Comparison of experimental and finite element analytical results for the strength and the deformation of pipes with local wall thinning subjected to bending moment

2006 ◽  
Vol 236 (2) ◽  
pp. 140-155 ◽  
Author(s):  
Seok-Hwan Ahn ◽  
Ki-Woo Nam ◽  
Koji Takahashi ◽  
Kotoji Ando
Keyword(s):  
Finite Element ◽  
Bending Moment ◽  
Analytical Results ◽  
Wall Thinning ◽  
Local Wall Thinning

Failure Strength Assessment of Pipes With Local Wall Thinning Under Combined Loading Based on Finite Element Analyses

2004 ◽  
Vol 126 (2) ◽  
pp. 179-183 ◽  
Author(s):  
Do-Jun Shim ◽  
Jae-Boong Choi ◽  
Young-Jin Kim
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Nuclear Power ◽  
Bending Moment ◽  
Combined Loading ◽  
Assessment Procedure ◽  
Finite Element Analyses ◽  
Maximum Moment ◽  
Wall Thinning ◽  
Local Wall Thinning

Failure assessment of a pipe with local wall thinning draws increasing attention in the nuclear power plant industry. Although many guidelines have been developed and are used for assessing the integrity of a wall-thinned pipeline, most of these guidelines consider only pressure loading and thus neglect bending loading. As most pipelines in nuclear power plants are subjected to internal pressure and bending moment, an assessment procedure for locally wall-thinned pipeline subjected to combined loading is urgently needed. In this paper, three-dimensional finite element (FE) analyses are carried out to simulate full-scale pipe tests conducted for various shapes of wall-thinned area under internal pressure and bending moment. Maximum moments based on ultimate tensile stress were obtained from FE results to predict the failure of the pipe. These results are compared with test results, showing good agreement. Additional finite element analyses are then performed to investigate the effect of key parameters, such as wall-thinned depth, wall-thinned angle and wall-thinned length, on maximum moment. Moreover, the effect of internal pressure on maximum moment was investigated. Change of internal pressure did not show significant effect on the maximum moment.

Finite Element Creep Damage Analyses and Life Prediction of P91 Pipe Containing Local Wall Thinning Defect

2016 ◽  
Vol 35 (3) ◽  
pp. 283-295 ◽  
Author(s):  
Jilin Xue ◽  
Changyu Zhou
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Life Prediction ◽  
Bending Moment ◽  
Creep Damage ◽  
Orthogonal Experimental Design ◽  
Continuum Damage ◽  
Rupture Stress ◽  
Wall Thinning ◽  
Local Wall Thinning

AbstractCreep continuum damage finite element (FE) analyses were performed for P91 steel pipe containing local wall thinning (LWT) defect subjected to monotonic internal pressure, monotonic bending moment and combined internal pressure and bending moment by orthogonal experimental design method. The creep damage lives of pipe containing LWT defect under different load conditions were obtained. Then, the creep damage life formulas were regressed based on the creep damage life results from FE method. At the same time a skeletal point rupture stress was found and used for life prediction which was compared with creep damage lives obtained by continuum damage analyses. From the results, the failure lives of pipe containing LWT defect can be obtained accurately by using skeletal point rupture stress method. Finally, the influence of LWT defect geometry was analysed, which indicated that relative defect depth was the most significant factor for creep damage lives of pipe containing LWT defect.

