Methods for Collapse Pressure Prediction of UOE Linepipe

2006 ◽  
Author(s):  
Andreas Liessem ◽  
Ulrich Marewski ◽  
Johannes Groß-Weege ◽  
Gerhard Knauf
Keyword(s):  
Boundary Conditions ◽  
Large Diameter ◽  
External Pressure ◽  
Test Method ◽  
Future Research ◽  
Line Pipe ◽  
Cold Forming ◽  
Research Issues ◽  
Collapse Pressure ◽  
Strain Behavior

Line pipe intended for deep water applications has to be designed predominantly with regard to external pressure in order to avoid plastic collapse. As a consequence of cold forming during UOE pipe manufacture and the subsequent application of anticorrosion coating, the characteristic stress strain behavior has to be taken into account for a reliable prediction of the collapse pressure. Verification of collapse resistance of large diameter pipes against external pressure requires adequate and reliable component testing using a sufficient number of pipe samples. These samples have to be subjected to test conditions, which closely simulate the situation in service. As the test results may depend significantly on its boundary conditions, the results needs to be thoroughly analysed and compared with existing prediction methods. It is for these reasons that such full-scale testing is time-consuming and costly. The work presented in this paper aims at clarifying and quantifying the effect of existing test boundary conditions on the results of collapse tests (collapse pressures). Correlations will be established between material properties found in laboratory tests and associated component behavior. In this context it had been necessary to develop an accurate and reproducible compression test method. The actual collapse pressures and those predicted using current available equations are compared and verified by Finite Element calculations. The paper concludes with a discussion of the major findings and with a brief outlook to future research issues.

On the Effect of the U-O-E Manufacturing Process on the Collapse Pressure of Long Tubes

1994 ◽  
Vol 116 (1) ◽  
pp. 93-100 ◽  
Author(s):  
S. Kyriakides ◽  
E. Corona ◽  
F. J. Fischer
Keyword(s):  
Manufacturing Process ◽  
Large Diameter ◽  
External Pressure ◽  
Cold Forming ◽  
Collapse Pressure ◽  
Circular Shape ◽  
Strain Behavior ◽  
Offshore Pipeline ◽  
Numerical Process ◽  
Two Stages

A commonly used process for manufacturing large-diameter tubes for offshore pipeline, riser and tension-leg platform tether applications involves the cold forming of long plates. The plates are bent into a circular shape and then welded. The circumference of the pipe is then plastically expanded to develop a high tolerance circular shape. Collectively, these steps comprise the U-O-E manufacturing process. These mechanical steps cause changes in the material properties and introduce residual stresses in the finished pipe. This paper presents the results of a combined experimental and analytical study of the effect on the U-O-E process on the capacity of the tube to resist collapse under external pressure loading. The U-O-E manufacturing process for a 26 in. (660 mm) diameter, 1.333 in. (33.86 mm) wall thickness pipe was simulated numerically. The numerical process was validated by comparing the predicted stress-strain behavior of the material at two stages in the process with properties measured from actual pipe specimens obtained from the mill. Following the simulation of the U-O-E process the collapse pressure was calculated numerically. The manufacturing process was found to significantly reduce the collapse pressure. A similar pipe for which the final sizing was conducted (simulated) with circumferential contraction (instead of expansion) was found not to have this degradation in collapse pressure.

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.

Collapse Performance of HTS (Helical Seam Two Step) Welded Line Pipe

2006 ◽  
Author(s):  
Franz Martin Knoop ◽  
Johannes Groß-Weege ◽  
Ulrich Marewski
Keyword(s):  
Finite Element Analysis ◽  
External Pressure ◽  
Future Research ◽  
Test Program ◽  
Element Analysis ◽  
Line Pipe ◽  
Research Issues ◽  
Various Boundary Conditions ◽  
Collapse Resistance ◽  
Pipe Manufacturing

Line pipe intended for offshore applications has to be designed predominantly with regard to external pressure in order to avoid collapse. High resistance to external pressure is vitally important for the use of pipes in such applications. A test program has been carried out in order to verify the resistance of HTS (helical seam two step) welded line pipe against collapse. It was demonstrated that the two step pipe manufacturing process has a beneficial effect on collapse resistance. HTS pipes therefore shows a good collapse performance compared to the design equations given in relevant offshore standards. One aim of the work carried out was to quantify the influence of relevant parameters on the result of full-scale collapse test by finite element analysis. The actual collapse pressures and those predicted using currently available design equations are compared and verified for various boundary conditions. The paper concludes with a discussion of the major findings and with a brief outlook to future research issues.

