Large Diameter Deepwater Gas Pipelines Subjected to Global Buckling Behavior

2019 ◽  
Author(s):  
Bruno R. Antunes ◽  
Rafael F. Solano ◽  
Carlos O. Cardoso
Keyword(s):  
Structural Integrity ◽  
High Pressures ◽  
Large Diameter ◽  
Hydrate Formation ◽  
Gas Pipelines ◽  
Production Flow ◽  
Buckling Behavior ◽  
Production Platform ◽  
Global Buckling ◽  
Made In

Abstract In general, gas export pipeline designs have low restrictions concerning the flow assurance requirements, i. e., hydrate formation is not a great concern once processes in production platform facilities can significantly decrease the water content in the gas to be exported. Thus, these pipelines have only a small thickness of a single or multilayer anticorrosive coating and export gas at low temperatures. However, high pressures are required in order to overcome long distances and to increase the production flow rates. Large diameter gas pipelines submitted to high pressures even with low associated temperatures can be susceptible to global buckling, mainly if the pipelines are simply rested on a seabed of low resistance. This scenario characterizes strictly the gas pipelines installed in Brazilian Pre-Salt fields, where currently a relevant amount of export lines is operating in these conditions. Post-installation and operating pipeline surveys have identified marks on seabed confirming the buckle formation in some gas pipelines. In addition, axial movements of end equipment (PLETs) have been also observed. These issues require at least a verification and confirmation of the assumptions and predictions made in detailed design phase. This paper aims to present evaluations of the global buckling behavior of large diameter deepwater gas pipelines. Lateral buckles on very soft clayey seabed and displacements in ends and crossing locations are addressed in this work. Finally, numerical analyses confirm that gas pipelines structural integrity has not been jeopardized.

Lateral Buckling Behaviour of Snake-Lay Pipeline With Vertical Support at Crown

2013 ◽  
Author(s):  
N. Raveendra Reddy
Keyword(s):  
Structural Integrity ◽  
High Pressures ◽  
Large Diameter ◽  
Compressive Force ◽  
Mitigation Measures ◽  
Potential Hazard ◽  
Lateral Buckling ◽  
Axial Compressive Force ◽  
Euler Buckling ◽  
Reliable Solution

Most hydrocarbon pipelines installed recently in the Middle East operate at relatively high pressures and temperatures: maximum inlet operating temperatures >90°C and pressures >135 barg. These pipelines are susceptible to Euler buckling from high axial compressive force induced in the pipeline by the temperature and pressure. Any uncontrolled lateral buckling is a potential hazard for a pipeline’s structural integrity, especially when all compressive force is released at one point and excessive feed-in occurs. Possible mitigation measures include lateral restraint by rock dumping or trenching, or midline spools. Another possibility is to induce the pipeline to buckle in a controlled manner, perhaps at several locations, rather than allowing it to suffer an uncontrolled, large buckle at one location only. This is known as buckle initiation. “Snake-lay” and “Vertical Imperfection” are two methods that have been implemented successfully to initiate controlled buckling. “Buoyancy” is another method, but is yet to be implemented. Snake-lay is a relatively reliable solution but, depending on pipe-soil interaction, sometimes requires a very short radius to initiate the buckle. Installing large diameter pipelines with short radii may invite other problems such as pipeline instability during laying, or may require additional counteracting measures to maintain the specified lay radius. The lay radius can be increased with additional sleepers at the crown of the snake-lay, with a well-defined low friction factor between the pipeline and the support. This paper discusses the behavior of snake-lay pipeline with and without vertical sleeper supports at the crown of the pipeline, and demonstrates what effects supporting the pipeline at the crown will have on the buckling mechanism and the pipeline integrity.

Design of crack arrestors for ultra high grade gas transmission pipelines: simulation of crack initiation, propagation and arrest

2011 ◽  
Vol 2 (2) ◽  
pp. 307-319
Author(s):  
F. Van den Abeele ◽  
M. Di Biagio ◽  
L. Amlung
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Large Scale ◽  
Large Diameter ◽  
Pipe Material ◽  
High Grade ◽  
Gas Pipelines ◽  
Ductile Crack ◽  
Reinforced Plastics ◽  
Four Point Bending

One of the major challenges in the design of ultra high grade (X100) gas pipelines is the identification of areliable crack propagation strategy. Recent research results have shown that the newly developed highstrength and large diameter gas pipelines, when operated at severe conditions, may not be able to arrest arunning ductile crack through pipe material properties. Hence, the use of crack arrestors is required in thedesign of safe and reliable pipeline systems.A conventional crack arrestor can be a high toughness pipe insert, or a local joint with higher wall thickness.According to experimental results of full-scale burst tests, composite crack arrestors are one of the mostpromising technologies. Such crack arrestors are made of fibre reinforced plastics which provide the pipewith an additional hoop constraint. In this paper, numerical tools to simulate crack initiation, propagationand arrest in composite crack arrestors are introduced.First, the in-use behaviour of composite crack arrestors is evaluated by means of large scale tensile testsand four point bending experiments. The ability of different stress based orthotropic failure measures topredict the onset of material degradation is compared. Then, computational fracture mechanics is applied tosimulate ductile crack propagation in high pressure gas pipelines, and the corresponding crack growth inthe composite arrestor. The combination of numerical simulation and experimental research allows derivingdesign guidelines for composite crack arrestors.

