Introduction. Pressure-operated thick-walled hull structures are the most common type of high-duty welded structures. When these structures are loaded with internal pressure, a complex biaxial stress field arises in them, which is summed up with the fields of residual welding stresses. Therefore, when selecting a technology for manufacturing critical welded structures, the results obtained during conventional uniaxial tests of samples are insufficient. The variety of factors affecting the performance of structures, and the difficulties of separate assessment of their influence, caused the need to maximize the approximation of experimental conditions to the real working conditions of the structure.Materials and Methods. Testing of full-scale structures has a number of advantages, but they are extremely expensive, and, as a rule, only one, the weakest link, is identified, the bearing capacity of the other structural elements remains unclear. For testing, UDI radiometric installations designed for different sample sizes were used. The presented installations allow testing samples of various shapes, types of welded joints (butt, T-bar), changing the position of welded parts.Results. Without rejecting the results obtained during the testing of full-scale structures in the works of the Bauman Moscow State Technical University, DSTU, NRC «Kurchatov Institute» – CRISM «Prometey», and the authors proposed to conduct the basic scope of the research on individual structural elements that would reflect the characteristic features of loading, manufacturing technology, and operating conditions. The design of the «fitting-sheet» connections was applied, which made it possible to increase the indicators of the failure initiation and propagation to the level of the base metal.Discussion and Conclusions. Schemes of structures for obtaining a biaxial tension or bending field in samples were presented. Samples tested according to the proposed schemes allowed us to draw conclusions about the performance of welded joints under conditions close to the actual operation of the structures under study. The proposed test scheme is used by research laboratories in our country and around the world.

On the basis of the coordinate measuring machine CMM, there is a computer-digital technique for measuring the transition radius and the angle of conjugation of the metal with the base metal φ. It allows in automatic mode, with high accuracy and reliability, to determine the above parameters of welds, which are used in calculating stress factors and in assessing the fatigue strength of welded structures.

Welded circular seams of “choke joints”, as a rule, have deviations from the specified diameter. This leads to uneven deformation, and sometimes to the absence of deformations in some areas of the seam. With repeated static loads, destruction arises in these places. To connect to the maintenance system of connections with the base metal, used as a guide, surface plastic deformation of the zone zone is carried out. A technology and equipment have been developed that allow plastically deforming the area of transition from the weld to the base metal along the entire length of the circular weld. As a result of plastic deformation along the technological groove, the characteristics of low-cycle fatigue of welded joints are obtained, which are not inferior to the base metal. To reduce stresses in the zone of transition from the weld to the base metal, it is proposed, first, to perform a circular groove on the base metal by machining, as close as possible to the specified zone. To assess the influence of the shape and size of the groove on the stress-strain state of the zone of conjugation of the weld metal with the base metal, FEM calculations were carried out

Introduction. The sources of damage and wear of the main shaft of the  drier  toaster  are  analyzed.  The  repair  know-how  and welding operations execution limitations which must be considered when developing the technique providing the restoration of the structure performance  features are studied. The work objective is to develop a technique of repair without dismantling  for  the  main  toaster  shaft.  To  solve  the  task,  a design   repair   structure   was   installed,   and   postwelding operations  that  meet  the  engineering  and  regulatory requirements for this structure were performed.Materials   and   Methods.   In   “Kompas   3D”   software,   the following models were developed: integral shaft (project shaft design); damaged shaft as a result of long-term operation (more than  15  years);  and  damaged  shaft  with  a  welded  repair structure. Numerical simulation of the stress-strain state (SSS) was carried out.Research Results. Software for the computational modeling of the repair structure SSS is developed. The repair shaft structure in which the maximum stresses do not exceed the shaft stresses in the project design is obtained using the model. To eliminate the aggressive medium effect on the corrosion fatigue strength of the shaft, an insulating method is used. A technique for mounting  the  repair  structure  to  the  shaft  allowing  for  the outrun limitation 0.12 mm is developed.Discussion and Conclusions. Torsion shafts damaged deeply by wear and corrosion are considered. To restore their structural integrity, it is worthwhile using the following complex of techniques:— constructive (consists in the installation of optional parts that compensate for insufficient strength, and provides a reduction in stress concentration in the most loaded zones);— processing (reduces residual welding stresses due to the reasonable sequence of deformation that contributes to generating favorable residual compressive stresses);—  isolation  (is  based  on  the  application  of  anticorrosion coatings).The economic expediency of the developed repair technique is obvious. The repairing of the shaft without dismantling costs 180,000 rubles, while a new shaft costs 3.8 million rubles.