Lessons Learned From Deepwater-Spool Design on Aasta Hansteen

2015 ◽  
Author(s):  
Tore Jacobsen ◽  
Kristian Norland ◽  
Venkatapathi Tharigopula
Keyword(s):  
Bending Moment ◽  
Optimization Methods ◽  
Fe Analysis ◽  
Lessons Learned ◽  
Design Criteria ◽  
Design Code ◽  
Straight Pipe ◽  
Linear Finite Element ◽  
Reaction Forces ◽  
Pipeline Design

Spools are frequently used to tie-in pipelines to subsea structures with the purpose of absorbing expansions at the pipeline end, in addition to the connection between pipeline and structure. Deepwater rigid spools have to be designed to accommodate expansion movements resulting from high product temperatures, low strength soils and phenomena such as pipe walking. They also have to accommodate spool fabrication and installation tolerances. These requirements drive the spool geometry and can lead to complex spool geometries that are difficult to install. The design code usually used for spool analysis is DNV-OS-F-101 [1] which is a primary design code for pipeline design. While using this design code for straight-linepipe and bends, careful considerations should be made because the bends tend to behave different from a straight pipe. Especially the ovality response under in-plane bending is of interest for establishment of a design criteria. The most accurate way to establish this design criteria is by utilising a 3-D non-linear finite element (FE) analysis. The bending moment at failure should be compared with the corresponding bending moment under design conditions. By using FE analyses, more flexible spool can be designed giving lower reaction forces and moments. In addition there are other design-optimization methods to reduce the required spool size and complexity which are further described in this paper. The present paper shows the reduction in wall thickness that is possible through design by analyses. The spool design process is also outlined, and a comparison made on different spool size optimization concepts.

Design criteria for steel I columns under axial load and biaxial bending

1976 ◽  
Vol 3 (3) ◽  
pp. 466-473
Author(s):  
D. A. Ross ◽  
W. F. Chen
Keyword(s):  
Ultimate Strength ◽  
Axial Load ◽  
Bending Moment ◽  
Design Criteria ◽  
Biaxial Bending ◽  
Design Code ◽  
Simple Modification ◽  
Strength Design ◽  
Depth Ratio

The design code, Canadian Standard S16.1-1974, permits ultimate strength design steel H columns subjected to axial load and biaxial bending moment. However, this is permitted only for sections in which the flange width to section depth ratio is equal to or greater than 0.8. In this paper a simple modification to the previous formulas is proposed which enables the restriction on flange width to section depth ratio to be removed so that they are also applicable to steel I columns.

Greater Plutonio Riser Tower Installation: Studies and Lessons Learnt

2009 ◽  
Author(s):  
Charles-Alexandre Zimmermann ◽  
Guilhem Layrisse ◽  
Daniel de la Cruz ◽  
Jeremy Gordonnat
Keyword(s):  
Water Depth ◽  
Bending Moment ◽  
Lessons Learned ◽  
Field Development ◽  
System A ◽  
Analysis Methodology ◽  
Lessons Learnt ◽  
Future Improvement ◽  
Tower System

The BP operated Greater Plutonio field development offshore Angola comprises a spread-moored FPSO in 1,300 m water depth, serving as a hub processing the fluids produced from or injected into the subsea wells. The selected riser system is a Hybrid Riser Tower comprising 11 risers bundled around a central structural tubular (Core Pipe), tensioned by a steel Buoyancy Tank at its top and maintained by an anchor base at its bottom. The Riser Tower is fabricated onshore and then towed to the field for final installation in deepwater near the FPSO. Once the Riser Tower installation is completed the risers are connected to the FPSO by means of flexible jumpers and to the flowlines by means of rigid spools. All fabrication and installation work has been performed by Acergy. This paper presents the studies performed to cover all the steps of the installation phase: build-up of the Orcaflex model, miscellaneous studies to determine model and analyses parameters, towing analysis, upending analysis, Buoyancy Tank ballasting and deballasting analyses, and contingency analyses. This paper is mainly focused on the Riser Tower installation but also covers the installation of the Riser Tower anchor and of the flexible jumpers in order to give a complete overview of the operations related to the Riser Tower system. A comparison between computed data and data measured during operations is also presented to support the overall installation analysis methodology. Lessons learned are provided for future improvement of Riser Tower installation covering main challenges such as Riser Tower modeling, weight/buoyancy repartition along the Riser Tower, Buoyancy Tank ballasting adjustment in Lobito bay, fatigue issues during surface and subsurface tow, bending moment issues during upending, etc.

