Effects of Reeling on Pipe Structural Performance—Part I: Experiments

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Stelios Kyriakides
Keyword(s):  
Mechanical Properties ◽  
Local Buckling ◽  
External Pressure ◽  
Structural Performance ◽  
Plastic Range ◽  
Cross Sectional ◽  
Collapse Pressure ◽  
Bending Strain ◽  
Testing Facility ◽  
Different Levels

The winding and unwinding of a pipeline in the reeling installation process involve repeated excursions into the plastic range of the material, which induce ovality, elongation, and changes to the mechanical properties. The reeling/unreeling process involves some back tension required to safeguard the pipe from local buckling. This study examines the effects of winding/unwinding a pipe on a reel at different values of tension on the induced ovality and elongation and the resulting degradation in collapse pressure. In Part I, a model testing facility is used to simulate the reeling/unreeling process in the presence of tension. The combination of reel and tube diameters used induces a bending strain of 1.89%. A set of experiments involving three reeling/unreeling cycles at different levels of tension is performed on tubes with diameter-to-thickness ratios (D/t) of 20 and 15.5 in which the progressive changes in cross-sectional geometry and elongation are recorded. Both ovalization and elongation are shown to increase significantly as the back tension increases. A second set of experiments on the same two tube D/ts is performed in which following a reeling/unreeling cycle at a chosen level of tension, the tubes are collapsed under external pressure. The collapse pressure is shown to decrease significantly with tension, which is primarily caused by the reeling/unreeling-induced ovality. Part II presents models for simulating reeling and the induced structural degradation. The experimental results in Part I are used to evaluate the performance of the models.

Effect of Reeling on Pipeline Structural Performance

2016 ◽  
Author(s):  
Yafei Liu ◽  
Stelios Kyriakides
Keyword(s):  
Kinematic Hardening ◽  
Element Model ◽  
External Pressure ◽  
Structural Performance ◽  
Loading History ◽  
Cross Sectional ◽  
Collapse Pressure ◽  
Comparison Of The Results ◽  
Tension Loading ◽  
D Model

The winding and unwinding of a pipeline in the reeling installation process involves repeated excursions into the plastic range of the material, which induce ovality and changes to the mechanical properties. We present two modeling schemes for simulating reeling/unreeling capable of capturing these changes and can be used to assess their impact on the structural performance of the pipeline in deeper waters. In the first model, the complete 3-D reeling process is simulated through a finite element model that includes proper treatment of contact and nonlinear kinematic hardening for plasticity. The second model includes the pipe geometric cross sectional nonlinearities, contact, and nonlinear kinematic hardening, but variations along the length of the line are neglected. Instead, an axially uniform curvature/tension loading history is applied that corresponds to that experienced by a point of the line during the process. The two models are used to simulate a set of experiments in which tubes were wound and unwound on a model reel at different values of tension. Both models are shown to reproduce the induced ovality and elongation very well. Several of the reeled tubes were subsequently tested under external pressure demonstrating the effect of the reeling cycle on structural performance. The two models are shown to also reproduce the decrease in collapse pressure as a function of the applied back tension. Comparison of the results of such simulations highlight when a fully 3-D model is required and when the simpler 2-D model is adequate for evaluating the structural performance of a reeled pipe.

Effects of Reeling on Pipe Structural Performance—Part II: Analysis

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Yafei Liu ◽  
Stelios Kyriakides ◽  
Jyan-Ywan Dyau
Keyword(s):  
3D Model ◽  
Kinematic Hardening ◽  
Three Dimensional ◽  
Element Model ◽  
External Pressure ◽  
Structural Performance ◽  
Collapse Pressure ◽  
Reverse Loading ◽  
Tension Loading ◽  
Different Levels

Part II presents two modeling schemes for simulating the reeling/unreeling of a pipeline, with the aim of establishing the degrading effect of the process on the structural performance of the pipeline. A three-dimensional (3D) finite element model of the winding/unwinding of a long section of pipeline onto a rigid reel is presented first. The second model applies the curvature/tension loading history experienced at a point to a section of pipe in contact with a rigid surface of variable curvature. Both models use nonlinear kinematic hardening plasticity to model the loading/reverse loading of the material. The 3D model first demonstrates how the interaction of the problem nonlinearities influences the evolution of deformation and load parameters during reeling/unreeling. The two models are subsequently used to simulate the three-reeling/unreeling cycle experiments under different levels of back tension in Part I. The ovality-tension and axial elongation-tension results are reproduced by both models with accuracy for the first cycle, adequately for the second cycle, and are overpredicted for the third cycle. The two models are also used to simulate the reeling/unreeling followed by collapse of the tubes under external pressure experiments. Both models reproduce the measured ovality-tension results and the corresponding collapse pressures accurately. Since the two-dimensional (2D) model is computationally much more efficient, it is an attractive tool for estimating the effect of reeling on collapse pressure. Questions that require exact tracking of the winding/unwinding history and the interaction of the pipe with the reel are best answered using the 3D model.

