Metal Tanks Research Articles

The behaviour of locally-supported cylindrical shells: unstiffened shells

Many metal silos and tanks are locally supported on columns or other discrete supports to permit easy access beneath the vessel. The discrete supports introduce local forces into the cylindrical shell, which in turn produces zones of local high axial compression. The strength of compressed cylindrical shells has long been known to be governed by buckling considerations, but the buckling strength of discretely supported cylinders has only been investigated in recent years. Design rules which pre-date this study were empirical in nature and not based on rigorous buckling calculations or tests. In the present study, the theoretical buckling behaviour in the elastic–plastic range has been found to be so complicated that much work is needed to define the buckling strength for the purposes of structural design. This paper presents a description of the linear and nonlinear behaviour of isotropic unstiffened cylinders which are discretely supported at the lower edge. Much of the information given here is vital to the development of a more reliable design rule for shells under these loading conditions.

Bioremediation of Greenhouse Effluent using Constructed Wetlands

Due to problems of water shortages and increased legal constraints concerning effluent content, nursery and greenhouse operations are in need of new methods of cleaning and reusing irrigation water. Using constructed wetlands to improve water quality is a low-cost and rapidly emerging ecotechnology, and is currently used for treating wastewater from cattle operations, catfish ponds, and residential subdivisions. To examine the effectiveness of constructed wetlands, a greenhouse was equipped with five free-standing wetland cells planted with Equisetum hyemale (Horsetail). Cells consisted of 0.9 × 2.4-m metal tanks filled with pea gravel (about 0.7 m deep) with inlet and outlet sampling ports. Each cell collected runoff from individual greenhouse benches stocked with impatiens or marigolds grown in pots containing Sunshine LC1 media and fertigated using trickle irrigation. Runoff flow rates and volume entering each cell were measured. Water samples were taken 1) directly from the irrigation line, 2) as bench crop runoff, 3) after entering the cell, and 4) after exiting the cell, and were analyzed for various N fractions. Preliminary studies indicated that the cell size used in these studies was sufficient to handle runoff volume from each bench and could reduce overall N concentration in the runoff. There was significant variability in effectiveness between the cells, which appears to be due to differences in cell vegetation growth and establishment. Overall evaluation of the system and recommendations will be discussed.

Nitric oxide: physiology and pharmacology.

Nitric oxide: physiology and pharmacology.

Nitric Oxide

Nitric Oxide

Sanitary survey of private drinking water reservoirs in Northern Jordan

A sanitary survey for individual drinking water reservoirs in the rural areas in northern Jordan was conducted using purpose designed forms. 567 water samples were collected from the four main types of private reservoirs. 228 from cisterns, 128 from under‐ground concrete reservoirs 92 from ground‐level metal tanks, and 119 from taps receiving water from roof metal tanks. Twenty‐four more samples were collected directly from public supply systems. Water samples containing E. coli were considered contaminated. The results indicated that although water is supplied to houses free from contamination, more than 37.4% of private drinking water reservoirs in the rural areas were contaminated including 53.9% of cisterns and 30.9% of the reservoirs used to store water coming from public supply and 20% of tap water coming from roof tanks were contaminated. Seepage pits located within 15 m of the underground water reservoirs (at the same level or higher) significantly (p < 0.05) increased the possibility of water con...

Occupational risk factors for multiple myeloma among Danish men.

A large population-based case-control study evaluated occupational exposures in 1,098 Danish males diagnosed with multiple myeloma from 1970 to 1984 and in 4,169 age- and gender-matched controls alive at the time of case-diagnosis. Industrial histories were obtained from the Supplementary Pension Fund which, since 1964, has recorded employments of adult Danes; occupation came from subjects' most recent tax records. Four industrial hygienists created a job-exposure matrix for 47 substances based on 15,000 unique industry/occupation combinations in subjects' histories. Risk of myeloma was significantly elevated among road and railroad workers, precision metalworkers, and workers in the transportation and communication industries. Risk increased significantly with duration of employment in: production of synthetic yarns, plastic packaging, and miscellaneous chemical compounds; fabricating structural metal and stationary tanks; body factories; electrical plants; and retail sale of paint and wallpaper. Risks of myeloma were elevated, though statistically nonsignificantly, in all categories of exposure to gasoline and engine exhausts. Risks rose with likelihood and duration of exposure to phthalates, and were statistically significant and nearly fivefold with probable exposure to vinyl chloride for five or more years. After adjusting for multiple exposures and disregarding exposures within 10 years of diagnosis (or selection as a control), probable exposure to vinyl chloride was associated with increased risk of myeloma, which rose to fivefold with longer exposure. Associations with gasoline, engine exhausts, and phthalates persisted, but were inconsistent with duration and probability of exposure. Previously reported associations with agriculture were not confirmed by these data.

