1. Modern gas mains are expensive and metal-consuming constructions;therefore, when designing them, optimum conditions are sought to ensure minimum expenditures on the construction and operation of gas transmission systems.nThe solution of this technico-economic problem depends on precise calculation of gas pipeline capacity and on analysis of interdependent gas pipeline basic parameters, such as diameter and wall thickness, ini-tial pressure, rate and power of compression, distance between compressor stations, etc.n2. When calculating gas pipeline sizes, the choice of an appropriate flow formula is of the greatest impor¬tance. The same care is necessary in the evaluation of associated parameters, such as flow resistance fac¬tor, gas compressibility factor and gas temperature. Such a formula is obtained from the system of equa¬tions relating to volume, continuous flow and gaseous state.nTo arrive at an exact formula, one must take topography into account if the pipeline, is to be laid over rugged terrain.nThanks to studies of industrial gas transmission by pipeline, and to special investigations in. the Soviet Union, it has been possible to establish a number of empirical relations for flow resistance factor for pi¬pes and specials, as well as to express gas compressibility factor as a function of pressure.n3. Modern methods for calculating gas pipelines are based on steady gas flow.nIn reality, the steadiness of flow is disturbed, especially in the last section of the pipeline, because of variations in gas consumption.nIn the Soviet Union, particular attention is paid to the scientific investigation of non:steady conditions of gas flow. Theoretical and experimental investigations have made it possible to obtain equations relating transmission changes of gas pressure and throughput with time. The difference between theoretical and experimental results does not exceed 2 per cent for pressure and 8 per cent for throughput.n4. The presence of solid or liquid suspensions in the gas flow considerably influences gas pipeline trans¬mission capacity.nTherefore, an attempt has been made in this paper to give a theoretical estimate of this influence, and equations are stated for pipeline flow calculations in the case of a two-phase gas transmission system.n5. The analysis of interdependent gas pipeline basic parameters given in the paper, both in mathematical and diagrammatic form, makes it possible to find the optimum conditions for gas transmission.nIn particular, the use of pipes with wall thickness equal to 0,01 diameter for gas mains permits in thenSoviet Union a reduction of 5 per cent in the amount of metal used whilst retaining constant the specificnpower of compressor stations;or, by diminishing by 12 per cent the total specific power, one may saventhe same amount of metal.nAn analysis of the possibilities of laying gas pipelines of graded wall thickness shows that it is possiblento save 2 to 4 per cent of metal for larger diameters in excess of 500 mm. However, complications in thenoperation of such pipelines renders them of little practical value.nAnalysis of tendencies and of the laws governing the terms in gas pipeline natural indices will enablenengineers and planners to elicit the optimum alternative conditions for each particular case.
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