scholarly journals Ultimate Axial Load Prediction Model for X65 Pipeline with Cracked Welding Joint Based on the Failure Assessment Diagram Method

2021 ◽  
Vol 11 (24) ◽  
pp. 11780
Author(s):  
Jianping Liu ◽  
Hong Zhang ◽  
Shengsi Wu ◽  
Xianbin Zheng ◽  
Dong Zhang ◽  
...  
Keyword(s):  
Axial Load ◽  
Support Vector ◽  
Pipe Material ◽  
Safe Operation ◽  
Diagram Method ◽  
Factors Affecting ◽  
Failure Assessment Diagram ◽  
Comparison Results ◽  
Failure Assessment ◽  
Girth Welds

Crack defects in the girth welds of pipelines have become an important factor affecting the safe operation of in-service oil pipelines. Therefore, it is necessary to analyze the factors affecting the safe operation of pipelines and determine the ultimate load during pipeline operation. Based on the failure assessment diagram (FAD) method described in the BS 7910 standard, the key factors affecting the evaluation results of the suitability of X65 pipeline girth welds are analyzed, and the effects of crack size, pipe geometry, and material properties on the evaluation results are investigated. The results indicate that the crack depth is more crucial to the safe operation of the pipeline than the crack length. While the effect of wall thickness is not significant, the misalignment can seriously aggravate the stress concentration. In general, the higher the yield ratio and tensile strength of the pipe material, the more dangerous the condition at the weld. The ultimate axial load that a crack-containing girth weld can withstand under different combinations of the above factors was determined. Furthermore, a data driven model via the optimized support vector regression method for the ultimate axial load of the X65 pipe was developed for engineering application, and the comparison results between the FEM results and the predicted results proved its accuracy and reliability.

scholarly journals Admissibility of External Cracks in a Pipeline API X60 Using the SINTAP Procedure

2017 ◽  
Vol 61 (4) ◽  
pp. 261
Author(s):  
Kaddour Bahram ◽  
Benattou Bouchouicha ◽  
Mohamed Benguediab ◽  
Abdelkader Slimane
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Modeling And Simulation ◽  
Safety Factors ◽  
Diagram Method ◽  
Failure Assessment Diagram ◽  
Failure Assessment ◽  
Abaqus Software

In this paper we tried to apply the failure assessment diagram method on an API X60 pipeline under two pressures 70 and 90 bar, this work will be divided into two parts; the first part will be devoted to modeling and simulation of a pipeline under pressure 70/90 bar. With abaqus software to determine the stress intensity factor of several ratios, The second part will focus on the exploitation of these results in order to draw the diagram of evaluation of the failure (FAD), once finished, We can pronounce on the vulnerability of the cracks which can cause the ruin of the pipeline to study, on mode of ruin and proposed safety factors.

Comparison of Numerical Methods for Strain Based ECA

2015 ◽  
Author(s):  
Josef Navarro ◽  
Andrew Low ◽  
Thao (Joe) Tran
Keyword(s):  
Numerical Methods ◽  
Pipe Material ◽  
Corrosion Resistant ◽  
Design Life ◽  
Failure Assessment ◽  
Corrosion Resistant Alloy ◽  
Pipe Joints ◽  
Girth Welds ◽  
Mn Steel ◽  
Numerical Approaches

The integrity of subsea pipe girth welds is routinely ensured through Engineering Criticality Assessments (ECAs) based on fracture mechanics principles. In order to capture the whole design life, the ECA must cover loadings that the pipeline is subjected to during both installation and operation. Stress based semi-analytical methods using Failure Assessment Diagrams (FAD) have been used extensively for ‘run of the mill’ assessments as far as C-Mn steel pipe with overmatching weld is concerned. These stress based methods are captured in depth in industry codes such as BS7910 and DNV-OS-F101. In recent years however, with industry seeking to transport more corrosive fluids, the use of pipe containing a corrosion resistant alloy (CRA) layer is becoming increasingly popular. Together with the CRA layer, anti-corrosion weld consumables material would be used at the pipe joints to protect the whole pipeline from corrosion. Some of these weld consumables, especially at high temperature, partially overmatch or even undermatch the parent pipe material, resulting in difficulties in application of conventional FAD approach. Industry has turned to numerical methods to fill in gaps which are not covered by the FAD based approach. However no codified approach/standard exists for executing numerically based ECAs. This paper attempts to outline the FAD and numerical approaches being used by industry. The different approaches will be assessed for their range of application, limitations of execution and comparison of results obtained. The study is carried out for the case of a typical external surface flaw in a 12″ pipe.

