Vitalijus Rudzinskas

Operation Reliability of Bent Elbows of Steam Pipelines

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.

Thermite welding of Cu–Nb microcomposite wires

Abstract 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.

The Investigation on Destruction of the Compressor in Residue Conversion Set

In the paper, the problems of reliability and safe exploitation of the piston compressor in a residue conversion set are discussed upon. After a long exploitation, an emergency shutdown of the above-mentioned compressor occurred. On the primary examination, a fracture of the cylinder and the hub of the compressor were found. The goal of the investigation: to identify the cause of destruction of the compressor of the naphtha residue conversion set.

Investigation of Alloy Elements Transfer in Arc Facing by High Carbon and Chromium Content Electrodes

Consistent patterns for transfer of chromium and carbon from the electrode coating into the fused metal, impact of their amounts on transfer of other alloying elements into the alloy are considered. Respective compositions of electrode coatings are made so, that Cr content in coated layers would change from 2 % up to 40 % (content of C ~ 3 %). At research of transfer of carbon patterns, the compositions of electrode coatings are made so, that C content in coated layers would change from 0.1 % up to 4 % (content of chromium in this case is approximately 20 %). In both cases the content of other alloying elements remain in a settled level (Si ~ 2 %, Mn ~ 1.1 %, Ti ~ 0.5 %, B ~ 0.6 %).