Casing collapse pressure

During DST operations, the drill pipe may be affected by a combined effect of collapse pressure and tensile load. For such a case,... 

Collapse Assumed external fluid pressure gradient of 0.52 psi/ft and casing empty inside. Safety factor for collapse = 1.0. Reduction of collapse pressure resistance due to the axial load is considered. 

Step 1. Determine the lightest weight of casing to resist collapse pressure for a setting depth of 12,000 ft. Because the maximum collapse pressure is (12,000)(0.52) = 6,240 psi, select N-80, 29-lb/ft casing with collapse pressure resistance of 7,020 psi. (Note assumed safety factor for collapse = 1.0.) This is Section 1. 

SnO has received much attention as a potential anode material for the lithium-ion-secondary-battery. The conventional techniques require temperatures above 150°C to form phase pure SnO. Whereas, sonication assisted precipitation technique has been used to prepare phase-pure SnO nanoparticles at room temperature by Majumdar et al. [25]. In this study, ultrasonic power has been found to play a key role in the formation of phase pure SnO as with a reduction in the ultrasonic power authors have observed a mixed phase. For the case of high ultrasonic power, authors have proposed that, intense cavitation and hence intense collapse pressure must have prevented the conversion of SnO to Sn02-... 

As a final result of the explanations about strengthening measures the admissible static internal pressure for thick-walled cylinders is compared in Fig. 4.3-7 for different design strategies according to the equations (4.3-9), (4.3-10), (4.3-12) and (4.3-13) and the explained assumptions and optimisations. In the case of the monobloc (A), the two-piece shrink fit and the autofrettaged cylinders the maximum stress at the inner diameter stays within the elastic limit (00.2). Comparatively much larger is the admissible pressure when complete plastic yielding occurs as shown for the collapse pressure (pCOmpi pi. = Pcoii D). 

To identify the intrinsic role of the double layer one has to account for dissolution or pre-empt it. One, not very appealing procedure is to compress very rapidly to avoid dissolution. An alternative is to experiment with films of longer chain fatty acids at not excessively high pH. Figure 3.83 is an example for stearic acid., given by Tomoaia-Cotisel et al. ). In this case the authors found that the collapse pressure was the same (51 mN m ) for each pH, but collapse took place at different... 

There is always an uncertainty associated with the exact quantification of the collapse pressure generated. Use of the Rayleigh-Plesset equation will dictate the termination condition as bubble-wall velocity exceeding the velocity of sound in the medium, whereas for the case of equations considering the compressibility of liquid, new termination criteria will have to be considered. Thus, for some other conditions with better computational facilities, a different collapse criteria (cavity size lower than 1 or even 0.1% of the initial size) may look feasible. Another collapse criteria based on Vander Wall s equation of state has also been considered [Gastagar, 2004]. The criteria considers that the cavity is assumed to be collapsed when the volume occupied by the cavity is equal to the material volume given by the product of the constant b in the Vander Wall s equation of state and the number of moles. The exact predictions of the collapse pressure pulse is always a matter of debate, nevertheless, a new proportionality constant to avoid this uncertainty can always be developed based on the relative rates of the reaction. 

The low-temperature/low-pressure cycle theoretically results in a low product temperature. However, the drying rate is low and there is a risk that primary drying is not over when the temperature of the shelves is raised. In this case, collapse or retrograde collapse may occur. In addition, final product moisture may be above specification. 

Snedden (1985) experimentally obtained similar load-deflection curves and developed simplified analyses to determine the collapse pressure and evaluate the first three ranges noted above. He considered the lateral stiffness once convolution contact occurred to be infinite and thus any constraint to be rigid, though as can be seen from his results, this is far from the case (Fig. 7 of Snedden, 1985) and a more gradual approach to failure develops. 

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