Numerical Simulation of UOE Pipe Process and its Effect on Pipe Mechanical Behavior in Deep-Water Applications

2015 ◽  
Author(s):  
Giannoula Chatzopoulou ◽  
Spyros A. Karamanos ◽  
George E. Varelis
Keyword(s):  
Deep Water ◽  
Manufacturing Process ◽  
Large Diameter ◽  
Structural Response ◽  
Structural Instability ◽  
External Pressure ◽  
Line Pipe ◽  
Simulation Tools ◽  
Large Diameter Pipes ◽  
Pipe Manufacturing

Large-diameter thick-walled steel pipes during their installation in deep-water are subjected to a combination of loading in terms of external pressure, bending and axial tension, which may trigger structural instability due to excessive pipe ovalization with catastrophic effects. In the present study, the UOE pipe manufacturing process, commonly adopted for producing large-diameter pipes of significant thickness, is considered. The study examines the effect of UOE line pipe manufacturing process on the structural response and resistance of offshore pipes during the installation process using nonlinear finite element simulation tools.

Improved Prediction of External Pressure Collapse of Seamless Pipe

2009 ◽  
Author(s):  
Josef Navarro ◽  
Philip Cooper
Keyword(s):  
Cross Section ◽  
Wall Thickness ◽  
Design Method ◽  
External Pressure ◽  
Thickness Variation ◽  
Seamless Pipe ◽  
Line Pipe ◽  
Collapse Pressure ◽  
Average Wall Thickness ◽  
Improved Design

Seamless pipe typically features well controlled average wall thickness around its cross-section, but is prone to significant local thickness variation arising from the manufacturing process. Pipeline design codes, such as DNV OS-F101, provide little guidance on how to treat thickness variation whilst designing for collapse resistance. Standard practice is to consider minimum wall thickness across the whole cross-section, an assumption that two dimensional finite element simulations have proven conservative. This justifies the need for an improved design method. A program of simulations has been carried out to investigate the effect of wall thickness variation on collapse pressure. A modification to the DNV OS-F101 collapse design equation using average wall thickness over the whole crossection together with a fabrication factor is presented based on the results of this study. The fabrication factor de-rates the collapse pressure according to the amount of thickness variation present. The correction has been calibrated for thickness variations up to the maximum permitted by typical line pipe specifications. A number of FE trials demonstrate that the proposed formula predicts simulated collapse pressures with 98% accuracy. Adopting this method could provide significant wall thickness savings for deep water flowlines which in turn could lead to a reduction in steel costs and transportation and lay vessel requirements.

Numerical Simulation of JCO Pipe Forming Process and its Effect on the External Pressure Capacity of the Pipe

2017 ◽  
Author(s):  
Giannoula Chatzopoulou ◽  
Konstantinos Antoniou ◽  
Spyros A. Karamanos
Keyword(s):  
Manufacturing Process ◽  
Large Diameter ◽  
Structural Response ◽  
Structural Instability ◽  
External Pressure ◽  
Forming Process ◽  
Line Pipe ◽  
Structural Capacity ◽  
Large Diameter Pipes ◽  
Pipe Manufacturing

