Analysis of Clump-Weight Interference With Offshore Pipelines: Mechanisms and Actions

2016 ◽  
Author(s):  
Hagbart S. Alsos ◽  
Åsta O. Wendel ◽  
Stig Olav Kvarme ◽  
Svein Sævik
Keyword(s):  
Contact Friction ◽  
System Of Equations ◽  
Offshore Pipelines ◽  
Design Load ◽  
Offshore Pipeline ◽  
Design Loads ◽  
Pipeline Model ◽  
Cost Aspect ◽  
Diameter Effect

The article addresses challenges and actions from interference between trawl gear and offshore pipelines. Interaction from twin trawlers and their clump weights presents a particular challenge for offshore pipelines, especially in free-spans. The design loads are typically derived from DNV-RP-F111 and are of such magnitude that protection by rock installation is often required. This is especially the case for small and medium sized diameter pipelines, and has an obvious cost aspect tied to it. The paper investigates the detailed behavior of clump weights interfering with pipelines by breaking down the kinematics of the clump weight and its interaction with an offshore pipeline to a set of differential equations. The system of equations is solved numerically and verified with tests. Next, the response of the clump weight and pipeline is assessed for various parametric variations. This involves assessing the sensitivity of the response for variations such as: interaction with free spans versus flat seabed, effect of varying the pipeline diameter, effect of contact friction, effect of trawl drag and warp line stiffness, effect of clump weight rigging, and the effect of lateral dragging resistance of the pipeline. Finally, the clump weight response solver is applied in case study to provide the trawl pullover design load for an FE pipeline model. The response and consequence for the pipeline is then finally compared with the equivalent scenario generated from the DNV-RP-F111 design pullover load.

The Implementation of Biological Phosphorus and Nitrogen Removal with the Bio-Denipho Process on a 265,000 PE Treatment Plant

1992 ◽  
Vol 25 (4-5) ◽  
pp. 161-168 ◽  
Author(s):  
J. Einfeldt
Keyword(s):  
Nitrogen Removal ◽  
Treatment Plant ◽  
First Year ◽  
In Series ◽  
Design Loads ◽  
Last Stage ◽  
Two Stages ◽  
The City ◽  
Biological Phosphorus

A process, called Bio-Denipho, for combined biological phosphorus and nitrogen removal in a combination of an anaerobic tank and two oxidation ditches is described. In this process the anaerobic tank consisting of three sections working in series is followed by two oxidation ditches. These too are working in series, but with both inlet to and outlet from the tanks changing in a cycle. The Bio-Denipho process is described specifically for the process itself and as a case study for the implementation of the process on a 265,000 pe wastewater treatment plant for the city of Aalborg in Denmark. The plant was designed and erected in two stages and the last stage was inaugurated October 31,1989. Lay-out and functions for the plant is described and design loads, plan lay-out and tank volumes are given in this paper together with performance data for the first year in operation.

Tangguh Project: Multidisciplinary and Challenging Design of a Novel Concept of Buckle Initiator

2021 ◽  
Author(s):  
Formentini Federico ◽  
Luigi Foschi ◽  
Filippo Guidi ◽  
Ester Iannucci ◽  
Lorenzo Marchionni ◽  
...  
Keyword(s):  
Soil Liquefaction ◽  
Operating Conditions ◽  
Contributing Factors ◽  
Operating Life ◽  
Foundation Design ◽  
Production Pipeline ◽  
Offshore Pipeline ◽  
Design Loads ◽  
Pipeline Route ◽  
Novel Concept