Role of Constraint in Specimen Geometries When Evaluating Fracture Toughness/Material Fracture Resistance for a Surface-Flawed Elbow

2019 ◽  
Author(s):  
S. Kalyanam ◽  
G. Wilkowski ◽  
F. W. Brust ◽  
Y. Hioe ◽  
E. Punch
Keyword(s):  
Surface Crack ◽  
State Of The Art ◽  
Crack Depth ◽  
Bending Moment ◽  
Compact Tension ◽  
Fe Analysis ◽  
Significant Finding ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Variable Surface

Abstract The fracture behavior of a circumferential surface crack in an elbow was evaluated using past data from the International Piping Integrity Research Group (IPIRG-2) Experiment 2-4. The elbow tested was nominal 16-inch diameter Schedule 100 TP304 material, which was solution-annealed after final fabrication. The elbow was loaded with an in-plane-closing bending moment and internal pressure of 15.51 MPa (2,250 psig) at 288 C (550 F). The surface crack was 180-degrees on the ID surface and centered on the extrados, but after fatigue precracking the depth was variable and the greatest was at about 45-degrees from the extrados. FE analysis of the IPIRG-2 elbow test was conducted with a state-of-the-art and precise 3D FE mesh (including variable surface crack depth, variable thickness, and initial elbow ovalization). The flaw depth for the single-edge notch tension (SENT) tests was selected to be equivalent to the deepest point in the elbow specimen crack front that provided the largest J-value in the elbow experiment, i.e., ao/W = 0.68. Comparison of the J-value for initiation (Ji) and crack-tip-opening displacement (CTODi) at crack initiation suggested that there was a slight difference in constraint between an identical depth SENT specimen (a/W = 0.68 with the same L-R orientation as the surface crack in the pipe) and an elbow with a circumferential surface crack (a/t = 0.68) [Ji was 0.368 MN/m, (2.1 ksi-inch) in the SENT tests, while it was 0.490 MN-m (2.8 ksi-inch) in the elbow test]. The more significant finding in this work was that the compact tension (C(T)) test Ji-value was much higher at 1.086 MN/m (6.2 ksi-inch) or ∼3 times higher. The elbow to SENT to C(T) specimen comparison illustrates very large differences in constraint between these geometries. From past work by several researchers it was determined that the constraint in C(T) specimens gives Ji-values that agree well with a circumferential through-wall crack in a straight pipe, but this difference with surface-cracked elbow or pipe is envisaged to be new information to the international research community. Additionally, from state-of-the-art FE analysis of the 180-degree surface-cracked elbow test it was found that the maximum J-value occurs at a position that was about 45-degree away from the extrados location. This trend showed that caution should be exercised when selecting the crack locations for elbow integrity evaluation, since for shorter flaw lengths it may be more critical to consider a crack that is closer to the 45-degrees from the extrados, which could be true for fracture as well as stress corrosion cracking (SCC) elbow evaluations.

Fitness-for-Purpose Assessment of Encirclement Split-Tees

2002 ◽  
Author(s):  
S. Wheat ◽  
C. S. Jandu ◽  
D. N. Bramley ◽  
J. H. Liu
Keyword(s):  
High Pressure ◽  
Design Criteria ◽  
Plastic Collapse ◽  
Fitness For Purpose ◽  
Design Code ◽  
Gas Industry ◽  
Fatigue Design ◽  
The Uk ◽  
Transmission Pipelines

Hot tap tees of the full encirclement split tee design are currently used in the UK gas industry to provide connections onto existing high pressure gas transmission pipelines and above ground installations. The fitness-for-purpose of this type of tee is not covered by the UK design code for above ground gas installations, IGE/TD/9. A fitness-for-purpose methodology has been developed by Advantica Technologies to determine the integrity of the fitting and attachment welds. The fitness-for-purpose assessment addresses the following: • The compliance of the fitting to plastic collapse, shakedown and fatigue design criteria. • The integrity of the attachment welds onto the carrier pipe. • The use of Engineering Critical Assessments in conjunction with existing procedures to ensure overall integrity.

