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By R. J. Sandrea, S. M. Farouq Ali

The results of an experimental and theoretical study of the effects of rectilinear impermeable barriers and highly permeable channels on the sweep efficiency and conductivity of a five-spot network are presented. The study was carried out using Hele-Shaw, and conductive sheet analogs for both. normal and inverted flood patterns. A functional relationship was developed which provides quantitative prediction of the above parameters; i.e., sweep efficiency and conductivity, for the nonhomogeneous system. To evaluate this, it is necessary only to measure the interference modulus of the obstacle using a simple expression. The results indicate that impermeable barriers, with an interference modulus greater than zero, always cause a decrease in the conductivity and the sweep efficiency of the pattern. On the other hand, permeability channels do not have a significant effect on these parameters, unless they are located along the streamlines. The study also discusses a method of formulating the difference equations pertaining to the two-dimensional Laplacian in a system containing rectilinear barriers. In addition, a technique is described for tracing the progress of a free surface, using marked particles, in a stream containing discontinuities SuCh as those occurring at the extremities of barriers. The above computational scheme was used in a digital computer program to simulate results of the Hele-Shaw analog. The computed values of sweep efficiency mere in good agreement with the experimental values. INTRODUCTION At the present time waterflooding remains the most widely used technique for the secondary recovery of oil. Among the numerous factors that affect the performance of a waterflood, the areal sweep efficiency constitutes one of the most critical parameters. It is a function only of the geometric distribution of the wells for a homogeneous medium and unit mobility ratio. Geological considerations, however, such as the presence of sealing faults or solution channels in the rock matrix, would generally exert an adverse effect on the areal sweep efficiency of a waterflood network. Surprisingly little information is presently available on the quantitative implications of such permeability interferences. It was the object of this investigation to consider the presence of rectilinear, impermeable and highly permeable interferences in an otherwise homogeneous five-spot pattern, and to analyze their effects on the resulting sweep efficiency and pattern conductivity. The experimental phase of the study was conducted using two different models: the Hele-Shaw flow cell and the field plotter. For experimental convenience, the geometric boundaries of the five-spot were assumed to constitute streamlines even in the case where the interference was asymmetrically placed with respect to a repeated five-spot pattern. A second object of the study was to develop a computational scheme for numerically calculating the pressure distribution in a five-spot flow pattern containing rectilinear, impermeable barriers, and to use this distribution to compute the sweep efficiency. EXPERIMENTAL PROCEDURE HELE-SHAW ANALOG The Hele-Shaw analog was used both as a visual model and for determining the sweep efficiency for systems involving impermeable barriers. The physical limitations of this model as a means of experimentally studying the motion of a fluid in porous medium have been adequately discussed elsewhere.2,7 Likewise, it can be easily verified that the analogy remains valid when a portion of the region between the plates contains an obstacle of the same thickness as the distance between the plates. The model used in this study was composed of

By Raymond Ladoo

THE milling of talc, as is the case of many non-metallic minerals, until recently, has not received adequate technical consideration, for the talc industry has become of importance only within the last decade. At first, talc was used only in the massive form, for foot warmers, griddles, and so on, and milling methods were unnecessary. As the demand for ground talc increased, producers adopted the machinery used in the milling of flour; in fact, many talc mills were rebuilt flour mills. Improvement has been slow, but today several types of grinding and separating machinery are in use; many of them, however, are still inadequate and inefficient. To determine the best methods of milling talc, it is necessary to understand the essential properties a talc must possess to fit it for a particular use. For toilet purposes, whiteness, freedom from lime and grit, fineness of grain, and good "slip" are essential. As a paper filler or coating, the talc must be white, have a good slip, be free from grit and iron, uniform, and fine grained; freedom from lime is a disputed point. Fibrous talc is supposed to be superior to massive on account of the interlocking of grains in the paper, thus increasing its strength; this point, though, is in doubt. In general, talc for the paper industry need not be of as high quality or as fine grained as that used for toilet purposes. Talc is usually bought by sample, for which reason it is difficult to state the essential properties for use in paint, rubber, roofing, and so on. The adoption of standard screen tests and standard grades by producers is necessary before an accurate basis for manufacturing or selling standards can be established. Off-color tales might be utilized, as in Germany and-Austria, by the establishment of standard grades of colored tales.

