Steel biological corrosion

Localized biological corrosion of stainless steels. There are three general sets of conditions under which localized biological corrosion of austenitic stainless steel occurs (Figure 6.29). These conditions should be examined for metals that show active-passive corrosion behavior. Microbiological corrosion in austenitic steel weldments has been documented. (Wahid)61, (Krysiak)14... 

Biological Corrosion due to fouling organisms non-uniformly adhered on steel in marine environments. 

However, IRB still have the power to surprise us Lee et al. reported that a mixed culture (biofilm) containing IRB (Shewanella oneidensis ) and SRB (Desul-fovibrio desuljuricans) that had been formed on mild steel could provide a shortterm (four days) protection to the steel [116]. As the authors put it, [t]he fact that an iron-reducing bacterium can inhibit corrosion when a corrosion-enhancing bacterium is present warrants future study with respect to its potential applicability to the design of biological corrosion-control measures . Such reports can lead us into another aspect of IRB a corrosion-inhibiting bacteria This matter is discussed in Section 5.2, Corrosion deceleration effect of biofilms of Chapter 5 and will not repeated here. 

Biological corrosion inside the seal drum. The bacteria metabolized HjS and iron in the warm seal drum aqueous phase to form the sludge. If the internal seal drum legs are made of carbon steel [should use 316 (L) stainless steel], the internal seal drum legs will hole-through and unseal the barometric legs. 

A typical microbiological analysis in a troubled carbon-steel service water system is given in Table 6.2. Table 6.3 shows a similar analysis for a cupronickel utility main condenser that showed no significant corrosion associated with sulfate reducers. When biological counts of sulfate reducers in solid materials scraped from corroded surfaces are more than about 10, significant attack is possible. Counts above 10 are common only in severely attacked systems. 

The triggering mechanism for the corrosion process was localized depassivation of the weld-metal surface. Depassivation (loss of the thin film of chromium oxides that protect stainless steels) can be caused by deposits or by microbial masses that cover the surface (see Chap. 4, Underdeposit Corrosion and Chap. 6, Biologically Influenced Corrosion ). Once depassivation occurred, the critical features in this case were the continuity, size, and orientation of the noble phase. The massive, uninterrupted network of the second phase (Figs. 15.2 and 15.21), coupled... 

In the last decade, some systems, such as the Dionex DX-500, have been manufactured with a flow path using corrosion-resistant materials such as polyetheretherketone (PEEK , ICI Americas Wilmington, DE), rather than the traditional stainless steel. Since stainless steel is prone to corrosion by salts, particularly halides, the introduction of titanium, ceramic, and PEEK was welcomed by those performing chromatography in aqueous systems, particularly in biological applications. PEEK , however, is not useful in applications requiring pressures greater than about 4000 psi. 

For liquid formulations, the choice of using either a salt or a carbohydrate to adjust the osmolality of the solution is made by the impact on protein stability. Sodium chloride is one of the most commonly used salts in the formulation of both traditional pharmaceutics as well as biological pharmaceutics. It is extremely safe, well tolerated, and inexpensive. However, the presence of sodium chloride in a formulation of rhuMAb HER2 was found to increase oxidation when the formulation was stored in stainless steel containers, presumably because the sodium chloride promoted corrosion of the stainless steel. Interactions of salts with the proteins must be investigated on an individual basis because the type and concentration of salt may lead to protein aggregation. 

An advantage of reversed-phase chromatography in the analysis of alkaloids in biological fluids is that an analysis can be carried out directly without any laborious sample clean-up procedure. However, the use of a precolumn to avoid a too rapid deterioration of the HPLC column is advisable (see Chapter 11). When using aqueous salt solutions in reversed-phase chromatography, one has to be aware of the risk of corrosion of stainless steel columns (see Table 1.3)38. 

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