Local Buckling Assessments for the Medgaz Pipeline

2007 ◽  
Author(s):  
D. DeGeer ◽  
C. Timms ◽  
J. Wolodko ◽  
M. Yarmuch ◽  
R. Preston ◽  
...  
Keyword(s):  
Finite Element ◽  
Gas Flow ◽  
Local Buckling ◽  
External Pressure ◽  
Full Scale ◽  
Regression Equations ◽  
Finite Element Analyses ◽  
Bending Strain ◽  
Primary Focus ◽  
Full Scale Tests

Medgaz is a consortium of leading international energy companies, with the aim of designing, building and operating an Algerian-European gas pipeline via Spain. The offshore section of this pipeline will be 210 km long, traversing the Mediterranean Sea floor at a maximum depth of 2160 metres. The 24-inch diameter, grade X70 line will provide up to 8 billion cubic metres of natural gas per year, with first gas flow expected in 2009. To support the technical issues surrounding such an ultra-deepwater pipelay, a number of full scale local buckling tests and detailed finite element analyses were undertaken at the C-FER facility in Edmonton, Canada. Local buckling conditions of concern included buckling of the pipe section at the pipe-buckle arrestor interface and collapse of the plain pipe under high external pressure. These conditions may arise during various phases of pipeline installation and operation, but the primary focus was to evaluate the local buckling integrity of the pipe during installation using the S-lay method. These conditions were assessed for both as-fabricated pipe and pipe that was heat treated to simulate a pipe coating process. This paper describes the Medgaz pipeline, its current state of development, the installation challenges that necessitated the buckling assessments, and some of the work performed throughout the study, including full scale tests, finite element analyses, and regression analyses. Collapse and critical bending strain predictive equations were developed and are also presented, and are compared to other well known collapse and critical bending strain equations. The results of these assessments have suggested that, for the local buckling conditions presented herein, the S-lay method can be successfully employed for ultra-deep water pipelay. The results demonstrated that the proposed pipe-buckle arrestor connection design will not cause premature buckling as the pipe traverses along the stinger during installation. In addition, potentially high bending strains in the overbend will not significantly influence the collapse strength of the pipe. The regression equations presented in this paper have also been shown to provide an accurate means of predicting pipe local buckling and collapse.

scholarly journals Local Buckling Characteristics of Stainless-Steel Polypropylene Deep-Sea Sandwich Pipe under Axial Tension and External Pressure

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4866
Author(s):  
Jianxing Yu ◽  
Weipeng Xu ◽  
Nianzhong Chen ◽  
Sixuan Jiang ◽  
Shengbo Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Local Buckling ◽  
External Pressure ◽  
Loading Path ◽  
Finite Element Models ◽  
Collapse Pressure ◽  
Loading Paths ◽  
Axial Tension ◽  
The Difference ◽  
Good Agreement

In this paper, the effects of different loading paths of axial tension and external pressure on the collapse pressure of sandwich tubes are studied by experiments and finite element models. The difference of the two loading paths is investigated. Eight experiments were carried out to study the influence of different loading paths on pipeline collapse pressure under the same geometric and material parameters. Parameterization studies have been carried out, and the results are in good agreement with the experimental results. The test and finite element results show that the loading path of external pressure first and then the axial tension (P→T) is more dangerous; the collapse pressure of the sandwich pipe is smaller than the other. Through parametric analysis, the influence of the axial tension and the diameter-to-thickness ratio of the inner and outer pipe on the collapse pressure under different loading paths are studied.

Optimization of UOE Pipe Manufacturing Process for Improved Collapse Performance Under External Pressure

2006 ◽  
Author(s):  
Stelios Kyriakides ◽  
Mark D. Herynk ◽  
Heedo Yun
Keyword(s):  
Mechanical Properties ◽  
Parametric Study ◽  
Large Diameter ◽  
External Pressure ◽  
Material Degradation ◽  
Forming Process ◽  
Cold Forming ◽  
Collapse Pressure ◽  
Large Diameter Pipes ◽  
Pipe Manufacturing

Large-diameter pipes used in offshore applications are commonly manufactured by cold-forming plates through the UOE process. Collapse experiments have demonstrated that these steps, especially the final expansion, degrade the mechanical properties of the pipe and result in a reduction in its collapse pressure, upwards of 30%. In this study, the UOE forming process has been modeled numerically so that the effects of press parameters of each forming step on the final geometry and mechanical properties of the pipe can be established. The final step involves simulation of pipe collapse under external pressure. An extensive parametric study of the problem has been conducted, through which ways of optimizing the process for improved collapse performance have been established. For example, it was found that optimum collapse pressure requires a tradeoff between pipe shape (ovality) and material degradation. Generally, increase in the O-strain and decrease in the expansion strain improve the collapse pressure. Substituting the expansion by compression can not only alleviate the UOE collapse pressure degradation but can result in a significant increase in collapse performance.

