Henderson Hoops: A New System for Marine Growth Inhibition on Offshore Tubulars

Polypropylene hoops encircling the tubulars of offshore structures are used to inhibit marine growth through their rotation which is induced by the action of current on flaps with a hinged connection to the hoop. Axial motion occurs naturally for inclined and horizontal tubulars in tidal flow and requires an extra vane attachment for vertical tubulars. Controlled tests in the marine environment suggest that the concept is nearly completely effective. The final design for the device which is being mass-produced is described.

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ISSC Technical Committee I.1 Environment

Volume 2: Structures, Safety and Reliability; Petroleum Technology Symposium ◽

10.1115/omae2007-29770 ◽

2007 ◽

Author(s):

Bruce L. Hutchison

Keyword(s):

Climate Change ◽

Marine Environment ◽

Rogue Waves ◽

Offshore Structures ◽

Technical Committee ◽

Environmental Data ◽

Offshore Structure ◽

Parametric Roll ◽

Modeling And Analysis ◽

The Past

This paper presents highlights of the report of the 16th International Ship and Offshore Structure Congress (ISSC) I.1 Environment Committee presented in August 2006 in Southampton, UK. Subjects addressed include notable accomplishments in the study of the marine environment pertinent to the design and operation of ships and offshore structures. These include advances in the past three years with respect to sensing, modeling and analysis of environmental data, discussion of rogue waves, climate change and parametric roll, and recommendations for further research.

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Structural Analysis of Rigid High-Pressure Risers for Seismic Loads

10.4043/31299-ms ◽

2021 ◽

Author(s):

Mahesh Sonawane ◽

Rohit Vaidya ◽

Hunter Haeberle

Keyword(s):

High Pressure ◽

Offshore Structures ◽

Mitigation Strategies ◽

Seismic Loads ◽

Wave Loading ◽

Design Data ◽

Final Design ◽

Design Loads ◽

Offshore Risers ◽

Low Probability

Abstract Typically, the design of all offshore risers focuses on environmental loads i.e. wave loading, wind loads and currents. While these loads are ubiquitous in an offshore environment, accidental loading in the form earthquake induced seismic loads is an important criterion in the design of offshore structures. API RP 2A recommends site-speciﬁc studies as a basis for developing the ground motion speciﬁcation of the design criteria, particularly for sites in areas of high seismicity (Zones 3–5). Seismic loads are low probability events in most cases and there isn't enough data in the initial pre-FEED / FEED phase of project to conduct seismic studies on the riser systems. Designers have to rely on past experience, code guidance, and assumptions for design data. In this paper through the means of two (2) case studies for a region prone with high seismic activities, we will demonstrate the challenges of designing rigid High-Pressure Riser Systems for seismic loads. A comparison will be provided for assumed loads based on code guidance and loads derived from preliminary seismic studies. In addition, comparisons will be provided for the final design loads achieved after the detailed platform design. The results will show the risks of relying solely on one source of data in the design process that can imperil the fabrication / procurement process with redesign due to unforeseen loads. Design optimization through proper centralization and other mitigation strategies will be presented for the benefits of future concrete based fixed platform projects.

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Design, Analysis, and Development of a Wave-Current Laboratory

Volume 6A: Ocean Engineering ◽

10.1115/omae2020-19253 ◽

2020 ◽

Author(s):

Nhu Nguyen ◽

Jacob Davis ◽

Ahmed Alshuwaykh ◽

Krish Thiagarajan Sharman

Keyword(s):