Elastic Stability of Cylindrical Shells with Weld Depressions

Metal silos and tanks are subject to axial compressive stresses in their cylindrical shell walls. The buckling strength is very sensitive to geometric imperfections in the wall. The most regular and well‐defined imperfection is the local depression adjacent to a circumferential weld, caused by the plate rolling process and shrinkage of the weld.

Response and failure of metal tanks from impulsive spot loading: Experiments and calculations

A series of experiments were performed to determine the impulse intensity of a spot load that would cause failure in pressurized and unpressurized thin aluminum tanks. Strain histories in the vicinity of the failure were successfully recorded in several of the experiments. Finite element analyses of four experiments were performed to determine the details of the strain histories at the failure locations. Verification of the finite clement modeling techniques are provided in a detailed comparison of strain histories for one of the experiments. A simple failure criterion, based on observations from the experimental and computational responses and additional biaxial tension tests, is used to predict the failure of the tanks.

Earthquake simulator studies of cylindrical tanks

An experimental investigation on the seismic response of ground-supported, cylindrical metal tanks is described. Experimental and analytical research by other investigators over the past forty years has provided a firm basis for the computation of free- and forced-vibration behavior in ideal liquid-filled circular cylindrical shells with a variety of elementary support conditions. However, the actual seismic behavior of ground-supported tanks has not been known, and practical design methods necessarily have been based on simplifying assumptions. The present results provide the first opportunity for rational evaluation of seismic design assumptions, and suggest theoretical developments which would enhance the realism of refined seismic analyses. The aluminum scale model discussed here, 12 ft in diameter and 6 ft high, represents a 36-ft diameter steel prototype. It was tested, in anchored and unanchored base configurations, under action of a time-scaled El Centro, 1940, earthquake with peak acceleration of 0.5 g, using the Earthquake Simulator Facility of the University of California, Berkeley. Stresses and displacements of the model, in both anchored and unanchored conditions, were dominated by effects of “out-of-round” response in higher-order circumferential modes, a result which is not predicted by current seismic analysis theory, and which contradicts basic assumptions of current design practice. The experimental observations are discussed in relation to dynamic analysis theory, practical design methods, and the history of tank performance in past earthquakes.

Underground Storage of LNG

The LNG industry requires a huge amount of investment in the facilities for liquefaction and marine transportation. In addition, the storage of LNG has posed a serious problem for both shipping and receiving points from technical and economical points Of view.The storage of LNG was normally made in double-wall metal tanks in the initial stage. However, this method was comparatively higher in cost and required highly advenced techniques in the construction. Furthermore it had another detrimental factor that a suitable location was not always readily available. As a counter-measure to this, an underground storage technique was developed and has since been gradually industrialized on a commercial basis.Additionally, instead of storing LNG in liquefied form, the underground storage of LNG in regasified form has come into wide use as a large-scale storage method.Japan is regarded to grow to the world largest importing country of LNG in the near future and, as her consumption of LNG increases she will be faced with the problem of how and where to keep these large supplies stored. A reasonably possible answer to this question will be an underground storage method of LNG in the Pacific belt regions of Japan which will be the principal areas to receive LNG import from abroad.Also, when the utilization of natural gas becomes prevailing, large scale storing of LNG will be a requisite for the purpose of peak-shaving. The most practical method for this will be underground storage in regasified form and for this purpose those depleted gas (oil) reservoirs located in the northern part of Japan on the Japan Sea will no doubt be most useful.