Elastoplastic Collapse of Tubes Under External Pressure

1970 ◽  
Vol 92 (4) ◽  
pp. 735-742 ◽  
Author(s):  
O. Heise ◽  
E. P. Esztergar
Keyword(s):  
Safety Factor ◽  
External Pressure ◽  
Code Design ◽  
Test Results ◽  
Plastic Range ◽  
Safety Factors ◽  
Characteristic Ratio ◽  
Collapse Pressure ◽  
Asme Code ◽  
Current Design

The specific objective of this paper is to develop external pressure design safety factors that are consistent with theory, test results, and service experience for application in pressure vessel codes. The standard methods of collapse pressure predictions for the buckling of tubes in the elastic and the plastic ranges are briefly reviewed. Test results on tubes made of various materials were collected from the literature and are compared with the corresponding predictions. For thin tubes which buckle in the elastic range, the correlation between the theory and experimentally measured collapse pressure is shown to be poor, justifying the large safety factors used in current design practice. For intermediate and thick tubes which buckle in the plastic range, it is demonstrated that the correlation of test results and theory improves significantly with decreasing radius-to-thickness ratio of the tubes. The range of improved correlation is identified by a material dependent “characteristic ratio” of tube radius and wall thickness. Based on the experimental evidence, a variable safety factor is proposed for inclusion in the ASME Code design charts. A simple formula for the conversion of the present plastic range allowable pressure into the new increased allowable pressure is presented. The consequences of the variable safety factor are discussed with respect to the resulting actual margin of safety, the economic advantages, and the requirements for the development of design rules for the creep range.

Discussion of “Mechanics of Confined Thin-Walled Cylinders Subjected to External Pressure,” (Vasilikis, D., and Karamanos, S., 2014, Appl. Mech. Rev., 66(1), p. 010801)

2013 ◽  
Vol 66 (1) ◽  
Author(s):  
Arnold M. Gresnigt
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Experimental Test ◽  
Mechanical Response ◽  
External Pressure ◽  
Strain History ◽  
Test Results ◽  
Fabrication Method ◽  
Collapse Pressure ◽  
Thin Walled

The collapse pressure of confined cylinders depends on many factors. In addition to the thorough investigations of Vasilikis and Karamanos, more factors can be candidates for further investigation, such as the effect of variations in the material mechanical properties of the liner pipe in compression and the effect of residual stresses. The mechanical response of the materials in compression depends on the type of steel and the stress-strain history, which depends on the fabrication method of the cylinder. This is illustrated with theoretical and experimental results on pipes under external pressure, as used in offshore applications. There is a need for more experimental test results for validation. More applications of confined cylinders are mentioned that are worth investigation.

scholarly journals Circulating bioactive sclerostin levels in an Austrian population-based cohort

2021 ◽  
Author(s):  
Katharina Kerschan-Schindl ◽  
Ursula Föger-Samwald ◽  
Andreas Gleiss ◽  
Stefan Kudlacek ◽  
Jacqueline Wallwitz ◽  
...  
Keyword(s):  
Serum Levels ◽  
Population Based ◽  
Negative Regulator ◽  
Total Serum ◽  
Mineral Density ◽  
Cross Sectional ◽  
Robust Parameter ◽  
Austrian Population ◽  
Different Levels

Summary Background Circulating serum sclerostin levels are supposed to give a good estimation of the levels of this negative regulator of bone mass within bone. Most studies evaluating total serum sclerostin found different levels in males compared to females and in older compared to younger subjects. Besides an ELISA detecting total sclerostin an ELISA determining bioactive sclerostin has been developed. The aim of this study was to investigate serum levels of bioactive sclerostin in an Austrian population-based cohort. Methods We conducted a cross-sectional observational study in 235 healthy subjects. Using the bioactive ELISA assay (Biomedica) bioactive sclerostin levels were evaluated. Results Serum levels of bioactive sclerostin were higher in men than in women (24%). The levels correlated positively with age (r = 0.47). A positive correlation could also be detected with body mass index and bone mineral density. Conclusion Using the ELISA detecting bioactive sclerostin our results are consistent with data in the literature obtained by different sclerostin assays. The determination of sclerostin concentrations in peripheral blood thus appears to be a robust parameter of bone metabolism.

