Bearing capacity of a pipeline with a local corrosion defect

UDK: 622.692.4
DOI: 10.24887/0028-2448-2021-8-106-109
Key words: pipeline, stress calculation, bearing capacity, beach mark, analytical calculations, finite-element design
Authors: V.M. Varshitskii (The Pipeline Transport Institute LLC, RF, Moscow), O.A. Kozyrev (The Pipeline Transport Institute LLC, RF, Moscow)

During the operation of main pipelines, in the event of a violation of their anti-corrosion coating and electrochemical protection, corrosion defects of the pipe surface may occur, which significantly reduce the bearing capacity of the pipeline. At present, to assess the strength of a pipeline with corrosion damage, semi-empirical dependences are mainly used, justified in a limited area of geometric parameters and mechanical properties of pipe metal. To solve such problems of the strength of corroded pipelines, it is possible to use numerical methods. To do this, you need to have expensive licensed software for performing calculations and highly qualified personnel. Also, this approach is difficult when it is necessary to assess the strength of a large number of pipes with corrosion defects, which is the case in trunk pipelines.

In this article, a solution to the problem of the bearing capacity of a cylindrical shell with an axisymmetric thinning of a rectangular wall is obtained, based on a finite (non-differential) relationship between the forces and moments of A.A. Ilyushin for ideally plastic materials and the equilibrium equation of a cylindrical shell. For a pipeline with asymmetric corrosion thinning, the bearing capacity is determined by interpolation (calculation of intermediate values) of the proposed solution and ratios for the bearing capacity of a pipe with crack-like corrosion-mechanical defects in ductile fracture. For comparison with the proposed approach, a computer simulation of the bearing capacity of a circular cylindrical shell with rectangular thinning was carried out using a software package that implements the finite element method. The comparative analysis made it possible to confirm the possibility of using the results of the work in practical applications.

References

1. Barbosa A.A., Teixeira A.P., Soares C.G., Strength analysis of corroded pipelines subjected to internal pressure and bending moment, Proceedings of 6th International Conference On Marine Structures, 2017, DOI:10.1201/9781315157368-91

2. Benjamin A.C., Vieira R.D., Freire J.L.F., de Castro J.T.P., Modified equation for the assessment of long corrosion defects, Proceedings of OMAE’01 20th International Conference on Offshore Mechanics and Arctic Engineering, 2001, June 3–8, Rio de Janeiro, Brazil, URL: https://www.researchgate.net/publication/249657141_Modified_Equation_for_the_Assessment_of_Long_Corr...

3. Amaya-Gómez R., Sánchez-Silva M., Bastidas-Arteaga E. et al., Reliability assessments of corroded pipelines based on internal pressure – A review, Engineering Failure Analysis, Elsevier, 2019, DOI:10.1016/j.engfailanal.2019.01.064.

4. Xu L., Assessment of corrosion defects on high-strength steel pipelines: thesis of PhD, Calgary, 2013, doi:10.11575/PRISM/25027

5. Orasheva J., The effect of corrosion defects on the failure of oil and gas transmission pipelines: A finite element modeling study: Master's Thesis, College of Computing, Engineering & Construction, 2017, URL: https://digitalcommons.unf.edu/ etd/763/

6. Khazhinskiy G.M., Mekhanika melkikh treshchin v raschetakh prochnosti oborudovaniya i truboprovodov (Mechanics of small cracks in strength calculations for equipment and pipelines), Moscow: Fizmatkniga Publ., 2008, 254 p.

7. Korolev V.I., Uprugo-plasticheskie deformatsii obolochek (Elastic-plastic deformation of shells), Moscow: Mashinostroenie Publ., 1971.

8. Il'yushin A.A., Plastichnost' (Plasticity), Moscow: Gostekhizdat Publ., 1948.

9. Kiefner J.F., Maxey W.A., Eiber R.J., Duffy failure stress levels of flaws in pressurized cylinders, In: Progress in flaw growth and fracture toughness testing: edited by Kaufman J. et al., West Conshohocken, PA: ASTM International, 1973, pp. 461-481, https://doi.org/10.1520/STP49657S

10. Neganov D.A., Varshitskiy V.M., Belkin A.A., Computational and experimental studies of the strength of full-scale samples of pipes with defects "metal loss" and "dent with groove" (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science & Technologies: Oil and Oil Products Pipeline Transportation, 2020, V. 10, no. 3, pp. 226–233.

