2019 №01 (01) DOI of Article
2019 №01 (03)

Technical Diagnostics and Non-Destructive Testing 2019 #01
Technical Diagnostics and Non-Destructive Testing №1, 2019, стр. 13-25

Statistical analysis of residual strength of defective pipelinesin high-temperature service

A.S. Milenin, E.A. Velikoivanenko, G.F. Rozynka, N.I. Pivtorak

E.O. Paton Electric Welding Institute of the NAS of Ukraine. 11 Kazimir Malevich Str., 03150, Kyiv, Ukraine.E-mail: office @paton.kiev.ua

A numerical procedure of analysis of residual static strength and performance, allowing for defects of corrosion-erosion loss of metal detected during technical diagnostics, was proposed for welded pipeline elements and pressure vessels, operating at higher temperatures. For analysis of non-uniform stress-strain state in the region of the geometrical stress-raiser, alongside the universally accepted statistical mechanics approaches, consisting in evaluation of fracture probability by integration of the stress field within Weibull distribution, an approach of similar consideration of the field of plastic deformation intensity was proposed. This allows correct evaluation of the kinetics of simultaneous development of irreversible deformations of instantaneous plasticity and creep, which determines the limiting state of the defective structure under the impact of a specific system of operational temperature-force impact. This methodology was realized on the base of a complex of finite-element models for prediction of simultaneous development of the stress-strain state and subcritical damage of pipeline elements with surface metal loss defects. For adequate quantitative prediction of the probability of failure of defective pipelines from different materials, values of Weibull parameters were obtained, depending on the material properties and temperature. Equivalence diagrams of admissibility of the defect of local wall thinning of a pipeline element under different operational conditions were derived. Correspondence of the proposed procedures to the requirements of current normative documents is shown. 20 Ref., 13 Fig.
Keywords: pipeline element, corrosion-erosion defect, static strength, tough fracture, fracture probability

Received: 25.02.2019 25
Published: 06.03.2019

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