Carbon steel differences compared with

Exclusively for shell and tube heat exchangers, the Purohit Method has been used (Purohit, 1983). This method takes into account a large number of technical characteristics according to TEMA standard and allows the use of correction factors for different materials. Material factors compared with carbon steel have been updated in 2008 (Gilardi, 2008). 

The cost of various techniques can only be given very roughly, and any estimate will be incomplete, since the actual cost will vary from one application to another. Furthermore, different types of prevention mechanisms are not directly comparable. Beyond this, it can be said that with respect to normal carbon-steel reinforcement, use of galvanized and epoxy-coated bars costs about twice as much, and the cost of stainless-steel reinforcement is about 5 to 10 times higher. The use of nitrite inhibitors in higher doses costs approximately 30 /m of concrete (volume). Coatings may vary from 7 to 50 /m of concrete surface, hydrophobic treatment costs about 10 /m. Cathodic prevention varies from 50 to 100 /m. ... 

Atmospheric corrosion studies were performed in the Spanish Canary Islands exposing zinc, copper, and carbon steel sheets to the subtropical and coastal environment for a period of 3 years [45-47]. The first part of this study was to determine the corrosion rates on each sample at different times. The study also performed an analysis of the atmospheric conditions at the thirty-five test sites on the islands. With this information, the atmospheres were classified according to ISO. Measured corrosion rates were compared with the expected ISO values. The corrosion rates obtained based on ISO were determined deficient throughout the studied region... 

The oxidation resistance of stainless steel alloys with different compositions is compared to the oxidation resistance of carbon steel in Fig. 11.6 [4]. Carbon steels perform satisfactorily at temperatures below 500 °C. Chromium-molybdenum steels doped with up to 2% silicon have low corrosion rates up to 700 °C. Ferritic stainless and martensitic steels have superior oxidation resistance when compared to carbon and Cr-Mo steels. The corrosion rate of the alloy drastically decreased (increase in the resistance to oxidation) upon increasing the chromium content from 8% to 25%. 

Let us consider the different design solutions schematically shown in Figure 12.13. If the tank was made of carbon steel, this would be subject to rapid generalized nonuniform self-accelerating corrosion if the tank was made of stainless steel, it would be subject to much reduced weight losses compared to the case of carbon steel but with localized and perforating attacks, and the time reqnired to perforate the two tanks, one in carbon steel and the other in stainless steeL wonld be not very different. 

Hot corrosion studies were undertaken on a variety of Fe-5 mass% M - C alloys with different C contents (0.1, 0.4, 0.8 and 1.2 mass%) compared with plain carbon steels. The Nb steels were only marginally better than the plain carbon steels and not as good as W, Cr or Ni-containing steels. 

---