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Statistics of accident rate at Ukrainian and Russian railways is an evidence of increase in the recent years of the accidents, related with failure of cast bearing elements of two-axle three-component freight car bogies. Analysis of service reliability of cast structures of side frame and bolster of 18-100 type bogie shows that appearance of fatigue cracks is the main reason of reject. It is reasonable to search an alternative application of welding technologies in manufacture of indicated parts from sheet products for the purpose of increase of their safety and survivability. It is shown that existing Norms for designing of welded joints and assemblies of railway cars significantly overstate real cyclic load resistance of welded joints in comparison with the Recommendations of the International Institute of Welding. This disadvantage is typical for number of reference documents acting in Russia and Ukraine, which regulate calculation of fatigue resistance of welded joints and assemblies. This promotes negative results in designing with respect to required life of welded elements. Development of safe and technological welded elements of freight car bogie requires application of the recent achievements in the field of fatigue strength of welded joints. [ABSTRACT FROM AUTHOR]

Taking into account the special features of the thermophysical processes of polymer materials, the authors propose methods of welding polyethylene pipes for gas pipelines in which welding can be carried out without temporary cover at low temperatures of atmospheric air. [ABSTRACT FROM PUBLISHER]