The paper presents the study of the influence of mechanical damage on the safe operation of gas transmission pipelines. The main types of pipeline damage with the actual parameters and their influence on the operational parameters are analysed. The damaged fractures of the section of the pipeline Kaunas (Lithuania)-Kaliningrad (Russia) were investigated in the laboratory. The main operational characteristics and the structure of the pipeline's metal after the period of long-term operation were determined using various research and experimental methods. The influence of the pipeline's damage was modelled by using the Finite Element Method and the ANSYS code. The predictions of the failure pressure were made, taking into consideration the actual properties of the pipeline's metal. Techniques including the hardness and microhardness measurement, chemical analysis, the impact strength test, and metallography analysis with an optical microscope, were used in the experimental study.

With the rapid development of the road transport industry, trucks with semi-trailers have become the main means of transporting goods by road. High quality, durability and reliability of the construction are the main requirements for the production of trailers. Trailer and semi-trailer axles are one of the main and most important components of a truck. Due to the fact that semi-trailer axles are subjected to additional static and dynamic loads during operation, their proper construction is extremely important, therefore they should be carefully designed and tested. The durability of the suspension components refers to the duration of the onset of fatigue. This article presents an analysis of damage to the rear axle of the semi-trailer using macroscopic observations of the damage site and dynamic FEA of stress distribution in the axle material. In order to identify the probable cause of the damage, eight cases of loading the semi-trailer axle were considered. Analytical solutions have shown that in various cases the yield point is exceeded and the strength limit of the modeled semi-trailer axle is reached. The risk of damage to the vehicle’s suspension system components increases on poor roads (bumps and winding road sections).

Thermite welding of Cu–Nb microcomposite wires was investigated. Suitable compositions of thermite material and slag were determined from the equation of the exothermic combustion synthesis reaction. The phase compositions of the thermite mixture and slag determined by X-ray diffraction analysis correspond to those assessed from the equation. According to non-destructive radiographic testing, the joint structure does not have welding defects. Microstructural examination of the joint cross-section with scanning electron microscopy showed that the Cu–Nb wire retained its shape and microstructure and only a thin surface layer of wire was melted during welding. The difference in electrical resistances of the conductor and welded joint was below 20 %. The thermite joint can withstand a maximum load equal to 62.5 % of the load-bearing capacity of microcomposite conductor.

Abstract. After JSC 'Lithuanian Railways' (AB 'Lietuvos geležinkeliai') bought new Siemens ER20 CF locomotives produced in Western Europe and brought them into service, some of them have already done about 170-200 thousand km that caused the appearance of indentations of an inadmissible size (the depth is more than 3 mm, the length -10 mm) the elimination of which turning cutting results in up to 20 mm loss of a wheel. Having grounded off the metal layer of indentation depth, indentation reappears (metal 'flakes off ') and needs to be removed by re-turning cutting the wheel. The purpose of the current investigation is to determine whether there is a reason to claim that the cause of wheel surface crumbling could be a chemical composition of the wheel or wheel-to-rail hardness ratio. The carried out investigations have revealed that there is no reason to claim that the cause of wheel surface crumbling could be the chemical composition of the wheel or wheel-to-rail hardness ratio.

The number of potentially dangerous equipment that has completed its established operational time, but is still being used, is permanently increasing. Therefore there is a problem of its further operations. A decision to continue to operate power-generating plants, when the initial resource of the equipment’s working time is ended, and its further operation without considerable expenditures on repair and the diagnostic of a metal state is possible only with the help of long-term research of metal in power-generating plants. Only a complex of research techniques can estimate the real state of a construction. In the article problems connected with the definition of operation reliability of steam pipeline elbows are investigated. Different areas of an elbow were researched. Results of a microstructure analysis, and mechanical characteristics (time history) research of an elbow metal are presented. Also results of calculation of an elbow on low - cyclic thermal fatigue are presented.