Numerical prediction of the current and limiting states of pipelines with detected flaws of corrosion wall thinning
Keywords:
3D discontinuity flaws, ductile fracture, failure probability, limiting state, mathematical modeling, the stress-strain state, welded pipeline.Abstract
The main assumptions have been made for the physical and mathematical models of combined development of the stressstrain
state and voids of ductile fracture in welded pipeline elements and pressure vessels with the detected 3D metal
discontinuities (local corrosion losses of metal, macrovoids), including the ones located in the area of site welds for
determination of the characteristic features of defective structures’ limiting state. Analysis of the stress-strain state of the welded
pipeline section has been carried out based on finite element solution of the problem of non-stationary thermoplasticity by tracing
elastic-plastic deformations from the beginning of welding to the complete cooling of the structure and subsequent loading to the
limiting state. The continuum dilatation model of fracture is based on a stepwise prediction of micro- and macro-damage of
material both in welding and under loading with internal pressure and external force bending moment to the limiting state on the
basis of the Gurson–Tvergaard–Needleman theory. The criteria for macroscopic fracture of structure on a brittle-ductile
mechanism have been proposed.
Methods for probabilistic estimation of the stressed state of the pipeline structure from the point of view of fracture
susceptibility, which are based on the integration of the calculated field of principal stresses within the framework of the Weibull
statistics, have been developed. Functional dependences of Weibull coefficients on the properties of the metal, namely yield
stress and degree of strain hardening, were obtained for correct quantitative assessment of the state of critical structures based on
a complex analysis of the limiting state of steel pipelines under internal pressure.
Specific features of the limiting state under loading with internal pressure and bending moment have been investigated
based on an example of typical cases of operation damage of main pipeline elements such as local metal losses in the area of the
site weld. It was shown that nature of interaction of residual post-weld stress state of metal with operation stresses from the
geometry concentrator significantly affected the value of limiting pressure in the pipe. Besides, effect of the additional bending
moment on load-bearing capacity of the pipeline section with isolated flaw of local corrosion wall thinning has been determined.
The change of failure probability of the structure as a result of internal pressure and bending moment loading at various geometry
dimensions of thinning flaw has been investigated based on the results of integral analysis of the pipeline flawed section state.
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References
JC 1995, ‘Failure Analysis of Power Stations: a Case Study’,
Proceedings of an International Symposium on Materials
Ageing and Component Life Extension, ed. V. Bicego, A. Nitta
and R. Viswanathan, CISE, Milan, pp. 1357–1365.
[2] Janelle, JL 2005, An overview and validation of the
fitness-for-service assessment procedures for local thin areas.
University of Akron, USA.
[3] Wintle, JB, Kenzie, BW, Amphlett, GJ & Smalley,
S 2003, Best practice for risk based inspection as a part of
plant integrity management. Contract research report
363/2001, Health and Safety Executive, Merseyside.
[4] Makhnenko, VI, But, VS, Velikoivanenko, EA,
Rozynka, GF & Pivtorak, NI 2001, ‘Mathematical modelling
of pitting flaws in active oil and gas pipelines and
development of a numerical method for estimation of
permissible parameters of arc welding repair of flaws’, Paton
Welding Journal, no. 11, pp. 2–8. (in Ukrainian).
[5] Hancock, I & Mackenzie, AC 1976, ‘On the
mechanism of ductile failure a high strength steel subjected in
multi-axial stress state’, Journal of the Mechanics and Physics
of Solids, vol. 24, no. 213, pp. 147–149.
[6] Alashti, RA, Jafari, S & Hosseinipour, SJ 2015,
‘Experimental and numerical investigation of ductile damage
effect on load bearing capacity of a dented API XB pipe
subjected to internal pressure’, Engineering Failure Analysis,
vol. 47, pp. 208–228.
[7] Ruggieri, C & Dotta, F 2011, ‘Numerical modeling
of ductile crack extension in high pressure pipelines with
longitudinal flaws’, Engineering Structures, vol. 33, no. 5,
pp. 1423–1438.
[8] Dong, P, & Brust, FW 2000, ‘Welding residual
stresses and effects on failure in pressure vessel and piping
components: A millennium review and beyond’, Journal of
Pressure Vessel Technology, vol. 122, no. 3, pp. 329– 338.
[9] Sedmak, A, Younise, B, Rakin, M, Medjo, B &
Gubeljak, N 2010, ‘Ductile Fracture Resistance of the Weld
Metal and Heat Affected Zone in a HSLA Steel Welded Joint’
TC1 Meeting, European Structural Integrity Society, Freiburg,
pp. 1–34.
[10] Frolov, VV (ed.) 1988, Theory of welding
processes, Vysshaya shkola, Moscow. (in Russian).
[11] Johnson, GR & Cook WH 1983, ‘A constitutive
model and data for metals subjected to large strain, high strain
rates and high temperatures’, Proceedings of Seventh
International Symposium on Ballistics, Koninklijk Instituut
van Ingenieurs, Hague, Netherlands, pp. 541–547.
[12] Xue, L 2007, ‘Damage accumulation and fracture
initiation in uncracked ductile solids subject to triaxial
loading’, International Journal of Solids and Structures,
vol. 44, no. 16, pp. 5163–5181.
[13] Tvergaard, V 1990, ‘Material failure by void
growth to coalescence’, Advances in Applied Mechanics,
vol. 27, pp. 83–151.
[14] Karzov, GP, Margolin, BZ & Shvetsova VA 1993,
Physical-mechanical modeling of fracture processes,
Politekhnika, St. Petersburg. (in Russian).
[15] Makhnenko, VI 2013, ‘Problems of examination of
modern critical welded structures’, Paton Welding Journal, no. 5,
pp. 22–29. (in Ukrainian).
[16] Makhnenko, VI 2006, Resource of safe service of
welded joints and assemblies of modern structures, Naukova
Dumka, Kyiv. (in Ukrainian).
[17] Makhnenko, VI 1976, Computational methods of
investigation of welding stress and strain kinetics, Naukova
Dumka, Kyiv. (in Ukrainian).
[18] Kitching, R & Zarrabi, K 1982, ‘Limit and burst
pressures for cylindrical shells with part-through slots,
International Journal of Pressure Vessels and Piping, vol. 10,
no. 4, pp. 235–270.
[19] Weibull, W 1951 ‘A statistical distribution function
of wide applicability’, Journal of Applied Mechanics, vol. 18.
pp. 293–297.
[20] Neymark, BE (ed.) 1967, Physical properties of
steels and alloys, used in power engineering. Handbook,
Energiya, Moscow. (in Russian).
[21] Directive. Determination of residual strength of
main pipelines with flaws. DSTU-N B V.2.3-21:2008:
Minregionbud of Ukraine. (in Ukrainian).
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