Reliability Analysis of Pipelines With Local Corrosion Defects Under External Pressure

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
A. P. Teixeira ◽  
O. G. Palencia ◽  
C. Guedes Soares
Keyword(s):  
Model Uncertainty ◽  
External Pressure ◽  
Experimental Results ◽  
Local Corrosion ◽  
Design Code ◽  
Uncertainty Factors ◽  
Corrosion Defect ◽  
Collapse Strength ◽  
Corrosion Defects ◽  
Strength Models

This paper aims at assessing the reliability of pipelines with local corrosion defects subjected to external pressure. Several collapse strength models are calibrated and then used to formulate the reliability problem of corroded pipelines. Model uncertainty factors are derived for the various collapse strength models based on available experimental results to better predict the effect of local corrosion defects on the reduction of the collapse strength of pipelines. The model uncertainty factor is defined as function of the depth of the local corrosion defect and calibrates the overconservative predictions of collapse strength models that deal with the effect of corrosion defects by considering a uniform reduction of the pipe thickness. The collapse strength models together with the corresponding model uncertainty factors are then used to formulate the reliability problem of pipelines with local corrosion defects subjected to external pressure. Parametric and sensitivity analyses are performed for different levels of corrosion damages to identify the influence of the various parameters on the collapse probability of corroded pipelines under external pressure. Finally, an approach is suggested to calibrate a design code formulation that is conservative when the minimum pipe thickness is used to represent a local corrosion defect. The approach consists of identifying an equivalent depth of the corrosion defect, corresponding to an intermediate thickness of the corroded pipeline larger than the minimum thickness, that adjusts the design code to match the safety levels of the collapse strength model calibrated to the experimental results.

Uncertainty in Collapse Strength Prediction of Sandwich Pipelines

2021 ◽  
Author(s):  
U. Bhardwaj ◽  
A. P. Teixeira ◽  
C. Guedes Soares
Keyword(s):  
Probabilistic Models ◽  
Uncertainty Propagation ◽  
Simulation Method ◽  
External Pressure ◽  
Design Parameters ◽  
Collapse Strength ◽  
Parameters Uncertainty ◽  
Wide Range ◽  
Model Predictions ◽  
Strength Models

Abstract This paper assesses the uncertainty in the collapse strength of sandwich pipelines under external pressure predicted by various strength models in three categories based on interlayer adhesion conditions. First, the validity of the strength models is verified by comparing their predictions with sandwich pipeline collapse test data and the corresponding model uncertainty factors are derived. Then, a parametric analysis of deterministic collapse strength predictions by models is conducted, illustrating insights of models’ behaviour for a wide range of design configurations. Furthermore, the uncertainty among different model predictions is perceived at different configurations of outer and inner pipes and core thicknesses. A case study of a realistic sandwich pipeline is developed, and probabilistic models are defined to basic design parameters. Uncertainty propagation of models’ predictions is assessed by the Monte Carlo simulation method. Finally, the strength model predictions of sandwich pipelines are compared to that of an equivalent single walled pipe.

Experimental Study and Finite Analysis on Flexural Capacity of Laminated Glass

2011 ◽  
Vol 243-249 ◽  
pp. 258-262
Author(s):  
Jun Chen ◽  
Jia Lv ◽  
Qi Lin Zhang ◽  
Zhi Xiong Tao ◽  
Jun Chen
Keyword(s):  
Experimental Results ◽  
Laminated Glass ◽  
Test Results ◽  
Design Code ◽  
Flexural Capacity ◽  
Equivalent Thickness ◽  
High Rise ◽  
Safety Glass ◽  
Current Design ◽  
Good Agreement

Laminated glass has been increasing widely used in high rise buildings as a kind of safety glass in recent years. So we should analyze its material property. In this paper, we use flexural experiments and ANSYS program to analyze the main factors that affect the flexural capacity of the laminated glass. The test results show that the flexural capacity is closely related to film. And the ANSYS program had got good agreement with the experimental results. Comparison of experimental results with calculated ones indicates that the current design code will lead to conservative results and the equivalent thickness of laminated glasses provided in the code should be further discussed.