Jan 1, 1921

By M. Muskat, R. D. Wyckoff

The general problem of the simultaneous movement of water and oil in a connected sand is of considerable practical interest from two points of view. First, there is the situation usually described as "edge-water encroachment." Here the water in the sands contiguous to and flanking the oil sand begins to enter the latter as the oil is removed and the reservoir pressure declines. The physical questions involved concern an understanding of the mechanism of the advance of the water and its control, so as to aid the oil recovery rather than to hinder it. In so far as the entry of the water into the oil sand means at least the partial replacement of the oil from the region of the encroachment by the advancing water, it is quite appropriate to consider this type of situation as one of natural water-flooding. For the present discussion, however, we are primarily interested in the problem of artificial flooding. Here the water is deliberately injected into the oil sand with the intention of displacing the oil and removing it through prearranged output wells. For the practical development of such a procedure rather large areas are included in the flooding program and the injection and output wells are arranged in regular patterns or networks, which are felt to be most favorable for a high oil recovery. Although remarkable success has already been obtained in such flooding programs, especially in the Bradford field of Pennsylvania, essentially by the application of the lessons of practical engineering experience, a more thorough physical analysis of the problem appeared to offer promise of leading to results of some interest and value. Another phase of the problem, which stimulated both the experimental and mathematical analysis, is that it is susceptible in large measure to empirical field tests. It, is in itself but an example and illustration of the general theory of the flow of dead (gas-free) liquids through porous media, in which the authors have been interested for the last several years. From the point of view of its applicability to actual petroleum technology problems, however, water-flooding is a particularly favorable

Jan 1, 1934

By E. C. Bain, E. S. Davenport

When annealed carbon, or low-alloy, steels are suitably heated the ferrite (alpha iron solid solution) and the carbide, of which they are composed, react together to form a single solid solution of carbon (and other elements) in gamma iron (austenite). This reaction may begin only at a certain minimum temperature called the eutectoid temperature. The first ferrite and carbide thus to react together do so in definite proportions known as the eutectoid composition. With further heating the original constituent that is present in excess is dissolved in the austenite until exhausted. Whether the excess constituent be ferrite (hypoeutectoid steels) or carbide (hypereutectoid steels) the procedure is much the same, and upon slow cooling the homogeneous austenite expels the excess of either (proeutectoid ferrite or carbide) until the eutectoid composition is reached. Thus the reaction upon heating is strictly reversed upon cooling and accordingly an equilibrium diagram of this process may be constructed. Such an equilibrium diagram concerns itself only with the temperatures involved and with the proportions and compositions of the phases developed under conditions that suffice to permit equilibrium. Specifically it has no concern for the type or mode of distribution of these constituents nor with any extra-equilibrium conditions such as undercooling, which is almost universally encountered in metals. Actually, however, of great importance is the sluggishness toward equilibration caused by the not inconsiderable time involved in diffusion. Thus instead of the theoretical transformation point AF, we find for a certain rate of heating or cooling the use of the designations Ar and Ac (transformation temperature found on cooling and upon heating). These figures obviously have no particular meaning except as measured and expressed for a definite heating or cooling rate, and represent the apparent temperature displacement caused by an inadequate time allowance. In this paper are presented the results of a study of the time required for the transformation of austenite to ferrite and carbide at a variety of temperatures and also of the time required for the reaction austenite? martensite at the temperatures at which this reaction occurs instead of

Jan 1, 1930

By D. Ott

Results of a research project on investment or lost wax casting will be presented. The project was concerned with various aspects of the process as they are typical for the production of jewellery from gold alloys. During these investigations testing methods for investment quality as well as for casting quality and the various process parameters were developed and charateristic defects as they occur in practice were traced back to their origin in the process. Investigated were various static casting and centrifugal casting methods in different atmospheres as well as vacuum casting in devices of different design. It was shown that independent of the method a close control of the many process parameters interfering with each other is essential for a quality casting.

