Viscoelastic Behaviour of Bitumen in Dynamic Control Umbilicals

2014 ◽  
Author(s):  
Elise Olsen ◽  
Kay André Hansen-Zahl ◽  
Stian Karlsen
Keyword(s):  
Cross Section ◽  
Oil And Gas ◽  
Steel Wire ◽  
Optical Signal ◽  
Galvanized Steel ◽  
Offshore Platforms ◽  
Force Transmission ◽  
Steel Wires ◽  
Friction Factors ◽  
Section Analysis

By combination of elements like hydraulic tubes, electrical and optical signal cables and electrical power cables, umbilicals provide remote control of subsea oil and gas wells. For extra tensile strength and outer protection the umbilicals may be armoured by galvanized steel wires. Dynamic umbilicals are terminated at offshore platforms or vessels. They are exposed to tension and bending variations caused by waves and vessel motions. As such a project specific analysis is normally required to verify that a given dynamic umbilical design with all its elements is able to withstand a service life of typically 20–30 years [5]. Understanding how forces are transmitted between the elements in an umbilical is vital for correct calculation of a dynamic umbilical design life. Cross section analysis is therefore performed by a finite element method program specially designed for this purpose. This software takes into account all effects in an umbilical cross section, including friction between elements. For solid elements, commonly known friction factors may be applied. However, for the steel wire armour which is corrosion protected by bitumen, the friction factors may not be valid. The force transmission between the steel wires may not be governed by friction but by the viscoelastic properties of bitumen. In such a case the transition force is not only a function of contact pressure but also of sliding velocity and dimensions. A project was therefore initiated with the aim of describing such force transmission between bitumen and steel wires for typical umbilical conditions. Material testing has included characterization by a controlled stress rheometer and cyclic tensile testing at various temperatures, speeds and geometries. On basis of these tests, a calculation model describing the mechanical behavior of bitumen in cyclic movement is suggested. This model may later be implemented in the umbilical cross section analysis program.

Influence of Carbon Content on the Mechanical Properties of Ultra-high Strength of Coated Steel Wire

2014 ◽  
Vol 69 (1) ◽  
Author(s):  
Cho Myung Hyun ◽  
Suhaimi Salleh ◽  
Norhayati Ahmad ◽  
Ali Ourdjini ◽  
Esah Hamzah
Keyword(s):  
Tensile Strength ◽  
Carbon Content ◽  
Coating Layer ◽  
Steel Wire ◽  
Cold Work ◽  
Zinc Coating ◽  
High Strength ◽  
Galvanized Steel ◽  
Steel Wires ◽  
Torsion Deformation

Ultra-high strength of steel wire for offshore mooring lines can be achieved by increasing carbon content, addition of alloying elements and increasing cold work. The influence of carbon content and zinc coating on the tensile strength and torsion deformation have been investigated for drawn and hot dip galvanized steel wires at various drawing strain. In this work, experiments were conducted to increase the tensile strength of hyper-eutectoid steel wires by increasing carbon content from 0.87%wt to 0.98%wt. The samples with various diameter was drawn to their final diameter, then hot dip galvanized at 460ᵒC in a zinc bath to improve the anti-corrosion property. Torsion deformation has been investigated by twisting the drawn steel wires to different number of revolutions. Fractured samples after torsion test were analysed by optical and Field Emision Scaning Electron Microscope. The results showed that by increasing carbon content up to 0.98%wt (sample D) at drawing strain of 1.97 greatly increased the tensile strength up to 2338 MPa. However, delamination occurred at the zinc coating layer at strength exceeding 2250 MPa and the maximum limit of tensile strength of 0.92% C (sample D) is 2026 MPa without delamination. The effect of zinc coating layer on torsion degradation also revealed that the zinc alloy layer had a significant effect on delamination in the hot dip coating which associated with the higher carbon and silicon content (sample B) in the steel wires.

