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By R. Stefanko, R. H. King, L. A. Morley

Coal mine fires, injuries and electrocutions, and many production delays have resulted from trailing cable splice failures. Research was carried out at The Pennsylvania State University to determine the failure causes and recommended solutions. The study revealed that current splice kit materials are generally adequate with the exceptions of connector flexibility, adhesives bonding, and abrasion characteristics of taped jackets. Research indicated that the most prevalent breakdowns result from workmanship defects. Therefore, guidelines for improved splice construction are reported in detail.

Jan 1, 1976

By A. K. Gangopadhyay, J. J. Moore

The effect of grinding media composition, mineral type, and slurry environment on the wear rate of various grinding media (balls) are discussed. Sufficient wear data have been obtained and correlated. Modes of wear were determined from examination of the ball surfaces using scanning electron microscopy. Five modes of wear have been identified to be operative under certain slurry conditions for the various ball compositions studied.

Jan 1, 1986

By Harold L. Bare, Frank R. Barnako

Coal mining historically has been a. hazardous occupation but, in recent years, tremendous progress has been made in reducing accidental coal mine deaths and injuries. The purpose of this chapter is to discuss the basic principles of accident prevention as they are related to coal mining. Accident prevention fundamentals are no different for coal mining than for any other type of work. The fundamentals apply to all industries. Construction workers may be struck by falling tools and materials, and miners may be struck by falling slate and coal. Sailors may be trapped by shipboard fires, and miners may be trapped by mine fires. Railroad brakemen may lose hands and fingers positioning couplers, and miners may lose hands and fingers positioning couplers. Many other examples could be cited, but the point is that accidents that happen in coal mines are basically similar to accidents that happen in other industries. Thus, the basic principles for preventing accidents apply in coal mining as they do in any other type of work. COAL MINE ACCIDENT EXPERIENCE The US Mine Safety and Health Administration (MSHA) is the main source for accident experience data in coal mines. Coal mine operators are required, by law, to forward to MSHA monthly the number of fatal and disabling injuries, man-hours worked, and tons of coal mined. This information is compiled and published quarterly, with annual summaries, by MSHA. Trends in the number of fatalities and fatal injury rates are shown in Fig. 1. Major coal mine disasters, with number of miners killed, and dates of coal mine safety legislation are shown in Table 1. The fatal and disabling injury frequency rates for the coal industry are shown in Fig. 2.

Jan 1, 1981

By B. B. Cox

Since our last review of Iraq,' considerable progress has been made not only in exploiting Iraq's potential resources but in building pipe lines to carry the oil to the Mediterranean. No new fields were discovered in 1933. The Naft Khaneh field, discovered in early 1927 by the Khaniqin Oil Co. (subsidiary of the Anglo-Persian Oil Co.), continues to supply the local markets through the Rafidain Oil Co. Kirkuk field, discovered by the Turkish Petroleum Co. Oct. 14, 1927, remained shut in pending the completion of the Mediterranean pipe lines, and the Qaiyarah field, discovered by the same company on Oct. 13,1927, was abandoned in 1928. The principal development of interest during the year was the progress made on construction of the Iraq Petroleum Company's 1152-mile pipe line from Kirkuk to the Mediterranean. The line is double 10-in. and 12-in. pipe for 156 miles west of Kirkuk, where the parallel lines bifurcate, one leg going through British mandated territory to the new port of Haifa and the other through French mandated Syria to Tripoli. Each line may be operated independently of the other. There are three double stations on the Kirkuk-Haditha portion, four single stations on the Tripoli leg, and five on the Haifa in addition to a relief station in the Jordan Valley. Except for the Jordan Valley section and two other short stretches on the Haifa leg where pressures are exceptionally high, the line is single. Sea loading lines will be used exclusively at Tripoli and both sea loading lines and dock loading will be employed at Haifa. All pipe was welded and buried before the end of December, 1933. It is anticipated that enough stations will be completed to make 50 per cent capacity operation possible some time during the latter half of the current year. Some months will then be required in which to fill the line, so that if terminal facilities are ready and no unexpected emergencies arise, partial daily deliveries of Iraq crude may be received at the Mediterranean some time during the final quarter of the current year. Capacity operation of 84,000 bbl. per day is not anticipated much before the middle of 1935. Oil and Gas Production No gas is produced commercially and, except for Naft Rhaneh production, no crude is marketed. Although the Turkish Petroleum Co. and