Jan 1, 1984

By J. H. Berryman

THE use of oxygen as a bath reagent in hearth furnaces during the refining period is a familiar story. Investigations and tests in which oxygen was substituted for iron ore to reduce carbon date back 25 years and include the work of Bigge,1 Browne,2 and Chelius.3 During this past year the majority of the experimental work in the use of oxygen was carried on mainly in open-hearth shops, since it was felt that the greater field for application lay in this type of furnace. Much constructive work was done in evaluating the carbon-oxygen relationships, as reported by Slottman and Lounsberry4 and by Hughes.5 Steelmakers using the electric furnace have been actively engaged meanwhile in an experimental program of their own, with such success that the oxygen injection pipe has become a tool in the day to day production of low-carbon and stainless steels.

Jan 1, 1947

By E. G. Leonardon, C. Schlumberger, M. Schlumberger

Since the beginning of the year 1928 the senior authors and their associates have applied a series of procedures which makes possible the detailed study in situ of the formations traversed by a drill hole before the casing has been landed. They have given the name "electrical coring" to the ensemble of these processes, which now replace in a large measure the mechanical coring performed by the drillers, and permit the gathering of bottom-hole data hitherto unobtainable. Three years have elapsed since the technique and interpretation of these measurements emerged from the experimental stage and entered the field of industrial application on a large scale. The total length of drill holes so far surveyed by the authors and their associates, all over the world, amounts to several millions of feet. Practical and strongly built equipment has been evolved, which permits the examination in a short time of an open hole several thousand feet long. No comprehensive paper has yet been published discussing the essential principles of the processes applied and bringing into evidence their economic interest. This is the object of the present paper.' Numerous examples of field work performed under varied geological conditions are given, constituting a concrete illustration of the services rendered by the new methods. The study in situ of the formations penetrated by a drill hole is based on the measurement of a given physical factor or parameter associated with these formations. Generally the measurements are made systematically along the whole length of the open hole. The physical factors , or parameters which are now utilized by us to this end are: (1) the resistivities of the rocks; (2) their porosity; (3) their electrical anisotropy; (4) their temperature; (5) the resistivity of the muds. In order to

Jan 1, 1934

By J. J. Jakosky

A REVIEW of the progress in applied geophysics during the recent depression years reveals marked advances "over the methods employed several years ago. Of late, geophysical work has been curtailed to a con-siderable extent in the fields of oil and base-metal exploration, its especial domains a few years ago. Greater attention has been directed toward the use of geophysical technique in other engineering problems. Constantly maintained research programs have developed new instruments and per-fected better field, laboratory and interpretation techniques based on experience and skill acquired from years of application in the older geophysical field. During the past two years, geophysical methods have been employed in problems that required information on thickness of fill materials and subsurface bedrock contours. Considerable success has been attained, with subsequent drilling checking the predicted depths within one to five per cent. In general, these problems were similar as far as the fundamen-tal physical and geological conditions were concerned, but they have varied widely in specific detail and in engineering aspects. Character-istic of the different problems are: (1) yardage and bedrock profile in gold-placer mining; (2) water supply, involving underground drainage and storage conditions; (3) bedrock contours in dam-site and other structural investigations; (4) gravel and fill yardage, and other structural features along rights of way and in rock and gravel quarrying. Of particular interest, perhaps, to mining men are the problems of gold placer deposits and water supply. Geophysical work on gold placers is of especial interest because of the present expanded activity in all phases of gold mining. The development of a suitable water supply at, an economical cost is often of prime importance in insuring a successful mining venture. Particularly is this true in the arid Southwest. How-ever, the use of geophysical work in water supply is not confined to the needs of mining development.