Large-diameter thick-walled steel pipes during their installation in deep-water are subjected to external pressure, which may trigger structural instability due to excessive pipe ovalization with catastrophic effects. The resistance of offshore pipes against this instability mode strongly depends on imperfections and residual stresses introduced by the line pipe manufacturing process. In the present paper, the JCO pipe manufacturing process, a commonly adopted process for producing large-diameter pipes of significant thickness, is examined. The study examines the effect of JCO line pipe manufacturing process on the structural response and resistance of offshore pipes during the installation process using nonlinear finite element simulation tools. At first, the cold bending induced by the JCO process is simulated rigorously, and subsequently, the application of external pressure is modeled until structural instability is detected. For the simulation of the JCO manufacturing process and the structured response of the pipe a two dimensional generalized plane strain model is used. Furthermore, a numerical analysis is also conducted on the effects of line pipe expansion on the structural capacity of the JCO pipe.

scholarly journals Numerical Simulation of JCO-E Pipe Manufacturing Process and Its Effect on the External Pressure Capacity of the Pipe1

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Konstantinos Antoniou ◽  
Giannoula Chatzopoulou ◽  
Spyros A. Karamanos ◽  
Athanasios Tazedakis ◽  
Christos Palagas ◽  
...  
Keyword(s):  
Manufacturing Process ◽  
Large Diameter ◽  
Welding Process ◽  
Structural Instability ◽  
External Pressure ◽  
Forming Process ◽  
Line Pipe ◽  
Geometric Deviations ◽  
Large Diameter Pipes ◽  
Pipe Manufacturing

Large-diameter thick-walled steel pipes during their installation in deep-water are subjected to external pressure, which may trigger structural instability due to pipe ovalization, with detrimental effects. The resistance of offshore pipes against this instability is affected by local geometric deviations and residual stresses, introduced by the line pipe manufacturing process. In the present paper, the JCO-E pipe manufacturing process, a commonly adopted process for producing large-diameter pipes of significant thickness, is examined. The study examines the effect of JCO-E line pipe manufacturing process on the external pressure resistance of offshore pipes, candidates for deepwater applications using nonlinear finite element simulation tools. The cold bending induced by the JCO forming process as well as the subsequent welding and expansion (E) operations are simulated rigorously. Subsequently, the application of external pressure is modeled until structural instability (collapse) is detected. Both the JCO-E manufacturing process and the external pressure response of the pipe, are modeled using a two-dimensional (2D) generalized plane strain model, together with a coupled thermo-mechanical model for simulating the welding process.

The Effects of Plate Stress-Strain Behavior and Pipemaking Variables on the Yield Strength of Large-Diameter DSAW Line Pipe

1984 ◽  
Vol 106 (2) ◽  
pp. 119-126 ◽  
Author(s):  
A. K. Shoemaker
Keyword(s):  
Yield Strength ◽  
Order Approximation ◽  
Large Diameter ◽  
Strain Level ◽  
Plate Material ◽  
Stress Strain ◽  
Line Pipe ◽  
Strain Behavior ◽  
Accumulated Strain ◽  
Cyclic Straining

Recent stringent specifications for large-diameter double-submerged-arc-welded gas-transmission line pipe include requirements that limit the range of allowable pipe yield strengths instead of the previous requirement of a minimum yield-strength value. These restricted pipe yield-strength ranges require control of the range of the yield strength in the plate used to make the pipe, knowledge of the relationship between the plate and pipe yield strength, and the effect of pipemaking (forming) variables on this relationship. The present study was conducted to determine the interrelationships among plate yield strength, plate stress-strain properties, pipe-forming variables, and pipe yield strength. In the first part of this work, pipe-forming strains were measured after each forming operating during actual pipe fabrication and the strains compared to the calculated values. The experimental and analytical values were in good agreement; thus, the cyclic straining of the original plate material during pipe forming was determined. In the second part of the program, specimens of typical line-pipe steels were cyclically loaded in the laboratory according to the cyclic histories that sections in the plate would experience when fabricated into pipe. The results showed a significant effect of the plate stress-strain behavior, as well as the amount of straining (or forming) on the resulting yield strength. Because of the complexities of all these interrelationships and the strain gradients developed through the pipe wall during pipemaking, a series of pipe were fabricated from steels having different plate stress-strain properties and the plate and pipe yield strengths were compared. Varying amounts of sinking (compressive straining) in the pipe O press and of pipe expansion were examined. Correlation of the plate and pipe yield strengths showed that, as a first order approximation, the pipe yield strength equated to the flow stress in the plate at a strain level equal to the total accumulated strain that occurs at the neutral axis of the pipe during the pipemaking operation. This approximation can only be made if work hardening occurs in the plate material at that total accumulated strain level. Otherwise, it can only be stated that the pipe yield strength will be less than that of the original steel plate.

