scholarly journals Numerical Simulation and Safety Assessment Analysis for Pressure Pipe with Incomplete Penetration Defects

2018 ◽  
Vol 382 ◽  
pp. 052052
Author(s):  
Facai Ren ◽  
Bo Li ◽  
Xiaoying Tang
Keyword(s):  
Numerical Simulation ◽  
Safety Assessment ◽  
Pressure Pipe

Simulation and Analysis of Swing Motion of Lifting Load System on Rescue Vehicle

2012 ◽  
Vol 538-541 ◽  
pp. 725-729
Author(s):  
Han Ming Liu ◽  
Heng Zhao ◽  
Ning Li
Keyword(s):  
Numerical Simulation ◽  
Theoretical Basis ◽  
Safety Assessment ◽  
Kinematic Model ◽  
Excitation Frequency ◽  
Lagrange’S Equation ◽  
Set Up

In lifting, remoted operated dive vehicle（ROV） may swing with the effect of wave. Based on the general form of Lagrange’s equation, a 3-DOF nonlinear swing motion kinematic model was set up. The kinematic response was studied using methods of numerical simulation. The results demonstrated that the kinematic response depends on the length of cable, lifting speed and excitation frequency. Conclusions drawn from this work can be used for safety assessment and theoretical basis for lifting ROV.

Research on Safety Assessment Method for Pressure Pipe With Incomplete Welding Defects Under Complicated Loadings

2010 ◽  
Author(s):  
Zhijiang Jin ◽  
Xianping Wan ◽  
Chenghang Jiang
Keyword(s):  
Internal Pressure ◽  
Safety Assessment ◽  
Limit Load ◽  
Assessment Method ◽  
Curved Surface ◽  
Assessment Procedure ◽  
Plastic Limit ◽  
Pressure Pipe ◽  
Welding Defects ◽  
Plastic Limit Load

Since most pressure pipe materials have good toughness, the failure mode of pipe is usually the plastic failure controlled by limit load. The incomplete welding defect is very common in the pipe, and its existence will reduce the load-carrying capacity of pipes. The pipe with incomplete welding defects can be continued using only after passing the appropriate safety assessment, so the research on safety assessment procedure for pressure pipe with incomplete welding defects under combined bending, torsion and internal pressure loadings has a great theoretical and practical engineering value. By using theoretical analyzing method of plastic limit load, the plastic limit load of pressure pipe with different defect size or pipe diameter ratio are calculated in this paper, then safety assessment curved surface and its express equation are obtained by fitting calculation data. Finally a safety assessment procedure is developed for pressure pipes under combined bending, torsion and internal pressure loadings according to the curved surface.

Limit Load Analysis of Elbow with Local Wall Thinning under Combined Loads

2015 ◽  
Vol 750 ◽  
pp. 198-205
Author(s):  
Peng Cui ◽  
Chang Yu Zhou
Keyword(s):  
Safety Assessment ◽  
Bending Moment ◽  
Limit Load ◽  
Orthogonal Experimental Design ◽  
Limit Loads ◽  
Pressure Pipe ◽  
Combined Loads ◽  
Wall Thinning ◽  
Volume Defect ◽  
Local Wall Thinning

The local wall thinning(LWT) is a kind of common volume defect in pressure pipe. The limit loads of elbows with LWT under pressure, bending moment, torque and their combined loads have been studied in detail by orthogonal experimental design and finite element method. The results have shown that the influence of depth and circumferential length of LWT on the limit load is more obvious compared to that of axial length when an elbow is under pressure, bending moment or torque. The change of limit bending moment and torque with the depth of LWT and circumferential length is significant for an elbow under combined bending moment and torque. At last, the safety assessment equations for elbow under combined in-plane closing bending moment and torque were proposed by regression analysis.

The Limit Load and Safety Assessment of Pressure Pipe With an External Pit Defect at High Temperature

2011 ◽  
Author(s):  
Bo Wang ◽  
Changyu Zhou ◽  
Xiaohua He ◽  
Jilin Xue
Keyword(s):  
High Temperature ◽  
Safety Assessment ◽  
Relative Length ◽  
Bending Moment ◽  
Limit Load ◽  
Relative Depth ◽  
Strain Criterion ◽  
Limit Loads ◽  
Pressure Pipe ◽  
Strain Data

