Mild-carbon steel

It is reported that mild carbon steels may be effectively protected by as little as 55 ppm of KTc04 in aerated distilled water at temperatures up to 250oC. This corrosion protection is limited to closed systems, since technetium is radioative and must be confined. 9sTc has a specific activity of 6.2 X lOs Bq/g. Activity of this level must not be allowed to spread. 99Tc is a contamination hazard and should be handled in a glove box. 

The reaction vessel (nitrator) is constructed of cast iron, mild carbon steel, stainless steel, or glass-lined steel depending on the reaction environment. It is designed to maintain the required operating temperature with heat-removal capabiUty to cope with this strongly exothermic and potentially ha2ardous reaction. Secondary problems are the containment of nitric oxide fumes and disposal or reuse of the dilute spent acid. Examples of important intermediates resulting from nitration are summarized in Table 3. 

Basis Tubing is 1 in. OD X 16 BWG, except as noted. Heat exchangers are TEMA-type BEM with in. OD x 16 BWG X 20 ft welded tubing and mild-carbon steel shells. 

At low water contents, HF has a very low corrosion rate on mild carbon steel, but as the water content rises above 5%, the corrosion rate rapidly increases. Corrosion is anticipated wherever there is a possibility of acid or acid-hydrocarbon mixtures in contact with water. Copper, silver, and platinum are resistant to corrosion from all concentrations of HF, with the exception that copper and silver are attacked in the presence of sulfur compounds and oxygen. Lead is useful only if the water content is above 35%. Finally, stainless steel has poorer corrosion resistance to HF than carbon steel. 

The properties of carbon steels depend upon the percent of carbon present. They are classed as mild, medium, and high on this basis. Because mild-carbon steels are ductile, sheets of it can be cold-formed to mold fenders and body parts for cars. Medium-carbon steels have more strength but are less ductile so they are used as structural materials. High-carbon steels are hard and brittle they are used for wear-resistance purposes. 

R. D. Zaho, Y. H. Zhu, and D. C. Liu, Experimental Investigation of the Compatibility of Mild Carbon Steel and Water Heat Pipes, Proc. 6th Int. Heat Pipe Conf, Grenoble, France, pp. 200-204,1987. 

Figure 2.3 The coefficient of friction varies with temperature for DuPont Vespel SP-21 (against mild carbon steel) [4],...

Figure 743 Wear factor versus velocity limit at 395°C against unlubricated mild carbon steel of two DuPont Engineering Polymers Vespel SP PI plastics [10],...

Figure 7.44 Wear rate versus PV against unlubricated mild carbon steel in thrust bearing tester of DuPont Engineering Polymers Vespel SP-21—15% graphite-filled PI [9],...

Steels for structural use are classified as carbon steels, high-strength low-alloy steels, and alloy steels. For design purposes, these steels can be assumed to have a density of 7.85 g/cm, a modulus of elasticity of 210 GPa, and a Poisson s ratio of 0.3. Carbon steels are classified based on the percentage of carbon. Mild carbon steels (0.15-0.29 % C) with yield points in the range of 220-250 MPa and tensile strengths of 400-500 MPa are the most common structural carbon steels. Typically, an increase in carbon percent raises the yield point and increases hardness, but reduces ductility and makes welding more difficult. These drawbacks can be minimized by heat treatments. 

Brookhaveri National Laboratory has used both types of valves exten-,si ely [22,34]. The 1/2-in. IPS 150-lb Y pattern globe valves constructed from AISI type-347. staudess steel for all parts in contact with bismuth (including bellows, stem, and disk) have, been used continuously for over 8000 hr at 930°I without mishap. Similar valves with mild carbon steel disks (instead of type-347 stainless steel) have been used at 930°F for over 13,000 hr without failure or extensive corrosion. 

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