Tests and Their Significance

The many accelerated corrosion tests reported in this book should not be regarded as a direct guide to performance, even in apparently related service conditions. They are mainly of value as sorting tests for coatings of the same type or as guides for research workers, as is the case with electrochemical tests. Many tests relating to corrosion and corrosion protection are now standardized, and an advertised book by Fomin—in Russian—aims to identify and discuss all relevant tests. 

As early as 1943, Committee B-8 of ASTM confirmed that salt spray does not reveal initial porosity in zinc coatings and provides only a poor means of estimating the coating thickness. The test was not considered to be suitable for sacrificial coalings. 

This point was considerably amplified by Carter (1972), who refers to comments by Sample in a paper on the use and misuse of salt spray testing in which he also pointed out that a plentiful supply of well conducting electrolyte could lead to erroneous results by comparison with atmospheric exposure where there is alternate wetting and drying by a poorly conducting electrolyte. In such a case there is an acceleration of the yield of the voluminous white corrosion products that appear on zinc and can cause zinc to have a poor rating from some organizations. 

Carter also quotes Le Que on the unsuitability of salt spray tests for sacriflcial coatings and comments on the failure of the latter investigator to place cadmium and zinc in the same order as in outdoor exposure. He makes the further point that the comparative performance of zinc and cadmium varies with the composition of the salt solution used for spraying. For example, the superiority of cadmium is lost when natural seawater (containing, e.g., magnesium salts also) is substituted for a pure sodium chloride solution. It is suggested that variations in relative performance may be explained by the nature of the corrosion products formed and the extent to which condensation occurs on the surface of the specimens. 

The inadequacy of salt spray tests is well demonstrated by Van Eijns-bergen (1970) in Table 1.15. He adds that corrosion is a topochemical 

---

Ore-dressing tests and their significance. 16. Ore-testing studies." U. S. Bur.. Mines Rept. Investigations 3328. 

Each of these irradiation-induced effects can be evaluated in "separate effects" tests and their significance on crack propagation can be formulated. This extensive amount of work has been reviewed [122,123] and only the major conclusions are given. For instance, the effect of irradiation on corrosion potential and hence crack propagation is shown in Figure 18.33, which compares the observed and predicted crack depth vs. time relationships for thermally sensitized stainless steel specimens exposed in the unirradiated recirculation line and in an irradiated core instrumentation tube of a BWR. The observed and predicted effect of irradiation in increasing the crack propagation rate via its effect on the corrosion potential alone is apparent. 

Methods used for the tensile testing of single fibers and fibers taken from yams and tows are discussed in ASTM D3822 and D2101. Measurement equipment used in fiber tensile testing is described in ASTM D76. An overview of test procedures and their significance is also available (3,10). 

As for (ii), Mendeleev was, as indicated, quite ready to change atomic weight assignments from those accepted at his time to avoid significant discrepancies in his tables. This may sound ad hoc, but in fact, and as we already pointed out, some of these contra-predictions could be independently tested and their success in independent tests played an important evidential role—one which, as Brush allows, there is no reason (either historical or methodological) to suggest was any less significant than that played by the prediction of new elements. 

Kim et al. [123] conducted the kinetic study of methane catalytic decomposition over ACs. Several domestic (South Korea) ACs made out of coconut shell and coal were tested as catalysts for methane decomposition at the range of temperatures 750-900°C using a fixed-bed reactor. The authors reported that no significant difference in kinetic behavior of different AC samples was observed despite the differences in their surface area and method of activation. The reaction order was 0.5 for all the AC samples tested and their activation energies were also very close (about 200 kj/mol) regardless of the origin. The ashes derived from AC and coal did not show appreciable catalytic effect on methane decomposition. 

Estrogens, Natural, the Determination and Significance of (Brown), 3, 158 Flame Photometry (MacIntyre), 4, 1 Flocculation Tests and their Application to the Study of Liver Disease (Reinhold), 3, 84... 

The significance of radioactivity in water, food, and air has been under particular scrutiny since the advent of nuclear bomb tests and their accompanying radioactive fallout. This scrutiny has resulted in much documented data gathered over the past few decades on the health characteristics of man under various environmental conditions, such as the Denver populace who are subjected to more intense cosmic ray irradiations than the New York City populace the radium dial workers of the 1920,s who have provided data on life spans, general health, and causes of death population s drinking water with varying radium contents persons living... 

Although it is likely that the reaction rate is influenced by steam, hydrogen, and carbon monoxide partial pressures, these did not vary significantly during the tests, and their effect cannot be determined at this time. 

Records should be kept of the results of all sterility tests and control tests. Contamination rates for different products and for different sterility test techniques should be calculated periodically and compared and their significance assessed (see also Appendix C). 

Bishop, A.W., and Eldin, A.K.G. 1950. Undrained triaxial tests on saturated sands and their significance in the general theory of shear strength. Geotechnique, 2 129-150. 

Table 4.2 summarises all tests required together with their purpose and their significance of use. 

Toxicity studies are expected to be performed in compliance with Good Laboratory Practice (GLP) however, it is recognised that some studies employing specialised test systems which are often needed for biopharmaceuticals, may not be able to comply fully with GLP. Areas of non-compUance should be identified and their significance evaluated relative to the overall safety assessment. In some cases, lack of full GLP compliance does not necessarily mean that the data from these studies cannot be used to support clinical trials and marketing authorisations. 

The odor detection-threshold values of organic compounds, water, and mineral oil have been determined by different investigators (Table 2 and 3) and may vary by as much as 1000, depending on the test methods, because human senses are not invariable in their sensitivity. Human senses are subject to adaption, ie, reduced sensitivity after prolonged response to a stimulus, and habituation, ie, reduced attention to monotonous stimulation. The values give approximate magnitudes and are significant when the same techiriques for evaluation are used. Since 1952, the chemistry of odorous materials has been the subject of intense research (43). Many new compounds have been identified in natural products (37—40,42,44—50) and find use in flavors. 

Application. A stimiihis was tested for its effect on blood pressure. Ten men were selected randomly, and their blood pressure was measured before and after the stimiiliis was administered. It was of interest to determine whether the stimiihis had caused a significant increase in the blood pressure. 

Much of the experience and data from wastewater treatment has been gained from municipal treatment plants. Industrial liquid wastes are similar to wastewater but differ in significant ways. Thus, typical design parameters and standards developed for municipal wastewater operations must not be blindly utilized for industrial wastewater. It is best to run laboratory and small pilot tests with the specific industrial wastewater as part of the design process. It is most important to understand the temporal variations in industrial wastewater strength, flow, and waste components and their effect on the performance of various treatment processes. Industry personnel in an effort to reduce cost often neglect laboratory and pilot studies and depend on waste characteristics from similar plants. This strategy often results in failure, delay, and increased costs. Careful studies on the actual waste at a plant site cannot be overemphasized. 

---