During the operation of main pipelines, in the event of a violation of their anti-corrosion coating and electrochemical protection, corrosion defects of the pipe surface may occur, which significantly reduce the bearing capacity of the pipeline. At present, to assess the strength of a pipeline with corrosion damage, semi-empirical dependences are mainly used, justified in a limited area of geometric parameters and mechanical properties of pipe metal. To solve such problems of the strength of corroded pipelines, it is possible to use numerical methods. To do this, you need to have expensive licensed software for performing calculations and highly qualified personnel. Also, this approach is difficult when it is necessary to assess the strength of a large number of pipes with corrosion defects, which is the case in trunk pipelines.

In this article, a solution to the problem of the bearing capacity of a cylindrical shell with an axisymmetric thinning of a rectangular wall is obtained, based on a finite (non-differential) relationship between the forces and moments of A.A. Ilyushin for ideally plastic materials and the equilibrium equation of a cylindrical shell. For a pipeline with asymmetric corrosion thinning, the bearing capacity is determined by interpolation (calculation of intermediate values) of the proposed solution and ratios for the bearing capacity of a pipe with crack-like corrosion-mechanical defects in ductile fracture. For comparison with the proposed approach, a computer simulation of the bearing capacity of a circular cylindrical shell with rectangular thinning was carried out using a software package that implements the finite element method. The comparative analysis made it possible to confirm the possibility of using the results of the work in practical applications.

References

1. Barbosa A.A., Teixeira A.P., Soares C.G., Strength analysis of corroded pipelines subjected to internal pressure and bending moment, Proceedings of 6th International Conference On Marine Structures, 2017, DOI:10.1201/9781315157368-91

2. Benjamin A.C., Vieira R.D., Freire J.L.F., de Castro J.T.P., Modified equation for the assessment of long corrosion defects, Proceedings of OMAE’01 20th International Conference on Offshore Mechanics and Arctic Engineering, 2001, June 3–8, Rio de Janeiro, Brazil, URL: https://www.researchgate.net/publication/249657141_Modified_Equation_for_the_Assessment_of_Long_Corr...

3. Amaya-Gómez R., Sánchez-Silva M., Bastidas-Arteaga E. et al., Reliability assessments of corroded pipelines based on internal pressure – A review, Engineering Failure Analysis, Elsevier, 2019, DOI:10.1016/j.engfailanal.2019.01.064.

4. Xu L., Assessment of corrosion defects on high-strength steel pipelines: thesis of PhD, Calgary, 2013, doi:10.11575/PRISM/25027

5. Orasheva J., The effect of corrosion defects on the failure of oil and gas transmission pipelines: A finite element modeling study: Master's Thesis, College of Computing, Engineering & Construction, 2017, URL: https://digitalcommons.unf.edu/ etd/763/

6. Khazhinskiy G.M., Mekhanika melkikh treshchin v raschetakh prochnosti oborudovaniya i truboprovodov (Mechanics of small cracks in strength calculations for equipment and pipelines), Moscow: Fizmatkniga Publ., 2008, 254 p.

7. Korolev V.I., Uprugo-plasticheskie deformatsii obolochek (Elastic-plastic deformation of shells), Moscow: Mashinostroenie Publ., 1971.

8. Il'yushin A.A., Plastichnost' (Plasticity), Moscow: Gostekhizdat Publ., 1948.

9. Kiefner J.F., Maxey W.A., Eiber R.J., Duffy failure stress levels of flaws in pressurized cylinders, In: Progress in flaw growth and fracture toughness testing: edited by Kaufman J. et al., West Conshohocken, PA: ASTM International, 1973, pp. 461-481, https://doi.org/10.1520/STP49657S

10. Neganov D.A., Varshitskiy V.M., Belkin A.A., Computational and experimental studies of the strength of full-scale samples of pipes with defects "metal loss" and "dent with groove" (In Russ.), Nauka i tehnologii truboprovodnogo transporta nefti i nefteproduktov = Science & Technologies: Oil and Oil Products Pipeline Transportation, 2020, V. 10, no. 3, pp. 226–233.



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