This paper presents an overview of the current state-of-the-art in scale modeling of liquefied natural gas sloshing in ship tanks. The numerous potentially significant scaling parameters are discussed in detail and laboratory test data illustrating the effects of the important scaling parameters are presented. In view of current knowledge, an indication of appropriate scaling criteria is presented and recommendations for additional research efforts are outlined.

Venericardia planicosta of authors is considered as a monophyletic group of species rather than as a single specific unit. This group is restricted stratigraphically to the Eocene, but it is world-wide in geographic distribution. Each of the included species is generally confined to a single formation or member, but within its zone each is widely distributed, abundant, and conspicuous by reason of its size and ornamentation. As guide fossils the members of the plan•icosta group are therefore among the most significant of the Mollusca. Although no ancestral types have been recognized in the Cretaceous of the Gulf region, two virile branches of the planicosta group were already established in the region at the beginning of the Eocene epoch, and the present study is an attempt to trace their progress and development through the Eocene. Both of the branches, represented in the Midway deposits by V. smithii and V. mediaplata, are abundantly represented in the Wilcox deposits, particularly in the eastern Gulf province, by descendants of the Midway species. During the deposition of the middle Wilcox Tuscahoma and Bashi formations the planicosta group probably attained its greatest prominence in the size and abundance of individuals and in the diversification of the species, but their development is provincial. The faunas of the lower Claiborne deposits, on the other hand, especially those from the upper part of the lower Claiborne, are the most cosmopolitan of all the Eocene venericard faunas. The transgressional seas were not confined to the Gulf province but invaded Mexico, the Isthmus of Panama, and northern South America. So far as the venericards are concerned, the marine upper Claiborne, best represented by the Gosport sand, contains nothing more than a greatly reduced lower Claiborne fauna. After the widespread emergence at the end of Claiborne time, the venericards failed to regain their former prominence. Several species are known in Jackson deposits, but none of them are abundant, and the decline in the number of individuals and species during the Jackson epoch heralded the extinction of the group at the end of the Jackson. The occurrences of the planicosta group in western North America, South America, and the Old World are briefly considered. For the Asia-European representatives of the planicosta group, the life cycle was essentially the same as in America. In this paper 44 species and subspecies are deffcribed and illustrated; of these, 24 are new.

It is shown that the gravity-induced draining of liquid from a tank does not cease when the pressure differential at the outlet is zero if the liquid level is still above the outlet. Instead, either air or exterior liquid is ingested, depending on whether or not the tank outlet is submerged. Analytical models are developed to predict both the onset of ingestion and the subsequent discharge rates; experimental results are used to guide these developments. The models are shown to agree well with tests of draining during air ingestion and during water ingestion when the tank liquid is denser than water. When the tank liquid is less dense than water, however, the predictions of water ingestion are only in qualitative agreement with tests. Some possible reasons for this discrepancy are advanced.

Automatic and remotely controlled main line valves are used in natural gas transmission pipelines to provide early shutoff of gas flow in the event of a pipeline rupture. Operating experience, however, shows that these valves and their associated rupture detection and valve operator systems are not always reliable in sensing a line break and in achieving valve closure. There are documented instances of pipeline ruptures going undetected, and of main line valves not closing completely after even a full line break. False valve closures have also occurred, causing pipelines to be shut down unnecessarily. Under sponsorship of the Gas Research Institute (GRI), a technology assessment program was conducted by Southwest Research Institute (SwRI) to define the present state of the art of automatic and remotely controlled main line valves, to evaluate their effectiveness in achieving isolation of a ruptured line, and to identify technology improvements that are needed to improve valve reliability. This study was based on a survey of the U.S. natural gas industry’s experience with line break control equipment, and upon computational modeling of typical pipeline systems to simulate the generation and propagation of pressure and flow transients created by a line break. Line break transients were also compared to the transient levels generated by normal pipeline operations (start-up and shutdown of compressors, branch load changes, etc.). Also during this study, a semi-empirical computer model was developed to calculate pipeline blowdown time as a function of break size, pipeline configuration, and operating conditions, even in cases where valve closure is delayed for some period after the line break occurs. This information can be of value to pipeline engineers and emergency response planners. Results of the technology assessment show that the primary source of unreliability in present day line break control systems lies in their inability to discriminate between a line break transient, and those generated by other pipeline operations. In most cases, automatic control valves (ACV’s) sense the rate of pipeline pressure drop (ROPD) to detect a line break. In many field applications, however, transient pressure signals caused by compressor operations and load changes are stronger than those produced by a line break. In order to avoid false valve closures which could otherwise result, sensitivity of the rupture detection systems is “backed off,” often to the point of inoperability of the ACV. Other fluid transient signals besides pressure drop are also generated in the pipeline during a line break, and these can sometimes be used advantageously to replace or confirm the traditional ROPD signal. In looped parallel pipelines, for example, crossover flow rate is usually a more reliable line break signal when crossovers are open. The resultant line-to-line differential pressure also provides a viable option when crossovers are either open or closed. In general, however, no one detection parameter is optimum for all applications. Of even more importance is the rupture sensor location. The concept of locating additional sensors between the main line valves (rather than just at the valves) provides the most promising approach for enhancing the reliability of present ACV’s and for providing needed line break information to remote controlled valves (RCV’s). In either case (ACV’s or RCV’s), rupture sensor location is much more important than valve location or valve spacing in ensuring reliable rupture isolation. However, valve spacing does affect the volume of gas blown down after shut-in of a ruptured section. This time can often be from 10 to 60 minutes for typical pipeline valve spacings.

The purpose of the work is to assess the safety and operational advantages and establish guidelines for using subsurface safety valves in gas storage well applications.