scholarly journals Identification of peat type and humification by laboratory VNIR/SWIR hyperspectral imaging of peat profiles with focus on fen-bog transition in aapa mires

2020 ◽  
Author(s):  
L. Granlund ◽  
M. Keinänen ◽  
T. Tahvanainen
Keyword(s):  
Hyperspectral Imaging ◽  
Near Infrared ◽  
Support Vector ◽  
High Resolution Imaging ◽  
Factors Affecting ◽  
Vector Machines ◽  
Resolution Imaging ◽  
Shortwave Infrared ◽  
Type Classification ◽  
Wide Potential

Abstract Aims Hyperspectral imaging (HSI) has high potential for analysing peat cores, but methodologies are deficient. We aimed for robust peat type classification and humification estimation. We also explored other factors affecting peat spectral properties. Methods We used two laboratory setups: VNIR (visible to near-infrared) and SWIR (shortwave infrared) for high resolution imaging of intact peat profiles with fen-bog transitions. Peat types were classified with support vector machines, indices were developed for von Post estimation, and K-means clustering was used to analyse stratigraphic patterns in peat quality. With separate experiments, we studied spectral effects of drying and oxidation. Results Despite major effects, oxidation and water content did not impede robust HSI classification. The accuracy between Carex peat and Sphagnum peat in validation was 80% with VNIR and 81% with SWIR data. The spectral humification indices had accuracies of 82% with VNIR and 56%. Stratigraphic HSI patterns revealed that 36% of peat layer shifts were inclined by over 20 degrees. Spectral indices were used to extrapolate visualisations of element concentrations. Conclusions HSI provided reliable information of basic peat quality and was useful in visual mapping, that can guide sampling for other analyses. HSI can manage large amounts of samples to widen the scope of detailed analysis beyond single profiles and it has wide potential in peat research beyond the exploratory scope of this paper. We were able to confirm the capacity of HSI to reveal shifts of peat quality, connected to ecosystem-scale change.

Integrity Management of Ground Movement Hazards

2016 ◽  
Author(s):  
Yong-Yi Wang ◽  
Don West ◽  
Douglas Dewar ◽  
Alex McKenzie-Johnson ◽  
Millan Sen
Keyword(s):  
Management Program ◽  
Ground Movement ◽  
Tensile Failure ◽  
Weld Strength ◽  
Factors Affecting ◽  
Ground Movements ◽  
Decision Points ◽  
Starting Point ◽  
Integrity Management ◽  
Girth Welds

Ground movements, such as landslides and subsidence/settlement, can pose serious threats to pipeline integrity. The consequence of these incidents can be severe. In the absence of systematic integrity management, preventing and predicting incidents related to ground movements can be difficult. A ground movement management program can reduce the potential of those incidents. Some basic concepts and terms relevant to the management of ground movement hazards are introduced first. A ground movement management program may involve a long segment of a pipeline that may have a threat of failure in unknown locations. Identifying such locations and understanding the potential magnitude of the ground movement is often the starting point of a management program. In other cases, management activities may start after an event is known to have occurred. A sample response process is shown to illustrate key considerations and decision points after the evidence of an event is discovered. Such a process can involve fitness-for-service (FFS) assessment when appropriate information is available. The framework and key elements of FFS assessment are explained, including safety factors on strain capacity. The use of FFS assessment is illustrated through the assessment of tensile failure mode. Assessment models are introduced, including key factors affecting the outcome of an assessment. The unique features of girth welds in vintage pipelines are highlighted because the management of such pipelines is a high priority in North America and perhaps in other parts of the worlds. Common practice and appropriate considerations in a pipeline replacement program in areas of potential ground movement are highlighted. It is advisable to replace pipes with pipes of similar strength and stiffness so the strains can be distributed as broadly as possible. The chemical composition of pipe steels and the mechanical properties of the pipes should be such that the possibility of HAZ softening and weld strength undermatching is minimized. In addition, the benefits and cost of using the workmanship flaw acceptance criteria of API 1104 or equivalent standards in making repair and cutout decisions of vintage pipelines should be evaluated against the possible use of FFS assessment procedures. FFS assessment provides a quantifiable performance target which is not available through the workmanship criteria. However, necessary inputs to perform FFS assessment may not be readily available. Ongoing work intended to address some of the gaps is briefly described.