Abstract This paper is based on the experience made during the design and installation of an offshore pipeline recently completed in Indonesia, where a 24” subsea production pipeline (16km long in 70m water depth) was found susceptible during design to lateral buckling. To limit the development of excessive deformation within the acceptance criteria, a mitigation strategy based on interacting planned buckles has been adopted installing three Buckle Initiators (BI) along the pipeline route. Buckling is a well understood phenomenon. However, this project was characterized by major uncertainties mainly driven by soil characterization, soil-pipe interaction, seabed mobility and soil liquefaction. These uncertainties have played a key role in the in-service buckling design. A lot of engineering efforts have been spent to go through the screening between alternative concepts, the validation of the chosen solution and its detailed engineering phase. This paper discusses the main contributing factors and how the uncertainties have been tackled. The Buckle Initiators are quite large and heavy structures with two main bars: the first ramp has an inclination equal to 30° and the pipeline has been laid on it; a second horizontal ramp was used as sleeper to accommodate the development of the lateral buckle during the operating life. A rotating arm was also used to restrict the pipeline lay corridor on the inclined ramp guaranteeing a combined horizontal and vertical out-of-straightness in the as-laid configuration. The rotating arm has been released as soon as the pipeline passed the BI permitting the pipeline to slide freely over the two BI ramps. The foundation of the Buckle Initiator has a footprint surface of about 60m2 guaranteeing its stability for different soil types characterizing the three installation areas. This more complex solution was preferred with respect to a typical sleeper to increase the robustness of the system in terms of buckle mobilization. The design of the Buckle Initiator was a multidisciplinary activity where many novel concepts were developed and many issues were faced (i.e. pipeline laying on an inclined sleeper, anti-scouring system, foundation design, etc.). The Buckle Initiator design was focused on structural calculations against design loads expected during temporary and operating conditions, geotechnical verifications, installation analysis, pipeline configuration and fatigue assessment. This paper presents all main engineering aspects faced during design and first feedbacks from field after the pipeline installation.

Local Buckling in end Expansion of Subsea Pipelines

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Jaswar Koto ◽  
Abd. Khair Junaidi ◽  
M. H. Hashim
Keyword(s):  
Crude Oil ◽  
Axial Force ◽  
Oil And Gas ◽  
Local Buckling ◽  
Offshore Platform ◽  
Offshore Pipeline ◽  
Specific Rule ◽  
Subsea Pipelines ◽  
Study Development

Offshore pipeline is mainly to transport crude oil and gas from offshore to onshore. It is also used to transport crude oil and gas from well to offshore platform and from platform to another platform. The crude oil and gas horizontally flows on the seabed, and then vertically flows inside the riser to the offshore platform. One of current issues of the oil and gas transportation system is an end expansion caused by the axial force. If the end expansion occurs over it limit can cause overstress to riser. This paper explores the effect of axial force toward local buckling in end expansion. In the study, development of programming in visual basic 2010 firstly was constructed using empirical equation. The programming code, then, was validated by comparing simulation result with actual data from company. As case study, the end expansion for various thicknesses of pipes was simulated. In this programming, DNV regulation is included for checking either design complied or not with regulation. However, DNV regulation doesn’t have specific rule regarding the end expansion but it is evaluated under load displacement control under strain condition.

Field Performance and Analysis of 3-m-Diameter Induced Trench Culvert under a 19.4-m Soil Cover

2008 ◽  
Vol 2045 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Bethanie A. Parker ◽  
Rodney P. McAffee ◽  
Arun J. Valsangkar
Keyword(s):  
Pressure Distribution ◽  
Earth Pressure ◽  
Field Performance ◽  
Overburden Pressure ◽  
Vertical Pressure ◽  
Earth Pressures ◽  
Design Loads ◽  
Horizontal Pressure ◽  
Two Stages

An induced trench installation was instrumented to monitor earth pressures and settlements during construction. Some of the unique features of this case study are as follows: (a) both contact and earth pressure cells were used; (b) part of the culvert is under a new embankment and part was installed in a wide trench within an existing embankment; (c) a large stockpile was temporarily placed over the induced trench; and (d) the compressible material was placed in two stages. The maximum vertical pressure measured in the field at the crown of the culvert was 0.24 times the overburden pressure. The maximum horizontal pressure measured on the side of the culvert at the springline was 0.45 times the overburden pressure. The column of soil directly above the compressible zone settled approximately 40% more than did the adjacent fill. The field results at the crown and springline compared reasonably with those observed with numerical modeling. However, the overall pressure distribution on the pipe was expected to be nonuniform, the average vertical pressure calculated by using numerical analysis on top of the culvert over its full width was 0.61 times the overburden pressure, and the average horizontal pressure calculated on the side of the culvert over its full height was 0.44 times the overburden pressure. When the full pressure distribution on the pipe is considered, the recommended design loads from the Marston–Spangler theory slightly underpredict the maximum loads, and the vertical loads control the design.

