Developments in Testing and Manufacture of Thick-Walled Pipe

2017 ◽  
Author(s):  
Alastair Walker ◽  
Jayden Chee ◽  
Peter Roberts
Keyword(s):  
Safety Factor ◽  
Deep Water ◽  
Maximum Level ◽  
External Pressure ◽  
Full Scale ◽  
Test Facility ◽  
Collapse Pressure ◽  
Pipe Joints ◽  
Collapse Failure ◽  
Pipe Joint

Over the past 20 years there has been a considerable development of the capability to design and manufacture thick walled pipe to manufacture pipelines to operate in ultra-deep water. Design guidance is available in DNV OS F101 [1] in which the safety from pressure collapse failure during pipeline installation is determined by the use of a safety factor. The safety factor has been calibrated using the Load and Resistance Factor Design (LRFD) method in comparison with collapse pressure test results available at the time of preparation of DNV guidance. Because of the huge financial implications of loss of a very long pipeline during installation in ultra-deep water it has been the practice further to base the design of such a pipeline on specific pipe joint collapse tests in conjunction with the DNV information. Pressure testing full-scale pipe joints is an expensive undertaking that requires a suitable pressure chamber. Only a few chambers capable of applying pressures corresponding to very deep water are available in the world and transport of the pipes from the pipe mill to a suitable test facility may be very inconvenient and certainly expensive. This paper describes an alternative approach which could provide data that would enable the preparation of a safe approach specific to the pipeline diameter and design water depth. The approach could enable optimisation of the pipe design, particularly the pipe wall thickness. The proposed method is based on replacing costly full scale pipe tests by corresponding tests on ring specimens cut and machined from manufactured pipe joints. The proposal to use ring testing as the basis for design has been included successfully in the design of pipe for a recent ultra-deep water project [2]. The paper describes equipment used to subject the rings to external pressure and reports on tests carried out to validate the correspondence between the ring collapse pressure and that for the pipe joint from which the ring was obtained. Based on results from such tests it is concluded in this paper that ring pressure collapse testing is indeed a valid method to use as the basis for the design pipes in the next stage of ultra-deep water, i.e. increasing the capability to install pipeline in water depths down to 3500m from the current maximum level of 2500m.

The Effect of the Reeling Laying Method on the Collapse Pressure of Steel Pipes for Deepwater

2004 ◽  
Author(s):  
Ilson P. Pasqualino ◽  
Silvia L. Silva ◽  
Segen F. Estefen
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Element Model ◽  
External Pressure ◽  
Test Facility ◽  
Collapse Pressure ◽  
Steel Pipes ◽  
Custom Made ◽  
Nonlinear Finite Element Model

This work deals with a numerical and experimental investigation on the effect of the reeling installation process on the collapse pressure of API X steel pipes. A three-dimensional nonlinear finite element model was first developed to simulate the bending and straightening process as it occurs during installation. The model is then used to determine the collapse pressures of both intact and plastically strained pipes. In addition, experimental tests on full-scale models were carried out in order to calibrate the numerical model. Pipe specimens are bent on a rigid circular die and then straightened with the aid of a custom-made test facility. Subsequently, the specimens are tested quasi-statically under external pressure until collapse in a pressure vessel. Unreeled specimens were also tested to complete the database for calibrating the numerical model. The numerical model is finally used to generate collapse envelopes of reeled and unreeled pipes with different geometry and material.

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.

scholarly journals COLLAPSE PRESSURE ESTIMATES AND THE APPLICATION OF A PARTIAL SAFETY FACTOR TO CYLINDERS SUBJECTED TO EXTERNAL PRESSURE

2010 ◽  
Vol 42 (4) ◽  
pp. 450-459 ◽  
Author(s):  
Yeon-Sik Yoo ◽  
Nam-Su Huh ◽  
Suhn Choi ◽  
Tae-Wan Kim ◽  
Jong-In Kim
Keyword(s):  
Safety Factor ◽  
External Pressure ◽  
Collapse Pressure ◽  
Partial Safety Factor

Collapse Failure Analysis of Subsea Corroded Pipeline Under Combined External Pressure and Axial Force

2020 ◽  
Author(s):  
Yanfei Chen ◽  
Guoyan He ◽  
Shaohua Dong ◽  
Fuheng Hou ◽  
Shang Ma ◽  
...  
Keyword(s):  
Axial Force ◽  
External Pressure ◽  
Combined Loading ◽  
Engineering Practice ◽  
Regression Equations ◽  
Collapse Pressure ◽  
Corrosion Depth ◽  
Integrity Assessment ◽  
Collapse Failure ◽  
Subsea Pipelines

Abstract The subsea pipelines are usually located in a corrosive external and internal environment. Corrosion presents to be the most common defect type in subsea pipelines, and it is regarded to be one of the main causes of subsea pipeline failure. Due to subsea subsidence, mudslides, and seismic activities, the pipeline is presented under combined external pressure, bending moments and axial force combined loading cases. The accurate determination of the collapse pressure of corroded pipelines under combined loading is important in engineering practice. On the basis of the finite element method, collapse failure of subsea corroded pipelines under combined loads is investigated. The influence of corrosion length, corrosion width, corrosion depth and diameter-thick ratio on the collapse failure pressure is studied. It is observed that corrosion depth has the most significant impact on pipelines’ collapse capacity. Furthermore, regression equations for predicting the collapse pressure of subsea corroded pipelines are proposed based on numerical results. The solution can be referred to in structural integrity assessment of subsea corroded pipelines.