Jan 1, 1934

By George D. Roberts

INTRODUCTION CIVIL engineers are primarily interested in maximum core recovery. This is even more important in foundation work than in mining investigations where sludge samples are of some value. The soft materials, such as clay, gouge, or partially decomposed seams that are most readily ground up or washed away, are the materials that usually have the greatest influence on foundation and leakage conditions. Undisturbed samples of such materials should be obtained for detailed geological examination and laboratory tests. Therefore the attainable goal of sampling in connection with foundation investigations is the recovery of 99.9 pct of undisturbed core. FACTORS CAUSING CORE LOSSES The principal factors contributing to core losses are: (I) coring badly fractured or very soft material; (2) use of improperly designed coring equipment, including the use of bits of too small a diameter; (3) lack of the proper training and attitude on the part of the drillers and pertinent technical information on the part of the supervising personnel. Little can be done about the character of the material being cored but the other two factors contributing to unsatisfactory performance can be corrected. Although the title of this paper is the improvement and standardization of core barrels, it is believed that the drillers' shortcomings and the lack of pertinent technical literature are more detrimental to good core recovery than either of the other factors. USES FOR LARGE DIAMETER CORE BARRELS It is well known that the use of larger diameter bits and core barrels generally produce better cores, particularly when sampling soft or broken material. The use of larger and larger bit diameters and the insistence on better core recovery is well demonstrated by the change in practices of the various districts of the Corps of Engineers. Today NX core is the smallest diameter commonly permitted for investigational work and the more active districts are using coring bits up to 6 in. in diameter, as well as 36 and 40-in. calyx rigs. The latter size has proved to be just as economical because it provides more room for core removal and cleanup operations. The use of large diameter cores to replace the driving and jacking methods of obtaining soil samples is also increasing. The 5 7/8-in. Denison sampler, developed by H. L. Johnson to obtain samples from soft formations, is one example. The principal uses for bits larger than NX are: sampling soils and semi-consolidated rock; sampling decomposed rock or rock with soft seams; sampling concrete; obtaining samples for laboratory tests; drilling drainage holes, and other miscellaneous work. CORE DRILLING PRACTICES OF SEVERAL ENGINEER DISTRICTS Little Rock District The writer was employed in the Little Rock District from 1938 until 1942. Prior

Jan 1, 1947

By D. K. Crampton, H. l. Burghoff, J. T. Stacy

THE effect of cold-working upon electrical conductivity of copper and of copper alloys appears not to be generally known in detail Although several papers on the subject have been presented, showing variable effects according to alloy composition, it is often assumed that the 2 to 3 per cent lowering of the conductivity of ordinary tough-pitch copper by severe cold-working is typical for copper alloys Because of this situation it was decided to carry out the present work upon several types of copper, copper-zinc alloys over the commercial range of brasses, other binary alloys, and numerous age-hardening alloys in the quenched, and quenched and aged conditions The large number of alloys investigated made it impossible to study every one in the detail it may have merited Inasmuch as several interesting points that could not be satisfactorily explained came to light, further work is contemplated by the authors It is usually considered that the normal effect of cold-work on ductile metals and unordered alloys is to decrease conductivity slightly In alloys that are in the ordered state, as annealed or otherwise heat-treated, cold-working tends to disorder the structure, resulting in very marked lowering of conductivity The random state of atomic arrangement produces lower conductivity than the ordered state for the same composition 1 PREVIOUS WORK previous work in the authors' laboratory has shown the electrical conductivity of several copper alloys to be decreased by greater amounts than might have been expected, in view of the general knowledge on the subject, when cold-worked Guillet and Ballay2 investigated the influence of cold-work upon the resistivity of several metals and alloys, including copper and some copper alloys The increase of resistivity due to severe working was less than 4 per cent for all pure metals tested, while the increases for the alloys were generally higher In the copper-zinc alloys, they found that the increase of resistance due to drawing increased with zinc content, and reported a 21 7 per cent increase of resistance for an alloy containing 67 9 per cent Cu as severely worked Masima and Sachs3 studied the change in electrical resistance of three brass crystals when stretched in the tensile test, obtaining increases in resistance of the order of 3 per cent for 30 to 40 per cent reduction of area of the specimens The resistance decreased again when the cold-worked crystals were subsequently annealed Bardenheuer and Schmidt4 found that the conductivity of copper was decreased by 3 to 4 per cent when reduced 50 per cent by working The conductivity of 72-28

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