scholarly journals Simulation of the External Pressure Influence on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

2011 ◽  
Vol 278 ◽  
pp. 247-252
Author(s):  
Inmaculada Lopez-Galilea ◽  
Stephan Huth ◽  
Suzana Gomes Fries ◽  
Ingo Steinbach ◽  
Werner Theisen
Keyword(s):  
Single Crystal ◽  
Microstructural Evolution ◽  
Phase Field ◽  
Structural Evolution ◽  
Field Method ◽  
External Pressure ◽  
Experimental Results ◽  
Alloying Elements ◽  
Phase Field Method

The phase field method has been applied to simulate the microstructural evolution of a commercial single crystal Ni-based superalloy during both, HIP and annealing treatments. The effects of applying high isostatic pressure on the microstructural evolution, which mainly retards the diffusion of the alloying elements causing the loss of the orientational coherency between the phases is demonstrated by the simulation and experimental results

The Evaluation of Failure Pressure for Corrosion Defects Within Girth or Seam Weld in Transmission Pipelines

2004 ◽  
Author(s):  
Young-pyo Kim ◽  
Woo-sik Kim ◽  
Young-kwang Lee ◽  
Kyu-hwan Oh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Limit Load ◽  
The Body ◽  
Element Analysis ◽  
Burst Test ◽  
Corrosion Defect ◽  
Seam Weld ◽  
Failure Assessment ◽  
Corrosion Defects

The failure assessment for corroded pipeline has been considered with the burst test and the finite element analysis. The burst tests were conducted on 762mm diameter, 17.5mm wall thickness and API 5L X65 pipe that contained specially manufactured rectangular corrosion defect. The failure pressures for corroded pipeline have been measured by burst testing and classified with respect to corrosion sizes and corroded regions — the body, the girth weld and the seam weld of pipe. Finite element analysis was carried out to derive failure criteria of corrosion defect within the body, the girth weld and the seam weld of the pipe. A series of finite element analyses were performed to obtain a limit load solution for corrosion defects on the basis of burst test. As a result, the criteria for failure assessment of corrosion defect within the body, the girth weld and the seam weld of API 5L X65 gas pipeline were proposed.

A Simple Procedure for the Prediction of the Collapse Pressure of Pipelines With Narrow and Long Corrosion Defects: Uncertainty and Sensibility Analysis

2018 ◽  
Author(s):  
Nara Oliveira ◽  
Theodoro Netto
Keyword(s):  
Simple Procedure ◽  
Experimental Tests ◽  
External Pressure ◽  
Experimental Program ◽  
Small Scale ◽  
Test Results ◽  
Collapse Pressure ◽  
Operational Conditions ◽  
Sensibility Analysis ◽  
Corrosion Defects

The collapse pressure of pipelines containing corrosion defects is usually predicted by deterministic methods, either numerically or through empirical formulations. The severity of each individual corrosion defect can be determined by comparing the differential pressure during operation with the estimated collapse pressure. A simple deterministic procedure for estimating the collapse pressure of pipes with narrow and long defects has been recently proposed by Netto (2010). This formulation was based on a combined small-scale experimental program and nonlinear numerical analyses accounting for different materials and defect geometries. However, loads and resistance parameters have uncertainties which define the basic reliability problem. These uncertainties are mailyrelated to the geometric and material parameters of the pipe and the operational conditions. This paper presents additional experimental tests on corroded pipes under external pressure. The collapse pressure calculated using the equation proposed by Netto (2010) is compared with this new set of experiments and also with test results available in open literature. These results are used to estimate the equation uncertainty. Finally, a sensitivity analysis is performed to identify how geometric parameters of the defects influence the reduction of collapse pressure.

