Residual life assessment of steam turbine casing containing crack defect

• Published in: International journal of pressure vessels and piping Vol. 78; no. 11; pp. 977 - 984
• Main Authors: Hakl, Jan, Bielak, Ondrej, Vlasák, Tomáš
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01-11-2001; Elsevier
• Subjects: Analysing. Testing. Standards; Applied sciences; Casting; Continuous cycle engines: steam and gas turbines, jet engines; Creep crack growth; Engines and turbines; Exact sciences and technology; Fractures; Industrial metrology. Testing; Life-time assessment; Low alloy steel; Measurement of properties and materials state; Mechanical engineering. Machine design; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Nondestructive testing; Turbine casing; Casting; Low alloy steel; Creep crack growth; Life-time assessment; Turbine casing; Steel-CrMoV; Turbomachine casing; Measurement; Steam turbine; Creep fracture; Durability; Low alloy cast steel; High temperature; Modeling; Crack propagation
• ISSN: 0308-0161; 1879-3541
• DOI: 10.1016/S0308-0161(01)00112-0

In steam turbine casing made of cast steel of type 0.6Cr0.5Mo0.25V (ČSN 42 2744), which run about 25% over designed life, several crack defects were found. The most serious case was represented by a crack in valve chest, which reached nearly up to one half of wall thickness. In spite of this it was necessary to operate the turbine for some time. The aim of this contribution is to describe procedures used for assessment of safe residual life.
Material data necessary for this life assessment were evaluated during research of material properties of another steam turbine casing made of the same type steel whose operating time was finished after 1.23×10
5
h. The mentioned material data are also presented.