Steels total immersion tests

Rust Layers in Steels Submitted to Total Immersion Tests... 

Room temperature Mossbauer spectra of rust from carbon steel (a) and weathering steel (b) submitted to total immersion tests in 0.6 M NaCI concentration for 42 days. 

It is worth mentioning that at 0.6 M NaCI concentration for 46 days, the corrosion rate for CS and WS were of 3l00 xm per year and 3686 xm per year, respectively. For comparison purposes, it is possible to see that the performance of both steels in such aggressive environments of high chloride content is very poor, but it is even three to five times worse than in the case of total immersion tests. These corrosion rates seem to be inversely related to the iron conversion factor, which is lower (about 0.21) in the immersion tests than in the dry-wet tests (about 0.80). The different behaviors should be related to the type of iron phases, their characteristics, and their relative amounts. 

All ordinary ferrous structural materials, mild steels, low-alloy steels and wrought irons corrode at virtually the same rate when totally immersed in natural waters. Wrought iron may be slightly more resistant than mild steel in a test in sea-water at Gosport, Scottish wrought-iron specimens lost about 15% less weight after 12 months immersion than specimens of ordinary mild steel. As shown in Table 3.5, the process of manufacture and the composition of mild steel do not affect its corrosion rate appreciably . 

Part 1, p 874, Test A262-44T ("Tentative Recommended Practice for Boiling Nitric Acid Test for Corrosion-Resisting Steels ) Part 1, p 878, Test A279-44T (Total Immersion Corrosion Test for Stainless Steels) 18) Kirk Othmer 4 (1949)... 

Laboratory Corrosion Test. The laboratory test procedure for the determination of corrosion rates of coal slurry used in this study was adapted from the method developed by Bomberger (26). The corrosion rates were determined by using ASTM Standard Corrosion Test, also known as the Total Immersion Method (27). The Bomberger technique consists of keeping coal slurry in suspension in a two-liter reaction vessel at a constant temperature. The corrosion rates are determined either by actual weight loss of steel coupons... 

The ASTM Corrosion Test procedure by Total Immersion Method requires that all specimens in a test series should have the same dimensions when comparisons are to be made. In these experiments, carbon steel was used representing the pipeline material. The coupons were cleaned, polished and weighed. Coal-water slurry, 10 to 40 weight percent, was used in the corrosion tests. For the coal-water slurry the intitial pH of the medium varied from 2.3 to 2.6 and the test series containing the nutrient media, the microorganisms and the inhibitors the pH varied from 2 to 2.5. Specimens were immersed in the reaction vessel maintained at a constant temperature of 86°F for 72 hours or the specified time. The coupons were removed, washed with deionized water, dried and weighed. The loss in weight of the specimen, before and after the test was attributed to corrosion. 

Specimens of galvanized steel partially immersed in commercially pure test chemicals at ambient temperature for a minimum of 100 days corrosion rate based on total area of specimen. 

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