Comparative analysis of the fatigue characteristics of repaired compounds of the “T” and “K” types of fixed offshore platforms

Abstract

The study of the fatigue characteristics of repaired welded joints is an important task to determine their remaining lifetime. At present, there is no methodology that allows calculating the resource of reconditioned welded joints; therefore, industrial safety experts use the diagrams and fatigue equations given in the normative documentation for new joints when extending the resource. It is also not established whether there is a difference in fatigue characteristics depending on the type of pipe joint “T” or “K”. In this regard, the authors conducted research during which a new welded joint was brought to primary failure, and then repaired and brought to repeated failure. Based on these experiments, graphs were constructed that describe the dependence of the number of cycles on the values of the amplitudes of the alternating stresses and a mathematical equation was obtained that describes the fatigue parameters for both “T” and “K” types of welded joints.