Failure analysis in API X70 pipeline steel in sour environment with an emphasis on fracture surfaces and crack propagation

2021 ◽  
pp. 104600
Author(s):  
M.A. Mohtadi-Bonab ◽  
Mohammad Masoumi ◽  
J.A. Szpunar
Keyword(s):  
Crack Propagation ◽  
Failure Analysis ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Fracture Surfaces

Cracking Failure Analysis of X70 Pipeline Steel Weld

2018 ◽  
pp. 371-386
Author(s):  
Bin Wang ◽  
Senfeng Zhang ◽  
Cui Zhou ◽  
Nan Liu ◽  
Liang Wang ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Pipeline Steel ◽  
Steel Weld ◽  
X70 Pipeline Steel

Comparison of Various Damage Models in Modelling 3D Crack Propagation

2016 ◽  
Author(s):  
Bruce W. Williams ◽  
C. Hari M. Simha
Keyword(s):  
Crack Propagation ◽  
Damage Mechanics ◽  
Pipeline Steel ◽  
Plastic Anisotropy ◽  
Pressure Tube ◽  
X70 Pipeline Steel ◽  
Damage Models ◽  
Model Based ◽  
Fracture Crack ◽  
3D Crack Propagation

It is of interest to model crack propagation in irradiated Zr-2.5Nb nuclear pressure tubes and X70 pipeline steel. These materials can undergo a range of conditions leading to fracture with operating temperatures between room temperature and 300 °C for Zr-2.5Nb and strain-rates ranging from quasi-static to dynamic in the case of pipeline steel. In the case of the hexagonal closed-packed zirconium alloy, the influence of plastic anisotropy is also of interest. When trying to capture the fracture response under a wide variety of conditions, limitations of traditional Linear Elastic and Elastic Plastic Fracture Mechanics become apparent such as trying to capture effects of crack tunnelling, the transition from flat-to-slant fracture, and anisotropy. Various damage mechanics based approaches to model 3D crack propagation will be presented and discussed including the crack tip opening angle, a Gurson-Tvergaard-Needleman type damage model based on void nucleation, growth, and coalescence, and the Xue and Wierzbicki model based on the relationship between failure strain with stress triaxiliaty and lode angle dependence. A non-local damage scheme, which mitigates the mesh-dependence of results, will also be presented. For Zr-2.5Nb pressure tube, simulations were performed using Hill’48 and Cazacu-Barlat-Plunkett 2006 anisotropy yield functions. Experimental data from compact tension and rising pressure burst tests on irradiated Zr-2.5Nb pressure tube and both static and dynamic drop weight tear tests on X70 pipeline steel will be compared to predictions from finite element simulations. It is shown that simulations using the various damage models can capture the measured crack propagation behaviour, including crack tunnelling, to varying degrees of accuracy. The Xue and Wierzbicki fracture model was shown to capture the transition from a flat, tunnelling (ductile fracture) crack to a slanted (shear fracture) crack during propagation that was observed in both Zr-2.5Nb and pipeline steel.

Modeling of Corrosion Fatigue Crack Growth of X70 Pipeline Steel and Numerical Simulation of Crack Propagation

2014 ◽  
Vol 685 ◽  
pp. 43-47 ◽  
Author(s):  
Yu Tian ◽  
Jing Wang ◽  
Yang Liu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Corrosion Fatigue Crack ◽  
Corrosion Fatigue Crack Growth

To solve the problem that the change of curve slop was not considered in the common corrosion fatigue crack growth, a new corrosion fatigue crack propagation model based on Pairs formula was established in this paper; which corrected parametersCandnof Paris formula at the same time. Based on the fatigue crack propagation experimental data of X70 pipeline steel in hydrogen sulfide corrosive environment, the key parameters of the model were fitted. Based on the new model, a FRANC3D software was used, and the corrosion fatigue crack propagation processes of X70 pipeline steel in corrosive solution were simulated. It was demonstrated that the simulated fatigue crack growth processes obtained by the boundary element method were very close to the test results, and the maximum error is less than 10%. Therefore, boundary element method can be used to predict the life of corrosion fatigue on the project.

STRESS CORROSION CRACK INITIATION BEHAVIOR FOR THE X70 PIPELINE STEEL BENEATH A DISBONDED COATING

2012 ◽  
Vol 48 (10) ◽  
pp. 1267 ◽  
Author(s):  
Zhiying WANG ◽  
Jianqiu WANG ◽  
En-hou HAN ◽  
Wei KE ◽  
Maocheng YAN ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Stress Corrosion ◽  
Stress Corrosion Crack ◽  
Pipeline Steel ◽  
X70 Pipeline Steel ◽  
Disbonded Coating

Cleavage Planes of Icosahedral Quasicrystals: A Molecular Dynamics Study

2003 ◽  
Vol 805 ◽  
Author(s):  
Frohmut Rösch ◽  
Christoph Rudhart ◽  
Peter Gumbsch ◽  
Hans-Rainer Trebin
Keyword(s):  
Molecular Dynamics ◽  
Brittle Fracture ◽  
Crack Propagation ◽  
Three Dimensional ◽  
Propagation Direction ◽  
Mode I ◽  
Dynamic Crack ◽  
Fracture Surfaces ◽  
Icosahedral Quasicrystals ◽  
Crack Tip Plasticity