Exploratory Study on Engineering Ceramics Pressure Hulls for Deep-Sea Submergence Services

2005 ◽  
Vol 39 (3) ◽  
pp. 49-55 ◽  
Author(s):  
Yusuke Yano ◽  
Shinichi Takagawa
Keyword(s):  
Deep Sea ◽  
Syntactic Foam ◽  
Structural Materials ◽  
External Pressure ◽  
Engineering Ceramics ◽  
Practical Applications ◽  
Collapse Strength ◽  
Reinforced Plastic ◽  
Pressure Tests ◽  
The Relationship

An underwater vehicle for deep-sea operation should be as light as possible; therefore, development of premium structural materials such as titanium alloy, glass, and carbon-fiber-reinforced plastic (CFRP) for external pressure hulls has been ongoing. Engineering ceramics is one of the candidate materials, and the study of engineering ceramics has been underway for many years; however practical applications have been limited.The main purpose of this study is to establish the methodology of fabrication of ceramics pressure hulls for deep-sea submergence services. As the first step, prototypes of the spherical shells were fabricated from engineering ceramics, and their local radii of curvatures and wall thickness were precisely measured. In addition to these measurements, the strain on hemispheres and their collapse strength were measured by pressure tests in order to evaluate the relationship between spherical irregularities and collapse strength. The strength-to-weight ratios of fabricated pressure hulls were significantly higher than that of syntactic foam for deep-sea operations, therefore it is expected that engineering ceramics can be among the promising structural materials for lightening of an underwater vehicle's body.

Buckling of Fibre-Reinforced Plastic-Steel Torispherical Shells Under External Pressure

1988 ◽  
Vol 202 (6) ◽  
pp. 409-420 ◽  
Author(s):  
G D Galletly ◽  
A Muc
Keyword(s):  
External Pressure ◽  
Experimental Results ◽  
Steel Shell ◽  
Elastic Buckling ◽  
Geometrical Parameters ◽  
Initial Shape ◽  
Buckling Modes ◽  
Reinforced Plastic ◽  
Composite Layers ◽  
Spherical Caps

The paper deals with the buckling of torispherical shells consisting of a steel external layer plus different numbers of composite layers. It is assumed that the total thickness of the fibre-reinforced plastic (FRP)-steel shell is constant but that the thickness of the steel and of the composite may be varied. In the paper it is shown (a) how the orientation of the fibres and the composite lamina thicknesses affect the elastic buckling modes and (b) how substantial increases in elastic buckling pressures may be achieved by reinforcing the steel torispheres with layers of composite. The analysis is carried out for various values of the geometrical parameters describing torispheres, including spherical caps. The influence of the yielding of the steel layer on the buckling pressures of FRP-steel torispheres is also discussed. As might be expected, it is necessary to take plasticity into account when predicting the buckling pressures of these shells. Some experimental results are given which confirm this expectation. The effect of initial shape imperfections in the shells is also considered briefly. However, the dearth of experimental results on FRP-steel shells prevents a proper evaluation of the way in which imperfections decrease their buckling strength.

scholarly journals Stress distributions and cell flows in a growing cell aggregate

2014 ◽  
Vol 4 (6) ◽  
pp. 20140033 ◽  
Author(s):  
Morgan Delarue ◽  
Jean-François Joanny ◽  
Frank Jülicher ◽  
Jacques Prost
Keyword(s):  
Cell Density ◽  
Cell Polarity ◽  
Local Stress ◽  
External Pressure ◽  
Experimental Results ◽  
Pressure Jump ◽  
Local Pressure ◽  
Active Stress ◽  
Growing Cell ◽  
Short Time

We discuss the short-time response of a multicellular spheroid to an external pressure jump. Our experiments show that 5 min after the pressure jump, the cell density increases in the centre of the spheroid but does not change appreciably close to the surface of the spheroid. This result can be explained if the cells are polarized which we show to be the case. Motivated by the experimental results, we develop a theory for polarized spheroids where the cell polarity is radial (except in a thin shell close to the spheroid surface). The theory takes into account the dependence of cell division and apoptosis rates on the local stress, the cell polarity and active stress generated by the cells and the dependence of active stress on the local pressure. We find a short-time increase of the cell density after a pressure jump that decays as a power law from the spheroid centre, which is in reasonable agreement with the experimental results. By comparing our theory to experiments, we can estimate the isotropic compression modulus of the tissue.

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