Comparison of Early Litomosoides carinii Infections in Cotton Rats and Gerbils

Cotton rats (Sigmodon hispidus) and Mongolian gerbils (Meriones unguiculatus) were exposed under similar conditions to the bites of tropical rat mites (Bdellonyssus bacoti) infected with the filariid worm Litomosoides carinii in order to compare early infections in the two rodent hosts. The combined data from four experiments provided a picture of remarkable similarity with regard to number, sex ratio, and length of adult worms and number of microfilariae in the early infections. However, histological examination of lungs showed that tissue reactions were generally more severe in gerbils than in cotton rats. Cotton rats (Sigmodon hispidus), as natural hosts of Litomosoides carinii, have been used in most research with this filariid parasite. Ideally, filaria-free animals raised under known conditions should be used, but the demand for them has not been sufficient to encourage the commercial production of cotton rats. In addition, cotton rats are difficult to handle. These problems have led to our use of the Mongolian gerbil (AMeriones unguiculatus) which is commercially available and easy to handle. The susceptibility of the gerbil to L. carinii infection has been reported following the surgical implantation or the injection of infective larvae (Scott, 1960; Zein-Eldin and Scott, 1961; Zein-Eldin, 1965). We have used young male gerbils mainly in drug evaluation studies with all observations being restricted to mite-induced early infections, i.e., prophylactic tests or therapeutic trials during the 1st month of patency. Therapeutic trials regularly included systematic counting of microfilariae and examinations of adult worms at autopsy. A review of our published (Dickerson and Thompson, 1966; Thompson et al., 1968) and unpublished data confirmed the high susceptibility of gerbils to L. carinii. But the combined data showed that 35 of 132 (26.5%) of the untreated controls had at least a few dead worms at autopsy approximately 3 months after exposure. Usually, dead worms constituted only a low percentage of the recognizable worms. Our experience with cotton rats has been too limited for a comparison of early death of adult worms in the two hosts. However, Wharton (1947) has reported that Received for publication 17 June 1968. occasional cotton rats have dead adult worms but he did not specify the age of infection when this was observed. The convenience of using gerbils and indications that they may be suitable for drug evaluation, encourage systematic comparison of the course of L. carinii infections in the two hosts. This paper deals with early infections following exposure of comparable groups of animals of each species to infected mites under similar conditions. The parameters studied included (1) species and sex of host, (2) early death of adult worms, (3) numbers, length, and sex of adult worms, (4) pulmonary reactions to adult worms, and (5) the microfilaremia. MATERIALS AND METHODS Sources of parasites and vectors The strain of L. carinii used in these experiments was supplied by Dr. E. A. Zein-Eldin, University of Texas, Galveston, and has been maintained cyclically in this laboratory since 1963. Tropical rat mites, Bdellonyssus bacoti, were obtained initially from Dr. Zein-Eldin and later supplemented by a supply from Dr. Frank Hawking, National Institute for Medical Research, Mill Hill, England. Infection procedure Four experiments were carried out using a modification of the tank exposure method of Hawking and Sewell (1948). Metal tanks with dimensions of 23 by 17 by 12 inches, equipped with electrically heated rims (at approximately 40 C) to prevent mites from escaping were used. Tanks were placed on carts equipped with oilfilled moats around the legs as a safeguard against escape of mites in the event of a power failure. Each tank was provided with a wooden frame lid lined with wide-mesh screening, to contain the rodent hosts, and 12XX bolting silk (for milling purposes) to prevent entry of contaminating mites. The design of the experiments is shown in Table I. Four infected gerbils were exposed to large

746. Design concepts for a combined space environmental effects test facility: S J Babjac et al,Vacuum, 18 (2), Feb 1968, 57–63

Compared with traditional metal tanks, prototype linerless composite cryogenic propellant tanks can achieve weight reductions up to 20%–40%. This prototype has recently become the trend in developing lightweight space vehicles. Moreover, this prototype promotes the research and development of new generations of inexpensive, high-capacity and recoverable space vehicles. In this review, the progress in research on composite cryogenic storage tanks by various space agencies is systematically analysed. Several key issues, including liquid oxygen compatibility and cryogenic mechanical and antileakage properties, in the process of manufacturing composite cryogenic tanks are summarised. Various solutions to these technical difficulties are briefly discussed. Finally, the directions that the development of composite cryogenic propellant tanks may take are explored.

