Effect of Crack Depth on Burst Strength of X70 Linepipe With Dent-Crack Defect

2016 ◽  
Author(s):  
Hossein Ghaednia ◽  
Sreekanta Das ◽  
Jamshid Zohrehheydariha ◽  
Rick Wang ◽  
Richard Kania
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Parametric Study ◽  
Oil And Gas ◽  
Pipe Wall ◽  
Crack Depth ◽  
Fe Model ◽  
Burst Strength ◽  
Crack Defect

External interferences cause various defects, which significantly affect the transportation of oil and gas in pipelines. Corrosion, crack, puncture, dent, gouge, and combination of such damages from a variety of external interferences are some common examples of surface damage in pipelines. Gouges, dents, cracks, and punctures that form in the pipe wall as a result of contact and/or impact from foreign objects are often referred to as mechanical damage. Structural integrity of oil and gas transmission pipelines is often threatened by these mechanical damages and as a result, a failure of the pipeline may occur. A defect that contains both dent and crack, often known as dent-crack defect, may lead to a rupture or leak in the pipe wall. This kind of defect is a matter of serious concern for the pipeline operator since a rupture or a leak may occur. Hence, an experimental study was completed at the Centre for Engineering Research in Pipelines (CERP), University of Windsor on 30 inch (762 mm) diameter and X70 grade pipes with D/t of 90. This project was undertaken through laboratory based experimental work and numerical study using non-linear finite element analysis (FEA) method. The purpose of full-scale test was to collect test data to be able to validate finite element (FE) model. The validated FE model was then used to undertake parametric study for determining the effect of the crack depth and operating (internal) pressure on the burst strength of NPS30 X70 grade oil and gas pipe. The parameters chosen in the FE based parametric study are: (1) crack depth which was varied from 0.25 to 0.75 of pipe wall thickness and (2) internal pressure applied during denting process (operating pressure of linepipe) was varied from no internal pressure to 0.75py. This study found that the dent-crack defect with crack depth of 75% of wall thickness could reduce the pressure capacity by 54%.

Effect of Operating Pressure and Dent Depth on Burst Strength of NPS30 Linepipe With Dent–Crack Defect

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Hossein Ghaednia ◽  
Sreekanta Das ◽  
Rick Wang ◽  
Richard Kania
Keyword(s):  
Pipe Wall ◽  
Crack Depth ◽  
Test Procedure ◽  
Operating Pressure ◽  
Test Results ◽  
Burst Strength ◽  
Engineering Research ◽  
Line Pressure ◽  
Dent Depth ◽  
Crack Defect

Buried linepipe can be exposed to various external interferences and corrosive environment and as a result, damage in the form of dent or corrosion or crack or gouge or combination of any of these damages can form in the pipe wall. A defect combining dent and crack, often known as dent–crack defect, which may lead to a rupture or leak in the pipe wall and hence, the pipeline operator becomes concerned about the performance and safety of the pipeline. A research was recently completed at the Centre for Engineering Research in Pipelines (CERP), University of Windsor to study the influence of dent depth and operating line pressure on the pressure capacity (burst strength) of 30 in. diameter and X70 grade linepipe. This study found that the dent depth of 12% with crack depth of 4 mm or more can reduce the pressure capacity by 38%. This paper discusses the test specimens, test setup, test procedure, test results, and data obtained from finite element analyses.

Effect of Dent Depth on the Burst Pressure of NPS30 X70 Pipes With Dent-Crack Defect

2014 ◽  
Author(s):  
Hossein Ghaednia ◽  
Sreekanta Das ◽  
Rick Wang ◽  
Richard Kania
Keyword(s):  
Oil And Gas ◽  
Pipe Wall ◽  
Crack Depth ◽  
Test Procedure ◽  
Petroleum Products ◽  
Engineering Research ◽  
Line Pressure ◽  
Dent Depth ◽  
Crack Defect

Pipeline is the common mode for transporting oil, gas, and various petroleum products. Buried linepipe can be exposed to various external interferences and corrosive environment and as a result, damage in the form of dent or corrosion or crack or gouge or combination of any of these damages can form in the pipe wall. Such damage or combined damages can reduce the pressure capacity of the pipeline. A defect combining dent and crack, often known as dent-crack defect, can develop in the wall of a buried oil and gas linepipe. This combined defect may lead to a leak or a rupture in the pipe wall and hence, the pipeline operator becomes concerned about the performance and safety of the pipeline when a dent-crack defect is detected in the field pipeline. A long-term research program is currently underway at the Centre for Engineering Research in Pipelines, University of Windsor to study the influence of various parameters such as dent depth and operating line pressure on the pressure capacity or burst strength of 30 inch diameter and X70 grade pipes with D/t of about 90. From the study completed so far, it has been found that the dent depth of 8% with crack depth of 4 mm or more can reduce the pressure capacity by 32%. This paper discusses the test specimens, test setup, test procedure, test results, and data obtained from finite element analyses.