Determination of Friction Within a Riser Umbilical

2012 ◽  
Author(s):  
Elise Olsen ◽  
Stian Karlsen ◽  
Lars Jordal ◽  
Kay A. Hansen-Zahl
Keyword(s):  
Oil And Gas ◽  
Electrical Power ◽  
Optical Signal ◽  
Offshore Platforms ◽  
Friction Coefficients ◽  
Friction Forces ◽  
Friction Testing ◽  
The Individual ◽  
Contact Pressures

By combination of elements like hydraulic tubes, electrical and optical signal cables and electrical power cables, umbilicals provide remote control of subsea oil and gas wells. Riser umbilical’s are terminated at offshore platforms or vessels, and will be exposed to tension and bending variations caused by waves and vessel motions. Understanding how forces are transmitted between the elements in an umbilical is vital for correct calculation of the umbilical design life. When umbilicals are exposed to tension and bending, tension will be imposed in the individual elements. The magnitude of tension is governed by the overall tension and bending and also by the lay angles, placement in the cross section and the friction forces between the elements. Some friction coefficients may be found in literature, but not all material combinations, and not for the conditions inside an umbilical. A project was therefore initiated with the aim of developing a friction testing device capable of determining friction coefficients between all elements in environments that are representative for the conditions within an umbilical, i.e.: at various temperatures; in sinusoidal movements, like the bending movements in an umbilical; at representative contact pressures, speeds and temperatures; in various environments, like air and seawater; without crumpling soft elements like synthetic tapes.

Development of Cylinder Type Concrete FPSO With Tangerine-Shaped Cross-Section

2018 ◽  
Author(s):  
Jae-Young Cho ◽  
Jong-Heon Park ◽  
Jung J. Kim
Keyword(s):  
Cross Section ◽  
Optimization Design ◽  
Oil And Gas ◽  
Tensile Force ◽  
Concrete Structures ◽  
Oil And Gas Industry ◽  
Sensitivity Study ◽  
Offshore Platforms ◽  
Exterior Wall ◽  
Shaped Cross Section

Concrete platforms have proven to be a viable offshore solution for deep-water projects according to the documented performance of over 40 years [1]. Since concrete has resistance to seawater corrosion, reduced maintenance costs and motions, concrete structures have become attractive to the offshore oil and gas industry [2, 3]. There are many floating concrete structures such as barge, ship, platform and LNG/LPG terminals. While most concrete offshore platforms are the fixed structures, floating concrete platforms have been used for drilling, extraction /storage and production units for oil and gas including heavy lifter. There are two representative floating concrete facilities on the Norwegian shelf, Troll B and Heidrun A [4, 5]. Troll B is the first concrete semi-submersible product unit and Heidrun A is the floating concrete tension leg platform. The concrete FPSO (Floating Production Storage and Offloading), however, was assessed to be inferior to the steel FPSO in respect of feasibility. In this study, an optimization design of the cross-section for cylinder shaped concrete platform is presented in order to promote the feasibility of a concrete hull for an FPSO. Optimal aspect ratio (depth to diameter) with economic analysis is examined and tangerine-shaped section which can utilize the excellent material properties of the concrete in compressive strength is developed. Exterior wall having a small curvature are applied to transmit the load to interior bulkhead. A parametric sensitivity study was conducted to find the optimal curvature of the exterior wall. Subsequently, an arch-shaped wall is applied to center wall in order to improve the upper and lower tension force caused by bending moment. The tendon was placed in the center of any cross-section, taking into account the tensile force that can be caused by additional asymmetric loads. The effect of tangerine shaped cross-section can be clearly identified by comparing the results with the circular shaped cross-section.

Effect of environmental factors on electrochemical corrosion of galvanized steel wires for bridge cables

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Rou Li ◽  
Changqing Miao ◽  
Tinghua Wei
Keyword(s):  
Corrosion Rate ◽  
Ph Value ◽  
Steel Wire ◽  
Pure Water ◽  
Electrochemical Corrosion ◽  
Polarization Curves ◽  
Galvanized Steel ◽  
Content Type ◽  
Steel Wires ◽  
Relationship Of

Purpose This paper aims to investigate the electrochemical corrosion rate of galvanized steel wires for bridge cables. Design/methodology/approach The electrochemical corrosion test and response surface analysis of galvanized steel wires were carried out, and the variety of polarization curves of galvanized steel wires under different corrosion parameters was discussed. The expression of corrosion rate of galvanized steel wires under the action of single and multi-factor coupling was established. Findings The polarization curves of galvanized steel wires under different Cl- concentrations, pH value and temperature were basically similar, but all show different degrees of deviation and some anodic polarization curves had inflection points. For example, when the Cl- concentration reached 3.5%, the corrosion rate of galvanized steel wire was four times that of pure water. Originality/value The influence relationship of single and multi-factor coupling on the corrosion rate of galvanized steel wires was as follows: RCl > RT * Cl > RT > RpH > RpH * T > RpH * Cl.

