Heating-under-containment tests

Heat of Reaction. Haber investigated the heat of reaction at atmospheric pressure [91]. Numerous authors have estimated the pressure dependence under various assumptions. Today, most people use the Gillespie-Beattie equation [92]. This equation was used in calculating the values in Table 12. For further data see, for example, [33]. Reference [93] contains test results for the range 120-200 MPa (1200 - 2000 bar) and 450-525 °C. Additional literature can be found in [94]. 

A second test was conducted under the above conditions. Reaction of the uranium dioxide was assumed to be complete when gas evolution ceased. At that point, the temperature of the melt was reduced to 200°C, and nitric acid vapor was added to the melt. The nitric acid vapor was carried from a heated vessel containing 100% nitric acid with the inert gas sparge. Transfer lines were heated to minimize condensation. The quantity and transfer rate of the nitric acid were not determined. Addition of the nitric acid produced a reaction with the solids present, shown by gas evolution from the solid s surface, which yielded a soluble uranium species in the nitrate melt. The total solids were dissolved, which produced a characteristic uranyl color in the melt. After complete dissolution of the uranium species, the nitric acid sparge was removed, and the melt was open to the atmosphere. 

Several tests are available to determine the softening point of asphalt (ASTM D-36, ASTM D-61, ASTM D-2319,ASTM D-3104, ASTM D-3461, IP 58). In the test method (ASTM D-36, IP 58), a steel ball of specified weight is laid on a layer of sample contained in a ring of specified dimensions. The softening point is the temperature, during heating under specified conditions, at which the asphalt surrounding the ball deforms and contacts a base plate. 

A solution of the nitrile (or oxime) (1 mole) in 1-butanol (2300 ml) is heated to boiling in a 5-1 two-necked flask fitted with a wide condenser (2.5 x 100 cm), and sodium (161 g in 10-20-g portions) is then added during 20 min. When the reaction slackens, heating under reflux is continued until almost all the sodium is dissolved, then the solution is allowed to cool, water (1.5 1) is added, and the butanol and amine are distilled off (the distillate is tested for amine, and if necessary more water is added and distillation continued). The distillate is made weakly acidic and concentrated (to 300 ml), then water (500 ml) is again added and distillation is continued until no more butanol passes over. The resulting concentrated butanol-free solution of the amine hydrochloride is supersaturated with alkali, and the amine is separated (if necessary with addition of ether) and dried first with solid alkali and then with sodium, after which distillation affords the pure amine without forerun or subsequent fraction. (The reaction is said to fail if sodium containing 0.1-0.01 % of potassium is used.30)... 

The concentration of the material contained in the hydrocarbon that leads to the deposition of wax crystals may vary from very small percentages up to substantial amounts. The concentration will affect the so-called "cloud point" which is the temperature at which crystals first appear in the solution that is cooled under standard test procedures. Clearly this temperature will be of considerable significance in fouling by crystallisation of hydrocarbon wax, on cooled heat exchanger surfaces. Of less importance, but still relevant to the fouling process, is the so-called "pour point". The pour point, a temperature lower than the cloud point, is the temperature at which liquid does not flow under prescribed test procedures. Both the cloud point and pour point are empirical measurements useful for comparing the properties of different crude oils. 

An improved salt spray test employed a mixture of sodium chloride and acetic acid. A solution containing 50 g/L of sodium chloride in distilled water is adjusted to a pH value between 3.2 and 3.4 (electrometric) with glacial acetic acid. The solution is sprayed through a small aperture atomizing nozzle and mixed with a compressed air stream. The solution usually is heated to 95 to 100°F (35 to 38°C). Failure under this test is assessed visually, and results generally are obtained within 48 to 72 h, depending on the coating system. 

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