Jan 1, 1933

By Louis Jordan

THIS paper presents in an abbreviated form the chief points of interest in an investigation of the tarnish-resistant qualities of silver alloys, an investigation which has been carried out as a joint research by the Bureau of Mines and the Bureau of Standards and will later be reported in detail in an official publication from these bureaus. In 1923 a Commission of Gold and Silver Inquiry was created by a Resolution of the U. S. Senate to study the causes of the depressed condi¬tion of the gold and silver industry. In cooperation with this commission the Bureau of Mines made a preliminary survey to determine in what ways, if any, it might be possible to increase the uses of silver. One of the possibilities indicated by this survey was the development of silver alloys which should be non-tarnishing, or at least less-tarnishing, than the usual sterling silver (copper-silver). The preparation of a rather wide variety of silver alloys and the determination of their behavior under accelerated tarnish tests in the laboratory was therefore undertaken by the bureaus, of Mines and Standards as a joint investigation. PREVIOUS WORK ON TARNISH RESISTING SILVERS At about the time this work was undertaken interest in tarnish-resisting silvers was rather keen due to announcements from England that there had been developed a new silver alloy, "Silanca," which was resistant to tarnish. It was even frequently described in the popular press as "non-tarnishing." A few samples and several analyses of "Silanca" which were available indicated that it was an alloy of sterling fineness, that is, it contained about 93 per cent. of silver, with approximately 4.5 per cent. of antimony and either cadmium or zinc, or both, to make the remaining 2.5 per cent.

Jan 1, 1927

By M. G. Benz, J. F. Elliott

The austenite solidus of the iron-carbon system has been determined using a series of diffusion couples, each of which consisted of a specimen of austenite held in contact with a melt saturated with austenite. After the equilibrium distribution of carbon had been established by diffusion at a specified temperature, i.e. the austenite specimen had become austenite of the solidus conzposition, the diffusion couple was cooled, sectioned and anazlyzed for carbon. The solidus was found to be a straight line: A revised iron-carbon temperature-composition diagram is presented, COMPOSITION has a marked effect on the temperature at which austenite begins to melt and the austenite solidus of the iron-carbon system describing this effect has been the subject of many investigations.1-10 The significant results of these investigations are presented in Fig. 1. The experimental methods and purity of the materials used in them are summarized in Table I. In plotting the data in Fig. 1 no attempt has been made to convert these results to the International Temperature Scale of 1948," except for the data of Adcock,5 as this conversion would do little to reduce the uncertainty that exists as to the position and shape of the solidus. A point of major concern in evaluating these data is that the alloys studied, except those used by Adcock, were not binary alloys of iron and carbon, Table I. Also, it would appear that several of the methods did not permit equilibrium to be established through the system being studied. All that can be said for the results of these investigations is that they indicate only approximately the location of the solidus with the uncertainty as to its location at 1 pct C being approximately 100°C. The current investigation was undertaken to provide reliable data by which the austenite solidus could be established. It was hoped that information on the liquidus also could be developed at the same time, but experimental limitations prevented this as austenite segregated from the liquid on cooling. After a careful study of possible experimental methods and extensive laboratory tests, it was decided that the use of a series of austenite-liquid diffusion couples would provide the most reliable results. This paper describes the method and its results and also includes a complete iron-carbon temperature-composition diagram based on what are considered to be the best available data. EXPERTMENTAL METHOD The diffusion couple used for this investigation consisted of a small cylindrical pellet of austenite held in contact, at a specified temperature, with a melt saturated with austenite. The composition of the cylindrical austenite pellet was chosen to be approximately 0.1 wt pct C less than the estimated