A New Design 34.5 to 69 Kv Intermediate Capacity SF6 Circuit Breaker

A new line of SF6 breakers has been developed to cover the range of 34.5 to 69 kv and 500 to 2,500 mva (megavolt-amperes). A new puffer-type interrupter is used to operate in sealed and grounded metal tanks at 60 psig (pounds per square inch gage) gas pressure. Interrupting tests and impulse voltage withstand tests have been made according to proposed new ASA (American Standards Association) standards. Capacitor switching tests have been made which show these breakers to be well suited for switching large single or multiple banks.

Laboratory Studies of the Effects of Alkyl Benzine Sulfonate (ABS) on Aquatic Invertebrates

Experimental equipment, methods, and results of a number of experiments with stream bottom animals to determine the toxic effects of a packaged detergent containing 27 percent alkyl benzene sulfonate (ABS) are described. Most experiments were carried out in oval, metal tanks 3 feet long with channels 5 inches deep and 4 1/2 inches wide placed side by side. Currents simulating those found in streams were produced in the tanks with paddle wheels operated from a common shaft turned by a laboratory mixer. Each tank had a flow of 100 ml per minute. ABS was supplied from reservoirs to produce concentrations of 4, 8, 16, and 32 p.p.m. in the water of the tanks. Actual concentrations present were determined twice weekly by a methylene blue method. In general, mayfly nymphs (Stenonema ares, S. heterotarsale, Isonychia bicolor) were killed by 10 daysˈ exposure to ABS at 16 p.p.m. or more, and reduced in numbers by 8 p.p.m. Hydropsychidae larvae were more resistant, and in several experiments considerable numbers survived 10-day exposures at 32 p.p.m. Crayfish (Orconectes rusticus), freshwater shrimp (Synurella sp.), and sow bugs (Lirceus sp.) were seriously reduced in numbers by exposure to 10 p.p.m. ABS over a period of 2 weeks or more, but a snail (Goniobasis sp.) was apparently unaffected by this concentration.

A miniature tank for supply of carbon dioxide for carboangiocardiography.

SINCE THE INTRODUCTION of the method of intravenous injection of carbon dioxide into the right side of the heart, by Oppenheimer et al, 1 for visualization of the pericardium and right atrial wall, there has been an ever-increasing interest in this technique for the differential diagnosis of myocardial dilatation or enlargement and pericardial effusion and thickening. The procedure, carboangiocardiography, is safe and useful in clinical cardiology. 2,3 Unfortunately, CO 2 is supplied to hospitals and laboratories in large, heavy, and crude metal tanks which must be equipped with pressure gauges and reduction valves. This makes an otherwise simple procedure a cumbersome one which tends to discourage its general use. After obtaining more than 200 carboangiocardiograms at this institution in the differential diagnosis of pericardial disease, it became evident that a simple, inexpensive, and lightweight apparatus would facilitate the procedure and encourage its general use in radiology departments and medical services

Physical factors of a low-power medical reactor.

