Modes of ruptures

An important application of a rupture disc device is at the inlet of a pressure relief valve. The sizing of the pressure relief valve or rupture disc device combination requires that the pressure relief valve first be sized to meet the required relieving capacity. The normal size of the rupture disc device installed at the inlet of the pressure relief valve must be equal to or greater than the nominal size of the inlet connection of the valve to permit sufficient flow capacity and valve performance. The failure modes of rupture discs are [40] ... 

Figure 29 Different modes of mechanical stresses on adhesives (or sealants) joints. Modes of rupture of adhesives and sealants bonds.

A certain period at 20 or 23°C must elapse before testing, in order to standardize the test specimen. Then the test specimen is clamped in a tensile machine, such as the one shown in the colour section, and pulled with a constant rate of increase of the pull force, until it breaks, and the forces are recorded. The mode of rupture, adhesive or cohesive or mixed, is also carefully noted (Fig. 29b). 

Three attempts are knovm to define, and to account for, a work of rupture which is independent of the sample dimensions and thus may represent a property of the material studied. The most common mode of rupturing a solid involves the growth of a crack. In many instances it is possible, more or less convincingly, to separate the work / (ergs or joules) necessary for this gro rth from the v/ork done on the simultaneous gross deformation of the test sample (and the instrument employed). Usually it is found that this U is proportional to the area A of the new crack surfaces, so that fg/sec or kg/sec ) remains constant... 

Variational RRKM theory is particularly important for imimolecular dissociation reactions, in which vibrational modes of the reactant molecule become translations and rotations in the products [22]. For CH —> CHg+H dissociation there are tlnee vibrational modes of this type, i.e. the C—H stretch which is the reaction coordinate and the two degenerate H—CH bends, which first transfomi from high-frequency to low-frequency vibrations and then hindered rotors as the H—C bond ruptures. These latter two degrees of freedom are called transitional modes [24,25]. C2Hg 2CH3 dissociation has five transitional modes, i.e. two pairs of degenerate CH rocking/rotational motions and the CH torsion. 

Rupture discs should be removed from service at predetermined intervals for visual inspection. Depending on the condition of the disc and recommendations by the manufacturers, they are either replaced or returned to service. The most common mode of failure is case (c), premature rupture below the minimum bursting pressure. An analysis of this mode of failure indicates that this can be the result of ... 

The general mode of action for the control of foam is to displace organic solutes or other materials that are absorbed into the bubble film at the gas-BW interface. The new film tends to lack elasticity and is therefore prone to rupturing and instability. 

Monomeric sulfur diimides have an extensive coordination chemistry, as might be anticipated from the availability of three potential donor sites and two re-bonds.131 Under mild conditions with suitable coordinatively unsaturated metal complexes, sulfur diimides may coordinate without rupture of the -N=S=N- unit. Four modes of coordination have been identified or invoked as intermediates in fluxional processes (Scheme 8). 

The process is run in a semi-batch mode, and multiple reactors are used. There are several possible causes for a loss of control such as insufficient heat removal and loss of agitation. Overpressurization leading to the bursting of rupture discs takes place several times per year, indicating both the clear need for containment but also a need to consider design and control improvements. The reference describes the autoclave rupture disc assembly, procedures for replacement of the discs, the cleaning of the containment vessels, and the routine maintenance procedures for the containment vessels. 

Fracture modes of the forged steels were dominated by the dimpled rupture process in unexposed, hydrogen-exposed and tritium-exposed steels and welds. Heavily sensitized steels had a similar fracture appearance as tritium-exposed-and-aged steels... 

Violent oscillations of the axially symmetric type can be induced in single drops formed at a nozzle. Drops of chlorobenzene (Dg = 0.985 cm) were so formed, and allowed to fall in water. At about five inches below the nozzle two types of rupture were observed. A small droplet was formed at the front and hurled ahead of the drop by the next oscillation. A second mode of formation caused a droplet to be formed by inertial pinch at the rear of the oscillating drop. This rear-formed droplet was always larger than the very small one formed in front. There were, on occasion, two successive pinch-formed droplets from the rear. In a few instances both front and rear formation occurred, as shown in Fig. 13 in selected... 

Here it should be noted that secondary C-H bond rupture is only slightly more probable than the scission of primary bonds, despite the fact that D(iso-C3H7—H) is 5-6 kcal./mole lower than D(m-C3Ht—H) (70,71). Hence, the bond-dissociation energy does not appear to be the major determining factor in the primary mode of decomposition. However, the results obtained by Palmer and Lossing (73) for the isobutane reaction do indicate that methyl substitution on the secondary position in propane causes C-H bond cleavage to occur preponderately at the tertiary site. 

Although highly excited and energetically able to decompose, the molecules formed either by H-atom or by H2C addition survive many vibrations. The energy of reaction is distributed over the entire molecule prior to isomerization or bond rupture. This has been deduced from analysis of the proportions of the various products that are formed (when more than one path is available). The proportions change very little, if at all, with excitation energy. Thus, for complex excited molecules, their history, i.e. mode of formation, becomes irrelevant in the analysis of subsequent reactions. 

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