scholarly journals Predicting the change of hydraulic loads on bridges: a case study in Italy with a 100-year database

2019 ◽  
Author(s):  
Alessandro Pucci ◽  
Hélder S. Sousa ◽  
José C. Matos
Keyword(s):  
Climate Change ◽  
Climatic Variability ◽  
Value Theory ◽  
Peak Discharge ◽  
Greenhouse Gasses ◽  
Hydraulic Design ◽  
Design Loads ◽  
Hydrological Cycles ◽  
Existing Bridges

<p>Planet Earth is naturally subject to climatic variability, but over the recent decades extreme deviations have been observed. Climate change, as a manmade-induced process, is mainly due to the increase of greenhouse gasses emission. Global warming consequences drive also to an intensification of hydrological cycles, leading to more frequent and severe precipitations. In parallel, several bridges have collapsed in the last years due to extreme rainfalls. Although the impacts of climate change on built environment do not always present a direct cause-effect relation, analysis on specific parameters (as rain volume) that are inputs in bridge design, can clarify some aspects of this interaction. In this paper, the peak discharge variation of different rivers located in the northwest of Italy, within the last 100 years, is analyzed. A cluster analysis was performed to understand if the hydraulic design loads should be considered with a different intensity if the bridge had been built with reference to an up-to-date database, or if in the last decades, when the majority of these structures were built. The rainfall data was analyzed through classical techniques, such as the frequency-based statistical method, but without the stationary time hypothesis. In this case, the extreme value theory was used for the estimation of intensity-duration curve parameters. By introducing a second-order analysis, where random variables can change over time, an increase-trend of rainfall height was found, and the peak discharge was determined accordingly. The relevant parameters on the case-study area were preliminarily obtained through geographic information systems. The results evidenced that nowadays-floods parameters are significantly different from those of the past, and this behavior is escalated when high return period values are assumed. Furthermore, although hydraulic design loads are increasing, many existing bridges are not properly maintained, leading to an increased number of collapses.</p>

Qualification of UOE SAWL Linepipes With Enhanced Collapse Resistance for Ultra Deepwater Applications

2013 ◽  
Author(s):  
Fábio Arroyo ◽  
Rafael F. Solano ◽  
Luciano Mantovano ◽  
Fábio B. de Azevedo ◽  
Hélio Alves ◽  
...  
Keyword(s):  
New Technology ◽  
Large Diameter ◽  
Final Analysis ◽  
Load Testing ◽  
Offshore Pipelines ◽  
Cold Forming ◽  
Collapse Resistance ◽  
Offshore Pipeline ◽  
Key Factor ◽  
Combine Load

Large diameter UOE pipes are being increasingly used for the construction of offshore pipelines. 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. It is known that the cold forming, and the final expansion in the UOE linepipe manufacturing process, reduces the elastic limit of the steel in subsequent compression. Due to this, the DNV collapse formula includes a fabrication factor that derates 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. This paper presents the qualification of UOE pipes with enhanced collapse capacity focusing the use of a fabrication factor (αfab) equal to 1. TenarisConfab has performed a technology qualification process according to DNV-RP-A203 standard “Qualification Procedures for New Technology”. The main aspects of the qualification process are presented in this paper which included significant material and full scale testing, including combine load testing, and final analysis. The qualification process achieved successful results and this will allow 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.

Calculation of Arrival Intensity of Ridges Accounting for the Relative Angle Between Ridge Direction and Ice Drift Direction

2009 ◽  
Author(s):  
Jenny Trumars ◽  
Sveinung Lo̸set
Keyword(s):  
Arrival Rate ◽  
Relative Angle ◽  
Design Load ◽  
Ice Drift ◽  
Sea Ice Drift ◽  
Design Loads ◽  
A Site ◽  
Drift Direction ◽  
Load Conditions ◽  
Arrival Intensity

The purpose of the study is to investigate the effect of the relative angle between ice ridges and sea ice drift directions on the arrival rate of ridges. The arrival rate is of importance both for estimating the load conditions at a site and for possible ice management connected to the operation. If the number of encounters increases, the probability of encounter of an extreme ice feature and load increases. A Monte Carlo simulation has been made to calculate the ridge arrival intensity for input formulated as distributions. In probabilistic calculations of design loads today the average arrival intensity is used and the ridge directions are assumed to be uniformly distributed. The implications of accounting for the varying arrival intensity due to the distribution of the relative direction of ridges to velocity on the design load are discussed.

