There are several Fitness-For-Service (FFS) standards with evaluation rules in terms of plastic collapse for a pressure vessel or piping component possessing a local metal loss area simultaneously subjected to internal pressure and bending moment. The authors have already reported the results of a comparative study of FFS rules, including the remaining strength factor (RSF) approach in Part 5 of API 579-1/ASME FFS-1 and the p-M diagram method, which pointed out that there could be significant differences in allowable flaw sizes. This paper describes an additional comparative study on the difference of allowable flaw size for local metal loss assessment between the RSF approach in Part 5 of API 579-1/ASME FFS-1 and the p-M diagram method, focusing on the effect of decreasing yield strength of the material at high temperatures, such as 350 degrees C. The allowable flaw depth at high temperatures derived from API579-1/ASME FFS-1 is larger than that derived by means of the p-M diagram method. However, it is verified by the finite element analysis that the allowable flaw size of the p-M diagram method is set on the stress state of general yielding near a local metal loss area if safety factor is not considered and it is possible to evade ratcheting due to cyclic bending moment in service, such as that caused by earthquake, etc.
SUMMARYA comparative study of two male recombination factors (31. 1 MRF and 23. 5 MRF) isolated from the same Southern Greek natural population, revealed specific differences in their activities. 23. 5 MRF induces female sterility due to atrophie ovaries at a wide range of temperatures while 31. 1 MRF does so only at high temperatures. The gross morphology of the atrophie ovaries was the same and unilaterally affected pairs were found in the F1of crosses with both 23. 5 and 31. 1 MRF. Furthermore, 23. 5 MRF induces: (a) lower frequencies of abnormal anaphases I and II than 31. 1 MRF, (b) higher frequencies of ‘double crossovers’ resulting from deficiences or duplications, (c) large clusters of recombinants, suggesting premeiotic origin and (d) cases where one of the non-recombinant phenotypes was not produced. Such cases have never been observed with 31. 1 MRF. Moreover, the cytoplasm of theCy L4/Pmstrain that suppresses 31. 1 MRF does not affect the activities of 23. 5 MRF. Hypotheses to explain the different behaviour of the two factors are presented and discussed.
The cyclones are one of the most known apparatus destined to the solid-gas separation.
These equipments are used in the chemistry industry; its popularity is due mainly to the simplicity,
low energy requirements and ability to operate at high temperatures and pressures. One of the aims
of this work was to evaluate the influence of some geometrics variables in the performance of
conventional cyclones and filtering cyclones. The chosen variables were: conic part length (Zc),
the underflow diameter (Du), the overflow diameter (Do) and the finder length (Sc). The cyclones
conventional and with filter were compared and it was observed that the introduction of a filter
main in substitution to the metallic conic part of cyclones allows a appreciable reduction in the
pressure drop and consequently a smaller consumption of energy. The efficiency in the new
cyclone was a little smaller than the conventional equipment.