Published Corrosion Data

Theoretically, corrosion rates from naphthenic acids are proportional to the level of the neutralization number of feed stocks but investigators have been unable to find a precise correlation between these factors. Predicting con osion rates based on the neutralization number remains uncertain. Published data, however, indicate a scattered trend toward increasing corrosion with increasing neutralization number.-... 

High water velocities can result in erosion or corrosion due to the abrasive action of particles in the water and the breakdown of the protective film which normally forms on the inside surface of the pipe. Erosion can also result from the formation of flash steam and from cavitation caused by turbulence. Publishing data on limiting water velocities are in conclusive. Table 27.9 summarizes the available information. 

Most of the published data on galvanic corrosion concern solid metal couples rather than bimetallic coating systems, and it is important to bear... 

The new continuous casting processes, in contrast to ingot cast products, provide tin mill products which are exceptionally clean and formable. The deoxidizing processes required for continuous casting involve either aluminum or silicon killing, which adds aluminum or silicon to the steel. Experience with type D steels indicates that the added aluminum will not cause a corrosion problem. Laubscher and Weyandt (18) have shown that the silicon found in silicon killed, continuous cast, heavily coated ETP will not adversely affect the corrosion performance of plain cans packed with mildly acid food products in which tin usually protects steel. The data on enameled cans is not definitive. Additional published data are required to determine whether or not silicon actually reduces the performance of enameled cans made from enameled, heavily coated, silicon killed, continuous cast ETP. 

The object-oriented Socrates system is concerned with material selection such as corrosion-resistant alloys (CRA) in a chosen environment. The system uses published data in the literature involving both laboratory and field data in the oil and gas environments. 

The most desirable data are those obtained for the material of interest in the intended conditions of exposure. Such data are not readily available in the literature. Published data on atmospheric corrosion should be used with caution since atmospheric conditions are changing with time, as for example acid rain as a variable factor. Accelerated testing, including electrochemical tests, should have a good link with the natural and practical conditions. Published data should be consulted because they are generally useful. Some published data are mentioned here as examples since they are useful in selecting materials or discussion of case histories ... 

Predictions of the corrosion performance should be obtained from published data and through testing.The essential requirements of accelerated testing are that the acceleration should produce the same mode of failure and reflect at least a known order of resistance of some alloys in service media.168 The most common approaches employed to achieve testing objectives in SCC are the use of high stresses, slow continuous straining, precracked specimens, higher concentration of species in the test environment than in the service environment, increased temperature, and electrochemical stimulation.169 For electrochemical corrosion, the properties of the medium at the interface should be considered in accelerated tests. 

These corrosion guides can be used for the preliminary screening of materials that are likely to be suitable, but the fact that published data indicate that a material is satisfactory cannot be taken as a guarantee that it will be suitable for the process environment being considered. Slight changes in the process conditions, or the presence of unsuspected trace impurities, can markedly change the rate of attack or... 

Some common chemicals have been tested for the skin corrosion under DOT protocols at a variety of concentrations. The results of this study can be used as a guide when classifying some of these materials. It must be remembered that the responsibility of determining if a material belongs to a hazard class rests with the shipper and that the use of published data should only serve as a guideline. 

The right choice of a carbon support greatly affects cell performance and durability. The purpose of this chapter is to analyze how structure and properties of carbon materials influence the performance of supported noble metal catalysts in the CLs of the PEMFCs. The review chapter is organized as follows. In Section 12.2 we give an overview of carbon materials utilized for the preparation of the catalytic layers of PEMFC. We describe traditional as well as novel carbon materials, in particular carbon nanotubes and nanofibers and mesoporous carbons. In Section 12.3 we analyze properties of carbon materials essential for fuel cell performance and how these are related to the structural and substructural characteristics of carbon materials. Sections 12.4 and 12.5 are devoted to the preparation and characterization of carbon-supported electrocatalysts and CLs. In Section 12.6 we analyze how carbon supports may influence fuel cell performance. Section 12.7 is devoted to the corrosion and stability of carbon materials and carbon-supported catalysts. In Section 12.8 we provide conclusions and an outlook. Due to obvious space constraints, it was not possible to give a comprehensive treatment of all published data, so rather, we present a selective review and provide references as to where an interested reader may find more detailed information. 

There is less published data on the influence of calcium formate on durability but electro-potential tests of a blended calcium formate/sodium nitrite based accelerator have shown no corrosive influence. 

This material is used in the CCRs and EPRs of the LMRs installed in submarine factory number 601. The Group could find no published data on the corrosion behavior of this material, and assumptions had to be made for modelling purposes. Although pure Eu is a reactive metal, in ceramic Bj form it is expected to be stable and relatively impervious to corrosive attack. The BCR of 0.01 mm-a was selected on the assumption that it was unlikely to be any higher than this. The importance of this parameter in the LMR model relates to the criticality issue and its value is shown in Section 5.2 (Reactor Criticality) to be insensitive in the criticality analysis, and therefore not of significance with regard to accuracy. 

