Write your message
Volume 10 - Summer and Autumn 2018                   ijmt 2018, 10 - Summer and Autumn 2018: 37-44 | Back to browse issues page

XML Print

Download citation:
BibTeX | RIS | EndNote | Medlars | ProCite | Reference Manager | RefWorks
Send citation to:
Sharifi M H, Soheili R, Shaghaghi Moghaddam A, Azarsina F. Engineering Critical Assessment for Offshore Pipeline with Semi Elliptical Surface Cracks in Girth Weld – Comparison of FEM and BS7910 Guideline. ijmt 2018; 10 :37-44
URL: http://ijmt.ir/article-1-638-en.html
Engineering Critical Assessment for Offshore Pipeline with Semi Elliptical Surface Cracks in Girth Weld – Comparison of FEM and BS7910 Guideline
Mohammad Hossein Sharifi * 1, Reza Soheili2 , Ali Shaghaghi Moghaddam3 , Farhood Azarsina4
1- Faculty of marine science, Petroleum University of Technology, Mahmoudabad, Iran
2- Science and Research Branch, Islamic Azad University, Tehran, Iran
3- Department of Mechanical Engineering, Islamic Azad University, Takestan Branch, Iran
4- Department of Marine structure, Science and Research Branch, Islamic Azad University Tehran, Iran
Abstract:   (6148 Views)
Economical design with sufficient fracture resistance is of high importance in any offshore pipeline projects. Using an Engineering Critical Assessment (ECA), alternate acceptance criteria for pipeline girth weld inspection can significantly reduce the cost of constructing of offshore oil and gas pipeline by minimizing unnecessary repairs. Offshore pipelines consist of short pipeline segments connected by girth welding method. Surface and embedded elliptical cracks due to welding operation are often observed at welding zone which pose a potential threat to the reliability of the offshore pipelines. To derive the acceptance criteria for pipeline girth weld defects and pipeline safety during installation and operation phase, an ECA based on fracture mechanics is required. In this paper, ECA of offshore pipeline with semi elliptical surface crack under pure tension loading is performed according to finite element method and BS7910 guideline. Moreover, a comparison between these two methods is offered. It is concluded that, ECA by BS7910 guideline is more conservative than finite element method, and the difference between the two diagrams increases as strain levels are increased. Also, comparisons of critical crack size curve for various strain levels are studied.
Keywords: Engineering Critical Assessment, Offshore Pipeline Girth weld, Surface Cracks, Acceptance Criteria, FEM
Full-Text [PDF 1042 kb]   (4004 Downloads)    
Type of Study: Research Paper | Subject: Offshore Structure
Received: 2018/03/14 | Accepted: 2018/09/2
References
1. Berg, E., Ostby, E., Thaulow, C., (2008), Ultimate fracture capacity of pressurized pipes with defects – Comparisons of large scale testing and numerical simulations, Engineering Fracture Mechanics, vol. 75, no. 8, pp. 2352-2366. [DOI:10.1016/j.engfracmech.2007.09.004]
2. Thaulow,C., Jayadevan, K.R, (2005), Fracture Control Offshore Pipelines - Advantages of using direct calculations in fracture assessments of pipelines, 24th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2005) , halkidiki.
3. Pisarski, H., (2013), Assessment of flaws in pipeline girth welds—a critical review, TWI.
4. BS7910, (2005), Guide to methods for assessing the acceptability of flaws in metallic structures, British Standard.
5. API, (1999), American Petroleum Institute, Standard for Welding Pipelines.
6. DNV, (2012), Submarine Pipeline Systems.
7. Zhang, Y.M., Xiao, Z.M., Zhang, W.G., (2013), On 3-D crack problems in offshore pipeline with large plastic deformation, Theoretical and Applied Fracture Mechanics, Vols. 66-67, pp. 22-28. [DOI:10.1016/j.tafmec.2014.01.001]
8. Linkense, D., Formby,CL., (2000), A strain-based approach to fracture assessment, 5th International Conference on Engineering.
9. Wang,YY., Stephens, M., Horsley,D., (2008), Preliminary analysis of tensile strain capacity of full-scale pipe tests with internal pressure. 18th International offshore and polar engineering conference ISOPE. Vancouver, British Columbia, Canada
10. Tkaczyk, T., O'Dowd, N. P., Nikbin, K., (2009), Fracture assessment procedures for steel pipelines using a modified reference stress solution. ASME International Journal of Pressure Vessels and Piping, vol. 131
11. Nourpanah, N., Taheri, F., (2010), Development of a reference strain approach for assessment of fracture response of reeled pipelines. Journal of Engineering fracture mechanics, vol 77: p. 2337–2353. [DOI:10.1016/j.engfracmech.2010.04.030]
12. Linkens D, Formby CL, Ainsworth RA. A (2000). Strain-based approach to fracture assessment-example applications. Proceedings of fifth international conference on engineering structural integrity assessment. Cambridge: EMAS.
13. Yi, D. K., Sridhar, I., Zhongmin, X., Kumar, S. B., (2012). Fracture capacity of girth welded pipelines with 3D surface cracks subjected to biaxial loading conditions. International Journal of Pressure Vessels and Piping, vol. 92, no. 11, p. 115-126.
14. Zhang, Z., Yi, D., Xiao, Z., Huang, Z., (2015), Engineering critical assessment for offshore pipelines with 3-D elliptical embedded cracks, Engineering Failure Analysis journal, vol. 51, pp. 37-54.
15. Berg, E., Skallerud, B., Thaulow, C., (2008), Two-parameter fracture mechanics and circumferential crack growth in surface cracked pipelines using line-spring elements, Engineering Fracture Mechanics, vol. 75, no. 1, pp. 17-30. [DOI:10.1016/j.engfracmech.2007.03.023]
16. Schwalbe, K., (1994), The crack tip opening displacement and J integral under strain control and fully plastic conditions estimated by the engineering treatment model for plane stress tension, Fracture Mechanics, vol. 24, pp. 635-651.
17. "ZENCRACK software version 7.9" ZENTECH.CO.
18. "CRACKWISE software version 5", TWI company.
19. Cosham, A., (2008), ECAs: Are they fit-for-purpose ?, Amsterdam, The Netherlands, 27-28 February ,vol. 44, pp, OPT
20. Zhang, Y. M., Xiao, Z. M., Zhang, W. G., Huang, Z. H., (2014), Strain-based CTOD estimation formulations for fracture assessment of offshore pipelines subjected to large plastic deformation, journal of Ocean Engineering, vol. 91, pp. 64-72.
21. DNV-RP-F108, (2006), Fracture control for pipeline installation methods introducing, Det Norske Veritas.
22. "ABAQUS standard code version 6.14".
23. Yong-yi, W., Liu, M., (2012), Tensile Strain Models for Strain-Based Design of Pipelines, International Conference on Ocean, Offshore and Arctic Engineering,Rio de Janeiro.
Send email to the article author

Rights and permissions
Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Creative Commons License
International Journal of Maritime Technology is licensed under a

Creative Commons Attribution-NonCommercial 4.0 International License.