Jan 1, 1962

By H. G. Doll

The S.P. log is shown to be a measurement of the potential drop along the drill hole, caused by ohmic effect in the mud. The notion of static S.P. is brought forward, and its relation to the S.P. log is discussed. Other factors influencing the shape and amplitude of the log are considered; attention is given to conditions encountered in practice. Numerous figures are given illustrating graphically the results; these figures are of particular interest for comparison with field examples. The S.P. log, although indicating permeability, is not an absolute measurement of permeability, nor of porosity, of the formations traversed by a drill hole. It is affected by several parameters, such as resistivity of formations and mud, thickness of formations, and others, which should be appraised carefully. Simple rules have been established for a better distinction of the boundaries of permeabl: sections, particularly in difficult cases, such as those encountered in highly resistive formations. A systematic application of the established principles will assist in obtaining more information from the S.P. log than was possible thus far; for instance, under favorable conditions, presence of oil may be detected, or amount of shale in sands may be estimated. Introduction The S.P. log, or spontaneous potential log, has been known and widely used during the last 15 years for the location of permeable beds traversed by drill holes.1,2 In electrical logging practice, the S.P. log is shown on the left hand side track of the record (as may be seen in later examples) where it can be easily correlated and interpreted with the resistivity curves located to the right. Usually, the S.P. log consists of a base line, more or less straight, having excursions or "peaks" to the left. The base line frequently has been found to correspond to impervious beds, while the peaks are usually found opposite permeable strata. Measurements which will indicate positively the presence of permeability in the formations, and which will give accurately the boundaries of the permeable zones, are of great importance in oil-field practice. Thus far, the S.P. log is the best approach to such determinations; unfortunately, its interpretation is not always evident. With respect to the base line of the S.P. log, it may be noticed that this line is not always at a definite location on the chart. Sometimes it may shift abruptly, while other times a gradual drift is apparent. As far as the peaks are concerned, their shape is not uniform; some are rounded while others are sharp. Also, from other data, it may be found that occasionally the peaks extend appreciably beyond the boundaries of permeable zones into zones which are not everywhere permeable. A comparison with permeability measurements made on cores has often confirmed that there was no definite correspondence between the magnitudes of the peaks and the permeability values. In the same geological horizon, it generally will be found that most of the thick and permeable for-

Jan 1, 1949

By C. P. Proctor, J. T. Crawford

TROUGH washers were among the earliest methods used for concentrating ores; they are referred to by Agricola about the middle of the sixteenth century as already being used while the hand- operated jigging sieve had only recently come into use. For cleaning coal the trough washer apparently was first used in France and Belgium .about 1841. The early trough washers were intermittent and the refuse at least was shoveled out by hand. The invention of a continuous jig washer, by a Frenchman, Berard, in 1848, acted as a stimulus to coal washings in jigs and retarded progress in trough washing' in the nineteenth century. Chapman and Mott describe a number of trough washers developed in England and on the Continent from 1850 to 1900, such as the Bell and Ramsay, Ramsay, Bell and Green, Wunderlich, Scaife, McLellan; Lodge, Elliott, Blackett, and Murton. , The later of these removed the refuse mechanically, either intermittently or continuously, but in ways that interfered with stratification. THE RHEOLAVEUR A Belgian engineer, Antoine France, is responsible for the development of means to remove refuse materials continuously from a trough washer while preserving stratification and preventing the loss of coal with the refuse. The methods and equipment devised, which have become known throughout the world as Rheolaveur, were initiated at the St. Nicholas mine near Liége, Belgium, about 1912. This installation consisted of two units to wash 20 to 8-mm. (13/15 to 5/16 in.) and 8-mm. to 0 (5/16-in. to 0), each having only two superimposed inclined troughs. The first few "Rheo" boxes on the top trough removed refuse directly and the remaining Rheo boxes discharged impure refuse to the lower trough for rewashing. On the lower trough the first few boxes removed refuse and the following boxes removed a middling product

