Resource of repaired welded compounds of marine oil and gas structures

The article deals with the assessment about service life of welds for offshore oil and gas facilities. Research covered offshore fixed platforms (OFP) of the core type. It is noted that to date, any studies have not been undertaken on the service life of reconditioned (repaired) OFP welds. Through specialized software systems StructureCAD and SolidWorks, models of offshore platforms were built and maximum amplitudes of alternating stresses acting in welds in the Black Sea were established. As results of the tests and processing observed data, the endurance limits of the repaired welds were calculated, which amounted to approximately 13 MPa (1885.49 psi). We also obtained characteristic points of the dependence of the number of cycles to failure N on the values of the amplitude of the alternating stresses σ_a. The experiment made it possible to create fatigue diagrams for restored welds of offshore fixed platforms. Using the example of a T-type welded joint, it was shown that the service life of a restored weld is much lower than the service life of a new one.