Blue Stream Collapse Test Program

2005 ◽  
Author(s):  
D. DeGeer ◽  
C. Timms ◽  
V. Lobanov
Keyword(s):  
Black Sea ◽  
Wall Thickness ◽  
Large Diameter ◽  
External Pressure ◽  
Combined Loading ◽  
The Black Sea ◽  
Pipe Material ◽  
Test Program ◽  
Bend Testing ◽  
Strain Behavior

The Blue Stream pipeline is a gas transmission line delivering natural gas from the Russian grid. across the Black Sea, to Turkey. The submarine portion of this pipeline consists of a pair of 24-inch diameter, 31.8 mm wall thickness, API grade X65 pipelines running almost 400 km along the floor of the Black Sea. Over one half of the submarine pipeline lies at a water depth of more than 2000 metres, with the deepest portion of the line reaching a depth of 2150 metres. First gas was supplied through the lines in February of 2003. There were numerous engineering obstacles facing this technically challenging pipeline undertaking. including a lack of heavy-wall, large diameter pipe experimental data to support the pipeline design. Recognizing this need, PeterGaz commissioned a collapse test program during the preliminary engineering phase of the project to generate these data and to gain a better understanding of pipe behavior under combined loading conditions. Numerous full-scale tests were performed on prototype pipe samples, including external pressure testing, combined external pressure and bend testing, and bend testing. Hundreds of material coupon tests were also performed to characterize material stress strain behavior around the circumference of the pipe, through the wall thickness of the pipe, and before and after UOE manufacturing. Tests were also performed to quantify the strength recovery of thermally treated pipe material resulting from the pipe coating process. This paper presents the results of this experimental work and provides some comparisons to collapse predictions.

Collapse Resistance Enhancement in UOE SAWL Line Pipes During Coating Heat Treatment for Ultra Deepwater Applications

2014 ◽  
Author(s):  
Fábio Arroyo ◽  
Harold R. León ◽  
Ronaldo Silva ◽  
Luciano Mantovano ◽  
Rafael F. Solano ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Large Diameter ◽  
Final Analysis ◽  
Material Strength ◽  
Line Pipe ◽  
Offshore Pipelines ◽  
Cold Forming ◽  
Collapse Resistance ◽  
Offshore Pipeline ◽  
Key Factor

Large diameter UOE pipes are being increasingly used for the construction of offshore pipelines and in the last few year, since oil discoveries are moving towards ultra-deepwater areas, such as Pre-Salt in Brazil, collapse resistance is a key factor in the design of the pipelines the demand for pipes with high thickness near the limits for fabrication and installation capacity. It is known that the cold forming, and the final expansion in the UOE line pipe manufacturing process, reduces the elastic limit of the steel in subsequent compression. Due to this, the DNV collapse formula includes a fabrication factor that de-rates by a 15% the yield strength of UOE Pipes. However, DNV also recognizes the effect of thermal treatments and the code allows for improvement of the fabrication factor when heat treatment or external cold sizing (compression) is applied, if documented. In previous work [1] it was presented the qualification of UOE pipes with enhanced collapse capacity focusing the use of a fabrication factor (alpha-fab) equal to 1. A technology qualification process according to international standard has been performed. The main aspects of the qualification process were presented and included significant material, full scale testing and final analysis. In this paper, we compare those results with the ones of the new qualification tests analyzing the more important variables affecting the collapse resistance such as ovality, compressive material strength, thermal treatment control, etc. This new qualification obtained even better results than the previous one, which will allow the use of a fabrication factor equal to 1 directly in deepwater and ultra-deepwater offshore pipeline projects with a possible reduction in material and offshore installation costs and also potentially enhancing the feasibility of many challenging offshore projects.

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