Limit Load Interaction of Welded Piping Branch Junctions Subjected to Combined Internal Pressure and Bending

2005 ◽  
Vol 297-300 ◽  
pp. 685-690 ◽  
Author(s):  
Fu Zhen Xuan ◽  
Pei Ning Li ◽  
Shan Tung Tu
Keyword(s):  
Parabolic Equation ◽  
Internal Pressure ◽  
Small Diameter ◽  
Limit Load ◽  
Fe Analysis ◽  
Diameter Ratio ◽  
Linear Finite Element ◽  
The Individual ◽  
Linear Expression ◽  
Parameter Influence

Systematic detailed non-linear finite element (FE) analysis are described for limit load interaction of piping branch junctions subjected to internal pressure and bending. The results show that for the tees with a small diameter ratio, the limit load interaction closes to the linear expression; as diameter ratio d/D increasing, the interaction relationship tends to parabolic equation; for the piping branch junction with diameter ratio equaling to unit, the limit load combinations is approximately quadratic. Compared to the individual limit bending value, internal pressure slightly increases the bending capability as it is in the range of 0.2£P/PL£0.4, especially for the cases of the main pipe with thinner wall. A closed limit load solution is obtained from the FE results through accommodating the geometrical parameter influence, and validated by using experimental results.

Differential Equation for Evaluating Transverse Buckling Behavior of Tensile Armour Wires

2014 ◽  
Author(s):  
Svein Sævik ◽  
Guomin Ji
Keyword(s):  
Differential Equation ◽  
Numerical Study ◽  
Failure Criteria ◽  
Fe Analysis ◽  
Design Criteria ◽  
Transverse Tensile ◽  
Flexible Pipes ◽  
Buckling Behavior ◽  
Transverse Stability ◽  
Bending Behaviour

The present paper addresses aspects related to transverse tensile armour buckling in flexible pipes. An analytical model for evaluating the tensile armour buckling capacity is presented based on formulating the linearised differential equation describing the transverse stability of the thin curved wire assuming no friction. This is followed by a numerical study based on FE analysis to evaluate the extra capacity from friction during cyclic bending behaviour and where the yield stress is used as the failure criteria. The results is then compared to test data and a design criteria for transverse tensile armour buckling proposed.

Assessment of precast stringer highway bridges using mean load method

2006 ◽  
Vol 33 (11) ◽  
pp. 1359-1367 ◽  
Author(s):  
Daman K Panesar ◽  
F Michael Bartlett
Keyword(s):  
Bending Moment ◽  
Highway Bridges ◽  
Design Code ◽  
Reliability Indices ◽  
Dynamic Load Allowance ◽  
Bridge Approach ◽  
Specific Factors ◽  
The Mean ◽  
Axle Loads ◽  
Critical Sections

The mean load method of the Canadian Highway Bridge Design Code is used to evaluate the shear and bending moment reliability of existing precast "type G" stringer bridges in Alberta that date from the late 1950s. The overall stringer population is categorized into distinct subpopulations using bridge-specific factors, including the degree of deterioration and approach span condition, which are readily identified during a brief field visit or from inspection reports. Critical sections to be investigated for reliability resisting shear forces or bending moments are determined. The reliability indices decrease if the reinforcement is corroded or the bridge approach is not smooth, and the reduction of the maximum axle loads permitted by legislation due to these factors is quantified. For bridge subpopulations where the actual reliability index is less than the target value for current legal axle loads, the critical axle load for moment is less than that for shear. Therefore, if flexural distress is not noted during inspection of such structures, they are likely adequate for the actual loading they are subjected to.Key words: corrosion, deterioration, dynamic load allowance, mean load method, reliability, visual inspection.