Limit Load Capacity of Thick-Walled Pipe Loaded by Internal Pressure and Bending

2021 ◽  
Author(s):  
Ruud Selker ◽  
Joost Brugmans ◽  
Ping Liu ◽  
Carlos Sicilia
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Load Capacity ◽  
Limit State ◽  
Local Buckling ◽  
Limit Load ◽  
Combined Loading ◽  
Fe Model ◽  
State Equations

Abstract Internally pressurised pipe behaves differently than externally pressurised pipe. DNVGL-ST-F101 [4], a prevailing standard for the design of submarine pipelines, provides limit-state equations for combined loading that are valid only if the diameter-to-wall-thickness ratio (D/t) is between 15 and 45. A recent study has shown that the results are increasingly conservative for lower values of this ratio if the nett pressure is acting on the pipe’s outside [8], especially if it is below 20. In this paper, the applicability of the limit-state equations for thick-walled pipe with D/t less than 15 and loaded by a nett internal pressure has been investigated. The first step was a fundamental review of the formulations. Next, the predicted capacities were compared with those estimated using a finite-element (FE) model. The results greatly coincided, which indicates that the conservatism underlying the formulations does not depend on D/t. Hence they can be used for design against local buckling under internal overpressure, too, when the ratio is below 15.

Finite Element Study of the Cutting Mechanics of the Three Dimensional Rock Turning Process

2015 ◽  
Author(s):  
Demeng Che ◽  
Jacob Smith ◽  
Kornel F. Ehmann
Keyword(s):  
Finite Element ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Polycrystalline Diamond ◽  
Close Correlation ◽  
Experimental Results ◽  
Failure Behavior ◽  
Fe Model ◽  
Gas Drilling ◽  
Cutting Mechanics

The unceasing improvements of polycrystalline diamond compact (PDC) cutters have pushed the limits of tool life and cutting efficiency in the oil and gas drilling industry. However, the still limited understanding of the cutting mechanics involved in rock cutting/drilling processes leads to unsatisfactory performance in the drilling of hard/abrasive rock formations. The Finite Element Method (FEM) holds the promise to advance the in-depth understanding of the interactions between rock and cutters. This paper presents a finite element (FE) model of three-dimensional face turning of rock representing one of the most frequent testing methods in the PDC cutter industry. The pressure-dependent Drucker-Prager plastic model with a plastic damage law was utilized to describe the elastic-plastic failure behavior of rock. A newly developed face turning testbed was introduced and utilized to provide experimental results for the calibration and validation of the formulated FE model. Force responses were compared between simulations and experiments. The relationship between process parameters and force responses and the mechanics of the process were discussed and a close correlation between numerical and experimental results was shown.

3-D Finite Element Simulation of Pulsating T-Shape Hydroforming of Tubes

2007 ◽  
Vol 340-341 ◽  
pp. 353-358 ◽  
Author(s):  
M. Loh-Mousavi ◽  
Kenichiro Mori ◽  
K. Hayashi ◽  
Seijiro Maki ◽  
M. Bakhshi
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Finite Element Simulation ◽  
Wall Thickness ◽  
Filling Ratio ◽  
Shape Accuracy ◽  
Element Simulation ◽  
Hydroforming Process ◽  
Good Agreement

The effect of oscillation of internal pressure on the formability and shape accuracy of the products in a pulsating hydroforming process of T-shaped parts was examined by finite element simulation. The local thinning was prevented by oscillating the internal pressure. The filling ratio of the die cavity and the symmetrical degree of the filling was increased by the oscillation of pressure. The calculated deforming shape and the wall thickness are in good agreement with the experimental ones. It was found that pulsating hydroforming is useful in improving the formability and shape accuracy in the T-shape hydroforming operation.

