The methodology of laboratory modeling of the loading of utor welded joint of the tank is presented. The methodology is based on testing of the special design sample. It allows under uniaxial tension on the typical servo-hydraulic machines to reproduce in the zone of a utor welded joint the combined action of bending and shear forces, similar to that which occurs during the operation of a vertical cylindrical tank. To assess the distribution of the stress-strain state in the proposed design of the sample under its loading, the finite element modeling was performed in the ANSYS software package. It showed the fundamental correspondence of the stress distribution in the zone of the utor node in the sample and in the real tank. The experimental studies consisted in carrying out tests for the durability of a series of 16 samples loaded with the maximum force in the cycle, causing the calculated stresses in the zone of the welded utor node in the range of 100–200 % from the maximum permissible ones. The obtained results showed that the maximum loaded zone, where the destruction of the samples occurred, is the near-seam zone of the utor welded joint on the inside of the tank. This corresponds to the statistics of the real tank failures. It is established that the developed methodology ensures the possibility of carrying out correct resource tests of the tank utor welded joints. It is also possible to vary the stress-strain state scheme within a wide range in the area of the utor welded joint by changing the design parameters of the test sample. In compliance with the regulated welding technologies and the absence of unacceptable defects in the welded joint, the utor node has a high resource, which significantly exceeding 50 years of the tank operation.
The stress-strain state determination in pipelines welded joints
