FATIGUE CRACK RETARDATION BY THE APPLICATION OF REPAIR COATINGS TO GAS PIPELINES UNDER PRESSURE

摘要

We describe additional capabilities of the repair insulation coatings applied to main pipelines (without taking them out of operation) in increasing the durability of these pipelines. As a specific feature of this method, we can mention the retardation of the subsequent propagation of surface fatigue cracks as a result of the artificial formation of the effect of their closure by filling the crack cavity with liquid epoxy resins. After solidification, it plays the role of a wedge decreasing the range of cyclic plastic strains near the crack tip, i.e., the mechanical driving force of fatigue crack growth. By using the obtained experimental results, we analyze the mechanical situation formed at the crack tip by using the outlined method of retardation of the crack growth.