There have been many attempts to classify the rate of corrosion of zinc in relation to scientific measurements of sulfur dioxide and chlorides, and time of wetness at specific locations, and this effort has led to ISO 9223 (Table 2.12). However the committee concerned recognizes that available data do not always fit the classification adequately and that further work is needed. As just noted, an important series of tests (ISOCORRAG) is still in progress by a group working within ISO TC 156/WG4. The published results are of particular value because four metals have been tested and, in many cases, some environmental data are available on sulfur dioxide, chloride, and time of wetness. The published data for zinc and the calculated steel/zinc corrosion ratio is summarized in Table 2.7B. 

Corrosion prevention is another area where accurate published data were unavailable. In 1958 and 1963, the share of this component in the total electrochemical industry was approximately 3 %. Our estimate of the value of shipments of corrosion prevention products, which function electrochemically, was 147.7 MM in 1958 and 192.9 MM in 1963. The corrosion prevention products which were considered in this study were zinc coatings and cathodic protection systems. The estimates of the 1958 and 1963 shipments of zinc coatings were made by a representative of a leading firm in the zinc coating market. This estimate for 1958 was 3.0 MM and for 1963 8.0 MM. These figures only include the cost of the materials applied. The cost of application, which may equal many times the cost of materials, is excluded. The value added by zinc coatings was obtained from the value added-shipments ratio of the appropriate SIC category in the Census of Manufactures. 

ASTM International and NACE International. Other organizations, which also issue standards for the many types of corrosion tests, are CEN, ISO, JSA, and MTI. These professional organizations have produced industry accepted recommended practices and test procedures (see Table 3), which allow comparison with others through direct interaction or published data. 

Properties rosion cracking, few published data are available on the general or localized corrosion of Ti-8A1-IMo-lV. One study, however, indicates repassivation behavior that is similar to that of CP Ti and Ti-6A1-4V in neutral salt solution (see above figure). Like other titanium alloys, successful apphcation of Ti-811 can be expected in mildly reducing to highly oxidizing environments in which protective oxide films spontaneously form and remain stable. On the other hand, hot, concentrated, low-pH chlo-... 

Weldments and Castings. Few published data on the corrosion resistance of weldments fmd castings are available for most P alloys. Under marginal or active conditions (for corrosion rates. 10 mm ear or 4 mils ear) weldments may experience accelerated corrosion attack relative to the base metal. 

Analysis of published data obtained from conventional recirculating Installations, closed water loop experiments, etc., indicated that little net release of corrosion products would occur in the primary circuit itself and that the major contribution to impurities In the primary water would be derived from the feedtrain. The objectives, then, were to clean-up the condensate return at a point as high up the feedtrain as possible and to clean-up those impurities which reached and concentrated in the primary circuit. Calculations indicated that a satisfactory primary water quality could be obtained if condensate clean-up was effected just prior to the deaerator, and a primary circuit clean-up rate of 50,000 Ib/h (total condensate flow 1.2x10° Ib/h) was employed. 

Summary of RSP data. Published data relating to R additions indicate both positive or negative effects on corrosion resistance. Therefore, it is difficult to draw conclusions as to what conditions produce these effects simply because many of the studies have lacked a systematic approach to the variation of important variables such as type and concentration of R addition. Furthermore, in most studies control data for pure or commercially pure Mg were never determined. In some cases commercial alloys with no R content were used for comparison, but these alloys were usually complex ternary or quaternary alloys with very different basic concentrations and methods of production. It is therefore difficult to know what constitutes a low or base corrosion rate. 

The corrosion rate data published in the literature are generally values averaged over a period of time. They are based on measurements of the loss of material (the weight loss method), of the ferrous ions present in the solution (photocolorimetric method), and of the pH change in the solution and on volumetric methods (collection of evolved hydrogen). Electrochemical procedures have frequently been used. Thus, corrosion current has been determined at the intersection of the initial or steady-state cathodic and anodic Tafel lines, or any of these lines with E=Another way in which information has been acquired is through Stem-Geary linear polarization and impedance analysis. 

Many fluorides are corrosive to glass and some metals Even the very corrosive anhydrous fluorides, however, can be handled at room temperature in steel, stainless steel, copper, and Teflon equipment For reactions at higher temperature, nickel and Monel metal are indispensable More data on corrosion of matenals are given in pages 22 and 23 of Chemistry of Organic Fluorine Cowjpoundi, published in 1676... 

The Af-HjO diagrams present the equilibria at various pHs and potentials between the metal, metal ions and solid oxides and hydroxides for systems in which the only reactants are metal, water, and hydrogen and hydroxyl ions a situation that is extremely unlikely to prevail in real solutions that usually contain a variety of electrolytes and non-electrolytes. Thus a solution of pH 1 may be prepared from either hydrochloric, sulphuric, nitric or perchloric acids, and in each case a different anion will be introduced into the solution with the consequent possibility of the formation of species other than those predicted in the Af-HjO system. In general, anions that form soluble complexes will tend to extend the zones of corrosion, whereas anions that form insoluble compounds will tend to extend the zone of passivity. However, provided the relevant thermodynamic data are aveiil-able, the effect of these anions can be incorporated into the diagram, and diagrams of the type Af-HjO-A" are available in Cebelcor reports and in the published literature. 

Data from extensive trials investigating the effect of depth on corrosion of materials in the Pacific have now been published . 

For comprehensive reviews of published marine corrosion data refer to references 29 and 33. 

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