Ultrasonic flaw detection capabilities at first stage of technological process of ship engine overhaul

Abstract

The technological process of ship engine overhaul begins with dismantling, while the obligatory operation is flaw detection of parts. The flaw detection at this stage involves certain difficulties due to the fact that the entire repair process takes place directly onboard the ship. It is possible to simplify the task of assessing the technical condition of a particular part, if one can assess the performance of this part before dismantling, saving both material assets and time. However, in vessel design, the equipment developers do not pay due attention to ensuring its controllability. The article describes capabilities of ultrasonic flaw detection that can be realized in ship conditions during the first stage of the ship engine overhaul technological process. The ultrasonic technique for estimation of a crank-shaft metal damage through scavenging ports of the ship engine is discussed; as well as an option to address the issue of repair or replacement of tap bolts according to their actual technical condition.The described capabilities are due to the uniqueness of ultrasonic flaw detection: the internal space of almost all structural materials can be “observed” by waves of a mechanical nature. Elastic waves, probing the metal, react to all the processes occurring in it, they perform the functions of a universal sensor that delivers information about the controlled environment. They allow to recognize an early stage of defect accumulation – micro damage formation, which is quite natural, since the parameters of elastic waves depend on the density, moduli of elasticity, size and geometry of structural inhomogeneities and other characteristics of the test medium.