ABSTRACTThe propagation of mode I cracks in a three-dimensional icosahedral model quasicrystal has been studied by molecular dynamics techniques. In particular, the dependence on the plane structure and the influence of clusters have been investigated. Crack propagation was simulated in planes perpendicular to five-, two- and pseudo-twofold axes of the binary icosahedral model.Brittle fracture without any crack tip plasticity is observed. The fracture surfaces turn out to be rough on the scale of the clusters. These are not strictly circumvented, but to some extent cut by the dynamic crack. However, compared to the flat seed cracks the clusters are intersected less frequently. Thus the roughness of the crack surfaces can be attributed to the clusters, whereas the constant average heights of the fracture surfaces reflect the plane structure of the quasicrystal. Furthermore a distinct anisotropy with respect to the in-plane propagation direction is found.

Corrosion Behavior of X70 Pipeline Steel and Corrosion Rate Prediction Under the Combination of Corrosive Medium and Applied Pressure

2017 ◽  
Author(s):  
Kaikai Li ◽  
Wei Wu ◽  
Guangxu Cheng ◽  
Yun Li ◽  
Haijun Hu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Corrosion Rate ◽  
Tensile Stress ◽  
Partial Pressure ◽  
Corrosion Behavior ◽  
Pipeline Steel ◽  
Applied Pressure ◽  
Chloride Concentration ◽  
X70 Pipeline Steel ◽  
Co2 Partial Pressure

Natural gas transmission pipeline is prone to internal corrosion due to the combination of corrosive impurities in the pipe (such as CO2, H2S and chlorides) and applied pressure of the pipeline, which seriously affects the safe operation of the pipeline. In this work, the corrosion behavior of a typical X70 pipeline steel was investigated by using potentiodynamic polarization and electrochemical impendence spectroscopy (EIS). The polarization and EIS data under different CO2 partial pressures (0–1 atm), H2S concentrations (0–150 ppm), chloride concentrations (0–3.5 wt%) and tensile stress (0–400 MPa) were obtained. The results show that corrosion rate increases with the increase of CO2 partial pressure and chloride concentration, respectively, while first increases and then decreases with the increase H2S concentrations. The corrosion rate is less affected by elastic tensile stress. In addition, a quantitative prediction model for corrosion rate of natural gas pipeline based on adaptive neuro-fuzzy inference system (ANFIS) was established by fitting the experimental data which maps the relationship between the key influencing factors (i.e. CO2 partial pressure, H2S concentration, chloride concentration and tensile stress) and the corrosion rate. The prediction results show that the relative percentage errors of the predicted and experimental values are relatively small. The prediction accuracy of the model satisfies the engineering application requirement.

Characterization of the fracture behaviour of X42 microalloyed pipeline steel

2015 ◽  
Vol 6 (5) ◽  
pp. 567-577
Author(s):  
Halil Ibrahim Ünal ◽  
Hakan Atapek ◽  
Baran Gürkan Beleli ◽  
Seyda Polat ◽  
Serap Gümüs ◽  
...  
Keyword(s):  
Fracture Behaviour ◽  
Pipeline Steel ◽  
Sheet Material ◽  
Sheet Steel ◽  
Grain Morphology ◽  
Tensile Fracture ◽  
Pipe Material ◽  
Content Type ◽  
Fracture Surfaces ◽  
Impact Tests

Purpose – The purpose of this paper is to investigate the fracture of grade X42 microalloyed steel used as pipe material after tensile test at room temperature and impact tests at 0, −20 and −40°C, respectively. Design/methodology/approach – In the first stage of the study, X42 steels in the form of sheet and pipe materials were selected and etched samples were characterized using light microscope. In the second stage, mechanical properties of steels were obtained by microhardness measurements, static tensile and impact tests and all the broken surfaces were examined by scanning electron microscope to determine the fracture type as a function of both microstructure and loading. Findings – The examinations revealed that: first, the sheet material had a typical ferritic-pearlitic matrix, second, the transverse section of the sheet steel exhibited a matrix consisting of polygonal ferrite-aligned pearlite colonies and the longitudinal one had elongated ferrite phase and pearlite colonies in the direction of rolling, third, ferrite and pearlite distribution was different from the sheet material due to multiaxial deformation in the pipe material, fourth, tensile fracture surfaces of the steels had typical dimple fracture induced by microvoid coalescence, fifth, impact fracture surfaces of the steels changed as a function of the test temperature and cleavage fracture mode of ferritic-pearlitic matrix became more dominant as the temperature decreased, and sixth, grain morphology had an effect on the fracture behavior of the steels. Originality/value – The paper explains the fracture behaviour of X42 microalloyed pipeline steel and its fractographical analysis.

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