Relatively low-power, homogeneous, solid-fuel reactors became available for training and familiarization during the year 1957. These reactors were intended for the training of scientific and engineering students, in a program of reactor technology being supported by the U. S. Atomic Energy Commission (A.E.C.). A type offered by the Aerojet-General Nucleonics Laboratories of San Ramon, Calif., the AGN-201, stimulated the interest of staff members of the Isotope Branch of the U. S. Naval Hospital, Bethesda, Md. The reactor was investigated and, when it was found to be intrinsically safe for operation in proximity to a hospital, the process of licensure and procurement was initiated. The AGN-201 (Fig. 1) was designed to operate at 0.1 watt and, with the exception of the control console, was a unit package, including the shielding. In order to furnish medically useful isotopes, a minimum requirement of 3 and perhaps 5 watts of power was thought desirable. This higher power level, when authorized by the A.E.C., required some modifications of the 0.1-watt model. These modifications, chiefly reflected in the levels of instrumentation and increase in bulk shielding, were readily accomplished by the manufacturers. The reactor, for which a twenty-year license has been issued to the U. S. Naval Hospital (Bethesda), is an integrated part of the isotope branch of the Radiology Service of the hospital. In addition to x-ray therapy, an extensive radioisotope service for both diagnosis and treatment is maintained. A nuclear casualty evaluation facility is under consideration. The reactor is expected to augment all of these. The reactor is installed in a 21 × 21 × 21-foot air-conditioned concrete “block-house” type of building. With the console, it occupies most of the square footage of the building. “Cat-walks,” graphite column, and building services occupy the cubic footage. To utilize the reactor products, a radiochemical laboratory is located in the adjacent building with access to the reactor room through an interlocking door. Conventional chemical laboratories and radionuclide counting and assay rooms are also in the adjoining building, as is the office and health physics section. The characteristics of the reactor, reported by Biehl et al. (1) are as shown below. It must be noted, however, that Biehl's paper dealt with the 0.1-watt reactor and that power and flux levels have been adjusted for the 5-watt level at which we are licensed to operate. The reactor with these characteristics (Fig. 2) is a unit fabricated with three concentrically located waterproof metal tanks. The core tank is the inner tank of aluminum, containing the uranium core or fuel and is small and located in the reactor center. The larger tank containing the reflector and gamma shield, entirely encapsulates the core tank; this is known as the reactor tank.

Príspevok k problematike kvasenia a skladovania vín v kovových tankoch s uponovým náterom.

Pomocou elektroforézy na papieri sa dokázalo, že sa z epoxydového náteru Upon 1200 P po napučaní náteru vylúhováva tvrdidlo (polyetylénpolyamin), ktoré je najpravdepodobnejšou príčinou zhoršenia kvality vína.

LATEX/CEMENTS

For many years rubber has been employed to combat corrosion in numerous industries and new applications are continually being found for this versatile material. The accepted method of using rubber has, however, been in the form of sheet linings to concrete or metal tanks, etc., or as structures either constructed from or lined with ebonite. The modern corrosion engineer, however, has rubber at his disposal in yet another form, namely as one of the basic raw materials for a member of the acid‐resisting cement group, i.e. the latex/cements. These cements, whilst being comparative new‐comers to this field, have proved their worth under many widely varying conditions. The purpose of this article is therefore to outline the methods of preparation of these compounds, to detail their rather unique properties and to cover in detail their applications in a number of industries.

Consumption of Cereal Grains by Migratory Waterfowl

ager. Herewith are presented some observations on the consumption of cereal grains by representative species of captive wild waterfowl during the period, 1949-1951, at the Natural History Survey Laboratory located on the Chautauqua National Wildlife Refuge near Havana, Illinois. These data were taken from records on the rate of food consumption by healthy wild birds being held in captivity in connection with an investigation of lead poisoning in waterfowl (Jordan and Bellrose, 1951). The birds were held in large, wire-enclosed pens and were exposed to all elements of weather. Game-farm and wild mallards, Anas platyrhynchos L., blue-winged teals, Anas discors L., and Canada geese, Branta canadensis (L.) were generally penned in groups of at least 10 birds each; each group was provided with a constant supply of running water piped into large metal tanks 6 feet long, 3 feet wide, and 1 foot deep. The several diets made available to the birds in-

Studies on the Transmission of the Filarial Worms of the Cotton Rat 1

SummaryA method is described for infecting groups of cotton rats with relatively constant numbers of the filarial worms, Litomosoides carinii, all of which are of the same age. The infections were produced by exposing the rats in metal tanks to counted numbers of mites whose percentage of infection had been determined. Such rats are superior for chemotherapeutic studies and for studies on immunity to wild caught rats with infections of various numbers of worms of mixed ages. Further improvement along this line is needed, however, and to indicate possible lines of procedure the factors in the variability observed in these experiments are analyzed.