coatings on the ductile and cast iron pipes peeled and flaked. In addition rust spots were also present. 

Figures 7.107 and 7.108 show the corrosive attack on samples of cast iron pipe and ductile iron pipe buried under the soil for 20 and 9 yrs, respectively. The large hole in...

Figures 5.72 and 5.73 show the corrosive attack on samples of cast iron pipe and ductile iron pipe buried under the soil for 20 and 9 years, respectively. The large hole in cast iron pipe (Fig. 5.72) and the corrosion pit and perforation in ductile iron pipe (Fig. 5.73) show the severity of soil corrosion. It is suggested that cathodic protection can reduce the extent of corrosion of iron pipes.

Pipes of unalloyed cast iron have been used for more than 100 years for long-distance and distribution lines. By the end of the fifties, grey cast iron was used exclusively for these pipes, and since that time has been replaced by ductile cast iron. 

Observance of the standards and regulatory works as well as special ordinances The waste water pipe under examination is made of ductile cast iron and is manufactured according to DIN EN 598. The bell-and-spigot coupling system Tyton corresponds to DIN 28603. 

Pipes made of ductile cast iron i.e. cast iron with spheroidal graphite according to DIN EN 1593 [22] are used extensively in communal and industrial waste water disposal systems. The technical terms of delivery DIN EN 598 [16] contain information on the material parameters, on their joints, as well as on the testing and quality control of pipes. Some material parameters are given in Table 6. 

Table 6 Material data for pipes made of ductile cast iron according to DIN EN 598 [16, 24]...

Typical failures of cast iron pipes are characterized by leaks in pipe wall along the graphite flake/ferrite interface. The ratio of mechanical failure between the cast iron and ductile iron pipes is 2.5 to 1.0. Following is a comparison of pitting depths of ductile and gray cast iron pipes in aggressive soils (Table 9.18)[34j ... 

Cast iron and ductile iron pipes have been extensively used in the USA, Canada and European countries in water distribution systems. Cast iron pipes have been gradually replaced in recent years by ductile irons and PVC pipes. The ductile iron pipes enjoy a mechanical superiority over the traditional cast iron pipes as shown in Table 9.17. 

Ductile iron pipes and cast iron pipes, however, corrode at about the same rate in soil. 

Table 9.18 Average maximum pit depth for ductile and gray cast iron pipes in aggressive soils [34]...

State the advantages and disadvantages of ductile and cast iron pipes in an aggressive soil of low resistivity. 

Pipes for circulating hot (>40 °C) acid around the plant are usually constructed of either ductile cast iron (MondF or Meehanite ) or high silicon austenitic stainless steel. The advantages of using stainless steel for acid piping are ... 

Piping—acid systems >40 °C SARAMET or ZeCor or SX Ductile cast iron (Mondi or Meehanite ) Teflon lined carbon steel... 

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