Estimation of the V-Factor for Circumferentially Cracked Pipes Under Combined Thermal and Mechanical Stresses Using a Strain-Based Failure Assessment Diagram

2011 ◽  
Author(s):  
Chang-Young Oh ◽  
Yun-Jae Kim ◽  
Dong-il Ryu ◽  
P. J. Budden ◽  
R. A. Ainsworth
Keyword(s):  
Finite Element ◽  
Thermal Load ◽  
Thermal Stresses ◽  
Mechanical Stresses ◽  
Estimation Methods ◽  
Finite Element Analyses ◽  
3 Dimensional ◽  
Failure Assessment Diagram ◽  
Failure Assessment ◽  
Dimensional Finite Element

This paper presents finite element solutions for elastic-plastic J for circumferentially cracked pipes under combined mechanical and thermal loads in terms of the V/Vo factor used within a strain-based failure assessment diagram. In this study, 3-dimensional finite element analyses are conducted to calculate the V-factor under combined mechanical and thermal load. It is found that estimation of V/Vo is sensitive to the method used for its evaluation. For larger thermal stresses, currently proposed estimation methods are overly conservative.

Defective Pipeline Fatigue-Life Prediction Using Failure Assessment Diagram Technique

2004 ◽  
Author(s):  
Jinheng Luo ◽  
Xinwei Zhao ◽  
Qingren Xiong ◽  
Chunyong Huo
Keyword(s):  
Fatigue Life ◽  
Evaluation System ◽  
Life Prediction ◽  
Safety Evaluation ◽  
Load Ratio ◽  
Test System ◽  
Full Scale ◽  
Oil Pipeline ◽  
Failure Assessment Diagram ◽  
Failure Assessment

The life prediction, whose results can be used to define the inspection, repair or replacement cycle of in-service pipeline, is a main component of safety assessment of gas and oil pipeline. At present, failure Assessment Diagram (FAD) technique has been widely used in quantitative engineering safety evaluation system of pipeline that contains crack-like flaws. In past work, the authors developed a very useful model to predict the fatigue life of defective pipeline and established a computer calculating method. Based on FAD technique, toughness ratio and load ratio are calculated repeatedly with every crack increment in the model. With the self-developed full-scale test system, the full-scale pipe fatigue test was collected to verify the applicability of this method.

scholarly journals The Proposition of an EI Equation of Square and L–Shaped Slender Reinforced Concrete Columns under Combined Loading

2021 ◽  
Vol 11 (3) ◽  
pp. 7100-7106
Author(s):  
L. Hamzaoui ◽  
T. Bouzid
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Strength ◽  
Linear Regression Analysis ◽  
Strain Curve ◽  
Load Level ◽  
Combined Loading ◽  
Actual Behavior ◽  
Factors Affecting ◽  
Slender Columns

The stability and strength of slender Reinforced Concrete (RC) columns depend directly on the flexural stiffness EI, which is a major parameter in strain calculations including those with bending and axial load. Due to the non-linearity of the stress-strain curve of concrete, the effective bending stiffness EI always remains variable. Numerical simulations were performed for square and L-shaped reinforced concrete sections of slender columns subjected to an eccentric axial force to estimate the variation of El resulting from the actual behavior of the column, based on the moment-curvature relationship. Seventy thousand (70000) hypothetical slender columns, each with a different combination of variables, were used to investigate the main variables that affect the EI of RC slender columns. Using linear regression analysis, a new simple and linear expression of EI was developed. Slenderness, axial load level, and concrete strength have been identified as the most important factors affecting effective stiffness. Finally, the comparison between the results of the new equation and the methods proposed by ACI-318 and Euro Code-2 was carried out in connection with the experimental results of the literature. A good agreement of the results was found.

scholarly journals Corrosion defect harmfulness by domain failure assessment diagram

2018 ◽  
Vol 2 (3) ◽  
pp. 163-177 ◽  
Author(s):  
G. Pluvinage ◽  
◽  
O. Bouledroua ◽  
M. H. Meliani ◽  
◽  
...  
Keyword(s):  
Corrosion Defect ◽  
Failure Assessment Diagram ◽  
Failure Assessment
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