Lifetime prediction of aramid yarns applied to offshore mooring due to purely hydrolytic degradation

2019 ◽  
Vol 27 (8) ◽  
pp. 518-524
Author(s):  
Juliano Picanço Duarte ◽  
Carlos Eduardo Marcos Guilherme ◽  
Antonio Henrique Monteiro Fonseca T da Silva ◽  
Adriano Câmara Mendonça ◽  
Felipe Tempel Stumpf
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Oil And Gas ◽  
Steel Wire ◽  
Hydrolytic Degradation ◽  
Oil And Gas Industry ◽  
Oil Fields ◽  
Offshore Platforms ◽  
Gas Industry ◽  
Service Conditions

The discovery of oil fields in deepwater over the last decades led the oil and gas industry to the necessity of replacing the steel wire cables of the mooring systems of offshore platforms by polymeric ropes. These systems must be designed to work for at least 20 years without showing substantial loss in tensile strength or in their mechanical behavior along this period. However, some polymers present degradation by seawater through the process of hydrolysis, and the question whether it affects significantly the materials’ ultimate tensile strength arises. Accelerated hydrolysis tests were conducted in yarn samples of aramid at high temperature in order to use the Arrhenius correlation to predict their lifetime under service conditions. In order to decouple the total degradation into a thermal and a purely hydrolytic part, separate aging experiments were performed into a dry chamber and the conclusion was that thermal degradation does not play a significant role in the total degradation of aramid due to the water submersion at the temperatures tested.

A method of technical diagnostics for offshore structures

1994 ◽  
Vol 16 (2) ◽  
pp. 43-48
Author(s):  
Do Son
Keyword(s):  
Diagnostic Method ◽  
Joint Venture ◽  
Oil And Gas ◽  
Residual Life ◽  
Life Time ◽  
Offshore Structures ◽  
Technical Diagnostics ◽  
Offshore Platforms ◽  
South Vietnam ◽  
Local Destruction

This paper describes the results of measurements and analysis of the parameters, characterizing technical state of offshore platforms in Vietnam Sea. Based on decreasing in time material characteristics because of corrosion and local destruction assessment on residual life time of platforms is given and variants for its repair are recommended. The results allowed to confirm advantage of proposed technical diagnostic method in comparison with others and have been used for oil and gas platform of Joint Venture "Vietsovpetro" in South Vietnam.

Failure Modes, Reliability Analysis and Case Studies on the Integration of Copper and Low-K Technology

2004 ◽  
Author(s):  
Huixian Wu ◽  
James Cargo ◽  
Huixian Wu ◽  
Marvin White
Keyword(s):  
Failure Analysis ◽  
Case Studies ◽  
Cross Section ◽  
Focused Ion Beam ◽  
Failure Modes ◽  
Ion Beam ◽  
Copper Interconnects ◽  
Wet Chemical ◽  
Low K ◽  
Section Analysis

Abstract The integration of copper interconnects and low-K dielectrics will present novel failure modes and reliability issues to failure analysts. This paper discusses failure modes related to Cu/low-K technology. Here, physical failure analysis (FA) techniques including deprocessing and cross-section analysis have been developed. The deprocessing techniques include wet chemical etching, reactive ion etching, chemical mechanical polishing and a combination of these techniques. Case studies on different failure modes related to Cu/low k technology are discussed: copper voiding, copper extrusion; electromigration stress failure; dielectric cracks; delamination-interface adhesion; and FA on circuit-under-pad. For the cross-section analysis of copper/low-K samples, focused ion beam techniques have been developed. Scanning electron microscopy, EDX, and TEM analytical analysis have been used for failure analysis for Cu/low-K technology. Various failure modes and reliability issues have also been addressed.

Cross Section Analysis of Cu Filled TSVs Based on High Throughput Plasma-FIB Milling

2012 ◽  
Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Electron Backscatter ◽  
Section Surface ◽  
Backscatter Diffraction ◽  
Section Analysis

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.

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