scholarly journals AB0499 PHYSICAL ACTIVITY ASSESSMENT IN TUNISIAN PATIENTS WITH SPONDYLOARTHRITIS: THE IPAQ EVALUATION

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 1277.1-1277
Author(s):  
F. Majdoub ◽  
M. Sellami ◽  
S. Miladi ◽  
A. Fazaa ◽  
L. Souabni ◽  
...  
Keyword(s):  
Physical Activity ◽  
Disease Activity ◽  
Axial Spondyloarthritis ◽  
Cross Sectional Study ◽  
Urban Setting ◽  
Tnf Inhibitor ◽  
Sectional Study ◽  
Cross Sectional ◽  
Tunisian Patients ◽  
Different Levels

Background:The occurrence of Spondyloarthritis (SpA) often conditions patients’ quality of life and hinders their well-being. Physical activity (PA) is associated with various health-related benefits among adults with chronic inflammatory rheumatism but may be insufficiently performed.Objectives:This study aimed to assess PA in patients with SpA and explore its associated factors.Methods:This is a single-center cross-sectional study, involving patients with SpA, visiting our outpatient hospital over eight weeks. Patients responded to the International Physical Activity Questionnaire-Short form (IPAQ-S).Results:Sixty patients were included (39 M/21 F) with an average age of 45.8 years [25-78]. The mean duration of SpA was 13.2 years [1-25]. About 80% of patients were from an urban setting. Sixty-three percent of patients had a professional activity, while 13.3% were retired. Twenty-nine patients (48.3%) had axial and peripheral form, 18 patients (30%) had SpA with enteropathic arthritis, 8 (13.3%) with psoriatic arthritis, 3 patients (5%) had axial spondyloarthritis, and only 2 patients (3.3%) with SAPHO-Syndrom. About 23% of patients had hip arthritis and only 5% had uveitis. Fifty-eight patients were on TNF-inhibitor (21/58 Adalimumab, 15/58 Infliximab, 14/58 Etanercept, 8/58 Golimumab). The average BASDAI was 2.7/10. The average ASDASCRP was 2.1/10. The average BASFI was 3.3/10. IPAQ results were distributed as follows: 78.3% of patients were in the « low physical activity » category, 21.7% were in the « moderate physical activity » while none of the patients were in the « high physical activity ». Patients without employment had lower levels of physical activity (29.7%) but no association was observed between those two items (p=0.082). Disease activity objectified with BASDAI was related to low physical activity (p=0.045) whereas no association was observed with ASDASCRP (p=0.870) or BASFI (p=0.056). Otherwise, TNF-inhibitor treatment was not related to different levels of PA (p=0.09).Conclusion:Tunisian patients with SpA don’t perform enough physical activity. Except for high disease activity, the different levels of PA did not appear to be explained by other disease-related variables. Thereby, physical activity should be encouraged in SpA.References:[1]Fabre, S., Molto, A., Dadoun, S. et al. Physical activity in patients with axial spondyloarthritis: a cross-sectional study of 203 patients. Rheumatol Int 36, 1711–1718 (2016).Disclosure of Interests:None declared.

scholarly journals Effect of Multiple Reflows on the Interfacial Reactions and Mechanical Properties of an Sn-0.5Cu-Al(Si) Solder and a Cu Substrate

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2367
Author(s):  
Junhyuk Son ◽  
Dong-Yurl Yu ◽  
Yun-Chan Kim ◽  
Shin-Il Kim ◽  
Min-Su Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Heat ◽  
Interfacial Reactions ◽  
Future Application ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Automotive Electronic ◽  
Transmission Electron ◽  
Si Content ◽  
Lead Free Solders

In this study, the interfacial reactions and mechanical properties of solder joints after multiple reflows were observed to evaluate the applicability of the developed materials for high-temperature soldering for automotive electronic components. The microstructural changes and mechanical properties of Sn-Cu solders regarding Al(Si) addition and the number of reflows were investigated to determine their reliability under high heat and strong vibrations. Using differential scanning calorimetry, the melting points were measured to be approximately 227, 230, and 231 °C for the SC07 solder, SC-0.01Al(Si), and SC-0.03Al(Si), respectively. The cross-sectional analysis results showed that the total intermetallic compounds (IMCs) of the SC-0.03Al(Si) solder grew the least after the as-reflow, as well as after 10 reflows. Electron probe microanalysis and transmission electron microscopy revealed that the Al-Cu and Cu-Al-Sn IMCs were present inside the solders, and their amounts increased with increasing Al(Si) content. In addition, the Cu6Sn5 IMCs inside the solder became more finely distributed with increasing Al(Si) content. The Sn-0.5Cu-0.03Al(Si) solder exhibited the highest shear strength at the beginning and after 10 reflows, and ductile fracturing was observed in all three solders. This study will facilitate the future application of lead-free solders, such as an Sn-Cu-Al(Si) solder, in automotive electrical components.

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