Local pit is the common volume defect in high temperature pressure pipe which is widely used in the fields of electric plant, nuclear power station, petrochemical plant and so on. In this paper finite element analysis code ABAQUS was used to simulate limit load of high temperature pressure pipe with an external pit defect which is in service for 105 hours. Four-point bending loading model was applied to calculate the limit load of the pipe. There are three dimensionless factors: relative depth, relative gradient and relative length which characterized the shape of an external pit defect. Orthogonal test of three factors at four different levels was carried out to analyze the sequence of the influence of these three parameters. In present paper when the maximum principal strain reaches 2%, the corresponding load is selected as the limit load. According to this strain criterion and isochronous stress strain data of P91 steel, limit load of high temperature pressure pipe with an external pit was determined by using ABAQUS. Firstly, isochronous stress strain data was generated and was inputted into ABAQUS as equivalent elastic-plastic constitutive relation. Then, sustained load versus cumulative strain curves at high temperature during service was obtained after the simulation. At last, limit loads of high temperature pipe during service time was determined based on 2% total strain criterion. In order to obtain the safety assessment curve of high temperature pipe, five types of limit loads for pressure pipe with an external pit were needed: ultimate limit bending moment, limit internal pressure, limit bending moments at the pressure of 0.25PL,0.5PL and 0.75PL individually. 16 sets of data formed 16 groups of curves which expressed the relationship between the ratio of limit pressure and the ratio of limit bending moment for defective pipe and non-defective pipe. Based on the calculation results of limit load for pipe with 16 kinds of defects, a set of limit load formulae were established through multiple nonlinear regression of relative depth, relative gradient and relative length. So the equations of limit load and safety assessment for pressure pipe with an external pit under combined loading of pressure and bending moment were obtained. The results could provide a reference for safety assessment of high temperature creep pressure pipe with local pit defect.

Reliability Calculation of Welded Pressure Pipe with Circumferential Crack Based on 3-D Elastic-Plastic SFEM

2008 ◽  
Vol 575-578 ◽  
pp. 639-642
Author(s):  
Bo Lin He ◽  
Ying Xia Yu ◽  
Li Xing Huo ◽  
Yu Feng Zhang
Keyword(s):  
Surface Crack ◽  
Safety Assessment ◽  
Crack Depth ◽  
Three Dimensional ◽  
Bending Moment ◽  
Mean Value ◽  
Pressure Pipe ◽  
Circumferential Crack ◽  
The Mean ◽  
Welded Pipe

In this paper, the reliability of welded pressure pipe with circumferential surface crack was calculated by using three dimensional stochastic finite element method. This method has overcome the shortcomings of conservative results in safety assessment with deterministic fracture mechanics method. The calculation of reliability was based on three dimensional elastic-plastic stochastic finite element program which was developed by ourselves. The effects of variables such as fracture toughness, bending moment and the depth of the circumferential surface crack on the structure reliability were also discussed. The calculation results indicate that the crack depth has great effect on the reliability of the welded pipe. When the mean value of the crack depth is changed from 3mm to 7mm, the failure probability of the welded pipe will change from 10-8 to 10-2. The bending moment also has great effect on the reliability of the welded pipe. When the mean value of moment is changed from10000 N.m to 15000 N.m, the failure probability of the welded pipe increases dramatically for the same circumferential crack depth. Irrespective of the changing of moment, the pipe has higher reliability if the crack depth is less than 5mm(a/t<0.5, t is the thickness of the pipe). The method has put forward a new way for safety assessment of welded pipe with circumferential surface crack.

Impact and Safety Assessment of a Double-Tube Parallel Tunnel Excavation on Adjacent Pipelines

2014 ◽  
Vol 889-890 ◽  
pp. 1421-1424
Author(s):  
Dong Liang Guo ◽  
De Shen Zhao
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Finite Difference ◽  
Safety Assessment ◽  
Construction Safety ◽  
Tunnel Excavation ◽  
Project Construction ◽  
Parallel Tunnel

The interaction of a double-tube parallel tunnel excavation will have a larger additional shearing action on the adjacent pipelines. This paper, taking 202 Section of Line 2 on Dalian Metro as the background, uses the finite difference software to establish 3-D finite element analysismodel to simulate the double-tube parallel tunnel excavation. Deformation of adjacent pipelines is analyzed specially by numerical simulation of tunnel excavation and also the safety of the pipelines is forecasted. The conclusions and advices are important to design and guide the actual project construction safety.

Element Bearing Ratio Based Integral Safety Evaluation of Penstocks

2013 ◽  
Vol 671-674 ◽  
pp. 1604-1608
Author(s):  
Jian Wang ◽  
Wei Zhang ◽  
Jin Zhang ◽  
Wen Long Wu
Keyword(s):  
Elastic Modulus ◽  
Limit Analysis ◽  
Safety Assessment ◽  
Reduction Method ◽  
Safety Evaluation ◽  
Limit Load ◽  
Adjustment Procedure ◽  
Pressure Pipe ◽  
Element Bearing ◽  
Modulus Reduction

Though it had been employed for limit analysis and integral safety assessment of pressure pipe and vessel, most of the elastic modulus adjustment procedures were applicable to simple structures because their load multiplier was mainly determined by stress. In this paper, a series of element bearing ratio (EBR) based load multiplier algorithms are given, in which the influence of both stress and material on limit load are included. The EBR based load multiplier algorithms are investigated, and two efficient algorithms are suggested. Then the two algorithms combined with the elastic modulus adjustment procedure of elastic modulus reduction method are applied to limit analysis and integral safety assessment of penstocks.

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