Design Load Analysis for Wave Energy Converters

2018 ◽  
Author(s):  
Jennifer van Rij ◽  
Yi-Hsiang Yu ◽  
Ryan G. Coe
Keyword(s):  
Wave Energy ◽  
Design Guidelines ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Stage Design ◽  
Design Load ◽  
Wave Energy Converters ◽  
Order Of Magnitude ◽  
Design Loads ◽  
Computationally Intensive

This study demonstrates a systematic methodology for establishing the design loads of a wave energy converter. The proposed design load methodology incorporates existing design guidelines, where they exist, and follows a typical design progression; namely, advancing from many, quick, order-of-magnitude accurate, conceptual stage design computations to a few, computationally intensive, high-fidelity, design validation simulations. The goal of the study is to streamline and document this process based on quantitative evaluations of the design loads’ accuracy at each design step and consideration for the computational efficiency of the entire design process. For the wave energy converter, loads, and site conditions considered, this study demonstrates an efficient and accurate methodology of evaluating the design loads.

Combined Effects of Waves and Currents on Offshore Pipeline Bundles

2007 ◽  
Author(s):  
M. H. Kamarudin ◽  
K. P. Thiagarajan ◽  
A. Czajko
Keyword(s):  
Flow Behavior ◽  
Hydrodynamic Characteristics ◽  
Equivalent Diameter ◽  
Offshore Pipelines ◽  
Main Pipe ◽  
Offshore Pipeline ◽  
Waves And Currents ◽  
Industry Practice ◽  
Computational Fluid Dynamics Cfd ◽  
The Stability

It is common practice to accompany offshore pipelines by smaller diameter service lines or umbilicals to create a bundle. This gives rise to the so-called piggyback configuration. The flow behavior around the bundle is not well-known, leading to concerns on the stability of the configuration. This paper investigates the influence of the piggyback on the hydrodynamic loadings on the bundle in wave plus current condition using Computational Fluid Dynamics (CFD). Key parameters of the configuration that were investigated were the orientation of the smaller pipe with respect to the main pipeline and the flow conditions (different Keulegan-Carpenter numbers). The gap between the seabed and the main pipe was set to zero for all cases investigated. It was found that the hydrodynamic characteristics of the main pipe were significantly influenced by the presence of the piggyback. The numerical results also showed that the orientation of the piggyback plays an essential role in determining the drag, lift and inertia coefficients for the bundle. This phenomenon is explained by examining the vortex flow patterns around the cylinders. It is shown that the established industry practice of assuming the hydrodynamic characteristics of the bundle to be the same as an equivalent diameter cylinder may underestimate the forces on the bundle, and lead to a non-conservative design.

Business Risk Management Applied to Offshore Pipeline Field Development

2010 ◽  
Author(s):  
Lihua Gan
Keyword(s):  
Risk Management ◽  
Oil And Gas ◽  
Business Risk ◽  
Offshore Pipelines ◽  
Field Development ◽  
Class Project ◽  
Offshore Pipeline ◽  
World Class ◽  
The Cost ◽  
Production Facilities

A world class project must have a disciplined business risk management. As a good project manager, he should manage project risk successfully. Through business risk management, he can identify risk of the project, find the cause of all business risks, then define the influence of all risks. He can take measures to avoid, transfer, and mitigate the risk. A field development includes production facilities, risers and pipelines and subsea wells, in which the pipelines and risers connect the subsea wells and production facilities to transfer oil and gas. The cost of offshore pipelines and risers is major. In the following we shall take offshore pipeline and riser as a case study to practice the principal of business risk management step by step. It has been demonstrated that the method may be applied to maximize the returning for the stakeholders in an offshore field development. However, it is suggested to accumulate and update the data bases required for an accurate statistical evaluation.

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