Issue 36

A. Sedmak et alii, Frattura ed Integrità Strutturale, 36 (2016) 63-68; DOI: 10.3221/IGF-ESIS.36.07 63 Focused on Fracture Mechanics in Central and East Europe Integrity and life estimation of turbine runner cover in a hydro power plant A. Sedmak, S. Bosnjak Faculty of Mechanical Engineering, The University of Belgrade, Kraljice Marije 16, Belgrade, Serbia. asedmak@mas.bg.ac.rs M. Arsic Institute for Materials Testing, Bulevar vojvode Mišića 43, Belgrade, Serbia. miodrag.arsic@institutims.rs S.A. Sedmak Innovation Centre of Faculty of Mechanical Engineering, The University of Belgrade, Kraljice Marije 16, Belgrade, Serbia. Z. Savic Institute for Materials Testing, Bulevar vojvode Mišića 43, Belgrade, Serbia. A BSTRACT . This paper presents integrity and life estimation of turbine runner cover in a vertical pipe turbines, Kaplan 200 MW nominal output power, produced in Russia, and built in six hydro-generation units of hydroelectric power plant „Đerdap 1” in Serbia. Fatigue and corrosion-fatigue interaction have been taken into account using experimentally obtained material properties, as well as analytical and numerical calculations of stress state, to estimate appropriate safety factors. Fatigue crack growth rate, da/dN, was also calculated, indicated that internal defects of circular or elliptical shape, found out by ultrasonic testing, do not affect reliable operation of runner cover. K EYWORDS . Hydro power plant; Runner cover; Fatigue; Corrosion. I NTRODUCTION esigning, construction and running hydro power plants is a complex task. Due to limited possibilities of periodic inspections, hydro turbines and their components are designed for at least 40 years of operation. Therefore, extensive researches and testing of hydro power plant equipment have been carried out all over the world. Turbine and hydromechanical equipment testing has been introduced recently in Serbia as well. Special attention has been given to the problem of reduced material plasticity, as explained below. Along with experimental tests carried out on the cover, made of cast steel 20GSL (GOST), tests were performed in order to determine mechanical properties and fracture mechanics parameters. Test results indicated large dispersion of material plasticity, i.e. elongation (A5) and contraction (Z), [1,2]. Namely two specimens met the demands of the standard (A 5 = D