Effect of Torsion on Collapse Bending Moment for 24-Inch Diameter Schedule 80 Pipes With Wall Thinning

2012 ◽  
Author(s):  
Kunio Hasegawa ◽  
Yinsheng Li ◽  
Bostjan Bezensek ◽  
Phuong Hoang
Keyword(s):  
Power Plants ◽  
Bending Moment ◽  
Combined Loading ◽  
Bending Moments ◽  
Compressive Stresses ◽  
Wall Thinning ◽  
Nominal Thickness ◽  
Calculation Results ◽  
Loading Modes ◽  
Local Wall Thinning

Piping items in power plants may experience combined bending and torsion moments during operation. Currently, there is a lack of guidance in the ASME B&PV Code Section XI for combined loading modes including pressure, torsion and bending. Finite element analyses were conducted for 24-inch diameter Schedule 80 pipes with local wall thinning subjected to tensile and compressive stresses. Plastic collapse bending moments were calculated under constant torsion moments. From the calculation results, it can be seen that collapse bending moment for pipes with local thinning subjected to tensile stress is smaller than that subjected to compressive stress. In addition, equivalent moment is defined as the root the sum of the squares of the torsion and bending moments. It is found that the equivalent moments can be approximated with the pure bending moments, when the wall thinning length is equal or less than 7.73R·t for the wall thinning depth of 75% of the nominal thickness, where R is the mean radius and t is the wall thickness of the pipe.

3428 Finite element analysis of failure behavior of elbow pipe with local wall thinning

2006 ◽  
Vol 2006.1 (0) ◽  
pp. 567-568
Author(s):  
Tomohiro UENO ◽  
Koji TAKAHASHI ◽  
Kotoji ANDO ◽  
Akitaka HIDAKA ◽  
Masakazu HISATSUNE ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Behavior ◽  
Element Analysis ◽  
Wall Thinning ◽  
Local Wall Thinning

Allowable Limit and Finite Element Analysis of Pipes With Local Wall Thinning Subjected to Bending Moment

2004 ◽  
Author(s):  
Seok Hwan Ahn ◽  
Ki Woo Nam ◽  
Koji Takahashi ◽  
Kotoji Ando
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Failure Modes ◽  
Bending Test ◽  
Element Analysis ◽  
Allowable Limit ◽  
Pipe Surface ◽  
Wall Thinning ◽  
Plastic Analysis ◽  
Local Wall Thinning

Fracture behaviors of pipes with local wall thinning are very important for the integrity of power plant piping system. In this study, monotonic bending tests without internal pressure are conducted on 1.91-inch diameter Schedule 80 STS370 full-scale carbon steel pipe specimens. Fracture strengths of locally wall thinned pipes were calculated by elasto-plastic analysis using finite element method. The elasto-plastic analysis was performed by FE code ANSYS. We simulated various types of local wall thinning that can be occurred at pipe surface due to coolant flow. Locally wall thinned shapes were machined to be different in size along the circumferential or axial direction of straight pipes. We investigated fracture strengths and failure modes of locally wall thinned pipes by four-point bending test. From the test results, failure modes could be divided three types, ovalization, local buckling and crack initiation. And, the allowable limit of pipes with local wall thinning was investigated. In addition, we compared the simulated results by finite element analysis with experimental data. The failure mode, fracture strength and fracture behavior obtained from the tests showed well agreement with analytic results.

Capacity Analysis and Safety Assessment of Polyethylene Pipeline With Local Wall-Thinning Defect

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Weijie Jiang ◽  
Jianping Zhao
Keyword(s):  
Safety Assessment ◽  
Mechanical Performance ◽  
Orthogonal Design ◽  
Bending Moment ◽  
Limit Load ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Assessment Procedure ◽  
Wall Thinning ◽  
Local Wall Thinning

The purpose of this study is to propose a safety assessment procedure for polyethylene (PE) pipe with local wall-thinning defect. A uniaxial tensile test is performed to test the mechanical performance of PE. Then, the constitutive model for PE can be established. The limit load of the PE pipe with local wall-thinning defect can be studied with the method of combining the orthogonal design of experiment and finite element (FE) analysis. Then, the factors of local wall-thinning defect can be analyzed. The results show that the depth of the defect has a great effect on the limit load (internal pressure and bending moment) of PE pipe. The effects that the axial length of the defect and the circumferential length of the defect have on the limit load are not significant. Referring to the safety assessment of metal pipe proposed by GB/T19624-2004, a safety assessment for PE pipe with local wall-thinning defect is revised.

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