J-Integral Analysis of Surface Cracks in Round Bars under Bending Moments

2011 ◽  
Vol 52-54 ◽  
pp. 43-48 ◽  
Author(s):  
Al Emran Ismail ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Mariyam Jameelah Ghazali ◽  
Ruslizam Daud
Keyword(s):  
Finite Element ◽  
Crack Depth ◽  
Crack Tip ◽  
Bending Moment ◽  
Limit Load ◽  
Fe Model ◽  
Surface Cracks ◽  
Element Analysis ◽  
Reference Stress ◽  
Proposed Model

This paper presents a non-linear numerical investigation of surface cracks in round bars under bending moment by using ANSYS finite element analysis (FEA). Due to the symmetrical analysis, only quarter finite element (FE) model was constructed and special attention was given at the crack tip of the cracks. The surface cracks were characterized by the dimensionless crack aspect ratio, a/b = 0.6, 0.8, 1.0 and 1.2, while the dimensionless relative crack depth, a/D = 0.1, 0.2 and 0.3. The square-root singularity of stresses and strains was modeled by shifting the mid-point nodes to the quarter-point locations close to the crack tip. The proposed model was validated with the existing model before any further analysis. The elastic-plastic analysis under remotely applied bending moment was assumed to follow the Ramberg-Osgood relation with n = 5 and 10. J values were determined for all positions along the crack front and then, the limit load was predicted using the J values obtained from FEA through the reference stress method.

Effect of Expansion Ratio and Wall Thickness on Large-Diameter Solid Expandable Tubular after Expansion

2021 ◽  
Author(s):  
Changshuai Shi ◽  
Kailin Chen ◽  
Xiaohua Zhu ◽  
Feilong Cheng ◽  
Yuekui Qi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Internal Pressure ◽  
Wall Thickness ◽  
Performance Test ◽  
Large Diameter ◽  
Expansion Ratio ◽  
Fe Model ◽  
Laboratory Test Results ◽  
Low Efficiency ◽  
Pressure Resistance

Abstract The large-diameter solid expandable tubular with a smaller wall thickness faces the risk of internal pressure burst and external squeeze collapse in repairing damaged casing well. The internal pressure and external squeezing resistance calculation of the tubes using the analytical method require many expansion experiments and post-expansion tensile experiments, resulting in high costs and low efficiency. This paper gives a set of laboratory expansion and post-expansion performance test, which is based on the laboratory experiment and mechanical properties of material expansion. Two materials are studied: 316L and 20G. Then it analyses the error and causes of the error in the traditional analytical algorithm. Besides, it establishes an accurate finite element (FE) model to study the quantitative influence of expansion ratio and wall thickness on the burst strengths and collapse strengths of the tube. The results show that the toughness and hardening ratio of 316L is better than 20G at the same expansion ratio. The numerical simulation results of the model can effectively simulate the expansion process and the mechanical properties of SET in good agreement with the laboratory test results. The expansion ratio and wall thickness affect the mechanical properties after expansion. Thus the quantitative laws of the expansion driving force, internal pressure resistance, and external squeezing resistance under different variables are summarized. To ensure the integrity of the reinforced wellbore, the expansion ratio should not exceed 12.7%. In the current study lays a theoretical basis and technical support for optimizing SET and preventing downhole accidents.

Numerical Analysis of API 5L X42 and X52 Vintage Pipes with Cracks in Corrosion Defects Using Extended Finite Element Method

2021 ◽  
Author(s):  
Xinfang Zhang ◽  
Meng Lin ◽  
Allan Okodi ◽  
Leichuan Tan ◽  
Juliana Leung ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Pipe Wall ◽  
Crack Depth ◽  
Initial Crack ◽  
Extended Finite Element ◽  
Failure Pressure ◽  
Corrosion Defects ◽  
Element Method

Abstract Cracks and corrosion in pipelines can occur simultaneously, representing a hybrid defect known as cracks in corrosion (CIC), which is often difficult to model using the available assessment codes or methods. As a result, detailed modeling of CIC has not been studied extensively. In this study, the extended finite element method (XFEM) has been applied to predict the failure pressures of CIC defects in API 5L Grade X42 and X52 pipes. The pipes were only subjected to internal pressure and the XFEM models were validated using full-scale burst tests available in the literature. Several CIC models with constant total defect depths (55%, and 60% of wall thickness) were constructed to investigate the effect of the initial crack depth on the failure pressure. The failure criterion was defined when wall penetration occurred due to crack growth, i.e., the instance the crack reached the innermost element of the pipe wall mesh. It was observed that for shorter cracks, the failure pressure decreased with the increase of the initial crack depth. The results indicated that the CIC defect could be treated as crack-only defects when the initial crack depth exceeded 50% of the total defect depth. However, for longer cracks, the initial crack depth was found to have a negligible effect on the failure pressure, implying that the CIC defect could be treated as either a crack or a corrosion utilizing the available assessment methods.