The Design, Development and Validation of an Innovative High Strength, Self Monitoring, Composite Pipe Liner for the Restoration of Energy Transmission Pipelines

2006 ◽  
Author(s):  
Kyle Bethel ◽  
Steven C. Catha ◽  
Melvin F. Kanninen ◽  
Randall B. Stonesifer ◽  
Ken Charbonneau ◽  
...  
Keyword(s):  
High Pressures ◽  
Large Diameter ◽  
Cylindrical Tube ◽  
High Strength ◽  
Design Development ◽  
Energy Transmission ◽  
Engineering Research ◽  
Wide Range ◽  
Transmission Pipelines

The research described in this paper centers on a composite of thermoplastic materials that can be inserted in a degraded steel pipe to completely restore its strength. Through the use of fabrics consisting of ultra high strength fibers that are co-helically wrapped over a thin walled thermoplastic cylindrical tube that serves as a core, arbitrarily high pressures can be achieved. This paper first outlines the design, manufacturing and installation procedures developed for this unique material to provide a context for the engineering research. Based on this outline, the technological basis that has been developed for assuring the strength and long term durability of this concept during its insertion, and in its very long term service as a liner in energy transmission pipelines, is presented in detail. The research that is described includes burst testing of the material in stand alone pipe form, load/elongation testing of ultra high strength fabrics, and linear and nonlinear elastic and viscoelastic analysis models. This body of work indicates that the concept is fundamentally feasible for restoring a wide range of large diameter natural gas and liquid transmission pipelines to be able to carry arbitrarily high pressures over very long lifetimes. It also indicates that liners can be safely installed in long lengths even in lines with severe bends in a continuous manner. With further research the concept has the potential for eliminating hydro testing and smart pigging during service, and could possibly be installed in some lines that are currently unpiggable.

Pressure Test Planning to Prevent Internal Corrosion by Residual Fluids

2012 ◽  
Author(s):  
Trevor Place ◽  
Greg Sasaki ◽  
Colin Cathrea ◽  
Michael Holm
Keyword(s):  
Structural Integrity ◽  
Large Diameter ◽  
Long Distance ◽  
Internal Corrosion ◽  
Pressure Testing ◽  
Practical Strategy ◽  
Leak Testing ◽  
Pressure Test ◽  
Transmission Pipeline ◽  
Pipeline Project

Strength and leak testing (AKA ‘hydrotesting’, and ‘pressure testing’) of pipeline projects remains a primary method of providing quality assurance on new pipeline construction, and for validating structural integrity of the as-built pipeline [1][2][3]. A myriad of regulations surround these activities to ensure soundness of the pipeline, security of the environment during and after the pressure testing operation, as well as personnel safety during these activities. CAN/CSA Z662-11 now includes important clauses to ensure that the pipeline designer/builder/operator consider the potential corrosive impacts of the pressure test media [4]. This paper briefly discusses some of the standard approaches used in the pipeline industry to address internal corrosion caused by pressure test mediums — which often vary according to the scope of the pipeline project (small versus large diameter, short versus very long pipelines) — as well as the rationale behind these different approaches. Case studies are presented to highlight the importance of considering pressure test medium corrosiveness. A practical strategy addressing the needs of long-distance transmission pipeline operators, involving a post-hydrotest inhibitor rinse, is presented.

scholarly journals Ethyl alcohol, a product of high pressure syntheses

1931 ◽  
Vol 131 (818) ◽  
pp. 533-540 ◽  
Keyword(s):  
High Pressure ◽  
Ethyl Alcohol ◽  
Personal Experience ◽  
High Pressures ◽  
Catalytic Reactions ◽  
Chemical Research ◽  
Chemical Research Laboratory ◽  
Pressure Synthesis ◽  
Corroborative Evidence ◽  
Made In

In opening the “discussion on catalytic reactions at high pressures,” one of us (G. T. M.) referred to experiments made in the Chemical Research Laboratory of the Department of Scientific and Industrial Research which had led to the isolation of notable quantities of ethyl alcohol among the condensation products from carbon monoxide and hydrogen interacting at high temperatures and pressures in presence of catalysts. These experiments were first described in March, 1928, and since that date statements have appeared in the scientific press to the effect that ethyl alcohol is a possible exception to the whole sequence of higher alcohols which can be produced by such interactions. Moreover during the above-mentioned discussion Mr. M. P. Appleby, speaking on behalf of the Imperial Chemical Industries, Ltd., Billingham, said “that in our experience we have never succeeded in obtaining, with any catalyst whatsoever, more than a mere trace of ethyl alcohol.” To the latter statement we take no exception whatever. It is a record of personal experience. But we felt that it was desirable to substantiate our earlier experiments by such corroborative evidence as would leave no doubt that ethyl alcohol is a product of high pressure synthesis.

