NDLI: Hindcasting VIM-Induced Mooring Fatigue for the Genesis Spar

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	David, W. Smith Thompson, H. M. Kokkinis, T. Greiner, W. L.
Copyright Year	2004
Abstract	A number of spars are being installed in deepwater areas in the Gulf of Mexico (GoM) which are subject to loop / eddy current conditions and require that their mooring system be designed for Vortex Induced Motion (VIM). This paper presents insights into fatigue and wear issues for mooring systems of spars subject to VIM, and illustrates the importance of reassessing industry practices for mooring strength and fatigue design for mooring systems that must resist VIM. During the GoM Millennium Eddy Current Event in April 2001, the ChevronTexaco Genesis spar platform, which is installed in Green Canyon Block 205 in the GoM, underwent VIM which was greater than anticipated during the original design of the mooring and riser systems. A key part of developing a permanent solution for ensuring integrity in future large VIM events was the assessment of fatigue and wear damage accumulated in past VIM events, for the purpose of ensuring fitness of the components of the mooring system for future service. The main elements of this assessment were: (a) The hindcast of the mooring line tensions from measured platform motions. (b) The evaluation of stress concentration on the mooring chain in the fairleads. (c) The assessment of fatigue damage for high amplitude/low cycle conditions, and (d) The assessment of accumulated wear. The results of this fatigue assessment led to a decision to replace the fairlead chain segments on 4 of the 14 mooring legs of Genesis, in order to ensure that they would have adequate fatigue endurance under the Stepped Line Tensioning (SLT) solution developed to mitigate the risk of VIM of the spar in the future. The project team’s unique understanding of mooring system response under VIM and resulting mooring component fatigue and wear issues led to the development of novel fatigue and wear hindcasting procedures that allowed the project to reliably assess the remaining life of the mooring components, and make decisions to selectively replace some of the components to ensure integrity for the remaining life of the platform under the SLT solution.
Sponsorship	Ocean, Offshore, and Arctic Engineering Division
Starting Page	1005
Ending Page	1014
Page Count	10
File Format	PDF
ISBN	0791837432
DOI	10.1115/OMAE2004-51547
e-ISBN	0791837386
Volume Number	23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 1, Parts A and B
Conference Proceedings	ASME 2004 23rd International Conference on Offshore Mechanics and Arctic Engineering
Language	English
Publisher Date	2004-06-20
Publisher Place	Vancouver, British Columbia, Canada
Access Restriction	Subscribed
Subject Keyword	Chain Cycles Stress concentration Eddy currents (electricity) Mooring Fatigue design Fatigue Risk Spar platforms Design Pipeline risers Gulf of mexico Wear Vortices Eddies (fluid dynamics) Damage Risers (casting) Wing spars Fatigue damage
Content Type	Text
Resource Type	Article

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in