Design of the Full Scale Experiments for the Testing of the Tensile Strain Capacity of X52 Pipes With Girth Weld Flaws Under Internal Pressure and Tensile Displacement

2014 ◽  
Author(s):  
Celal Cakiroglu ◽  
Samer Adeeb ◽  
J. J. Roger Cheng ◽  
Millan Sen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Tensile Strain ◽  
Oil And Gas ◽  
Full Scale ◽  
Element Analysis ◽  
Simultaneous Application ◽  
Strain Capacity ◽  
Tensile Strain Capacity

Pipelines can be subjected to significant amounts of tensile forces due to geotechnical movements like slope instabilities and seismic activities as well as due to frost heave and thaw cycles in arctic regions. The tensile strain capacity εtcrit of pipelines is crucial in the prediction of rupture and loss of containment capability in these load cases. Currently the Oil and Gas Pipeline Systems code CSA Z662-11 0 contains equations for the prediction of εtcrit as a function of geometry and material properties of the pipeline. These equations resulted from extensive experimental and numerical studies carried out by Wang et al [2]–[6] using curved wide plate tests on pipes having grades X65 and higher. Verstraete et al 0 conducted curved wide plate tests at the University of Ghent which also resulted in tensile strain capacity prediction methods and girth weld flaw acceptability criteria. These criteria are included in the European Pipeline Research Group (EPRG) Tier 2 guidelines. Furthermore Verstrate et al 0 introduced a pressure correction factor of 0.5 in order to include the effect of internal pressure in the tensile strain capacity predictions in a conservative way. Further research by Wang et al with full scale pipes having an internal pressure factor of 0.72 also showed that εtcrit decreases in the presence of internal pressure [10]–[15]. In their work, Wang et al presented a clear methodology for the design of full scale experiments and numerical simulations to study the effect of internal pressure on the tensile strain capacity of pipes with girth weld flaws [10]–[15]. However, there has been limited testing to enable a precise understanding of the tensile strain capacity of pipes with grades less than X65 as a function of girth weld flaw sizes and the internal pressure. In this paper the experimental setup for the testing of grade X52 full scale specimens with 12″ diameter and ¼″ wall thickness is demonstrated. In the scope of this research 8 full scale specimens will be tested and the results will be used to formulate the tensile strain capacity of X52 pipes under internal pressure. The specimens are designed for the simultaneous application of displacement controlled tensile loading and the internal pressure. Finite element analysis is applied in the optimization process for the sizes of end plates and connection elements. Also the lengths of the full scale specimens are determined based on the results from finite element analysis. The appropriate lengths are chosen in such a way that between the location of the girth weld flaw and the end plates uniform strain zones could be obtained. The internal pressure in these experiments is ranging between pressure values causing 80% SMYS and 30% SMYS hoop stress. The end plates and connection elements of the specimens are designed in such a way that the tensile displacement load is applied with an eccentricity of 10% of the pipe diameter with the purpose of increasing the magnitude of tensile strains at the girth weld flaw location. The results of two full scale experiments of this research program are presented. The structural response from the experiments is compared to the finite element simulation. The remote strain values of the experiment are found to be higher than the εtcrit values predicted by the equations in 0.

Finite Element Modelling of Static and Fatigue Failure of Composite Repair System in Offshore Pipe Risers

2014 ◽  
Vol 875-877 ◽  
pp. 1063-1068 ◽  
Author(s):  
Park Hinn Chan ◽  
Kim Yeow Tshai ◽  
Michael Johnson ◽  
Hui Leng Choo
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Low Cycle Fatigue ◽  
Failure Mechanisms ◽  
Repair System ◽  
Fe Model ◽  
Composite Surface ◽  
Composite Repair ◽  
Bending Load ◽  
Static Conditions

The static and cyclic failure mechanisms of offshore pipe riser repaired with a designated laminate orientation of carbon/epoxy (C/E) system were studied. The finite element (FE) model takes into account failure mechanisms of the composite sleeve inter-layer delamination, debonding at the steel riser-composite surface interface, and the maximum permissible strain of the repaired riser. Design conditions of the combined static loads (coupled internal pressure, longitudinal tensile and transverse bending) were determined through a limit state analysis [1,2]. The limiting static bending load that causes catastrophic failure under a coupled internal pressure and tensile loadings was determined through Virtual Crack Closure Technique (VCCT). The effects of cyclic bending, mimicking the typical scenarios experienced in pipe riser exposed to dynamic subsea environment, were evaluated and compared against the static conditions. The low cycle fatigue of the composite repair system (CRS) is simulated using a direct cyclic analysis within a general purpose FE program, where the onset and fatigue delamination/disbonding growth are characterized through the Paris Law.

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