Ductile Failure and Safety Optimization of Gas Pipeline

Subject Areas : Engineering

P Zamani ¹ , A Jaamialahmadi ² , M Shariati ³

1 - Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
2 - Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
3 - Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

Received: 2016-07-11 Accepted : 2016-09-15 Published : 2016-12-20

Keywords: Finite Element Analysis, Taguchi Method, Semi-Elliptical Crack, Failure assessment diagram,

Abstract :

Safety and failure in gas pipelines are very important in gas and petroleum industry. For this reason, it is important to study the effect of different parameters in order to reach the maximum safety in design and application. In this paper, a three dimensional finite element analysis is carried out to study the effect of crack length, crack depth, crack position, internal pressure and pipe thickness on failure mode and safety of API X65 gas pipe. Four levels are considered for each parameter and finite element simulations are carried out by using design of experiments (DOE). Then, multi-objective Taguchi method is conducted in order to minimize x and y coordinates of Failure Assessment Diagram (FAD). So, desired levels that minimize the coordinates and rises the possibility of safety are derived for each parameter. The variation in FAD coordinates according to the changes in each parameter are also found. Finally, comparisons between the optimum design and all other experiments and simulations have shown a good safety situation. It is also concluded that the more design parameters close to optimum levels, the better safety condition will occur in FAD. A verification study is performed on the safety of longitudinal semi-elliptical crack and the results has shown a good agreement between numerical and experimental results.

References:

[1] Underwood J.H., 1972, Stress intensity factors for internally pressurized thick-walled cylinders, American Society for Testing and Materials 513 : 59-70.
[2] Raju I.S., Newman J.C., 1980, Stress-intensity factors for internal and external surface cracks in cylindrical vessels, Journal of Pressure Vessel Technology 102(4): 293-298.
[3] Newman J.C., 1976, Fracture analysis of surface and through cracks in cylindrical pressure vessels, National Aeronautics and Space Administration 39: 21-33.
[4] Liu A., 1996, Rockwell International Science Center, ASM Handbook Fatigue and Fracture.
[5] Lee S.L., Ju J.B., Kim W.S., Kwon D., 2004, Weld crack assessments in API X65 pipeline: failure assessments diagrams with variations in representative mechanical properties, Materials Science and Engineering 373(1): 122-130.
[6] Oh C.K, Kim Y.J, Baek J.H., Kim Y.P., Kim W.S., 2007, Ductile failure analysis of API X65 pipes with notch-type defects using a local fracture criterion, International Journal of Pressure Vessels and Piping 84: 512-525.
[7] Sandvik A., Ostby E., Thaulow C., 2008, A probabilistic fracture mechanics model including 3D ductile tearing of bi-axially loaded pipes with surface cracks, Engineering Fracture Mechanics 75: 76-96.
[8] Pluvinage G., Capelle J., Schmitt G., Mouwakeh M., 2012, Doman failure assessment diagrams for defect assessment of gas pipes, 19th European Conference on Fracture, Kazan, Russia.
[9] Zhang B., Ye C., Liang B., Zhang Z., Zhi Y., 2014, Ductile failure analysis and crack behavior of X65 buried pipes using extended finite element method, Engineering Failure Analysis 45: 26-40.
[10] Ghajar R., Mirone G., Keshavarz A., 2013, Ductile failure of X100 pipeline steel-Experiments and fractography, Materials & Design 43: 513-525.
[11] Sharma K., Singh I.V., Mishra B.K., Maurya S.K., 2014, Numerical simulation of semi-elliptical axial crack in pipe bend using XFEM, Journal of Solid Mechanics 6(2): 208-228.
[12] Dimic I., Medjo B., Rakin M., Arsic M., Sarkocevic Z., Sedmak A., 2014, Failure prediction of gas and oil drilling rig pipelines with axial defects, Procedia Materials Science 3: 955-960.
[13] Ainsworth R.A., 1984, The assessment of defects in structures of strain hardening material, Engineering Fracture Mechanics 19(4):633-642.
[14] Anderson T.L., Osage D.A., 2000, API 579: a comprehensive fitness-for-service guide , International Journal of Pressure Vessels and Piping 77(14):953-963.
[15] API 579, 2000, Recommended Practice for Fitness for Service, American Petroleum Institute.
[16] BS7910, 1999, Guide and Methods for Assessing the Acceptability of Flaws in Fusion Welded Structures, British Standard Institutions.
[17] R-6,1998, Assessment of the Integrity of Structures Containing Defects, British Energy.
[18] BS EN ISO 7448, 1999, Metallic Materials Determination of Plan-Strain Fracture Toughness, British Standard Institution.
[19] Shahraini S.I., Hashemi S.H., 2014, Effects of surface crack length and depth variations on gas transmission pipeline safety, Modares Mechanical Engineering 14:26-32.
[20] Habbit, Karlsson, Sorensen, 2007, Abaqus/Standard Analysis User’s Manual, USA.