scholarly journals A New Model for Shaft Design of Engine Using MATLAB-GUI

2021 ◽  
pp. 61-69
Author(s):  
Mahmoud Helal ◽  
Abdulaziz H Alghtani ◽  
Bassem F. Felemban ◽  
Abdullah Alharthi ◽  
Elsayed Fathallah ◽  
...  
Keyword(s):  
Bending Moment ◽  
Design Tool ◽  
Design Parameters ◽  
Matlab Code ◽  
Traditional Design ◽  
Reaction Forces ◽  
Machine Elements ◽  
Design Calculations ◽  
To Receive ◽  
Friendly Graphical User Interface

Shaft design is still has the most significant effect in design of machine elements as shafts are common elements in aircraft engines, gear boxes and mechanisms. In this paper, a MATLAB code is established to obtain the optimum shaft design automatically. A friendly Graphical User Interface (GUI) is developed to receive all design parameters such as; rotational speed, transmitted power, shaft material…etc. the proposed GUI also receives design parameters of shaft components such as pulleys and gears. Two case studies are introduced to illustrate the proposed shaft design tool to confirm its validity. All reaction forces, bending moment diagrams and torque diagrams are obtained using the proposed MATLAB code. These results are consistent with manual traditional design calculations.

scholarly journals Optimization Method for Solving the Reasonable Arch Axis of Long-Span CFST Arch Bridges

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Xuesong Zhang ◽  
Ningyi Liang ◽  
Xiaohong Lu ◽  
Anbang Gu ◽  
Jidong Shan
Keyword(s):  
Yangtze River ◽  
Spline Interpolation ◽  
Bending Moment ◽  
Optimization Procedure ◽  
Element Model ◽  
Optimization Methods ◽  
Optimization Method ◽  
Steel Tube ◽  
Long Span ◽  
Arch Bridges

With the continuous construction of 500 m concrete-filled steel-tube (CFST) arch bridges such as the Bosideng Yangtze River Bridge and the Hejiang Changjiang Highway Bridge, the deviation between the dead pressure line and the arch axis produced by extant arch axis optimization methods increases. Therefore, an arch axis optimization method for long-span CFST arch bridges with a truss section must be designed. Following the optimization of the truss arch axis, this study develops the minimum section eccentricity method that aims to optimize the arch axis of long-span CFST arch bridges. To minimize the main tube eccentricity of the truss arch, the bending moment of the main tubes is reduced by applying the main tube eccentricity method iteratively in a finite element model. Afterward, a smooth and reasonable arch axis is fitted by applying a cubic spline interpolation function in MATLAB. The entire optimization procedure is performed using the Bosideng Yangtze River Bridge as an example. Compared with that of optimal arch axis line types (e.g., parabola and catenary) and other traditional arch axes, the bending moment of main tubes optimized by the proposed method is substantially lower and more uniformly distributed along the arch axis span. The mechanical properties of the finished bridge, including its strength, stiffness, and stability, are all improved, thereby verifying the feasibility of using the proposed method to optimize the arch axis of CFST arch bridges with a truss section.

Residual Stress of Thin-Wall Pipe Subjected to Axisymmetric Plastic Expansion

2004 ◽  
Vol 126 (3) ◽  
pp. 300-306
Author(s):  
Norimasa Chiba ◽  
Yuji Ishida ◽  
Nagahisa Ogasawara ◽  
Hiroshi Ito ◽  
Kunio Enomoto ◽  
...  
Keyword(s):  
Residual Stress ◽  
Simple Formula ◽  
Plastic Region ◽  
Fe Analysis ◽  
Thin Wall ◽  
Straight Pipe ◽  
Pipe Expansion ◽  
Inner Surface ◽  
Peak Location ◽  
Axisymmetric Plastic

A straight pipe was expanded at one end by inserting a rigid disk. The residual stress measured at the inner surface shows a strong tensile peak beyond the region where the pipe was directly expanded by the insertion of the disk. The reason the residual stress reaches its peak at a location further into the pipe is discussed based on a FE analysis. The residual stress was found to reach its tensile peak at the plastic region front that was developed during the pipe expansion. A simple formula for identifying the tensile peak location is also proposed.

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