Jan 1, 1943

By Don B. Shupe, John K. Berry

The handling and disposal of mine water is a much larger problem than is apparent at first glance. Many more tons of water are removed from underground coal mines in the United States each year than tons of coal. In the old anthracite region of Pennsylvania the average was around 32.7 t (36 st) of water for each ton of coal produced, while bituminous mines average about 4.5 or 5.4 t (5 or 6 st). Water encountered in the mines may come from several different sources. In mines with light cover and without a firm solid roof, rain may seep directly into the workings. This is also true of deeper mines where pillar falls have broken the roof to the surface. The top under creek beds is generally faulty and broken and water comes through the roof at this point. Deeper mines are frequently overlain by water-bearing strata and pillar breaks and faulty top can admit water, while places running to the dip often accumulate water which comes up through the bottom. In all cases, except where passing under a year-round stream, the amount of water made is usually pretty closely connected with the weather-more water during the rainy season, less in the dry, although the deeper a mine is, the longer it is before changes in rainfall are felt. Another source of water, not connected with seasonal changes, is old water, accumulated over a period of time in abandoned workings of the mine, or from flooded adjacent mines. Here the water filters through the coal, the parting, or comes up through cracks in the bottom. Similarly, core holes, drilled to prospect the property, can be a source of unexpected water and modern safety requirements for dust-allaying water at the working faces can turn a pleasant working area into a soggy mess over the weekend if the system is not properly maintained and operated. Why water must be disposed of is obvious. If allowed to accumulate, sooner or later the mine will fill up, or at least it will become "roofed" in low places, blocking ventilation and traffic. It must be controlled long before it reaches this stage. Water standing in the working faces is

Jan 1, 1981

By C. R. Woodcock, J. S. Mason

In almost any situation where particulate or granular bulk solids have to be conveyed, whether for a distance of a few metres or for many hundreds of metres, a pneumatic conveying system may be considered. Conveying by pipeline is convenient and clean, but running costs may be substantial because of the heavy air consumption and the trend has therefore been towards dense-phase transport in which the ratio of conveyed solids to conveying air is kept high. This paper concentrates on air-float conveying, which can be regarded as an extreme form of dense-phase conveying where the bulk solid is fluidised in a channel and then caused to flow, either by inclining the channel or creating a pressure gradient along 'it. Various designs of air-float conveyor for upward, horizontal and down- ward transport of powders are discussed, with special emphasis on the latter case. In situations where a continuous downward slope can be provided, the combination of air-fluidisation and gravity flow results in a conveying system that, for many kinds of bulk particulate solid, would be hard to better in terms of convenience, reliability and economy. The paper is concluded with a discussion of design features and performance of practical air-gravity conveyors, involving the handling of various bulk particulate solids, both in research and in full-scale industria1 applications.

Jan 1, 1980

By Ernest N. Patty

Placer gold-bearing gravels of interior Alaska and the Yukon are, for the most part, permanently frozen, and are described as permafrost. The first step in preparing these gravels for dredging is to strip by bulldozer the surface layer of tundra, brush, and scrub timber, and to expose the ebony colored surface of the frozen mud at the grass roots. This mud varies from a frozen, muddy ooze to a sandy silt and locally may contain layers of peat. The whole mass is intercalated with ice dikes and lenses. The thickness will vary from a few feet up to 100 ft, depending upon local conditions. A freshly exposed surface will thaw to a depth of 4 in. per day during the summer season. Common practice is to expose a large surface of this mud to the sun and each day's thaw is then swept off by water and carried away in suspension.

Jan 1, 1951

By Bruce W. Gonser, Robert J. Nekervis

EACH metal has a unique combination of properties that distinguishes it from other metal;. Su& a combination may account for applications that cannot be met very well by anything else. This is particularly true of tin, one of the earliest metals used by man. Table i shows the consumption of tin in the United States by usage for the years 1949 and 1950, which may be considered to be generally typical of current usage. The major applications-tinplate, solders, bronze, and babbitt-were well established a century ago. Applications for the metal and (probably later) of tin alloys started more than 5000 years ago. Fortunately for the ancients, tin is one of the metals whose oxide is easily reduced by carbon. Nature further simplified the refining problem by providing only one ore of commercial importance, cassiterite (SnO2). Tin is easily reduced from cassiterite. All that is necessary is high heat in the presence of carbon. It is quite possible that back in the dawn of history, tin was discovered when black alluvial sand was thrown on a fire, either to bank it or to put it out. SOURCES OF TIN All the important tin-producing centers are in the southern hemisphere, far away from the' industrial consuming centers. Fig 1 shows their location and 1950 production. Reserves are adequate, and the industry is able to produce considerably more tin than is

