Significance chloride content

The corrosion rates for tests in Hamburg harbor are worth noting. The sea is about 100 km away, but there is a significant chloride content to supplement the effects of the industrial or urban atmosphere. 

One of the main factors which establishes the corrosivity of water to stainless steel is the chloride content. Also significant are oxygen content and pH, and it is also probable that other features such as hardness and the nature and concentration of other anions and cations have effects. Water temperature and flow velocity can also be important. Any corrosion takes the form of pitting or, if crevices are available, larger areas of attack within the crevice. 

The reactivity and transformation to yield soluble bioavailable species of metalbearing substances are expected to be significantly affected by the high chloride content and other unique chemical characteristics of marine waters. 

Allyl chloride did not react at temperatures below 220 °C. The total amount of products and the selectivity for allyldichlorosilane gradually increased as the temperature increased to 260 °C, but decreased beyond 280 °C. Reaction temperatures were significantly lower than those for unactivated alkyl chlorides, a reflection of the higher reactivity of allyl chloride. As hydrogen chloride content increased from 50 to 75 mol% in the mixture of allyl chloride and hydrogen chloride, the yield of allyldichlorosilane increased from 31 to 41% and that of diallyldichlorosilane decreased from 1.9 to 0.2%. However, the amount of trichlorosilane, formed from the reaction of elemental silicon with hydrogen chloride, also increased. 

In Table 1 the gold contents deposited on the Pt surface are reported. This method of preparation allows to obtain bimetallic catalysts in which the two metals are in close interaction. It can be seen the addition of a very low load of gold decreases the accessibility of Pt in a significant way. The Pt accessibility decreases with gold content. To avoid the chlorine role in catalytic properties, the chloride contents are also reported in Table 1, and was almost the same for all bimetallic catalysts. 

Sodium chloride content is closely related to ham quality, not only because of its direct effect on taste but also because of its effect on flavour development (75). The influence of sodium chloride content on volatile compound generation could be related to its effect on lipid-oxidation reactions, enzyme activity and microbial growth. As expected, salt content affected significantly a number of compounds described previously as dry-cured odorants (Figure 1) seven aldehydes and two acids. 

Figure 1. Odorants significantly affected by sodium chloride content at a level p...

The effect of sodium nitrite addition on the volatile compounds was barely related to reaction time no significant interaction appeared, although a slight effect (p < 0.1) was found for hexanal and 3-methylbutanoic acid. However, the effect of sodium nitrite was closely related to sodium chloride content significant interaction (p < 0.05) appeared for pentanal, hexanal, heptanal and oct-( )-2-enal, and a slight effect (p < 0.1) for hept-(E)-2-enal and octanal. 

The presence of chloride ions produces, at more positive potentials than Epi localized breakdown of the passive film and thus allows attack on the underlying metal. For potentials below Ep, the action of chloride is, to a first approximation, negligible. The chloride content being equal, Ep, decreases as the pH of the pore solution in concrete decreases and as temperature and porosity increase. Epj, is difficult to measure with laboratory measurements since during the measurement significant variations of pH and chloride level in the concrete near the surface of the steel can be introduced, altering the result... 

In case a, future penetration of chlorides has to be evaluated in order to assess if the chloride threshold will be reached at the surface of the reinforcement before time tf. If this is expected, the concrete with a chloride content higher than the critical value has to be removed (and replaced with a chloride-free material that prevents further penetration of chloride). Equation (1), Chapter 6, may be used to evaluate the future penetration of chlorides. By fitting the present chloride profile, the surface content and the apparent diffusion coefficient Dj j, may be calculated at time Since these parameters are evaluated on the actual structure and usually after a long time of service, it is often reasonable to assume that they will not change significantly in the future (unless the conditions of exposure of the structure will change). Equation (1), Chapter 6, can then be used to plot the expected chloride profile at time tf. 

There are also a significant number of private terminals for loading grain and coal owned by shipping companies and railroads. These private terminals are located in both freshwater and marine environments. The large size of most structures at port facilities requires that they be built with steel-reinforced concrete, steel, or a combination of both. The seawater environment is significantly more severe than river or lake waters because of the high chloride content in the seawater. 

Figure 7.63 Significance of oxygen and chloride content for SCC of an austenitic stainless steel in steam from alkaline-phosphate treated boiler water with intermittent wetting. (From [7.1] after Lee Williams.)...

Broomfield (2000) carried out regular surveys using LPR (see Section 4.12) on some reinforced concrete support pillars which had calcium chloride cast in as a set accelerator. These had been repaired with vapour phase corrosion inhibitors applied. Measurements from 1995 to 1999 showed the increase in the corrosion rate in treated and untreated control areas, with the corrosion rate peaking at around 0.5 to 1.0 A/cm (5-10 mm per year) with cracking seen approximately one year later. This demonstrated that the inhibitor applied with the chloride content of the structures was too high to stop corrosion. It also showed that a factor of two difference in corrosion rate between treated and untreated area made no significant difference to the rate and extent of cracking. 

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