Simplified Finite Element Models to Study the Wet Collapse of Straight and Curved Flexible Pipes

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Alfredo Gay Neto ◽  
Clóvis de Arruda Martins ◽  
Eduardo Ribeiro Malta ◽  
Rafael Loureiro Tanaka ◽  
Carlos Alberto Ferreira Godinho
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
3D Models ◽  
External Pressure ◽  
Finite Element Models ◽  
Flexible Pipe ◽  
Collapse Pressure ◽  
Flexible Pipes ◽  
Polymeric Layer ◽  
Collapse Failure

When the external sheath of flexible pipes experiences damage, seawater floods the annulus. Then, the external pressure is applied directly on the internal polymeric layer, and the load is transferred to the interlocked carcass, the innermost layer. In this situation, the so-called wet collapse failure of the interlocked carcass can occur. Simplified methodologies to address such a scenario, using restricted three-dimensional (3D) finite element models, are presented in this work. They are compared with full 3D models, studying both straight and curved flexible pipes scenarios. The curvature of the flexible pipe is shown to be important for wet collapse pressure predictions.

Assessment of Recent Experimental Data on Collapse Capacity of UOE Pipeline

2012 ◽  
Author(s):  
Erica Marley ◽  
Olav Aamlid ◽  
Leif Collberg
Keyword(s):  
Deep Water ◽  
External Pressure ◽  
Recent Experimental Data ◽  
Safety Factors ◽  
Governing Parameter ◽  
Collapse Pressure ◽  
Capacity Model ◽  
Water Pipelines ◽  
Offshore Industry ◽  
Water Depths

Recent developments in the offshore industry are resulting in an increasing demand for deep water pipelines. At greater water depths, the external pressure will be the governing parameter for wall thickness design, and the failure mode is collapse. DNV’s reliability based standard, DNV-OS-F101, uses the collapse capacity model and corresponding safety factors calibrated in the SUPERB Joint Industry Project, finalized in the mid 1990’s. Since then, a vast amount of research on collapse capacity of deep water pipelines is performed, indicating that it is time to re-visit the design equation and safety factors currently in use. This paper firstly summarizes the relevant collapse pressure equations for pipeline design. Secondly, the major points related to collapse capacity in SUPERB and DNV-OS-F101 are presented. Furthermore, results from an assessment of newer collapse tests of pipelines are described. Focus is on larger (UOE) pipes with D/t ratios less than 25, corresponding to water depths beyond 1000 m. The test results are compared to the outcome of earlier experimental projects. A difference between older and more recent tests is observed, with the newer having a considerably higher collapse capacity. Finally, a calibration of safety factors is performed, compared to existing factors and discussed.

Computer Optimizing of Bevel Angles for Welded Pipe Joints

1986 ◽  
Vol 2 (01) ◽  
pp. 18-22 ◽  
Author(s):  
H. W. Mergler
Keyword(s):  
Direct Relationship ◽  
Considerable Reduction ◽  
Pipe Joints ◽  
Welded Pipe ◽  
Weld Area ◽  
Pipe Joint

There is a direct relationship between pipe joint welding times and applied weld volume. This paper gives the computations necessary to define the locus for the branch saddle as a function of certain variables and of the optimized bevel angle. Joint configurations were studied for weld area variations for both fixed and optimized bevel angle configurations. Results demonstrated a considerable reduction in weld volume when the optimized volume was compared with the volume obtained using a fixed bevel angle.

Pipe Joint Management for Risers and Pipelines

2021 ◽  
Author(s):  
Ghiath (Guy) Mansour
Keyword(s):  
Fatigue Strength ◽  
Stress Concentration ◽  
Software Development ◽  
Wall Thickness ◽  
Stress Concentration Factor ◽  
Concentration Factor ◽  
Joint Management ◽  
Pipe Joints ◽  
Best Fit ◽  
Pipe Joint

Abstract Minimizing the stress concentration factor (SCF) in pipe joint welding subjected to fatigue is a major concern. Machining the joint ends is one way to achieve this. However, this adds cost, time, risk of potential crack starters, and loss of wall thickness which is detrimental for fatigue, strength, and engineering criticality assessment (ECA) in particular. Pipe joint sorting (certain joints in sequence) and end matching (rotating the pipe joints for best fit) are other ways. However, this adds time, costly logistics, risk of errors, and does not guarantee the minimum possible SCF is achieved. In a typical project, more pipe joints are procured than required in order to mitigate contingencies. For pipelines, this overage is typically a percentage of the required number of joints or pipeline length. For risers, typically double the required number of joints is procured where half of the joints is sent offshore for installation and the remaining half is kept onshore for a spare riser. Then, it becomes very important to send for installation the best pipe joints that produce the best (lowest) SCFs out of the entire batch of pipe joints. This requires calculating the SCF for every potential match of any random joints to be welded together, and then choosing the best joints. Performing such calculations by spreadsheet is not feasible considering the tremendous number of required iterations and calculations. A pipe joint management software development is presented herein which accomplishes this task and examples provided to illustrate the benefits. Note: Selecting pipe joints with the best end measurements, whether ID, OD, OOR, or thickness does not guarantee that the minimum possible SCFs will be achieved since the SCF is a function of all those measurements.

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