Guide Vane ◽

Offshore Structures ◽

Maximum Height ◽

Flow Uniformity ◽

Marine Energy ◽

Final Design ◽

S Period ◽

University Of Massachusetts ◽

Current Loading ◽

Flow Nonuniformity

Abstract In real ocean environments, offshore structures are exposed to a combination of wave and current loading conditions. This scenario presents the need to study fluid-structure interactions in the presence of both conditions, achievable through experimentation in a recirculating flume coupled with a wavemaker. The Ocean Resources and Renewable Energy (ORRE) group set out to design a recirculating wave-current flume at the University of Massachusetts Amherst to enable the study of technologies such as scale floating platforms and marine energy converters. In this paper, we present the methods used to arrive at an optimal flume design under strict spatial constraints posed by the available lab space. Limitations on the length, width, and height of flume are overcome via innovative flow designs and compact structures. The final design is approximately 11.5 m (37.7 ft) in length and 1.2 m (3.9 ft) wide with a nominal water depth of 1 m (3.3 ft). The 2 m long test section begins 6 m beyond the inlet of the flume to maximize flow uniformity. A 24” thruster driven by 75 hp electric motor maintains a current velocity of 0.5 m/s throughout the section while a wedge-shape plunger is implemented at the inlet to generate 0.6–2.8 s period waves with a maximum height of 0.2 m. During the design process, 2D computational fluid dynamics (CFD) simulations are employed to maximize flow uniformity over a range of inlet angles and guide vane configurations. In the optimal scenario, a flow nonuniformity of 8.7 % was obtained across a 0.7 m water column measured from the free surface. Results from the 3D simulation around the tight corner section showed significant increase in flow nonuniformity. The implementation of the screens along the flow path might be necessary in the future.

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Design of an Evaluative Tool for a Multi-Station Injection Molding System Using an Evolutionary Algorithm

Volume 3: 6th Design for Manufacturing Conference ◽

10.1115/detc2001/dfm-21187 ◽

2001 ◽

Author(s):

A. R. Wolf ◽

L. H. Shu ◽

R. D. Venter

Keyword(s):

Injection Molding ◽

Evolutionary Algorithm ◽

Evaluation Process ◽

Product Variety ◽

Algorithm Optimization ◽

Molding System ◽

Final Design ◽

Design Requirements ◽

System Variables ◽

New System

Abstract A tool to facilitate the feasibility study of a newly proposed multi-station injection molding system is developed. The conceptual design and proposed embodiment of the new system are geared toward the development of a system flexible enough to handle multiple part types and production volumes. A comprehensive design model is used to structure the problem by identifying the desired design objectives and the effect the system variables have on the final design. An Evolutionary Algorithm optimization is used to find the combination of system variables that yields optimal system outputs. The algorithm uses a number of components customized to suit the design requirements of the proposed system. This optimization and evaluation process provides a basis by which the new system can be compared with traditional injection molding practices. Results confirm that the new multi-station system is less affected by the degree of product variety than traditional molding machines.

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Selection and Characterization of Packaged FBG Sensors for Offshore Applications

Sensors ◽

10.3390/s18113963 ◽

2018 ◽

Vol 18 (11) ◽

pp. 3963 ◽

Cited By ~ 5

Author(s):

Lei Wu ◽

Muneesh Maheshwari ◽

Yaowen Yang ◽

Wensheng Xiao

Keyword(s):

Marine Environment ◽

Heavy Rain ◽

Offshore Structures ◽

Good Repeatability ◽

Fbg Sensors ◽

Long Term Performance ◽

Term Performance ◽

Term Monitoring

With the development in the exploitation of maritime resources, the structural health monitoring (SHM) of offshore structures becomes necessary. This study focuses on addressing the practical issues of application of fiber Bragg grating (FBG) sensors for the SHM of offshore structures, in particular an FPSO (floating, production, storage, and offloading unit) vessel. Due to the harsh marine environment and tough working conditions, the FBG sensors must have sufficient protection and good repeatability for long-term monitoring. Thorough research has been conducted to identify the most suitable, commercially available protection packaging for FBG sensors for offshore applications. Further, the performance of the selected FBG sensor packaging is tested under conditions of strong sunlight, heavy rain, and salty water in order to emulate the marine environment. Moreover, the installation method of the packaged FBG sensors is equally important, as it ensures the repeatability and durability of the sensors for their long-term performance. It is shown that the packaged FBG sensors can be installed using resin-based epoxy to maintain the repeatability of the sensor over the long-term. Further, the packaged FBG sensors are installed and tested on a simple FPSO model. The experimental results under full load and ballast draft conditions show that the proposed FBG sensors are competent for the SHM of offshore structures.

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