Jan 1, 1953

By M. C. Smith, W. V. Green, D. M. Olsen

The creep-rupture behavior of commercial powder-metallurgy molybdenum rod is reported in the temperature range 1600" to 250O°C, at stresses up to 9000 psi and times up to 1 month. The effects of temperature, stress, and grain growth are discussed. Rupture time is fitted to the Larson-Miller parameter and compared to lower-temperature and higher-stress results reported by pugh.1 BECAUSE of its high melting point, molybdenum should retain useful strength to relatively high temperatures. Combined with its ready availability in the United States, this makes it attractive for many applications in missiles, rockets, and so forth—wherever its susceptibility to oxidation can be tolerated or overcome. The mechanical properties of molybdenum rod in the temperature range —200" to 1540°C have been reported by pugh,' Bechtold,' Parke,3 and Carriker and Guard.4 Madden and chen5 have measured the tensile properties of molybdenum single crystals in vacuum up to about 2500°C. As one further step in evaluating its mechanical usefulness, the constant-load creep-rupture properties of commercial powder-metallurgy molybdenum rod have been investigated in the range 1600" to 2500°C. MATERIAL TESTED Creep specimens were machined from 1/2-in. round commercial molybdenum rod, manufactured from powder by pressing, sintering, and swaging. Spectrochemical analysis of the rod showed "traces" (less than 0.01 pct) of silicon, aluminum, chromium, iron, and zirconium, and "faint traces" (less than 0.001 pct) of manganese, magnesium, cobalt, and nickel. Carbon content was 130 to 200 ppm, nitrogen was 110 to 180 ppm, and oxygen 30 to 35 ppm. A typical microstructure of the as-received rod is shown in Fig. 1. Room temperature tensile properties for five specimens strained at about 0.015 in. per in. per min are shown in Table I. CREEP SPECIMENS USED The specimens used for creep-rupture testing are illustrated in Fig. 2. The 1/4-in.-diam gage section was 3/4 in. long, and terminated at shoulders 5 mils high. These shoulders served as fiducial marks for optical strain measurements. Surface finish on the gage section was 16pin. r.m.s. One specimen, for a "long-time" test described below, was modified by dividing the 3/4-in. gage length into three 1/4-in. long sections with individual diameters of 0.250, 0.230, and 0.210 in., each terminating in a pair of fiducial shoulders. TESTING PROCEDURE The constant-load creep-testing machine used has been described by Smith, Olson, and Brown.6 In it the specimen is held vertically on the axis of a cylindrical tantalum or tungsten heater tube by threaded molybdenum or tungsten grips. Both specimen and grips are heated by radiation from the heater-tube, which is heated by its own electrical resistance. The bottom specimen grip is held at its lower end by a clevis pin. The testing load is applied to the specimen through the upper grip by means of hanging weights, a constant force-multiplication lever system, and a pull rod sealed to the chamber lid by a bellows. The incandescent specimen is viewed by an external optical system through slots in the heater-tube and radiation shielding, and an enlarged image of it is projected on a ground-glass screen. Gage-length measurements are made on this image with a pair of cathetometers. Thorium oxide coatings were applied to the threaded ends of most specimens, to prevent diffusion-welding of specimens to grips during testing. Without such a coating welding usually occurred, and grips were often broken by subsequent efforts to remove the tested specimens.