A Justification for Designing and Operating Pipelines Up to Stresses of 80% SMYS

2002 ◽  
Author(s):  
Martin McLamb ◽  
Phil Hopkins ◽  
Mark Marley ◽  
Maher Nessim
Keyword(s):  
Yield Strength ◽  
Oil And Gas ◽  
Large Diameter ◽  
Pipe Material ◽  
Gas Pipelines ◽  
Long Distance ◽  
Remote Locations ◽  
Pass Through ◽  
The Impact ◽  
Minimum Yield

Oil and gas majors are interested in several projects worldwide involving large diameter, long distance gas pipelines that pass through remote locations. Consequently, the majors are investigating the feasibility of operating pipelines of this type at stress levels up to and including 80% of the specified minimum yield strength (SMYS) of the pipe material. This paper summarises a study to investigate the impact upon safety, reliability and integrity of designing and operating pipelines to stresses up to 80% SMYS.

GBT FORMULATION TO ANALYZE THE BUCKLING BEHAVIOR OF THIN-WALLED MEMBERS SUBJECTED TO NON-UNIFORM BENDING

2007 ◽  
Vol 07 (01) ◽  
pp. 23-54 ◽  
Author(s):  
RUI BEBIANO ◽  
NUNO SILVESTRE ◽  
DINAR CAMOTIM
Keyword(s):  
Finite Element ◽  
Major Axis ◽  
Shear Stresses ◽  
Longitudinal Stress ◽  
Stress Gradients ◽  
Stiffness Reduction ◽  
Buckling Behavior ◽  
Global Buckling ◽  
Thin Walled ◽  
Uniformly Distributed Loads

In this paper, one investigates the local-plate, distortional and global buckling behavior of thin-walled steel beams subjected to non-uniform bending moment diagrams, i.e. under the presence of longitudinal stress gradients. One begins by deriving a novel formulation based on Generalized Beam Theory (GBT), which (i) can handle beams with arbitrary open cross-sections and (ii) incorporates all the effects stemming from the presence of longitudinally varying stress distributions. This formulation is numerically implemented by means of the finite element method: one (i) develops a GBT-based beam finite element, which accounts for the stiffness reduction associated to applied longitudinal stresses with linear, quadratic and cubic variation, as well as to the ensuing shear stresses, and (ii) addresses the derivation of the equilibrium equation system that needs to be solved in the context of a GBT buckling analysis. Then, in order to illustrate the application and capabilities of the proposed GBT-based formulation and finite element implementation, one presents and discusses numerical results concerning (i) rectangular plates under longitudinally varying stresses and pure shear, (ii) I-section cantilevers subjected to uniform major axis bending, tip point loads and uniformly distributed loads, and (iii) simply supported lipped channel beams subjected to uniform major axis bending, mid-span point loads and uniformly distributed loads — by taking full advantage of the GBT modal nature, one is able to acquire an in-depth understanding on the influence of the longitudinal stress gradients and shear stresses on the beam local and global buckling behavior. For validation purposes, the GBT results are compared with values either (i) yielded by shell finite element analyses, performed in the code ANSYS, or (ii) reported in the literature. Finally, the computational efficiency of the proposed GBT-based beam finite element is briefly assessed.

Investigating the dynamics of gas hydrates in a gas dominant flow loop

2011 ◽  
Vol 51 (2) ◽  
pp. 734
Author(s):  
Yutaek Seo ◽  
Mauricio Di Lorenzo ◽  
Gerardo Sanchez-Soto
Keyword(s):  
Steady State ◽  
Gas Hydrates ◽  
Gas Hydrate ◽  
Gas Flow ◽  
Transient Flow ◽  
Hydrate Formation ◽  
Hydrodynamic Condition ◽  
Gas Pipelines ◽  
Flow Loop ◽  
Offshore Pipelines

Offshore pipelines transporting hydrocarbon fluids have to be operated with great care to avoid problems related to flow assurance. Of these possible problems, gas hydrate is dreaded as it poses the greatest risk of plugging offshore pipelines and other production systems. As the search for oil and natural gas goes into deeper and colder offshore fields, the strategies for gas hydrate mitigation are evolving to the management of hydrate risks rather than costly complete prevention. CSIRO has been developing technologies that will facilitate the production of Australian deepwater gas reserves. One of its research programs is a recently commissioned investigation into the dynamic behaviour of gas hydrates in gas pipelines using a pilot-scale 1 inch and 40 m long flow loop. This work will provide experimental results conducted in the flow loop, designed to investigate the hydrate formation characteristics in steady state and transient flow. For a given hydrodynamic condition in steady state flow, the formation and subsequent agglomeration and deposition of hydrate particles appear to occur more severely as the subcooling condition is increasing. Transient flow during a shut-in and restart operation represents a more complex scenario for hydrate formation. Although hydrates develop as a thin layer on the surface of water during the shut-in period, most of the water is quickly converted to hydrate upon restart, forming hydrate laden slurry that is transported through the pipeline by the gas flow. These results could provide valuable insights into the present operation of offshore gas pipelines.

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