Varieties and kinetics of fatigue cracking of fixed offshore platforms for oil and gas production

The article investigates the different types of cracks and kinetics of propagation of cracks in main structural components and welds of the support blocks of fixed offshore platforms. Describes the process of metal fatigue for offshore installations. The article provides methods for calculating of the stress intensity factor and describes the methods of calculation for some cases. Based on the analysis of scientific studies, the author provides methods allowing to calculate two parameters describing the kinetics of crack propagation in relation to the elements and welded joints of offshore fixed platforms, namely the methods of calculation of threshold and critical stress intensity factor. On the basis of the conducted research the author constructed the kinetic chart of the development of fatigue cracks in relation to the elements and welded joints of the supporting blocks of fixed offshore platforms. In addition, the author gives the equation in which it is possible to determine the growth rate of fatigue cracks in various areas of the kinetic diagram.