Jan 1, 1960

By Martin A. Mayers

It has long been recognized that it would be highly desirable to be able to predict the temperatures at various points in a burning fuel bed and their variations with changes of the properties of the fuel and the rate of air supply. Experimenta1 investigations of fuel-bed temperature1-4 have not been lacking, but the absence of any theoretical background has made it impossible to use the results of these tests as a basis for prediction, except in a very general may. A mathematical analysis", based on a somewhat simplified theory of the distribution of lieat in a fuel bed, lias recently been completed by the author. Even though numerical values of some of the coefficients are not known, the calculations result in some conclusions of general significance. Thus, for example, it appears that when the temperatures throughout the fuel bed can be calculated, the rate at which ignition of the fuel by underfeed action can be maintained can also be calcu1ated. The uncertainty concerning the values of the coefficients referred to above is serious limitation on the use of that method. The following paper presents a discussion of these coefficients and includes estimates of their values based on the data now available. A brief description of the theory on which the analysis is based, and some results of the calculations showing their degree of agreement with experimental results, are presented by way of introduction to the discussion of the coefficients. For a more. extended discussion of the theory, see the A.S.M.E. paper5. Theory and Comparison with Experiment The theoretical analysis is similar to that used in the calculation of the stationary temperatures in a conducting solid in the classical theory of heat concluction. The fuel bed is pictured as a uniform, continuous, porous solid through the interstices of which air can be blown and ill which combustion can take place. The solid lias a finite thermal conductivity, so that heat may be transported in any direction, against the flow of air as well as in the same direction. While it is true that nothing

Jan 1, 1938

By Martin A. Mayers

It has long been recognized that it would be highly desirable to be able to predict the temperatures at various points in a burning fuel bed and their variations with changes of the properties of the fuel and the rate of air supply. Experimenta1 investigations of fuel-bed temperature1-4 have not been lacking, but the absence of any theoretical background has made it impossible to use the results of these tests as a basis for prediction, except in a very general may. A mathematical analysis", based on a somewhat simplified theory of the distribution of lieat in a fuel bed, lias recently been completed by the author. Even though numerical values of some of the coefficients are not known, the calculations result in some conclusions of general significance. Thus, for example, it appears that when the temperatures throughout the fuel bed can be calculated, the rate at which ignition of the fuel by underfeed action can be maintained can also be calcu1ated. The uncertainty concerning the values of the coefficients referred to above is serious limitation on the use of that method. The following paper presents a discussion of these coefficients and includes estimates of their values based on the data now available. A brief description of the theory on which the analysis is based, and some results of the calculations showing their degree of agreement with experimental results, are presented by way of introduction to the discussion of the coefficients. For a more. extended discussion of the theory, see the A.S.M.E. paper5. Theory and Comparison with Experiment The theoretical analysis is similar to that used in the calculation of the stationary temperatures in a conducting solid in the classical theory of heat concluction. The fuel bed is pictured as a uniform, continuous, porous solid through the interstices of which air can be blown and ill which combustion can take place. The solid lias a finite thermal conductivity, so that heat may be transported in any direction, against the flow of air as well as in the same direction. While it is true that nothing

Jan 1, 1938

BASIC open-hearth slags have no obviously unique features when compared with slags from other metallurgical operations. Open-hearth slags form and exist at temperatures ranging from 2500 to 3100 F (1370 to 1700 C). In the course of an open-hearth heat, the liquid slag changes slowly and continuously in chemical analysis-the changes reflecting changes in temperature, changes in metal analysis, solution of charged materials, solution of feed additions, and solution of refractories. Throughout the process, the slag performs specific primary functions that are responsible for a large measure of the technical and economic importance of basic open-hearth steelmaking. It is intended in this chapter to present the chemical reactions by which the primary functions of basic open-hearth slags are carried out, to describe the physical and chemical principles governing the extent to which these reactions proceed and can be regulated, and finally to indicate the limitations imposed on other features of the process by the fulfillment of the primary functions. Basic open-hearth slags perform three primary functions. First and foremost, the slag provides a means of removing phosphorus from the liquid metal. The ability to remove phosphorus is largely responsible for the widespread use of the basic open-hearth process. Second, the slag serves as a controlling factor in transferring the oxygen required for the other oxidizing reactions. Third, the slag provides a means of eliminating some sulfur from the open-hearth bath. While the extent of sulfur removal is not comparable to that of phosphorus, the ability to remove some sulfur contributes much to the value of the process. The effectiveness with which the slag fulfills its functions varies with temperature and composition. Since operating temperatures are fixed largely by the specified nature of the product and the equipment, .the speed and extent to which the functions of the slag are carried out depend largely on its composition. The necessity for regulating slag composition to accomplish the re-

Jan 1, 1964